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A TEXT-BOOK
OF
(mechanical Engineering.


THE FITTING, MACHINING, AND PATTERN-MAKING DEPARTMENT OF THE ENGINEERING WORKSHOPS,
GOLDSMITHS' ms'g‘wﬂ-EWM ,
W i if i4_—____4d

A TEXT- BOOK
OF 6‘; 42, '7

{mechanical Engineering

BY .,°
WILFRID J?” LINEHAM,
HEAD OF THE ENGINEERING DEPARTMENT
AT THE GoLDsMITHs’ coMPANv's INSTITUTE, NEW cRoss;
LATE PROFESSOR OF ENGINEERING AT THE SCHOOL OF scIENcE AND ART
AND TECHNICAL COLLEGE, NEwcAsTLE-oN-TYNE;
MEMBER OF THE INSTITUTION OF MECHANICAL ENGINEERS;
OF THE NoRTH EAsT coAsT INSTITUTE OF ENGINEERs AND SHIP-BUILDERS;
THE SOCIETY OF ARTS, &c., &c.
PART I.—WORKSHOP PRAcTIcE.
PART II.-—TI-IE0RY AND EXAMPLES.
LONDON: CHAPMAN AND HALL; LIMITED,
AGENTS TO THE ScIENcE AND ART DEPARTMENT.
1894.
ALL RIGHTS RESERVED.
PREFACE.
T is now many years since the initiative of the City and
Guilds of London Institute, in providing an examina-
tion for Mechanical Engineers, ﬁrst suggested to me the
desirability of writing the present text-book. In preparing
students for this examination, I was being constantly asked
for a comprehensive work which would at least show them
the general lines on which their study, as engineer
apprentices, should proceed ; and, in seeking to meet their
request, I had to consider seriously (1) whether the whole
theory and practice of Mechanical Engineering, or even a
pre’cz's of it, could be compressed into one volume, and (2)
whether it was desirable so to compress it. That this work
has here been written is sufficient evidence of my own
solution of the above questions—a solution which has been
fully conﬁrmed by the successful use, in teaching engineer
students, of my chapters during the years of their prepara-
tion. I am perfectly aware that there are many who will
object to any attempt to convey the rationale of practical
processes by description on paper; others may accuse me
of ‘cramming,’ by attempting to condense the theories of
engineering into half a volume. I would earnestly ask all
these gentlemen, before condemning what may seem to
them a too ambitious undertaking, to ﬁrst consider care-
fully the following reasons which appeared to me to
support my decision :——(I) The saving of time to the
student, who need not now be always ‘beginning at the
viii Preﬁzre.
beginning,’ the disadvantage of having to use a series of
small text-books; (2) saving of space, reference being
made when necessary to previous pages, obviating much
needless repetition: and here it may also be noticed that
in a single volume, embracing so vast a subject, ‘padding’
had of necessity to be 122']; (3) the examples of great and
successful writers—to wit, Rankine, Ganot, Deschanel, and
others; (4) the fact that practical processes are now con-
stantly described, with good result, both in the engineering
journals and in the City Guilds’ examination answers.
I shall now explain the order of the chapters, and my
reasons for their arrangement.
Part I. makes the tour of the shops, with the intention
of initiating the student into their mysteries. The usual
method is to ﬁrst describe the tools, after that the general
processes, and then a series of graduated examples of their
application. A separate chapter is reserved for Machine
Tools. In the chapter on Fitting and Erecting, I found
much difﬁculty in selecting suitable examples, the work
being greatly interwoven. I therefore decided on the plan
of describing the constructing of a horizontal engine, thus
including most of the principal difficulties. Similarly, in
the Boiler chapter, I have considered in detail the setting-
out and building of a Marine Boiler. I am conscious that
Part I. is far from exhaustive, but the general method of
ﬁrst taking the castings and forgings, and then following
the work through the shops to its completion, seemed the
proper course to pursue, and I hope will be endorsed.
In Part II. I have treated, I believe, of all the principal
theories and investigations required by the engineering
student. Some one has said that, when designing, the
engineer uses about one part of calculation to six of judg-
ment. No amount of book study can impart the latter
most necessary quality: nothing but years of drawing-office
practice can effectively supply it; but any book should be
Preface. ix
Welcomed which attempts to lay the demon of ‘rule of
thumb,’ the autocrat of even my own apprentice days. To
encourage exactitude and prevent one source of error in
the application of formulae, I commence with a ‘synopsis
of lettering,’ and have here introduced what I believe to be
much needed, the retention of a certain letter wherever
possible solely for one purpose. Though this was not
always entirely practicable, I yet venture to think that
some improvement has been effected. It is unfortunate,
for example, that f stands both for stress and acceleration ;
but at least it need not be adopted both for tons and
pounds. I have, therefore, employed it for tons only.
Again, velocity per minute and per second are better
separately distinguished, as in the text, by the letters
V and 72 respectively.
While never introducing mathematics unnecessarily, I
have stated all the ‘steps’ that space permitted in such
mathematics as have been introduced, and the latter will
be found of but an elementary character, involving only
simple equations, fractions, and the use of tables of sines
and logarithms. The substitution of graphic treatment for
the higher mathematics will, I think, be appreciated by
most students, and, in its application to the investigation
of shaft strength, the methods are believed to be new.
As regards the order of Part II., the Strength of
Materials without doubt comes ﬁrst, to be followed by
Energy and Kinematics; these all assist in the treatment
of Prime Movers worked by gases or liquids. \/Vith the
knowledge acquired from Part I. and his own experience
in the workshop, supplemented by the theory of Part II.,
the student should be able to commence the study of
original design, for he is now in acquaintance both with
what theory directs and the workshop restricts.
Regarding illustrations, Icommenced with the intention
of admitting no highly-shaded _ perspective views, which,
b
x Preface.
showing nothing of interior parts, are only calculated to
confuse the student. Elaborate drawings, of course, ne-
cessitated great labour on my part, as well as considerable
co-operation from makers and the editors of engineering
journals. Such aid has in every case been afforded most
ungrudgingly, and in many cases has exceeded my most
sanguine hopes, both as regards drawings and matter.
The necessity of well-detailed, modern examples, has
always been present to me, and I conﬁdently believe that
such have been supplied. In connection with these, I
would ask the reader to unite with me in thanking the
following ﬁrms and gentlemen who have so kindly helped:
Messrs. the Britannia Company, Colchester.
,, George Booth & Co., Halifax.
,, Joshua Buckton & Co., Leeds.
Mr. john Cochrane, Barrhead, N .B.
Mons. Delamare-Deboutteville, Rouen.
Messrs. the East Ferry Road Engineering Works
Company, Millwall.
The Editors of Engineering, London.
Messrs. Greenwood & Batley, Leeds.
,, Andrew Handyside & Co., Derby.
,, Hulse & Co., Manchester.
,, B. & S. Massey, Manchester.
,, Priestman Bros., Hull.
,, David Rollo & Sons, Liverpool.
,, Samuelson & Co., Banbury.
,, Selig, Sonnenthal & Co., London.
,, James Simpson & Co., Pimlico.
,, Smith, Beacock, and Tannett, Leeds.
,, Smith & Coventry, Manchester.
the Sturtevant Blower Company, Boston
and London.
,, Tangyes Limited, Birmingham.
Preface. xi
Mr. Ralph H. Tweddell, Westminster.
Messrs. Sir J. Whitworth & Co., Manchester.
Mr. Wilson Worsdell, of the NE. Railway.
I have also to thank my assistants at the Goldsmiths’
Institute, Mr. William Ashton and Mr. George T. White,
for much valuable assistance in the correction of proofs,
and Mr. R. W. Weekes for assistance in the matter of
electric transmission. The bulk of the zincographic blocks
(Chaps. VI. to XI. inclusive) have been executed by Messrs.
Leslie Clift & Co., and I am greatly indebted to them for
the pains they have taken in reproducing my drawings.
In conclusion, it is my sincere wish that the book may
prove of real beneﬁt to engineers of every class. In
furtherance of this, I will gladly explain any portion that
may seem abstruse, and shall be greatly obliged by having
any errors pointed out. I must ﬁnally state that I do not
intend the work to be merely an aid to any particular
vexamination, but I have introduced whatever seemed to
me most helpful to those for whom it has been prepared.
WILFRID J. LINEHAM.
Golairmz'z‘lzs’ Insz‘z'tuz‘e, New Cross, SE.

CONTENTS.
PART I.——WORKSHOP PRACTICE.
CHAPTER I.
CASTING AND MOULDING.
Varieties of Cast Iron
The Cupola .
Moulding Sand .
Methods of Moulding
Examples in Greensand
Examples in Loam
Machine Moulding .
Chilled Castings
Malleable Castings .
Brass Founding
Mixtures .
CHAPTER II.
PATTERN MAKING AND CASTING DEsIGN.
Wood used
Pattern Building
Core Boxes and Prints
Wheel Patterns
Striking Boards
Contraction Allowance .
Plate Moulding, Stopping-off, &c.
Crystallisation and Unequal Shrinkage
xiv Contents.
CHAPTER III.
METALLURGY AND PROPERTIES OF MATERIALS.
PAGE
Chemical Elements . . . . . . . . 72
Cast and Wrought Iron . . . . . . . 73
Steel . . . . . . . . . . . 77
Bronzes and Brasses . . . . . . . 84
CHAPTER IV.
SMITHING AND FORGING.
The Hearth . . . . . . . . . 88
Blowers . . . . . . . . . . 90
Tools . . . . . . . . . . 93
Smaller Steam Hammer. . . . . . . 97
Heating and Welding . . . . . . . 100
Examples of Simple Forging . . . . . 1oz
Examples of Heavy Forging and Stamping . . . I 17
Case-Hardening . . . . . . . 124
Tempering . . . . . . . . . 125
The Forge . . . . . . . . . 129
Heavy Steam Hammer . . . . . . . 129
Piled-up or Scrap Forgings . . . . . . 131
Heavy Steel Forging . . . . . . . 133
CHAPTER V.
MACHINE TooLs.
Classiﬁcation . . . . . . . . . 137
General Principles . . . . . ‘. . . 138
Tool Angles . . . . . . . . . 140
The Screw-cutting Lathe . . . . . . 141
Supporting and Driving Lathe Work . . . . 150
Chucks and Toolholders . . . . . . I53
The Break Lathe . . . . . . . . 157
The Boring Machine . . . . . . . 16o
Drilling Machines . . . . . . . . 163
The Planing Machine . . . . . . . 169
The Shaping Machine . . . . . . - I7 I
The Slotting Machine . . . . . . . I73
Contents.
PAGE
The Milling Machine . . . . . . . I74
Milling Cutters . . . . . . . . I77
Machine Vice . . . . . . . . . 182
CHAPTER VI.
MARKING-OFF, MAcHININc, FITTING, AND ERECTING.
The Marker-off’s Tools . . . . . . . 183
The Fitter’s Tools . . . . . . . . I86
Machinist’s Requirements . . . . . . I95
Capstan Lathe . . . . . . . . 2oo
Erector’s Tools . . . . . . . . 202
General Processes . . . . . . . . 209
Application to the parts of a Horizontal Engine . . 215
Regulator Gear . . . . . . . 2I6
Valve Rods . . . . . . . . 226
Eccentrics . . . . . . . . 2 30
Slide Bars and Brackets . . . . . . 232
Crank Shaft Bearings . . . . . . 235
Crank Shaft . . . . . . . . 238
Connecting Rod . . . . . . . 24o
Crosshead and Piston . . . . . . 245
Governor Gear . . . ' , . . . 249
Cylinder and Valves . . . . . . 257
Fly-wheel and Bed Plate. . . . . . 262
Brass Work . . . . . . . . 264
Erecting the Engine . . . . . . 268
Sundry Notes . . . . . . . . . 274
CHAPTER VII.
BOILER MAKING AND PLATE WORK.
Materials . ‘ . . . . . . . . 279
Hand Tools and Hand Processes . . . . . 283
Punching 7/. Drilling . . . . . . . 287
Punching and Shearing Machines . . . . . 289
Plate-edge Planing Machine . . . . . . 294
Bending Rolls . . . . . . . . 297
Flanging Presses . . . . . . - A 300
Drilling Machines . . . . . . . . 303
Hydraulic Riveting Machines . . . . ~ 313
xvi
Contents.
Locomotive Boiler-shop .
Marine Boiler-shop
Ship Yard . . .
Pneumatic Caulker and other Tools
Electric Welding . . . . . .
Description of Boilers: Lancashire, Marine, Locomotive,
Tubulous, and Vertical . . . .
Geometry . .
Setting-out a Marine Boiler
Riveting the Boiler .
Setting-out other Boilers

PAGE
318
319
320
322
327
330
339
342
348
352
PART II.-—THEORY AND EXAMPLES.
Synopsis of Lettering
CHAPTER VIII.
358
STRENGTH OF MATERIALS, STRUCTURES, AND MACHINE
PARTs
Stress, Strain, and Elasticity .
Work Diagram . . . . .
Stress due to Impulsive Load, and to Heat .
Testing Machines .
Intensiﬁer _
Shackles for Specimens .
Strain Measuring .
Stress-strain Diagrams . .
Wohler’s Law and Factor of Safet)
Table of Stresses for Different Materials
Classiﬁcation of Stress~action
Tension Stress-action :—
Ropes, Pipes and Cylinders, Flywheel, Bolts, &c. .
a
Compressive Stress-action
Shear Stress-action :—
Suspension Link, Riveted joints, Cotter Joint,
Shafts, Coupling Bolts, Keys, Springs .
36 I
366
368
369
375
37 3
38 I
385
390
393
394
395
404
405
Contents.
Bending Stress-action and Theory of Beams :—
Neutral Axis and Moment of Resistance
Bending Moment and Shear
Theorem of Three Moments
Examples of Beams
Deﬂection of Beams . . .
Combined Bending and Tension Stress-action
Combined Bending and Compressive Stress-action
Pillars and Struts
Furnace Tubes .
Combined Torsion and Bending
Combined Torsion and Compression
Framed Structures .
CHAPTER IX.
xvi
PAGE
427
428
437
445
446
450
453
455
456
460
461
463
463
ON ENERGY, AND THE TRANsMIssIoN OF PowER To
MACHINES.
Force, Mass, Velocity, and Momentum . .
Energy Forms: Conservation, and Transformation
Transmitters of Power
Simple Machines
Kinematics: Lower Pairing
The Slider Crank Chain _
The Quadric Crank Chain
Higher Pairing . .
Velocity and Acceleration Curves .
Link Work . .
Shafting, Bearings, &c. .
Spur Gearing .
Bevel Gearing. .
Worm and Screw Gearin
Epicyclic Trains
Belt Gearing .
Cotton—rope Gearing
Wire-rope Gearing .
Pitch-chain Gearing .
Compressed-air Transmission
Hydraulic Transmission .
Electric Transmission
Friction and Work Lost .
Friction Gearing
473
476
479
480
485
486
487
488
491
496
501
509
519
520
52 I
526
534
544
545
549
549
555
57I
xviii Conz‘enz‘s.
PAGE
Dynamometers . . . . . . . . 57 5
Efﬁciencies of Machines. . . . . . . 577
Comparison of Transmitters . . . . . . 577
CHAPTER X.
ON HEAT AND HEAT ENGINES.
Dynamical Theory of Heat . . . . . . 581
Transfer of Heat . . . . . . . . 581
Measurement of Heat . . . . . . . 584
Expansion of Gases . . . . . . . 587
Latent Heat . . . . . 591
Saturated and Superheated Steam . . . . . 595
Mechanical Equivalent of Heat . . . . . 599
Internal and External Work . . . . . . 600
Speciﬁc Heats of a Gas . . . . . . . 602
Isothermals and Adiabatics . . . . . . 605
Carnot’s Engine and Reversible Cycle . . . . 608
Losses in Steam Engines . . . . . . 613
Expansion in Cylinder . . . . . . . 615
The Indicator and Indicator Diagrams . . . . 616
Multiple-stage Expansion . . . . . . 621
Combination of Indicator Cards . . . . . 622
General Idea of various Steam Engines. . . . 627
Distribution of Steam: by Cataract . . . . 634
,, ,, by Eccentric . . . . 636
,, by Link Motion. . . . 64o
,, ,, by Radial Gear . . . 642
Governors . . . . . . . . 647 & 655
Variable Expansion-Gear . . . 650
Automatic Expansion-Gear . . . . . . 654
Trip Gears . . . . . . . . . 656
Zeuner’s Valve Diagram. . . . . . . 66o
Ideal Indicator Diagrams for Compound Engines. . 666
Correction of Indicator Diagram for Inertia . . . 673
Curves of Crank Eﬁ'ort . . . . . . . 676
Weight of F ly-wheel . . . . . . . 679
Horizontal Compound Engine . . . . . 681
Triple Expansion Marine Engine . . . . . 685
Condensers . . . . . . . . . 686
Marine Details . . . . . . . . 688
Compound Locomotive . . . . . . . 689
Conlenz‘s.
Tractive Force
Boiler Fittings . . .
Combustion and Forced Draught .
The Gas Engine
Petroleum Engines .
CHAPTER XI.
HYDRAULICS AND HYDRAULIC MACHINES.
Head, Pressure, and Velocity Energy
The jet Pump. . . . . . .
Discharge of Water from Oriﬁces . . . . .
Measurement of Stream Horse-Power by Gauge N otches
Friction in Pipes, and Virtual Slope
Loss by Shock . . . . . . .
Principle of Momentum applied to Water Wheels.
Water Wheels . . . . . .
Turbines . . .
The Centrifugal Pump
The Impulse Ram .
Piston Pumps .
The Pulsometer . . .
The Hydraulic Press . . . . .
The Accumulator and Hydraulic Transmission
Hydraulic Lifts: and Intensiﬁers
Hydraulic Cranes .
Hydraulic Pressure Engines .
xix
PAGE
693
693
696
699
705
7Io
711
711
714
715
716
717
720
723
728
729
730
735
735
736
738
740
742
PLATE
IX.
. Arrangement of an Engineer’s Smithy
II.
III.
IV.
. IO ins. Centres Screw-cutting Gap Lathe
VI.
VII.
VIII.
LIST OF PLATES.
IO cwt. Steam Hammer
Steel-tempering Diagram
5 tons Steam Hammer
T reble-geared, Screw-cutting Break Lathe .
Boring Machine and Engine Combined
Double-geared Drilling Machine .
Planing Machine . . .
. 12 ins. Stroke Shaping Machine .
XI.
XII.
XIII.
XIV.
XV.
XVI.
XVII.
XVIII;
Slotting Machine . . . .
Universal Milling Machine .' . . .
Drilling Machine for Marine Boiler Shells .
Multiple Drilling Machine . . . . . .
Hydraulic Machine Tools for Locomotive Boiler Work
Hydraulic Machine Tools for Marine Boiler Work
Triple-expansion Marine Engines
Compound Express Locomotive .
TO FACE PAGE
90
98
126
686
692
*vrdr-d
. 42.
Hm
. 253.
. 364.
. 368.
. 390.
.391.
- 395-
. 396.
. 404.
. 405.
. 406.
. 407.
. 408.
. 409.
411.
417.
. 419.
ERRATA.
Note to ﬁrst paragraph, ‘ Unwin says : “ Re-melting improves the
strength, but if repeated too long the tensile and transverse strengths
suffer, though the crushing strength and hardness increase.” ’
Second paragraph, remove (3) to keep the tool in the threads when
returning, a very advisable method where possible.
Line 3, read the key-way for the mitre wheel.
Line I , read Table of elastic moduli in lbs.
2 11>
Line 6, reaa’V—ZZ— = F—‘z—s X Aft.
6
. 2
Line 8, read Total mean stress In lbs. = 111’?
2g[_\ @
At bottom, add f9, = new breaking stress in tons per sq. in.
Line 6 from bottom, read = $2; + ~/ f12 -— xS f1
Line 19, read % 1 for steel.
Line 6 from bottom, read safe (load or unit stress)
breaking (load or unit stress)
factor of safety

Line 9 from bottom, read ptons.
Line 3 from bottom, read W : 35'35 tons.
Line 2 from bottom, read W : 2973 tons.
Example 4, for H read 12.
Line 4, read Number of bolts :
_ 7 ptons D2
LIHE 7, read 071 = 55K’ W
Line 7, readr : J69'81 : 8'32 '. t = 9 - 8'32 = ‘68.
Example II, read A wrought-iron suspension-bridge link supports
23,3001bs., &0.
ft (4 x 2613) = 5a, and e = I/Z, = 2,
d1 : 1'32, 20 = 166 x 2 =3'32,
Line 11,f0r ‘5 read 5.
Line 13, read and C = N/(A + "71)3 “ (B 2 d1)2
Lines 3 from top, 9 from bottom, and 3 from bottom, jbr a’ read d1.
Line I, jbr a’ read d1.
Line 3, read cross centres = A/3'75 - 2'25 : 1131;.
7800><22><7><7
read 7X4X8X8
Line 9, read2(I'09) + d1 : 2'18 + (21.
End of line 2, reaa’fb.
Line 5, read e x r1.
'I'l'Dl
ed,
d='66 x 2 : 1'32,
t=-26 x 2: '52.

Line 10 from bottom,
P. 423.
P. 425.
P. 448.
P. 462.
P. 486.
P. 492.
P. 523.
P. 527.
Errata.
Example 20. In shaft A, S = {I —1— Ii, andﬂ : '87f1; in shaft B,
S = 1% + 2, andfz : '7I4f1. d for A 0: P125, and d for
B o: 1'41; or as I : 1i exactly.
For the whole of Example 21, substitute, The angle of torsion of a
round W. I. shaft is to be one degree for every 3 feet of length, and
the maximum stress is to be 8000 lbs. per sq. in. Find the one
diameter to satisfy both conditions.

__afsn>sl 22><2___2_><_8ooo><36 . __ _ .
9 — Cd 7 X 360 '— Io,5oo,ooo x d ' . 1 x I
Line II, read W : iflf—L : 2W = 2'35 t°n$~
. x l X
Line 13, read \/V = 4 [17 L = 4 201; T212 : 3'4 tons.

At bottom, read Equivalent Tm = 5'45 + \/547 = 12‘85, and a’:
1:01.16 __ 3 _12785 X 16 X 7
j}? “— \/ 6 X 22
At bottom, add CB : AB.
Line 18,_ read A new acceleration scale.
: 2'2.
Lines 13 and 14, and line 3 from bottom, read 3-3-5
A x C
B x L
End of line 4 from bottom, read t1.

Bottom line, read
While regretting t/zeir extent, the A ut/zor wishes to point out that
ﬁre above errata, relating principally to Chapter V1111, are caused by
that Chapter leaving been inadvertent/y struck of before the numerical
examples bad received a ﬁnal c/zecb.
T be Reader is advised to maize tlze necessary alterations wit/tin t/ze
rwor a before removing t/zis page.


PART I.

w
\t
MECHANICAL ENGINEERING.

PART I.——WORKSHOP PRACTICE.

CHAPTER I.
CASTING AND MOULDING.
UP to the time of Watt, and even later, a very great deal of
wood was used in engineering structures, even to the extent of
steam pipes, but as ﬂuid pressures became higher, other materials
were sought, and cast iron was the ﬁrst to recommend itself.
Cast Iron is the most crude form of the metal, and is
obtained direct from the blast furnace by the fusing of the ore
with some flux, which varies according to the
nature of the particular ore, sometimes requir-
ing clay, but in this country usually lime. The
molten iron runs down into channels or pigs
and is then called pg iron, while the slag is withdrawn
separately.
Of the pig iron thus formed there are eight commercial
varieties, according to the quality of the ore and the blast used ;
thus, increase of blast and diminution of fuel gives a whiter iron.
8
7 White (silvery,
6
5
4 Mottled. Strong foundry iron.
p16
hard, and
into wrought iron.
strong), for conversion
Commercial numbers.
2 } Grey (soft and weak) for ornamental castings.
I
l0
Composition of Cast Iron.
Most of the impurities disappear in the blast furnace, but
carbon is absorbed from the coke fuel, and the presence of this
carbon, mechanically mixed in the form of graphite, makes the
iron more liquid when molten, but at the same time produces
weakness in the casting. There is never more than ﬁve per cent.
of uncombined carbon, while in the white iron there is almost
none, it being chemically combined, and then actually increases
the strength of the iron.
Table showing chemical composition of the three principal
varieties of pig iron, in percentages :—
Grey. Mottled. White.
Iron ............................ .. 90 '24 .... .. 89 '39 .... .. 8986
Carbon (combined) ...... .. 1 '02 .... .. 1 '79 .... .. 2'46
Graphite (uncombined) .... .. 2‘64 .... .. I II .... .. '87
Silicon ........................ .. 3'06 .... .. 2'17 1'12
Sulphur .................... .. 1 '14 .... . . 1 '48 .... . . 2' 52
Phosphorus ................ .. ‘93 .... .. 1'17 .. '91
Manganese .................. .. '83 . . . '6 .... . . 2'72
99 '86 98 '6 3 I 0046
The Cupola.--The pig iron is re-melted in the foundry in a
kind of small blast furnace called a Cupola. The cupola is re-lit
every day (and is therefore not so economical as a blast furnace,
where the ﬁre is never allowed to die out),* but this cannot be
avoided on account of the intermittent demand made upon it.
Fig. I is such a cupola, where the pigs and coke are raised by
the lift H L, hydraulic or otherwise, together with the man, who,
after breaking each pig in three, puts them all in at the door D,
charging as follows :---First, 7 cwts. of coke, next 1 ton of iron;
then, alternately, 2 cwts. of coke and 1 ton of iron, until the
cupola is ﬁlled to D. The blast enters at B, and the mouth M is
stopped with luting clay. When all the iron is melted M is tapped,
and the metal taken away in ladles to the moulds.
During re-melting the iron is again apt to absorb impurities
from the fuel, such as oxides and silicates, the latter especially
producing more brittle material, and rendering the iron cold-short,
that is, easily snapped when cold. Formerly, re-melting was
believed to be an improvement, and founders were advised to
* One blast furnace in the North of England, known to the writer, burned
for over twelve years incessantly, and was then only blown out for repairs.
T he Capo/a. 3
melt again and again,
even to twelve or thir-
‘\ teen times, but this
has now been de-
monstrated to be a
fallacy.
To obtain a very
tough casting, such
as an hydraulic cy-
linder, wrought iron
‘RON turnings are some-
times mixed with the
pig in the cupola.
Moulding—We
will now consider
how the moulder
forms his casting into
any desired shape.
To do this it is me


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//"”‘/ "’ ///‘ . ' "Mme-‘w’ be the counterpart of
‘Ti-T the casting required 5
‘ Q for several reasons we
shall see, however,
that the pattern will
not always be exactly
similar to the casting.
But more of this as
we advance.
The pattern is
impressed in sand
contained in two
moulding boxes, or
ﬂasks, half the pat-
tern in one box, and
half in the other ;


4 Various Met/zods of Moulding.


these are sketched at Fig. 2. The boxes are light castings, ribbed
across as shewn, allowing space for the escape of gas from the
molten metal. _
Sand used in moulding is of two kinds, green sand and loam.
Green sand is obtained from the chalk or coal measures, that
of the London basin being among the best. Green sand should
contain a large percentage of silica to give porosity, together with
a very little magnesia and alumina for binding purposes. The
lining of Bessemer converters has about 85 per cent. of silica in its
composition, while many moulders prefer to have as much 'as 9 3 or
96 per cent. of silica, leaving only 4 or 7 per cent. of other substances.
The sand should not burn on setting, or it will stick too much when
wetted for use again, and, while cohesion is necessary, it should at
the same time be porous enough to allow for the passage of air,
though not so much as to permit of any molten metal entering it.
Loam is amixture of clay (ferruginous or calcareous) with a
considerable amount of rock sand (abraded rock). It is ground
in a mortar-mill and mixed with powdered charcoal, horse dung,
cow hair, chaff, &c., to give it binding power and porosity.
Besides the above, Cores require a mixture of rock sand and
sea sand (the latter for porosity), and Parting Sand, for the use
implied by its name, consists of ﬁnely powdered blast-furnace
cinder, brickdust, or ﬁne dust from castings; all‘perfectly dry.
Moulding is practised by three different methods: Green
Sand, Dry Sand, and Loam Moulding.
V arz'ons Met/lode of Moulding. 5
In green and dry sand moulding, patterns are generally used;
but .in loam moulding, which is only employed for objects of
regular form, the mould is struck out by means of a template,
and built up by the moulder himself.
Green Sand is the geological name of a sand of very ﬁne
texture. It appears black in the foundry because it is mixed with
a proportion of coal and charcoal dust; it is damped each time
that it is used. This is the most general method of moulding,
with castings not likely to warp too much by the more rapid
cooling.
Dry Sand is a mixture of old loam with an addition of
rock sand. It is so called because, after the pattern is moulded,
the sand is dried by means of ﬁres hung in pans or trays over
the moulds. It is ﬁrmer and more suitable for the support of
long castings, such as pipes, columns, and large ﬂy-wheels than
green sand is, and will produce ﬁner castings, with less fear
of pieces of sand being torn away by the
ﬂow of the metal. If pipes were moulded
in green sand, the tendency would be to
uneven thickness in the castings, through
sagging of the sand.
Loam Moulding, as we have said,
does‘ not require a pattern, the mould
being struck in the pasty loam (the latter
being mixed with water) by means of a
rotating or sliding template, called a
striking-board. Thus the core of a large
cylinder is built up in brickwork, and then
covered with a layer of loam, which is
smoothed by a rotating striking-board
(see Fig. 3), much as a plasterer would work the cornice of a
house ceiling. Cubical moulds, such as those for condensers,
may also be worked in loam.
The simplest moulding done in green sand is called Open
Sand Moulding, and consists in laying the pattern in the sand
on the foundry ﬂoor, withdrawing, and then pouring in the metal,
a cover not being used. This is the method employed for such
common objects as moulding boxes (see Fig. 4).

STR/KING 8 017/70 -

6 Simple Moulding.
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A Cattle Tr0ugh.——Our next example of moulding is an
ordinary cattle trough, and here two boxes are used to hold the-
sand. The pattern may be of wood in the ﬁrst instance, and of
the same shape as the ﬁnished casting. It is placed in the
bottom box, as in Figs. 5 and 6, and sand ﬁlled in to the line P P,
which is the parting. This parting is smoothed off, a dusting of
parting sand applied, and, the top box being put on and fastened
down, the whole is ﬁlled with sand and rammed well together.
The top box must now be removed and the pattern taken away,
a slight rapping being given to effect its detachment from the
sand, while the latter is dusted with Blackening, which is oak
charcoal dust. But ﬁrst, to make the blackening adhere, pease-
meal is sprinkled on the mould, absorbing the damp of the sand,
and thus becoming a pasty layer. The object of the blackening
is this: If the metal were to touch the side of the mould it would
enter into the sand surface, and thus produce a rough casting.
This is allowable in moulding boxes, where roughness is a decided
advantage, but where a smooth casting is desired, blackening is
needed, as it ignites on being touched by the metal, and so forms
a ﬁlm of gas between it and the mould, a clean casting being the
result.
Gates.--The mould having been sleeked and ﬁnished, and
any little break in the sand mended, the gates have now to be
made for the entrance of the metal. Tapering plugs of ‘wood are
usually left in the sand for that purpose, and these are now removed.
The more shallow the casting, the moregates are used; as
many as four even.
Vent Holes are made in the more solid parts of the sand
(but not to touch the surface of the mould) to facilitate the
passage of air from the latter.
The moulders, being provided with molten iron, taken from
Gates and Vents. 7
the cupola in ladles, as already described, pour it in simul-
taneously at the gates of the mould, and the sand being after-
: wards broken away, reveals the
Eéf casting which has ﬁlled the
mg l mairix left (ilpy tltle pattern. _
mM/,,,,,,,,m<§\\\\\\\\\\w s regar s t e proper posi-
tion in which to lay the pattern,
alittle thought is necessary, but
‘as a general rule the most un~
important part of the casting
should be upward, that being
the part to which the scum and
impurities rise. If possible, the
I scum should be entirely re-






,Peumne cam-.6
moved from the mould itself,
_ “ being allowed to ﬁll a large
gate or projection. This is
especially done in the case of
steam cylinders, where purity
is a necessity. Gates should be
as central as possible, and have
their mouths a little lnglzer than
the mould, but they should, as
a rule, enter the latter low down,
particularly in deep castings, in
order that the air may be made
to pass out at the vent holes 5
but much judgment has to be
exercised, and in most cases
they should be placed a little on
one side, namely, not to enter
on the top surface, otherwise
the corners of the sand may be
knocked off by the force of the
ﬂow; and ﬁnally, they should
be put where shrinkage is likely to occur, that they may tend to
ﬁll up any shrinking portion.
Our next example shall be a Hand Wheel for a large stop-


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8 Core Prints.





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valve. The pattern here will be of the same shape asv the ﬁnished‘
casting, excepting the square holes in the centre, which we will
suppose to be cast in, to be afterwards dressed up with a rough‘
ﬁle. Square core prints of any convenient length are put on either-
side of the boxes, and of a size equal to the hole to be cast, allowing
a small amount for cleaning up (see pattern, Fig. 7).
A core box is now to be made, which is shown in Fig. 8, and
consists of two blocks of wood, hollowed out in such a way as to
represent the square hole required, and of a length equal to that
across the core prints from end to end. The pattern is next
placed in the sand, as drawn in Fig. 9, and parting made, then
rammed up, with gate at G, and vents here and there. Core sand‘.
mixed with water is put in the core box (which ﬁts together by‘
means of the pegs PP), smoothed off, removed, and placed in the-
core stove to dry. The mould is ﬁnished and blackened, and
the core treated with black was/z, which is charcoal dust mixed
with clay water, and used for the same purpose as blackening.
The core being put in place, as shown in Fig. 9, everything is
ready for the reception of the metal.
We shall now take the moulding of a Chain Pulley by a
very ingenious method. Fig. 10 represents the pattern, with core
Pulley Moulding. 9








prints for the Centre hole, and divided in halves by a horizontal
plane. In all other respects it is the counterpart of the casting.
The operation is as follows: referring to Fig. II, we must ﬁrst
lay the bottom half of the pattern in the bottom box, and make
the parting e b 3 next put in the top half of pattern, and make the
parting tr; lastly, ﬁll up the box, and ram well together. The
pattern has now to be drawn out, and this is done by ﬁrst lifting
off top box, taking away the top half of pattern, and returning top
box. Now, on turning the whole upside down, the bottom half
of pattern becomes the top, and may be similarly released. The
ring of sand M, it will be noticed, has all this time remained
resting on that half which happened to be at the bottom. It
is only necessary to make the core as in last example, put it in
10 ' Worm I/l/Tlteel Moulding.
place by removing top box, form gates and vents, and complete
casting. .\
A Worm Wheel may have a pattern made in halves, and
vmoulded in an exactly similar manner (see Fig. 12) ; the teeth on






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the pattern being formed so as to gear with a wrought iron
worm which has been previously turned, the worm and wheel
pattern being rigged up on two axles to imitate their condition
when in actual work. In withdrawing the pattern from the sand
a slight screw motion must be given to allow for the angle of the
teeth.
Moulding boxes are entirely or to some extent dispensed with,
and the ﬂoor of the foundry used for the reception of the pattern
wherever convenient; and then, except in such cases as that
shown in Fig. 4, a cope or slab of sand is used, contained in a
box, to cover the impression. Examples of this kind of moulding,
with more or less complicated copes, will now be treated.
Fig. 13 is the plan of a Drilling Machine Table. The
pattern is of the same shape, with the exception of core prints
necessary for the slot holes. A core box is required for these
holes, and the whole is moulded face down, an extra piece being
left in the casting at top, if thought necessary, to allow for scum.
Instead of the bottom box the ﬂoor might have been used, if
previously well vented with coke.
Perhaps the most ready way to mould the Cylinder Cover
shown in Figs. I 5 and 16 is to use three boxes (or what really comes



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to the same thing, two boxes and the foundry ﬂoor), and make the
ﬂange A loose on the pattern. On taking off the top box, this
ﬂange may be withdrawn, while on replacing the top box, and lifting
it and the bottom box together, the main pattern may then be
removed. The core for the centre is inserted in the usual way,
and the casting made in the position ‘shown. The stakes ss ﬁx
the position of the boxes with regard to the ﬂoor.
Casting on.-—Sometimes it is necessary to attach cast iron
to wrought iron in the mould itself, and so do away with the
expense of bolts. Casting on is the term used for the operation
resorted to.
As an example, We will take the traction engine Road
Wheel, shown in section, Fig. 17.
A core box is made as in Fig. 18, consisting of a slab of
wood A, with the boss B fastened to it, and of a hollow cylinder
of wood 0 to contain the core sand. Two cores are thus formed
and baked in the stove. A second core box is required, shown
in Fig. 19, consisting, as before, of a hollow box to hold the core,
and of the bosses DD in two parts, to make the impression for
the central part of the wheel nave. As the line x in Fig. 18
corresponds to line x on Fig. 19, it will be seen that the prints
P P in Fig. 18 will leave spaces for the reception of the spokes.
It is only necessary to ﬁx the spokes loosely in place by bolts to
wheel-rim, at the same time laying them in the spaces left for them
in the cores; build up according-to

Fig. 20; add a central core, E, made 2, m“ j
in ordinary core box; make gates and F's-9,21
cast. The spokes are afterwards
rivetetd on wheel rim, and have the shape shewn in Fig. 21.
ROAD WH££L






Tin-ovum:
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CORE 80X. MIDDLE
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14 Loam Patterns.
Loam Moulding.—-We shall now proceed to consider the
moulding of such objects as may be done wholly or ‘partly in
loam by striking (or strickling), and ﬁrst we will take an ordinary
Gas Pipe Main, with spigot and faucet, the former being the
smaller end of the pipe which ﬁts loosely into the faucet or larger
end of the next pipe (see Fig. 22), which represents the ﬁnished
pipe in section. To mould the outer envelope, we may either




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have a wooden-pattern with the core prints at the ends, or may
strike out a loam pattern from a board. Assuming the latter
method, we need ﬁrst a pair of trestles, Fig. 23, on which is
placed a hollow cast iron cylinder with journals at the ends, and
pierced with holes along its length for the venting of the core.
Round this cylinder straw rope is tightly coiled, and after this
a layer of loam is laid on. The loam being dry, a second coating
is applied, and this time, as the handle is turned, the shape of
the core is struck out by means of a board B secured to the trestles.
The core b being dried in the stove, is blackwashed, and then
covered with another layer of loam to be struck out by the second
board A, and so the loam pattern is formed. Being again dried,
an impression is made in the mould, after which, the last applied
loam, or thickness piece, is removed (the blackwash facilitating this)
and the internal core b returned to its proper place in the mould
(see Fig. 24), gate made and casting performed as usual.
It is advisable to cast these pipes either vertically, or on an
incline, so that the metal may ﬂow more easily and bring the
scum to the end, and if they are very long, dry sand should be
used in the boxes instead of green sand, for reasons previously
stated. After the metal is poured, the escaping gas is lit at
either end of the pipe. -
Fig. 25 represents the moulding of a Bend for the pipe in last







I6 Bend in Loam.
example. To mould it we may either~
have a complete pattern and core
box, when it would be done in
green sand, and needs no
further explanation; or it
may be worked in loam
by the aid of tem-
plates. For the
latter method we
may proceed in
the following man-
ner: take an iron plate,
Fig. 25, and on it fasten
the bent wire A of square
section as a guide for the
template B.
Loam being laid, it is traced
out by B, which gives it the form
of the internal pipe. The length of
the bend is carefully measured off at c
and D, care being taken to allow an extra


£49
me.
fully dried and blackwashed. Now apply more
loam and trace out by means of the larger
template G, which gives the necessary thickness,
while the faucet is supplied .by the impression
of the core box H, and the spigot by that of J. The added
thickness is shown by the dotted lines. Drying and black-
washing are again resorted to. Lastly, cover the whole plate
with loam, which, as it is required to be lifted off entire, must
be well stayed with cross and longitudinal wires tied together
by small wire. A wire should also stiffen the internal cores.
(The whole of the foregoing is repeated opposite hand, on the
. plate F, the same bent wire being used.) .
The solid block of loam ‘thus formed on either board is
taken off, dried and blackwashed, and now all is ready for putting

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together to form the mould, with the exception of the thickness
layer on the internal core, which must ﬁrst be removed, and the
two half cores taken off the plate and put back to back, thus
forming a complete central core. The whole mould is shewn
at Fig. "26, the bent part of the core being supported by a chaplet
given in detail at K.
It must be quite understood that if many castings are required,
the above operation would not be performed, as a pattern would
give more expeditious results.

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A slightly different, but more usual way of moulding a pipe
bend, is to cast two plates, as at L, Fig. 26A, from a wooden
pattern of the shape of the pipe, a little margin being left at each
side, the ﬁgure being for a pipe having ﬂanges at the ends. The
template takes the form M, and has a few nails driven in at a, to
‘ \
I
Large Steam Cylinder. 19
prevent considerable wear as it travels along the plate. The
internal core is shown struck on the plate, and the opposite hand
having been made, these two are dried and laid aside. A larger





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template strikes out the patterns, right and left hand (the wooden
discs N serving as ﬂanges), and these being dried, it is clear that
we now have two half loam patterns and two half cores; the
moulding, therefore, may take place in green sand in the usual
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Steam Cylinder z'n Loam. 21
way. A few sprigs or brads in the ﬂanges N serve to fasten the
latter to the pattern.
The mould for a Large Steam Cylinder is usually made
entirely in loam, and this operation we will now examine.
Fig. 27 represents the casting in longitudinal section, elevation,
and in plan. The valve box is made separately, as is sometimes
done with these large cylinders, but in any case, no further
explanation is needed than that previously given, as a pattern
would be made for it. The body of the cylinder would be swept
out entirely by template boards, but special projections, such as
steam ports and exhaust ﬂange, will require core boxes and
patterns.
An iron plate A, Fig 27a, is laid on the foundry ﬂoor to
support the structure, and a centre B is sunk beneath the ground-
line, an upright spindle c being taken of sufﬁcient length, and
supported at the top by means of an arm D standing out either
from the wall or from a crane pillar; all is now ready to
begin.
A base of loam is swept out by the board E, shown in dotted
lines, and representing the bottom of the cylinder ﬂange ; this is
dried and blackwashed, a ﬂat ring d being then laid as a foundation
for the core structure.
Taking board E away, another (e) is used to strike out the
lower cylinder ﬂange ﬁ which is necessary as a support to help
plate a’.
The loam f being dried and blackwashed, the external Core of
the cylinder is next formed, because it is necessary to remove it
for the formation of the internal core, and the latter, being in one
piece and cumbrous, is made separately. The board F is now
used to strike the outer form, the central projection being for the
exhaust port, and an opening must be allowed at G, the full length
of the cylinder (see Fig. 29) for the reception of the port cores on
one side, and which may be traced out by a template board, while
a similar opening g, of the depth K J, must be left on the opposite
side for the exhaust ﬂange core. It will be noticed that this outer
mould requires, for building, the aid‘ of annular plates at H J K L M,
for the support of different pieces of the structure. These plates
do not go entirely round, being prevented by the ports at G, and’





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Steam. Cylinder z'n' Loam. 2 3
they now enable us to remove this outer portion in separate pieces
to a safe place to dry, and allow us also to build up the internal
core. Thus plate K may be lifted by crane, removing the 'upper
portion ﬁrst; next J and a’. Discarding the loam plate f, which
is no longer needed, our next proceeding is to take the board N,
Fig. 28, having built up the core loosely with bricks, vented at the
joints with coke powder, and strike out loam to represent the in-
ternal surface of the cylinder; this is dried in place by ‘open ﬁres
and blackwashed. The projecting portions only now remain,
which, as we have said, must be made from core boxes. Fig. 30
represents the box for the outer contour of the steam ports, and a
core is formed by laying it on a ﬂat plate and ﬁlling up with loam.
The parts a a, of the core box should be noticed: sides 6 b, can
be easily taken away, but in order to draw away the centre e, the
ﬂanges must be dovetailed to ein such a manner that they may
be left behind on withdrawal of the box.
This may be understood on reference to a, which shows one
of these loose pieces. They may afterwards be taken away in the
direction of the arrows. The box and core for the steam ports
are shown in Fig. 31, and need no explanation.
The inside core. for exhaust port, being circular, is struck out
on a separate plate by board (Fig. 32), box P being required to
give the projection on the steam side, and Q for that on the
exhaust side. There is left the exhaust ﬂange, which may be
formed from the box in Fig. 33, the ﬂange itself being loose on
the pattern to enable the core to be withdrawn, the latter being
made on a plate similarly to Fig. 30.
SS are patterns for the web at top and bottom of the cylinder,
and, having been built into the core at Fig. 27a, may now be
removed. '
Finally, all may be put together to form the mould, in the
manner drawn in Fig. 34, beginning at the bottom and putting
the different cores in their places as we proceed ; chaplets are
required to support the annular exhaust core. Gates are next
made, which had better enter the mould somewhat low down, in
order to have some head of metal at that point. The object of
this is to prevent air bubbles in the casting, by means of the
weight of in-pouring metal, whatever air there may be in the
24 Steam Cylinder in Loam.
mould being thus forced upward, where it escapes at holes there
provided, termed risers. The mouth of the pouring gate should
of course be a little higher than the top of the cylinder. Venting
is rarely necessary in loam moulding, except for such pieces as the
long 3 cores. Piece R, Fig. 34, is left for the purpose of receiving
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the scum, in order to leave the casting sound. Wherever the
molten metal is to touch the iron plates the latter should be
washed with loam.
Foundry Pits.-—It should be understood that the ﬂoor we
have spoken of in the last example is not strictly the foundry
ﬂoor, but that of a pit deep enough to hold the whole mould.
Important castings like the one last considered, and especially
upright ones, are always thus treated, and after the mould has
been ﬁnished the space left in the pit is ﬁlled in and rammed so
as to bed the mould tightly against the sides of the pit, and so
resist the pressure of the metal on casting.
A Screw Propeller can be best moulded in_loam, a pattern
being provided for the centre boss. Referring to Fig. 3 5, a board
A centred on the vertical spindle, and balanced by means of a
small weight, is revolved so as to travel along the incline B c,
which is only a template curved so as to have I) as its centre, and
forming part of a screw of the same pitch as the propeller. It is
very clear then, that by backing up the surface B C with loam, we
shall obtain a screw surface the same as that of the propeller blade
required. The next thing is to mark out the shape of the blade,
shown in dotted lines. On the blade thus marked out, dried and
blackwashed, we now lay strips of wood, as shown at e, Fig. 36,
representing the thickness of the propeller blade, and the surface
is then covered with loam up to this thickness, smoothed off, and
again dried and blackwashed. Now completely cover with loam,
and so form top mould, which in its turn is taken away and dried.
The thickness piece being removed, the blade is completely
moulded, and this may be repeated for the other blades. Setting
all the lower moulds then in position on the ﬂoor, the bottom half
of boss pattern is applied (Fig. 37), and, being ﬁlled round with
dry sand at EE, the top half is treated similarly. Lastly, the
mould is completed by the addition of a core for the central hole,
and of the top box, and the whole has the appearance of Fig. 38.
A large Fly-wheel may be moulded without the necessity
of making a pattern for the whole of it. A coke bed is ﬁrst
formed on the ﬂoor for the purpose of venting, and a centre is.
sunk for the spindle A, Fig. 39. Then the core box in Fig. 40 is
taken, which is formed so that a certain number of cores made
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from it may reach quite round the outer rim of the wheel, as suggested
by the dotted lines 3 the back and top boards B and 0 being loose, to
remove the core, which may be made in dry sand. After levelling the
ﬂoor by means of board D, Fig. 39, the cores from Fig. 40 are set up
at E, with the curved surface inward and gauged from the centre by
the striking board F, which has the same radius as the outside of the
ﬂy-wheel rim. A small space is, however, left for the application of a
coating of loam which is struck out at top and side by the board F.
We next require the arm cores. The box for these is shown at
Fig. 41, and suppose we have in our case six arms to the wheel
this box must be made a sector of one-sixth part of the circle.
The top, bottom, and sides are removable, so that when the
box has been ﬁlled with compact dry sand they may be taken
away, together with the rim part and boss, dowelled only into arm,
leaving the latter, which, being tapered, may be knocked out with
a mallet at G and so removed. Some moulders might prefer
loam for these cores, which would be baked in the usual way.
Putting the sector cores in place, as in Fig. 42, a pattern is
used for boss, and a top box of green sand at H. There only
remains the completion of the cope for the rim. This may be
done in dry sand, contained in boxes shown in plan at J, and by
means of a pattern K placed in the channel formed for the rim,
top box J being put on and rammed up there. This pattern K is
passed round until the whole of the top of the rim is formed, and
ﬁnally withdrawn by removing one of the boxes. The mould is
now complete, and it is only necessary to form the gate, which
should be pretty central, while risers (about four) are put in the
boxes J to show when the metal has ﬁlled the rim, which is known
by its lifting a metal ball placed upon them. Of course great care
must be taken in ﬁnishing the mould, so that no unsightly marks
be left on the casting at places where the cores join each other.
Marine Condensers,being usually large cubical castings, are
built up in loam in the manner described for other objects, but suﬂi-
cient has now been said to make a careful description unnecessary;
projecting ﬂanges, of course, must have patterns or core boxes.
Fig. 43 shows one or two objects suitable for loam moulding,
A being a large Air Vessel for a pump, and B a Cone Pulley
for some machine tool.





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The internal cores may be noticed in these examples. They
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boards a’ and e, with a thickness piece, blackwashed as usual; then
follow with internal core f, using board 4. Remove f when dry,
and strike out g by means of board e.
The core g is now removed, but returned in company with f,

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ﬁrst taking away the thickness a a, and the whole structure is then
bolted together ; it is a ring to stiffen g, and j is a pronged plate
to support the core f.
The cone pulley B may be struck out in the ﬂoor, while the
internal core is made separately on a plate; patterns being used
for webs and boss. In fact, any casting of regular shape, either
circular or cubical, may be moulded in loam much more
economically than by means of wooden patterns ; the symmetrical
parts being struck, and projecting pieces having core boxes.
A few other examples of moulds in green sand for different
objects, requiring no special description after what has been
previously said, are given in Fig. 44, where A is a stop-valve, the
larger core box for which has a loose pin to form the impression
needed to support the smaller core : B alarge marine or stationary
piston, the core being supported and vented by the pieces aa, which
are ﬁlled in on ﬁnished casting by screwed plugs. Boxes are needed
for the cores cc, and c represents the mould for a plummer block.
Wheel Moulding—Only a few years ago spur and bevel
wheels were moulded by providing. a ﬁnished pattern for the
wheel required, but as machine moulding is not only simpler, but
far more accurate, and as it does away with the necessity for
storing heavy patterns, which are sure to be out of truth by the
next time they are required, toothed wheels are now extensively
moulded by machine.
Scott's wheel moulding machine may be understood by
reference to Fig. 46, and it must be premised that three operations
are necessary in the working of it.
A board B is set upon the central spindle A (see Fig. 45), for
the purpose of striking out the greatest diameter of wheel, on
which the teeth are to be formed, giving at the same time the
height of the top and the bottom of the rim. The spindle being
removed, the machine is put in the central socket c, Fig. 46, and
the operations are now to be explained.
A pattern D, of two teeth, is accurately made in hardwood,
and being fastened to the upright arm E of the machine; this
arm needs to be—(I), ﬁxed to the requisite radius of wheel;
(2), raised or lowered; (3), passed round the rim of the wheel
by the rotation of the arm F.
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- The ﬁrst operation is done by means of the traversing screw G,
which slides the whole of F and E by the nut H, the latter being
ﬁxed to the centre piece. The lifting and lowering is done by
the hand wheel J, which by worm and worm wheel turns shaft K
and chain wheel L, and the sliding arm E is lifted up and down
by the chain which is fastened to each end and tightly wound
round wheel L. The third operation, the rotation of the arm F, is
effected by means of the handle M turning the shaft N and passing
through the change wheels ; the motion is transferred to the worm
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machine. Varying change wheels can be inserted in much the
same way as in a screw-cutting lathe, and the revolutions or
fractional parts made by the handle can be seen by means of the
graduated disc P, so that any part of a circumference, such as ‘the
pitch of the teeth, can be accurately traversed by the mechanism.
D
34 Bevel W/ieel Moulding.
last explained. The teeth then are formed in the ‘sand after the
proper radius of arm is ﬁxed, by lowering the tooth pattern,
ﬁlling up with sand, raising, rotating the amount of the pitch,
lowering again, and so on until the whole wheel is formed. The
machine is now taken away by attaching the crane chain to the
eye-bolt at the top of central spindle.
8 Core boxes are needed for the wheel boss and segments
between the arms, and for central hole. Wood strips are used as
gauges to ﬁx the cores in position and to preserve the proper
thickness of the rim and arms; a cope is placed over all, gates
formed and cast.
Bevel Wheels are moulded in a similar manner to the
above, the principal alterations being the strickle boards and tooth
patterns. Fig. 48 will make this clear. A board A strikes out
the back of the wheel in green sand, and parting sand is applied;
an impression of the wheel back is then taken in top box,
removed, and ﬁnished; board B next forms bottom face, cores
and boss pattern completing the remainder. It has not been
thought necessary to describe the arm cores for these wheels; for
the building up of similar cores the student may be referred to
Fig. 42. -
Chilled Castings.—Where a very hard and durable surface
is required to a casting, chilling is resorted to, which is simply
making that part of the mould, where the said face occurs, of iron.
When the molten metal meets the surface of cold iron, it cools
rapidly and forms crystals of white cast iron, hard yet brittle, where
it meets the mould, and for a depth of an inch or more, according
to the mixture used in casting, or the weight of the chill mould;
the rest of the casting is still grey and soft.
It would seem that the graphite crystals do not, under such
circumstances, have time to form, and so the carbon becomes
combined with the iron. Suitable objects for chill casting are :—
rolls for plate mills used in forging plates, and which require a
great depth of chilling, as they are turned up again on being worn
down; tram-car wheels, the rim only being chilled, this class of
trafﬁc not being capable of supporting the expense of steel tyres;
points of plough-shares, which wear away at a very rapid rate in
the earth; bushes for ordinary cart axles; railway chairs; pro-
Chilling.
jectiles for large guns; and, in fact, all classes of work required to
stand wear and tear, and not especially needing machining.

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rim; B, a plate roll; and c, a shell.
36 Malleable Castings.
of cast iron. The iron mould must be painted with a thin coating
of very ﬁne blackwash before casting, and some care must be taken
in the forming of the gates, as, if there should not be sufﬁcient'
pressure from the ‘head’ of metal used, the iron will recoil on
meeting the cold mould, and form a rough casting. Care must
also be used in the case of bushes, to remove the core chill before
the casting cools down ﬁrmly upon it. The chills (the name
given to the iron moulds) are usually made of good cast iron,
though, in some rare instances, wrought iron has been used. Some
of the details of chill moulding vary according to different autho-
rities. Some founders purposely rust their chills on being ﬁrst
made, to assist the blackening in resisting the action of the metal,
it being generally believed that the latter tends to fuse and injure-
the chill. Other founders, notably in the case of projectiles,
neither rust them nor use blackening. The chills ‘should be
warmed somewhat before casting in order to expel >moisture,
and they should be sufﬁciently heavy or the chilling will be-
too slow. i
Malleable Castings are obtained by taking the article,
after being cast and cleaned up (this last is very important), and
putting it, along with others, in an annealing furnace, in company
with some substance that will absorb the carbon from the cast
iron. Such substances are, oxide of iron in the form of scales
from the rolling-mill, or some other of the metallic oxides, placed
in the furnace in a state of powder. The'intensity of the heat,
and the time the casting should remain in the furnace, both
depend on the size of the casting and the amount of malleability
required, the usual rule being to keep it at a white heat for about.
a week, adding to this the time required to raise the temperature
and to cool down.
Fig. 49a shows an annealing furnace with cast iron boxes A
holding the castings, which are covered with a layer of sand. Of
course, it must be understood that it is only to a short distance
below the surface that the casting becomes converted into'
wrought iron.
Softening—If a casting is so hard that it cannot be machined,
it may be softened by heating and cooling out in common sa'n‘d,
many other bad conductor of heat. _
Brass Founding. 37
Brass Founding—The moulds used in the casting of
brass require no new description, the only difference in this
class of work being the manner in which the metal is melted.


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As the castings required are much smaller than those we have
recently been describing, the brass is made directly in crucibles
of some impermeable material, black-lead being the best. The
melting furnace is shown in Fig. 50, and usually there are several
of these side by side and separately connected with the chimney.
The top of the furnace is only a little above the ﬂoor level, and
in brass foundries it is customary to have the part of the shop
near the furnace entirely reserved for casting purposes; the
casting and moulding shops being entirely divided by a wall
in the best establishments. The principal difficulty in the making
of brass is that of the different fusing points of the two metals
used—Copper and Zinc. Thus, copper melts at 1996° F.,
while the melting point of zinc is as low as‘77 3° F.
The copper is ﬁrst melted, and the zinc is only introduced a
short time before casting, by means of tongs, pushing it down in
small pieces under the melted copper. It should flare up on
doing this, which is a sign that the heat is quick enough. If it
is left in too long, much of the zinc will be lost by evaporation.
In bringing this chapter on casting and moulding to a close,
38 Brass Furnace.
a few practical points may be mentioned, although it should be
clearly understood that perfect practice can only be obtained by
actual work on such articles as have been mentioned in the text.
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The Size of Gates, and the number of them, can only be
determined by constantly watching the results obtained from
previous work.
Flat gates _ should be avoided as much as possible, as‘
they tend to clog, though sometimes they are beneﬁcial when
they are required to break off of themselves, rather than damage
the casting. Fig. 51 is intended to represent diagrammatically
the different gates and channels used to supply a mould; the
pouring gate ; the skimming gate, for the purpose of retaining the
scum (and here some ingenuity is required to keep the latter-
in the skimming gate by centrifugal action, the whirling being
produced by admitting the metal at a tangent); the sprues or
connexions from skimming gate to mould (they may be of any
number considered necessary); the feeding gate or gates, the
use of which is to ﬁll up any part of the casting which is likely
to shrink; and the risers, which are to allow the whole of. the
air in the mould to pass out and so prevent blow-holes, the
Forms of Gates. 39
soundness of the casting being also in the hands of the pourer,
as he may keep the riser covered for a shorter or longer time.
The size of gates is determined by the fact that the metal
must neither ﬂow too slowly so as to choke, nor too quickly so as
to break the mould. All the while the pouring is going on, the
moulder agitates the metal in the gates by means of an iron rod,
which he moves up and down until the metal has cooled so far
as to prevent him doing so any longer; in this manner homo-
geneous casting is more likely to result.
A great deal of art- lies in the
ramming ‘of the mould, but as a
rule, the deeper portions of it should
be rammed most, as there will be
a greater head of metal on them.
The ﬂoor of the shop should be Well
vented by a bed of coke, and the
insertion of pipes to take away the -- .
gases from all work done on the Diagram’ 9‘ Gates’
ﬂoor, and coke dust should be put
in the joints of loam building; some cores too should have a
large amount of coke in their centre.
The venting of the mould is also a matter which requires
a great deal of practical experience to enable it to be done
with success. Large cores, enclosed on three sides by metal
(‘ pockets,’ moulders call them), should be particularly well
pierced, and green sand moulds should be much better vented
than loam or dry sand work, on account of the steam rising from
the damp‘ sand and the compactness of the latter.
Cores require good support by means of plates or wires,
especially such as those in Figs. 25, 34, and 43, and all cores
that are not held down by the shape of the mould, should be so
fastened, for they are so much lighter than the molten metal,
that they would ﬂoat out of position if left to themselves.
Cores should be dried in the stove for about twelve hours, and
should only be placed in the mould a short time before pouring,
to prevent the absorption of moisture by them from the mould.
Patterns are lifted out of the sand by screwing rods or
handles into them, and raising slowly, at the same time rapping
F EEO/N6
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the pattern carefully to prevent the sand adhering, and a few
points should here be noticed as regards the ﬁnishing of the
mould. The moulder uses trowels and ‘sleekers,’ which last
are only trowels of special shapes, to smooth away any broken
portion, but, if the mould is made too_ smooth, there is great
danger of blistering or scabbing, from the fact that the mould,
having lost to some extent its porosity, refuses to allow the
escape of gas, and it is generally understood by moulders that
the hand makes the best trowel, though certainly it is always
better to let a mould remain, if possible, just as the pattern left it.
In Fig. 52, a few moulders’ tools are sketched. '
The upper box is usually
% termed the ‘cafe,’ which also
applies to the outer mould,
and the lower box is often
called the ‘drag.’ The cope
should be well weighted to
ensure sound castings. When
two boxes are used, they ﬁt to-
gether as shewn in Fig. 2, and
can be easily replaced, but
if the ﬂoor serves as bottom
box, exact correspon- m,“
dence is obtained by '
driving stakes into the “


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m ground through the lugs of
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Chaplets have been before
ﬂ/OMWG' T/QO'LS- mentioned, and are required
_ , to stay cores that cannot be
otherwise supported; their use, however, is not advisable, for
they tend to produce weakness in the casting in which they
remain. They should be tinned, or at least free from rust, to
ensure uniting with the casting.
We have already described the charging of the cupola ; it
remains for us to' explain the method of tapping it. The man
at the cupola is provided with two iron rods; one he uses to pierce
a hole in the clay stopping, which he does as soon as the moulder
M ixtures. 41
has brought his ladle under the mouth of the Cupola; the other
rod has a ﬂat end, with a lump of clay adhering. As soon as the
ladle is full, he applies the clay to the mouth in order to stop the
ﬂow. To tap with safety, he should stand on one side of the
trough and use his tapping rod obliquely, while on stopping again,
he should cut off the stream from the top side.
Mixtures of Iron—This is another art which nothing but
observation and practical experience can reduce to a nicety,
different mixtures being used for the same purpose by diﬂ‘erent
founders 5 indeed, the success of certain ﬁrms depends in a great
measure on the mixtures used. Still, a good idea can be given
of what is required for each purpose.
The varieties of pig iron having been already stated, we will
now consider each separately.
No. I is the weakest but most ﬂuid of all the pigs, and may
be used by itself for ornamental castings on account of the ease
with which it ﬁlls the corners of the mould, but it is usual to mix
it with ‘scrap ’ to‘ increase its hardness, ultimate strength, and
closeness of grain.
No. 2 is ﬁner in grain and stronger than No. I, and is used
wherever some strength is required with great ﬂuidity.
No. 3 combines the greatest degree of strength consistent
with ﬂuidity, and is therefore most extensively used, and in great
favour with founders.
No. 4 is the strongest pig for foundry use (the remaining
numbers, 5 and upward, being only required for conversion into
wrought iron), and is therefore used for heavy castings requiring
strength, such as girders, columns, bed plates, &c.
For strong castings two-thirds of No. 4 may also be used with
one-third of No. 1.
Scrap is the name given to the broken up parts of old
castings, which of course may be divided into good and bad
scrap. Some founders place great reliance on it, using nothing
but scrap with an admixture of No. I, say two-thirds of scrap to
one-third of No. I, while others prefer using an iron like N o. 3,
mixing with it only a little scrap to strengthen it, and so produce
a harder, close-grained casting. It is also a good plan to mix
iron from different blasts.
42 Steel Casting.
While speaking of scrap, we cannot do better than endeavour
to understand the advantage or otherwise of remelting. We have
before said that remelting is a disadvantage. It is true that the
iron becomes purer as regards the elimination of graphite, ac-
quiring a winter appearance, with, at the same time, increased
strength and closeness of grain ; but, on account of other im-
purities, it is no longer as tough as before, and its ultimate
extension is therefore decreased.
For chilled castings, a strong iron, as Nos. 3 and 4, is needed,
because the chilling weakens the metal.
Malleable castings require a pure mottled iron, or at least one
having very little grey mixed with it ; for if the particles of graphite
present in coarse grey iron are taken away in the furnace, honey-
combing will be the result.
Girders and columns must have a strong and elastic mixture;
cylinders should be treated for hardness as well as strength, and
therefore require as much white iron as convenient ; pulleys need
a soft mixture, such as a large proportion of No. I with a little of
No. 3 for strength.
Steel Casting requires no explanation. Its conversion from
iron will be treated in a subsequent chapter. The only difference
in the foundry is, that in order to prevent ‘honeycombing,’ which
has been a great trouble ever since steel castings were ﬁrst used,
great care has to be exercised, and even then many castings are
wasted, while brittleness is only prevented by slow annealing for
over a week or a fortnight of time.
Sir Joseph Whitworth introduced a method of compressing the
steel while in the molten ingot by powerful hydraulic pressure,
in order to prevent this troublesome honeycombing, the only
objection to his process being considerably increased cost.
CHAPTER II.
PATTERN MAKING AND CASTING DESIGN.
THE arts of moulding ,and pattern making are so inevitably
interwoven, the pattern maker especially requiring to know at least
the principles of moulding, that it would be quite impossible to
make these two ﬁrst chapters independent of each other, and the
subject of pattern making has been so much entered on in our
last that there is little left to say as regards the forms which
patterns should take, but whatever has been omitted we will
endeavour now to supply.
Wood.—-Pine and mahogany are the two woods most
extensively used, and are kept in large stores until they are
perfectly dry. White and yellow deal are used for the larger and
less accurate patterns, but are not hard enough for the better
ones, nor so good to resist warping as other woods.
Mahogany warps and shrinks very little in drying, and is con-
sequently in great favour. On account of that fact, and the ease
with which it is worked, it is considered the best wood for pattern
making ; expense, however, precludes its use for large patterns.
Cherry wood ranks next to mahogany; it warps a little more,
and is rather more troublesome to work.
Sycamore, lime tree, and American walnut are other woods
used. ,
Iron patterns are employed for lighter objects, or those
requiring very great accuracy.
It would be well before proceeding further to consider the
way in which timber warps in drying, as this will show us some of
the reasons for building up a pattern in a particular way.
The shrinkage of wood in length is so inconsiderable that it
may be disregarded ; and, in fact, some imagine there is none.
The greatest contraction is across the grain. To prevent the
splitting of the tree, as at Fig. 53, it is sawn up into planks whilst
green, and these in drying take the form sketched in Fig. 54.
44 Warping of I/Vood.
The outside layers contract the most, and, as a consequence, the
centre plank is narrower at the edges, while the side planks
become drawn in, in the manner shown at A. If the tree is cut


‘ c




into quarters, each quarter will contract, according to the above
law, in the manner sketched at Fig. 55, the sector piece at B
becoming narrower, the square at c becoming rhomboidal, and
the circle at D elliptical. Even after timber has been thoroughly
dried, it will always warp if a good shaving be taken off it, as may
Pattern-makers’ Tools. 4 5'
be seen at Fig. 36, for a moist surface is exposed, which, drying,
must contract the side that has been planed. It is, therefore,
suggested by some authorities that, in ﬁrst beginning a pattern,
the wood should he marked out and cut to the size required, so
as to have some little time to set before being used.
Tools.--It would be unnecessary in a work like the present
to occupy the student with elaborate descriptions of tools used in


working wood, which almost every boy knows. But we may‘
mention those that are specially required by the pattern maker in
addition to the ordinary ones of a joiner. The latter include jack
and trying planes, rabbet and rounding planes, Chisels, and
gouges. - "
Among the former are accurate squares, housing plane
(Fig. 57) ; gauges (Fig. 58, giving a kind much used for drawing
46 I/Vood-turningr Lat/ies.
lines parallel to the edge of a plank), compasses and trammels,
and a contraction rule, the use of which will be explained
subsequently. -
Two or three lathes are required; the ﬁrst, with a long bed
and moveable centres, Fig. 59; the second, a large face lathe for
turning wheel rims, Fig. 60; and the third, a light face lathe for
small articles, Fig. 61. Their speeds must be considerably above
those used for iron turning. A tool rest is used to them all, and
the work is done entirely by hand, the tools necessary having such
edges as are sketched at Fig. 62.
The mandrel of the lathe is provided with a chuck, which has
a different form for each; thus, the face lathe has a screw on the
mandrel to receive the ﬂange chuck (see A, Fig. 60), and the face
plate on which the pattern is turned is supplied by a disc of wood
bolted to the chuck. The lathe with the moveable centres is
provided with a chuck of the form shown at B, Fig. 59, which is
well pressed into the end of the pattern, and so compels the
latter to turn with the mandrel; and in the small lathe, the
pattern is screwed on the mandrel at c.
Qther machine tools required are :-—a band saw, circular saw,
and, if possible, a wood-planing machine.
Arrangement of Mould.—It is the duty of the pattern
maker to so arrange the moulding of his pattern as to cheapen
it (the moulding) to the utmost, and give the least trouble in
the foundry. Thus, if the mould is to be in green sand, as
little dried core work is to be used as possible, and very often
a great deal may be done by the introduction of loose pieces,
which are left in the sand after the body of the pattern has been
withdrawn, and are then removed in another direction (see A,
Fig. 30). He should put as little of the pattern in the top box
as is practicable, for it is evident that this part of the mould
must receive the worst treatment, being lifted off and turned over,
perhaps more than once. Added to this, the fact that the cope
has to be taken away so as to leave the pattern behind, means the
using of a good deal of care, despite which much broken sand
may still appear; while the half pattern in the bottom box may be
lifted in full daylight, and no accident need happen to it. We
may here mention generally the method of withdrawing trouble-


I
124...... 60











48 .Drawoacks.
some parts of a pattern by lifting portions of sand on plates or
‘ draw/barks.’ An example often quoted, and a very good one for
purposes of explanation, is that of a lathe bed.
Fig. 62a shows a section of the pattern lying in the mould.
The bed is reversed, so that the planed surfaces shall be free from
00 PE


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scum; and these surfaces are in the pattern made loose pieces aa.-
The upper portion of . the pattern can be easily removed, but the
problem is to withdraw the pieces aa. This can only be achieved
" by building the sand at b a on plates 66, provided with handles, by
which they and the sand upon them may be removed, after the
Pattern Building. 49
upper portion of the pattern has been taken away. The pieces a a
may now be withdrawn inthe direction of the arrows. .
Of course the middle space in the pattern might have been
taken out by means of cores, as suggested by dotted lines, and
this example has been introduced to show how necessary it is for
the pattern maker to carefully consider the best way of moulding
the object in hand before commencing to make his pattern.
A_di__fﬁcult pattern may always be overcome by the use of
either. loose pieces or draw backs, or by coreing, but if there
should be too much of the former to do, the latter had better be
resorted to. In the case of the pulley in Fig. 11 we have
ingenious but diﬂicult moulding, and many would prefer to have
a print in the pattern, and a core box from which to mould the
hollow.
While speaking of loose pieces it may be mentioned that for
safety of withdrawal some portion of the pattern is often left
loosely attached, although not apparently necessary. In Fig. 62b
the boss and arms of the bevel pinion are loose, and are taken
away with the top box. The two portions of the pattern may
then be withdrawn without risk of breaking away the narrow
portions of sand a a.
Pattern Building.--The pattern is ﬁrst pencilled out, full‘
size, on chalked boards, and with sufficient ‘views’ to make the
subject clear. Core prints, core boxes, &c., are also supplied in
the drawing, and taper given to all faces parallel to direction of
withdrawal. '
All surfaces to be machined should have an allowance of one-
eighth of an inch for iron or steel, and for brass one-sixteenth of
an inch. These amounts vary somewhat in special Cases, as for
example in a long bed plate, where three-eighths of an inch or
more may be required on account of the probable warping of the
casting. An upward camber of one-eighth of an inch per six feet
is given in patterns for lathe beds. _ _
In small cylinders one-eighth of an inch all round the bore
would be sufﬁcient, but large cylinders would need a quarter of
an inch. ' ‘ -
Some ingenuity has to be used in the building of patterns. If
theyare carved out of the solid'they have more chance of warping, for
E




COM PLIT" PﬂTflRN











Building Pulley Pattern. 51
reasons which have been previously mentioned, and so, patterns
of the larger kind at least, are made of layers well glued together.
Fig. 6 3 represents the making of the pattern for the pulley shown
in Fig. 10. The rim is ﬁrst built on the face plate of the lathe in
the following manner :—
Pieces of wood of the form shown at A being sawn to shape,
are truly planed on one side at least, and also at the ends, by the
help of a shooting board B, which is used as a guide; they are
then ﬁtted together to form the ﬁrst layers of the rim, by glueing
to the face plate, taking care to put a imp ofpaper oetween, which
is always done when work is to be afterwards removed.
When dry, this layer is turned to a true plane, and another
superposed in a similar manner, but so as to ‘ break joint,’ and so
on ; the whole is lastly turned on the face E, and, being carefully
removed, is reversed, and again turned on the back side. So
much for the rim. The plate of the wheel is next formed, as at C,
by halving one plank over another at right angles, these being
grooved to receive the ﬁlling quarters a a ,- the plate is next bored
at the centre to receive the boss, and turned on the outside (see D).
A rabbet having been formed in the rim to receive the plate, one
half the pattern is complete.
Fig. 64 shows the halving for a pulley of six arms, each batten
being cut to a fraction of its depth indicated by the ﬁgures ; and
Fig. 65 shows the method used for ﬁve arms, the boss being re
quired for fastening purposes. These are for the arms themselves.
The upright ribs, used to strengthen such arms (see Fig. 12),
would be halved on their narrow edges, and the boss ﬁlled in by
segments as at E, Fig. 65.
Pipes.—Patterns for small pipes are made out of the solid,
but those of a large size are built up as in Fig. 65a. Polygonal
half discs are placed at either end, and at intervals. Upon these
are carefully fastened with glue (and screws if necessary) the pieces
forming the rim. The two surfaces A and B being made true
planes, the half pipes are glued together with paper between, and,
having dogs driven in at the ends C, are centred in the lathe
Fig. 59. If ﬂanges are needed the ends would be turned as in
Fig. 66, and the ﬂanges ﬁtted in the manner shown.
Bent pipes cannot be built in this way, on account of the




Egg. 65.


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Building Pipes.







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impossibility of bending each lath of wood,- they are therefore
made as in Fig. 67, which shows a plan anduzend view. In the
example shown, the pipe must be worked out by gouge and spoke-
54 Turning Quarter Bends.
shave, and tried from time to time by applying the template D ;:
in fact, working in wood much as the moulder works in loam at
Fig. 2 5 in the last chapter.
A still more handy way of making quarter bends is to turn a
built-up ring of semi-circular section on the face plate of the lathe,
Fig. 60, and afterwards to cut into four equal pieces, as shown in
dotted lines, Fig. 67A. On removing and placing back to back,






. anti.‘



we have clearly two complete patterns, and ﬂanges may be added‘.
as necessary.
If a single bent pipe—of whatever form of bend (so that it be
in one plane)—-is required, it should be moulded as at Figs. 25,
26, or 26a; the pattern maker will supply the necessary tem-
plates. Curiously shaped pipes, of varying bore, may have a
- core box only ; the outer pattern being built by the moulder, who
lays thickness pieces on the core, smoothing off with loam ;
after taking an impression, the thickness pieces are removed (see
description to Figs. 25 and 26.)
Joints—Many other methods of jointing, besides halving and
rabbeting, are, of course, used, such as dovetailing and tenoning,
but we must content ourselves with a general notion of the making
of a pattern.
varnishing—When ﬁnished and sand-papered, the pattern
Core Boxes and Prints. 55
is carefully varnished so as to preserve it from moisture, and
present a smoother surface to the mould.
Core Boxes.—The simplest kinds are such as are shown at
Figs. 8, 10, and 14, where half the core lies in
each box. Pegs to unite them are formed by
knocking rough rods of wood through the steel
plates, Fig. 68, and then driving them into holes
in the core boxes (see a, Fig. 69). These pegs
need not have more than a quarter or ﬁve-
sixteenth projection, as, if they are longer, they
may stick. The exact correspondence of peg
and socket is found by pressing some little
object, such as a pin head, between the boxes,
and using these marks as centres. Pegs are
also required to unite the halves of patterns. Wooden pegs
are now greatly superseded by brass dowels (Fig. 68A.)
The hollows of cylindrical core boxes are gauged by the‘luse
of a property of the semi-circle—viz.,
that the angle contained by it is always a
right angle. So that the box may be
gouged out as in Fig. 69, and tried from
time to time with a set square.
More complicated core boxes have
been already drawn at Figs. 30, 31, 33,
and 41. The last one may be noticed as
a case of a box that must be loose on
every side in order to effect the safe _
removal of the core.
Core Prints.-—At this point we may consider shortly the different kinds of core
prints.
Simple cylindrical core prints are shown at Figs. 10, I 5, 18,
37 : they require a slight taper in direction of withdrawal. Some-
times it is necessary for economy to core the bolt holes in the
ﬂange of a steam pipe, especially if the holes are to be square.
A little consideration here of direction of withdrawal will
show that, if we used prints, they would need to be of a very
special kind, so they are usually dispensed with altogether,




56 Core Prints.‘
and a template given to the moulder of the shape shown at
Fig. 69a.
The cores, of a length equal to the thickness (full) of the
ﬂange, are pushed down to their place, and held there by friction.



Egg. 69.
Gang/gig (low (was.

But a case similar to the above might occur, when, on account
of the weight of the core or the accuracy required, it might be
advisable to have prints, and as plain cylindrical ones would not
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draw, as previously stated, we are obliged to have recourse to the
‘tail’ prints in Fig. 69o. Here A represents the pattern with its
prints, B is the core box for the hole, and c represents the ﬁnished
mould. The portions M are to be ﬁlled in by the moulder either by
hand, ‘or in the case of a difﬁcult shape, by cores made from boxes.
Core Prints. ' 5 7
Yet another form of print is required, where the core can be
supported at one end only. That part of the core lying in the print


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matrix has then the whole weight of the core to support, and must
in consequence be large enough for balance. Fig. 69c will explain
58 Worm Wheel Pattern.
what , is meant: where A is the pattern, B the core box, and
c the mould, the object being a ‘dummy’ gland for a steam
cylinder.
Referring again to the Worm Wheel in Fig. 12, the method
of making the pattern will be understood by the help of Figs. 70,
71, and 72. It may be built in the way shown for the pulley in
Fig. 6 3, and, after being turned on the rim, blocks of hard wood
are ﬁtted on each half of the pattern, and glued in the manner
suggested at D (Fig. 72). .
The outside surface of these blocks is now turned so as to
give a solid rim of wood, from which the teeth are to be cut. To
do this a stud A, Fig. 71 (on the table of a wood-working machine),
is ﬁxed at the angle of the worm thread, and the wheel pattern set
upon it, so that it can be rotated carefully the amount of the
pitch, by gearing, much on the same principle as in a moulding
machine. A revolving cutter B, driven at from 2,000 to 3,000
revolutions per minute, is advanced to the pattern, and cuts out
the space between the teeth; the diameter a’ of this cutter must
be the same as that of the worm. When this operation is com-
pleted, the wheel is removed and placed on stud c, Fig. 72. The
wrought iron worm intended to work with the casting, being
marked with red ochre, is now advanced, together with its wood
bearings, to gear with the pattern, and the worm is rotated; then,
wherever a little mark is left by contact of the worm, the wood is
gouged away until a perfectly correct ﬁt is obtained.
Spur Wheels too small to make by machine moulding may
have their teeth formed by the revolving cutter shown at B, but of '
course, in that case, the axes of wheel and cutter are at right angles.
For machine moulded wheels, either spur or bevel, the moulder
is to be supplied with a block of pine with two teeth dovetailed in
harder wood, as in Fig. 72a; (the machine is shown at Fig. 46).
In both sketches the direction of withdrawal is shown by the
arrows, and it will be seen that, although the bevel teeth withdraw
without difficulty, there would be some risk of the sand sticking to
the pattern in the case of the spur teeth, which are made truly
perpendicular and without taper. To avoid such an accident a
ﬁnger bit A is provided, which, ﬁtting in the hollow between the
two teeth, presses down the sand as the block is lifted.




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6o Bevel Pinz'ons.
In Fig. 72& we have the core box required for the arms of a
machine-moulded spur wheel; its description will serve also for
bevel wheels. A represents the casting to be obtained, having
six arms, and the box at B is so designed as to core out a space of
One-sixth of that within the wheel rim. The box being in the


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foundry is placed on a true table a, and after ﬁlling with loam, is
smoothed off with straight-edged batten at a Six of these cores
being dried and blackwashed, a pattern for the boss of the wheel is
now necessary to complete the mould.
Small Bevel Pinions require the patience of the pattern
maker. Referring to Fig. 73, which is the section of a bevel
pinion, it will be seen that the teeth vary in size from A to B,
and must, therefore, be entirely gouged out by hand. The body
of the pattern is carefully turned as at c c, while blocks D, for
the teeth, are planted on in hard wood and again turned, as in
the last example. The section of the tooth now being set out by
compass or template at A and B, the teeth have to be cut out and
ﬁnished by hand. The teeth at B are made correctly lineable
with those at A by means of the wooden spindle E, carrying a
straight edge F so cut as to be always truly radial when moved
round the surface A B.

Learn Boards. 61
All wheels of strange form, such as worm wheels and helical
wheels,‘ should really be formed by templates at different planes
of section, viz., at top, bottom, and centre of tooth, but more will
be said'of the shaping of wheel teeth in Part II.


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will?‘ .zaheeLm/ns.
Striking, strickling, sweeping, or Loam Boards—various-
names for the same object—are the only remaining patterns that
need mention. They should be bevelled off at the striking edge,
and their various forms can be readily grasped by reference to
Chap. I.
62 Allowance for Contraction.
Contraction of Castings.-—This is a subject involving
both thought and practice, and although a few general rules can
be given, success depends on very many points. It has been
previously mentioned that the moulder raps the rod that draws
the pattern from the sand. This rapping taking place in a

._ Smn/snr EDGE

horizontal direction, it is evident that the sides of the mould
only are affected by it.
The pattern maker must not only take account of this, but
also of the particular moulder he has to deal with, for some
moulders lift a pattern with less rapping than others. In small
castings, up to about six inches across, the enlargement of the
mould by rapping will be about compensated by the shrinkage of
the casting, but in large moulds, the amount of shrinkage will be
so much greater than the effect of rapping, that‘ the latter may
be entirely overlooked, account being taken only of the in—
Plate M ouldzng. 6 3
crease in size of pattern necessary to compensate for contraction.
Patterns two to three inches across, or less, should be made
about 3%,” smaller to allow for rapping only, and as this does not
take place in an upward or downward direction, there should
always be full allowance for contraction at these places.
The greatest shrinkage due to cooling will usually occur where
there is the greatest body of metal, and use must be made of
this knowledge by the pattern maker.
The linear contraction for different metals is as follows :—
Cast Iron . .. a" per foot = '12 5”
Brass T3?” ,, = '187”
Gun Metal 11;" ,, = '166”
Steel . .. ,, = ‘187"
Malleable Cast Iron T33,” ,, = ‘187"
Spur wheels about 2 ft. 6 in. diameter, contract 3-1?" per foot,
and such wheels vary their contraction, increasing to 110” per
foot for a wheel 10 ft. diameter (Box).
Three-foot rules are used to facilitate pattern work, longer than
the ordinary rules by the above fractions, and are called ‘Con-
traction Rules,’ but care must be taken that entire reliance be
not placed upon them.
When wooden patterns are made, from which are to be
moulded metal ones, a double contraction should be allowed,
on account of the two mouldings necessary to produce the re
quired casting in the ﬁrst case, and the consequent double
shrinkage.
Metal Patterns are required for light work or when a great
length of service is required. Such patterns are usually the same
as the wooden ones from which they are made; but there are
other examples of moulding with iron or brass patterns, as in
Plate Moulding. This is handy for such small articles as
occur in a brass foundry; Fig. 73a will show the method. A
wrought iron plate a is provided with half patterns on either
side, made in brass and carefully ﬁnished. Prints are run for
connecting each pattern, so making channels‘ for the ﬂow of the
metal. The plate also has corners b b, so that when put between
the boxes e e, and rammed up with sand, exact correspondence of
the boxes is obtained. Except for blackening and ﬁxing of

64 S topping-of.
' pouring gate, &c., the mould is now complete, and will, no doubt,
be admitted as economically made. Of course this method will
serve only when a large number of castings are required of the
same kind.





Barron- Jog




Stopping-off is a process which often serves to utilise a
pattern temporarily for a slightly different purpose to that ﬁrst
intended, and so to effect economy. A simple example will
sufﬁce.
In Fig. 735, a pipe pattern with ﬂanges is shown 5 we will
suppose a shorter bend is required.
All that is necessary is to ﬁx a flange on at A, and provide a
stopping off piece B of the same size as the ﬂange, having a print
attached for the core.
0 represents a plan of the mould, with the stopping-off piece
in position 5 the portion D being ﬁlled up by the moulder. The
rest of the moulding will be easily understood.
Cnain Barrel in Loam. 65
In the propeller which we moulded in our last chapter
(Fig. 35) a screw template was placed outside the mould. There
are cases, however, when a screw is to be moulded in loam, but


STOPPING PI£CE
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MOMLD
73 b.
where the course mentioned cannot, for certain reasons, be
followed. Such is shown at Fig. 73c.
A Chain Barrel for a crane is formed with a helical groove
to receive the chain. A is the casting required ; B shows the
striking out of the loam, and C the ﬁnished mould. The only
portion requiring explanation is the screw d, made of hardwood.
It is ﬁxed to the bottom plate, and has the same pitch as the
chain groove, though, of course, a more abrupt rise (for this
reason made as large as convenient). The striking board runs on
the screw, being supported by a roller, and balanced by weight, as
in the case of the propeller.
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C rystallizatzon. 67
The rest of the mould is self-explanatory with what has gone
lbefore, and is entirely formed by loam boards.
Rapping plates have become a necessity in order to prevent
injury to the pattern by the moulder.
They are shown at Fig. 73a’, and are
screwed to receive a lifting rod as there
:shown.
Crystallization of cast iron. --
During the cooling of a casting the
crystals arrange themselves in lines per-
pendicular to the surface, but the interior
portion, being cooled more slowly, pre-
serves its granular nature. Fig. 74 will rial
:show the appearance of a bar of cast
iron when broken longitudinally (the W
ﬂﬂNoLi
my Plate
student should clearly understand that Pwre
"the markings are exaggerated). GD @
If the corners of the casting are made 0
‘quite sharp the crystals will be abruptly 0'’ a 0D


turned at these places, and, meeting each
other also abruptly for some distance , - ,... _
below the surface, namely, as far down
as they are formed, will create a line of
fracture or portion weaker than the rest. Whether these corners
be external or internal, matters not; the same thing happens.
Fig. 75 shows other examples having ‘re-entrant angles,’ as they
are called, A being a circular boss cast on a plate, and B a cylinder
with ﬂanges. It will be clear that breakage would always occur
more easily at these sharp angles.
When the Menai Bridge was built, the hydraulic press made
for the purpose of lifting the ‘tubes’ had a ﬂat bottom with
pretty sharp corners, as will be understood from Fig. 76, which is
a sketch of the press ﬁrst used. Stephenson took the precaution
-of building up at each 10 inches of lift, and had it not been for
this, great damage might have occurred, for the bottom of the
press suddenly gave way, and the tube fell through a space of ten
inches. Fig. 77 represents the press since adopted, the crystals being
allowed to take a gradual turn, so as to leave no line of fracture.
68 Re-entrant A ngles.
It is a general law that there should be no abrupt corners in a
casting, either external or internal, principally for the reasons

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already given, and also to permit of an easy ﬂow of the metal, and
prevent the breakage of corners of sand.
U negual S lzrinkage. 69
Warping and Shrinkage of Castings—The general
effects produced by unequal shrinkage during cooling should
be well understood in designing a casting. These may be pretty
well arrived at by the consideration that, other things being equal,
those places will cool last where the largest amount of metal is
aggregated. Our ﬁrst rule, therefore, is to endeavour to keep the
Casting uniform in thickness. For unequal cooling is sure to
produce internal strains, and tlzatportion cooling ﬁrst will set, and
le compressed by the contraction of the part tlzat is still cooling.
Besides, if a thin part join a thick part very abruptly, the cooling
may produce such strains as to break the thin piece away
altogether. We ought therefore to make the juncture of unequal
thicknesses as gradual as possible.
Take a Plate, Fig. 78, lying on a surface of sand. The top
part cools ﬁrst, on account of being open to the air, while the
under surface is still in Contact with the hot sand, and the eﬂ'ect
of cooling is to make the plate convex on the upper surface, by
the after contraction of the lower surface.
In a Hollow Cylinder, Fig. 79, the heat cannot pass
through the core so quickly as it can from the outside, so the
latter cools ﬁrst, and the cylinder is made barrel-shaped by the
contraction of the interior. We must also note that the outer
layer will be in compression (see Fig. 83), which is a cross section.
A Solid Ball will be found porous on the inside, if broken,
because the shell sets ﬁrst, and the internal metal, being thus held
fast, is bound to leave vacuities on shrinking.
A Girder of the form sketched in Fig. 80 will curve longitu—
dinally in cooling, for here the most metal is collected in the
larger ﬂange, and the casting is therefore pulled together on that
side, after the top web has cooled.
A Pulley with a thin rim, as in Fig. 81, will cool last at the
centre boss, and so produce a compressive strain in the rim; if
therefore a piece were broken out at A it could not be returned.
Shrinkage occurs while the metal is cooling from a red heat
downward, and the moulder can do a great deal to prevent it
occurring unequally by uncovering at the red-hot stage those
portions of the casting which are likely to retain heat longest, and
by keeping others covered, for equal cooling means equal shrinking.









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How A voided. 7 I
Hollow cylinders of all kinds are better moulded by inserting
an iron tube in the core, through which cold water is allowed to
circulate, and this can be so regulated as to produce a tensile
strain on the outside metal if needed, or, what is better, no strain
at all.
The pulley previously mentioned can be improved by curving
the arms, as in Fig. 82, thus giving them sufﬁcient elasticity to take
the strain off the rim ; and such an example as the girder must be
left to the moulder’s ingenuity.
CHAPTER III.
METALLURGY AND PROPERTIES OF MATERIALS.
IT will be well, so as to avoid repetition in succeeding chapters,
to digress somewhat, in order to consider the properties, and to
some extent the metallurgy of the materials used in mechanical
engineering, omitting only the consideration of their strength,
which will be treated of in the second part of this work.
These materials may be classiﬁed as follows :—

1. Cast Iron. 8. Gun Metal.
2. Wrought Iron. 9. Brass.
3. Cast Steel. 10. Phosphor Bronze.
4. Forged Steel. II. Muntz Metal.
5. Copper. 12. Manganese Bronze.
6. Zinc. 13. White Metal.
7. Tin. I4. Wood.
But we must ﬁrst become acquainted with such chemical
elements as are necessary to understand the processes we intend
to consider. Such are: Carbon (C), Silicon (Si), Iron (Fe),
Sulphur (S), Phosphorus (P), Manganese (Mn), and Oxygen
Carbon is an allotropz'e element, that is, it exists under
different forms, which are: Charcoal, blacklead, and diamond.
The ﬁrst is pure carbon, and so is coke, or nearly so. The
second is not lead, and is also called graphite and ,Mamﬁago; and
the third is the crystalline form. If carbon is allowed to unite
with oxygen it forms carbon dioxide (CO2), a gas. Carbonic oxide,
or Carbon monoxide (CO), is another gaseous combination of
carbon and oxygen.
A chemical combination is the union of elements in such a way
that they could only be separated by chemical action, while a
mechanical mixture requires only mechanical means (very often
ﬁltration) to break it up.
Cast Iron. 7 3
Silicon exists in combination with oxygen as silicon dioxide
or silica (Si 0,), and is so found in the crystals of sea-sand ; glass
is a mixture of several silicates.
Iron is found in combination with oxygen, the ore being
termed a ferric oxide (Fe2 Os), but it may be rendered quite pure
by chemical and mechanical means.
Sulphur is well known in the form of brimstone, and is con-
sidered an impurity in iron.
Phosphorus and Manganese are to some extent impuri-
ties, but may be of great value when mixed with iron and other
metals in certain deﬁnite proportions.
(I.) Cast Iron.-—-There are seven varieties of iron ore, con-
taining from ﬁfty to seventy per cent. of iron in their composition.
The blast-furnace (Fig. 84) is used for smelting the ore, which is

9109
\\
done at a very high temperature, with coke as fuel, and lime ‘or
clay as a ﬂux.* The molten iron is run into pigs, while the slag
* Lime is the usual ﬂux, but clay is sometimes required, as in the case of
hematite ore, and then is applied in the form of clay ironstone.
74 Blast-fa rnace Action.
formed by the combination of the ﬂux with the impurities of the
ore, is separately withdrawn.
The action in the blast-furnace is this :—-Air being introduced
by the blast to give us oxygen, and coke to provide carbon; then,
if the coke be heated to redness, carbon dioxide is formed,
From
Air. Coke. Gas.
20 + C = C02
As this gas ascends it takes up carbon from the coke, which it
passes on its way, thus:
Carbon Carbon
diox. Coke. monox.
COQ+C = 2CO
And we now have carbon monoxide.
Ascending further, this last-mentioned gas meets the iron ore,
which is now at a great heat. The oxygen in the ore has then
the choice of remaining where it is (Fe203) or of combining with
the CO ; preferring the C O, it forms with it carbon dioxide once
more,
Carbon Carbon
monox. Ore. diox. Iron.
3C0 + 2Fe,,O8 = 3C O2 + 4Fe
And the iron is now left, but in a viscous condition. As it takes
up carbon, however, it becomes more ﬂuid, descends to the
bottom of the furnace, and may be then run out.
Other substances have also been absorbed, which may be seen
on reference to the table at the commencement of Chapter I.,
shewing the general composition of the different pigs—grey,
mottled, and white.
Sulphur produces red-shortness in cast iron, that is, makes it
brittle when red hot, and Silicon and Phosphorus cold-shortness,
or brittleness when cold.
Carbon increases ﬂuidity at the expense of strength, and
Manganese seems to have the effect during the smelting of in-
ducing the combination of the carbon with the iron, thus tending
to prevent‘ the formation of graphite. ' '
_ (2.) tWrought Iron.--The white pigs are broken up and
subjected to the processes of reﬁning and paddling. As, however,
Paddling. 7 5
these are chemically the same, and the preliminary reﬁning is
very often dispensed with, we will give our attention simply to
the preparation of wrought iron by puddling.
The object of puddling is to eliminate the graphite entirely,
and the combined carbon so far as to leave only about '25 per
cent, which actually increases the strength of the iron.
In the rolling mill, where the metal is rolled into plates or
bars, scales of oxide of iron (Fe2 0,) are formed by the contact
of the hot iron with the air. These scales, being broken off,
are collected for the puddling furnaces, their use being that
of absorbing the carbon from the iron, exactly in the way already
described for malleable cast iron.
Being intimately mixed with the broken white pig in the
puddling furnace, Fig. 85, and subjected to a powerful ﬂame, the
(0) from the oxide unites with the (C) of the iron, and passes
away as (C 02) gas. Any silicon that is present in the iron
unites at the same time with some (0) and forms (Si 02), so that
the iron is left comparatively pure. During the process, the iron
is in the form of a spongy mass, and absolute contact of it with
the scales of oxide, now liquid, is ensured by the introduction of
a long rate through a small opening in the side door, for the
purpose of stirring the whole well together.* As the puddling
nears completion, the metal is kneaded by the rake or paddle
/ /
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* To avoid hard labour and increase the output, there are many mechanical
furnaces now in operation, notably Danks’ Rotary Furnace, and the Pernot
Revolving Hearth.
76 Puddled Bar.
into balls or blooms, and these are then removed and compressed
under a steam hammer by rapid blows, so as to squeeze out the
slag. The blooms are next rolled out and further squeezed by
being passed through the rolls of a rolling mill, giving us iron
called Pnddled Bar.
These bars are now broken up and re-worked by hammering
and rolling, more or less, depending on the degree of purity and
strength which is required, and we thus have the varieties of
wrought iron known as—eonzmon, best, doable best, ‘and treble best,
which are used for various ordinary forgings, while Low Moor iron
is required for the ﬁre-boxes of steam boilers and for more
difﬁcult forgings.
The puriﬁcation of the iron obtained in a puddled bar is
shown by the following table, which may be compared with the
table showing the composition of white pig :—
Table shewing chemical composition of Pnddled Bar in

percentages.
Iron. 99'3I
Combmed Carbon '3
Silicon '12
Sulphur ‘I3
Phosphorus ‘I4
roo'oo
Wrought Iron during its conversion from the pig, has lost
the capability of being cast into moulds, but has acquired a new
nature, becoming oz'seous or sticky, and, as a result, may be worked
by the smith, when white or red hot, its formation into different
shapes being assisted by the property of welding, which as cast
iron it did not possess. Repeated rolling gives a ﬁbrous quality,
making the iron both stronger and more homogeneous or uniform
in texture, and these ﬁbres may be seen on breaking a bar of
rolled iron, which then has the appearance shewn at A, Fig. 86,
while cast iron or even puddled bar gives a granular fracture (B).
Rolling or hammering iron when cold or nearly so gives it a
crystalline structure near the surface, so that T iron is not so
strong as bar iron, and plates still weaker. Re-heating and slow
cooling tends to remove this source of danger.
Composition of Steel. 77
Generally, then, wrought iron is tough, and more capable of
resisting vibration than cast iron, its ﬁbrous character giving it
also a distinct advantage in the direction of the ﬁbre, which
property may be made use of by judicious crossing in the opera-
tions of filing and re-heating the iron after puddling.
Wm!" man cnsr men


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The best forgings are usually made by the filing of wrought
iron scrap.
(3 and 4.) Steel is intermediate in composition between
wrought and cast iron, thus :
Cast iron may have 2 to 5 per cent. of carbon.
Steel (for casting) 1'8 ,, ,,
Steel (for forging) ' 5 to 1'5 ,, ,,
Wrought iron ‘25 7) 79
It will be clear, however, that the exact limits between which
we may ‘call the substance ‘steel,’






without intruding on either wrought or CAST ,_ 57°
cast iron, are very difﬁcult to deﬁne, so __ ,
that we may have steel which is almost 2'31 r81-
as brittle as cast iron, or we may have mass (.51,
it on the other hand nearly as soft as SALES‘; .57.,
wrought iron. imp; -25 ‘72.
Although steel has an intermediate .
composition, it has not, as we might
. . . Car/bow
expect, an Intermediate tenacity or use, 7W5:
but is stronger even than wrought iron
and consequently more useful. It never has, however, the
toughness of good wrought iron, although many operations are
performed on it to improve that quality.
It will also be readily seen that, as steel is intermediate in
78 Cementation Process.
composition, it may be made either from wrought or cast iron.
We shall ﬁrst consider the former method.
Cementation.—In this, the oldest process, bars of wrought
iron are placed in ﬁre-clay boxes, Fig. 88, with charcoal dust
around and between them, and a layer of ﬁre-clay over all (this
being the cement giving the name to the process). Being then
subjected to a bright-red heat, for a time varying with the amount
of carbon required to be introduced, and which may be as much
as a fortnight for the more highly carbonised steels, the charcoal
has now become combined with the iron, and the steel so pro-
duced is called blister steel, from the fact that the bars are covered
with blisters. These bars are next broken up, piled, and heated
in a furnace almost exactly like the one in Fig. 85, hammered by
rapid blows from a tilt-hammer, Fig. 89, and shear steel of a



ﬁbrous quality is thus produced.*_ Double shear steel is made by
breaking in two and re-hammering. Crucible cast steel is obtained
by melting fragments of blister steel in covered crucibles made of
a mixture of ﬁre-clay and plumbago, and placed in sets of six or
twelve in furnaces having a similar section to the one shown in
* The steam hammer is used in recently built works. For drawing, see
Chapter IV.
. Bessemer Process. 79
Fig. 50. Several of these crucibles are poured simultaneously to
form the ingot, many well-drilled workmen co-operating to do it
carefully. This variety of steel is much more homogeneous and
has a greater tenacity than shear steel, having a ﬁne granular
structure. Brittleness is corrected, and the property of weld-
ability restored by the introduction of manganese in the form of
carbonate of manganese. '
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The Bessemer Process is used for the purpose of obtain-
ing steel from cast iron. Fig. 90 is intended to show the neces-
sary plant employed. The converter A is ﬁlled with molten cast
iron, and air is blown through the metal by means of the tuyeres
at the bottom. The (O) of the air combines with the (C) of the
iron and passes away as (C 02) gas, leaving the mass as pure iron,
8o Open-beard: Process.
the silicon forming a slag (Si 02) on the surface, which is
separately removed. The temperature must be exceedingly high
in order to preserve the iron in its ﬂuid state after the expulsion
of the carbon; the entire absence of the latter is discovered by
the application of the speetrosoope, this being the most practical use
of that most wonderful instrument. The next operation‘ is the
adding of so much carbon as is needed to produce the steel re-
quired, and this is done by putting into the converter a measured
amount of very pure cast iron called Spzegelezlsen, and mixing it
well with the metal by re-applying the blast for a short time. The
now converted steel is transferred to the ladle B, which is swung
round by the crane c, and the metal poured into the ingot through
the hole D on releasing the plug at the bottom of the ladle.
The ingots may be afterwards piled and rolled as previously
i described, to produce a ﬁbrous steel, and if used for forging and
welding purposes should not have too much carbon in their com—
position 5 or, if required for steel castings, may be re-melted in
suitable quantities, much as in the way already mentioned for
cast iron.
Siemens-Martin, or open-hearth process, is carried on in a
special kind of furnace, called a regenerative furnace, invented by
Dr. Siemens. Fig. 91 is a drawing which will show all the neces-
sary parts. A is the hearth, sloped in the side elevation, so that
the metal may run out when tapped at T. A current of air is
allowed to pass under the hearth at c, to prevent the melting of
the ﬁre-clay. The combustion of a mixture of common coal gas
and air is the source of heat, the arrows showing the passage to
the interior of the gas through the valve G, while the air enters
through the valve A. In the ﬁgure the mixture is seen entering
the right side of the furnace. Being ignited at J by means of a
red-hot bar, gradually and carefully at ﬁrst, the ﬂame is directed
by the roof on to the metal, and the heat passes away by the left
side of the furnace, returning through the valves and past the
damper D to the chimney. Were it not, however, for Siemens’
beautiful regenerative principle a great deal of heat would be
wasted. The regenerators are shown at RRrr 5 they are hard
ﬁre-clay or silica bricks piled as a grating. The rejected heat
from the ‘hearth is intercepted by those marked R R, so that
Regenerative Furnace. 8 1
although the mixture enters at 700° F. the products of combustion
pass to the chimney at 200° or 300° F. In a short time the bricks
become white hot, and the valves AG are then reversed as is
shown at v1 and v,, the former being the position for the action
already mentioned, and the latter allowing the gas and air to
daemons ’ Regenemczlv/e Furnace.


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enter ﬁrst the leﬂ side of the furnace and leave on the opposite
side. Doing so, it is evident that the heat which was absorbed in
the last operation by the regenerators R R is now taken up again
by the entering gases, and the bricks rr, in their turn receive the
rejected heat.
By this means a large amount of heat is made useful. which
G
82 Whitworth Compressed Steel.
would otherwise be wasted, the valves being reversed regularly
whenever the bricks acquire too much heat.
The furnace is ﬁrst charged with pig iron, and when this is
melted, heated wrought iron and steel scraps are added by'
degrees (these three in nearly equal proportions). When all is
thoroughly mixed a little piece of cast iron, in the form of
spiegeleisen, is added, together with a very little manganese.
Experience, the principal guide for this mixture, is again called
into play immediately before completion of the operation, the
foreman trying small samples taken from the furnace and cooled
in water, by breaking them and examining the fracture. If satis-
factory, the steel is now poured into ladles by tapping at T.
As soon as the metal ceases to ﬂow easily it is known that
there is only slag left. The ladle is then removed, and the slag
allowed to run to the ground or into moulds.
The Landore-Siernens process, also the patent of Dr.
Siemens, differs in the fact that iron ore is used direct. On being
ﬁrst reduced and the slag got rid of, it forms spongy balls of
malleable iron, which are then dissolved in molten pig iron,
spiegeleisen being added as before. It often receives the name
of the ‘ pig and ore ’ process.
In the Siemens process the ore and ﬂux are mixed direct
with the pig ; more slag is therefore produced.
Steel Castings made by any of the above methods must
be annealed slowly in a closed furnace for a week or more,
to prevent cold-shortness. Honeycombing, or the presence of
vacuous spaces in the metal, is the principal trouble, and is partly
prevented by the addition of silicon, as silicoferromanganese,
but is only perfectly got rid of by the Whitworth process, where
the molten ingot is compressed by powerful hydraulic pressure
until it is quite set. The great advantage of this compression,
which amounts to from six to twenty tons per square inch, is
shown by the fact that the ingot is made to contract as much
as one-and-a-half inches per foot of length. The mould consists
of a steel cylinder, lined with refractory material, and so con-
structed that when placed under an hydraulic press, the gases
may escape through the sides of the mould.
We may always expect highly carbonised steel to be deﬁcient
C opper. 83
in toughness, and therefore inferior to wrought iron in that
respect. It may be improved by the annealing spoken of, but
steel that is required for boiler or bridge work, must be capable
of resisting vibration, and so a milder quality is used, which,
though it may be very little stronger than iron, is more homo—
geneous and has a ﬁner grain.
The amount of carbon varies with the use to which the steel
is to be put, and is shown by the following table :—


Razor temper .... .. 11} °/° Carbon .... .. Will spoil with over heating.
Sawﬁle ,, .... .. 1% °/° ,, .... .. To be heated only cherry red.
Tool ,, Ii °/° ,, .... .. May weld with great care.
Spindle ,, .... .. 1% °/o ,, .... .. Ditto.
Chisel ,, .... .. I 0/o 7, .... .. Tough ; will harden at low heat.
Sett ,, % °/° ,, .... .. Stands hammer ; welds easily.
Die ,, .... .. {,1 °/o ,, .... .. Stands pressure ; welds like iron.

Cutting tools require most carbon.
Temyerz'ng, or the capability of receiving any degree of hard
ness, is a property of steel, and was formerly applied as a test
to distinguish it from wrought iron; while ease-Izardenz'ng is the
method of partially converting wrought iron into steel, but both
these subjects will be reserved for our next chapter. '
Test—A rough test to distinguish between wrought iron
and steel is to put a drop of dilute nitric acid on the
polished metal, when a greenish-grey stain will indicate iron,
and a black spot will show steel; the denser the black, the
more carbon may be suspected, so that we may even get a notion
of quality.
(5.) Copper Ore is various in character, but may have iron,
sulphur, antimony, or arsenic associated with it. The operations
are three in number :—-(I) Roasting, to get rid of arsenic and
sulphur, the iron forming an oxide. (2) Smelling, to dissolve
the iron oxide, and leave copper combined with sulphur. (3)
Roasting and Smelting, to remove the sulphur and obtain metallic
copper. The furnaces used throughout are of the same class as
the puddling furnace, Fig. 85, and called reoerleratory on account
of the arch beating bark the ﬂame. Other reﬁning processes have
84 Gun Metal.
to be gone through before the metal is considered ﬁt for the-
market.
The metal thus obtained is rolled into plates and hammered
to any shape. Besides its malleability it is exceedingly ductile,
being easily drawn into wires 5 it becomes brittle if hammered
cold, but its tenacity may be restored by annealing.
Copper is an expensive material, and is only used for pipes
that require bending cold, and for ﬁre-boxes, where ductility as
well as power to conduct and resist heat are needed : it must be
remembered, however, that copper loses its strength ‘somewhat
with increase of temperature. .
It is also very useful for electrical purposes, being, next to
silver, the best metallic conductor. -
(6 and 7.) Zinc and Tin are of little importance singly to the
mechanical engineer.
(8.) Gun Metal is an alloy of Copper and Tin, and is often -
called bronze. The proportions are varied for different purposes.
Thus to make 100 parts :—
Copper. Tin.
Soft gun metal requires 90 10 (General Ordnance purposes.)
Hard gun metal ,, 82 18
Bell metal ,, 8o 20
Usually some zinc is added to make the metal more
malleable, as :—

Copper 84'22
Tin 10'52
Zinc 5'26
IOO'OO
Gun metal produces ﬁne castings, and being much stronger
than cast iron, is almost the only other metal preferred
besides cast steel, for the castings required in modern
gunnery. It is often in its harder form made into bearings
for shafts. Both strength and toughness are increased by rapid
cooling.
(9.) Brass is made by alloying copper with zine. The pro-
Bronzes and Brasses. 8 5
portions vary somewhat, depending on the colour and strength
required.
Parts Copper °/° Parts Zinc °lo
666
Fine yellow brass has 333
The proportion of copper may vary from 66 to 70 per cent., or
even higher. A little lead is sometimes added. Brass is principally
used on account of its ﬁne colour, and because it is easily tooled.
(10.) Muntz Metal is a brass having the proportion of 60
per cent. of copper and 40 per cent. of zinc. It is largely used
for bolts in marine work that are liable to rust, and especially for
pins that have to turn in their sockets, on account of its great
strength, as well as the faculty of being forged, which it possesses.
(11.) Phosphor Bronze is, like gun metal, a mixture of
copper and tin, but with the addition of a small measured quantity
of phosphorus.
Its strength is so much increased as to be equal to that of
wrought iron, and it has consequent-1y been extensively used,
within recent years, where strength is required, coupled with
intricate form, such as must be cast rather than forged; as for
example, toothed wheels subjected to shock. Gun metal is
deteriorated by subsequent meltings, while phosphor bronze may
be re-melted without injury.
It has considerable ductility, and may be formed into wire, and
‘used for spiral springs subjected to steam or water.
(12.) Manganese Bronze-is of recent introduction, and is
‘the same as the last, except that manganese takes the place of
phosphorus, the proportion being about 7 lbs. manganese per cwt.
-of bronze. The strength is thereby still more increased; and it
is used now for a variety of purposes where strength and ductility
are required combined, such as hydraulic pipes, which may be
then drawn considerably thinner than copper ones; and it is
advantageous in many other cases, as may be understood from the
fact that it may be both cast into moulds and forged under the
hammer. It can also be used to resist rust, so as to keep nuts
and bolts free that would otherwise sieze.
(13.) White Metal, otherwise white brass, and in America
Babbitt’s Metal, or ‘ Babbitt,’ is an alloy used for lining bearings.
Tin is the principal metal used, and is mixed with copper and
86 _ Brazing.
antimony in varying proportions, the following percentages being,
principally used :-—
Copper 8 , 3
Tin 84 90
Antimony 8 7
I 00 1 00
One advantage of white metal for bearings is that it can be
run into the bracket when the journal is in place, and so ensure a
good ﬁt. It causes considerably less friction than brass or.‘
bronze.
To sum up then, alloys of copper and tin are termed bronzes,
and may have a little zinc added up to about 1% or 3 per cent..
Those of copper and zinc are called brasses, Muntz metal being;-
one of them; and those having tin and antimony, with a little-
copper, are white metals. I
Brazing—Brass or gun metal may be united by this process,
which is also termed hard soldering; and the joint will be as.
strong as the original casting.
Iron or steel may be also connected by brazing if more
convenient, especially ﬁnished pieces of work. The method is to’
ﬁrst carefully clean the work with acid, then take some brass
ﬁlings and mix with powdered borax as a ﬂux, the borax being,
preferably moistened with water. The ﬁlings are placed between
the parts to be brazed so as to form a joint, as much surface
being used for the latter as possible, and the two are held together
in red-hot tongs, having thick jaws to keep the heat. The tongs
will melt the ﬁlings and grip the pieces until perfectly set, and the
whole may be ﬁnished off in the vice.
If the work cannot be easily gripped, another way is to insert
the ﬁlings as before, and, binding with iron wire, place the pieces
in a clean coke ﬁre until the operation is complete.
Or, still another method is to use the blow-pipe. Here a ﬁne
tongue of very hot ﬂame is directed on to the work by blowing with
this instrument through a lighted ‘ Bunsen.’
(14.) Wood is not used to so great an extent as formerly.
Roofs are made of wrought iron; and men-of-war of iron and
Wood. 7 87
steel instead of oak: pillars of cast iron: while morticed wheel
teeth are almost out of fashion. Brake blocks, too, are made of
cast iron, to give a longer time of wear ; and wooden buffer beams
for locomotives are now being discarded.
Little then need be said of wood. For pattern-making, as
already stated, pine, mahogany, cherry, sycamore, lime tree, and -
walnut are the woods used. English oak is the best for beams,
but American oak is much cheaper, and the latter is used for the
framing of railway and traction waggons, and for locomotive
buffer beams. Ash is also much employed in waggon work,
especially for cart shafts. Mortice teeth are made of heech or
hornbeam. Lzgnum vita is of great service for bearings that are
immersed in water as, for example, with the screw-propeller and
some turbines. '
Railway sleepers are rendered very durable by impregnation
with creosote or-black oil, air being ﬁrst sucked from the pores of
the wood. The creosote is then forced in at great pressure.
The following table gives the melting points in degrees
Fahrenheit of the principal metals mentioned in this chapter :—
Cast Iron ....... .. 275o°F. Zinc ............. .. 773°F.
Wrought Iron .... .. 32 50° * ; Tin ................ .. 442°
Steel ............. .. 32 50° Gun metal ....... .. Igoo°
Copper .......... .. 1996° @ Brass .... .. 17oo° to 1900°
* Castings of ‘ wrought iron ’ have now been made, though the process is '
somewhat intricate, and has not as yet been extensively applied. The method ‘
consists principally in lowering the high melting point of wrought iron by the
addition of aluminium. Swedish wrought iron is used, and from ﬁlm to 7%,,
of its weight of aluminium is mixed with it.
CHAPTER IV.
SMITHING AND FORGING.
WROUGHT iron is formed into the required shape by drawing
down and bending while hot; but if there should be insufficient
‘stuff,’ or if it should be more difﬁcult to entirely ﬁnish by
drawing down, recourse is had to welding.
The working of de-ca'rbonised iron may be best treated under
two heads, smit/zing and forging. The ﬁrst includes the making
of such as the smaller objects which can be conveniently done at _
a smith’s ﬁre, while the second term may be applied to the
shaping of all articles that require heating in a close furnace, and
ﬁnishing under a heavy steam hammer. In either case the result
is denominated a forging.
THE SMITHY.
We will ﬁrst consider shortly the plant and tools employed by
the smith.
The Hearth.—-This is represented in Fig. 92. A is a sectional
elevation, and B a front view. It is necessary to explain here that
the smith may arrange his coal on the hearth in two distinct ways,
the one being called an ‘open’ ﬁre, and the other a ‘ stock’ ﬁre.
The hearth shown in Fig. 92 is by Messrs. Handyside, and is .of
iron throughout. It is only adapted for ‘ open’ ﬁre working,
being short in length from a to b. a is the tuyere or blast nozzle,
constantly surrounded by water contained in the tank e, so as to
avoid burning at the outlet, or the accumulation of caked slag.
The work to be heated is placed in the hollow portion of the
hearth surrounded by coal, and as the coal burns away more is
supplied from the hillock b. It will then be seen that there is no
special diﬁiculty in arranging the coal for ‘ open’ ﬁre working.
‘ Stock ’ working requires a certain amount of trouble in ﬁrst pre-
paring the coal, which is usually done ﬁrst thing every morning.
After this ﬁrst preparation it will, however, keep in working order


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STOCK
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90 Smith’s Fire.
for the rest of the day, and has many advantages, as will be seen.
Fig. 95 represents an ordinary smith’s hearth, built up partly of
brick and partly of iron. a is the blast nozzle, which need not
now be surrounded by water, because the ﬁre will never be nearer
to it than the position marked b, and so no caking can happen.
In building the ‘ stock’ a loose brick is ﬁrst taken out at c, and a -
bar passed through and inserted in the tuyere. The coal is now
damped by sprinkling water upon it with a wisp of straw, and is
built up into the form shown, the ridge d being neatly ﬂatted
down, by using the back of the shovel. Beginning at the tuyere
and advancing frontwards the ‘ stock’ is ﬁnished round the piece
of wood e, which is called the ‘stock block.’ We may now
remove both bar and block, and make the ﬁre in the space e.
The iron to be heated is placed in this space and covered up with
loose coal, which is always brought from the front end c, so
that the stock gradually burns away to the end b by the close of
the day. The advantages of ‘stock’ working are these: (1) we
need no water tuyere nor consequent attention to water supply;
(2) the bar to be heated is only acted on by the ﬁre to the length
required (whereas ‘S'open ’ working has a tendency to heat it to a
greater extent) ; and is generally more economical.
The Blast.—Air is constantly supplied to the ﬁre, when
working, by means either of bellows, fan, or blower, one of the
two latter being in use at an engineers’ smithy, where all the
ﬁres are connected to one main blast pipe. Fig. 95A, Plate 1.,
represents a fully equipped smithy, as designed by Messrs.
Handyside, and ﬁtted with their hearths throughout. The
main blast pipe is shown by the dotted lines in plan.
Fig. 93 is a drawing of a Fan by Sturtevant. There should
be a good large space left beyond the vanes, to allow the velocity
energy given to the air by them to be easily transformed into
pressure energy in the pipe, and so prevent waste by eddies.
Roots’ Blower, as made by Messrs. Samuelson, of
Banbury, is shown at Fig. 94. The air in this machine is
literally scraped out of the casing on the side A, by the revo-
lution of the two ﬁgures s s, in opposite directions, and is delivered
at B, a fresh supply replacing the partial vacuum formed. The
rollers, as the above ﬁgures are called, are compelled to work
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correctly by the introduction of equal spur wheels, shown dotted
at cc, being covered by a casing, and the shafts are rotated in
opposite directions by means of crossed and open belts, as shewn
S m ith’s Tools. 9 3
in the side elevation. The power absorbed in running this
machine is very slight, and the speed need not be more than 300
revolutions per minute. A fan, on the other hand, to be effective,
must be driven at a great velocity, say from 1000 to 2000
revolutions per minute; more shafting and pulleys are required,
as shown in Fig. 93, and the percentage of loss by friction is
consequently high.
Tools—Among these we must ﬁrst mention the Anvil.
Fig. 96. It is made of wrought iron, and has a surface of steel
about a quarter of an inch thick welded on at A to form the top
face; B is the heah or horn ,- C and D are square holes to receive
‘bottom’ tools, and E E are used in punching. At Fig. 96B is
illustrated a French anvil. It is not provided with any holes,
the swage block (described later) serving instead.
Two kinds of Hammer are required: the hand hammer
weighing two-and-a half to three lbs., for the smith; and the
sledge hammer, used by his helper, weighing from eight to four-
teen lbs., and even more. If the sledge is only worked by lifting
over the shoulder, a short handle is used, say three ft. long, but,
when swung, in making heavy forgings, a long shaft is required,
the right hand being drawn inward to the end as the hammer
approaches the work, thus giving the latter the full effect of the
stored energy.
Other tools, shown in Fig. 97, are principally for the purpose
of ﬁnishing work for which the simple hammer would be in-
suﬂicient. They often go in pairs, as top and bottom tools, the
smith holding the ﬁrst by means of a hazel rod wrapped round it,
while the second is placed upright in one of the square holes in the
anvil. A A are chisels, B B fullers, C is a ﬂatface or ﬂatter, D a punch,
and E E are savages. The last term is applied to any specially-
shaped top and bottom tool designed for the purpose of ﬁnishing
work with greater ease and accuracy to a particular form, such as
round, hexagonal, &c. F is a set hammer, having either a square
or circular face ; it is held steadily on the work while being struck,
so that in that sense it is not a hammer at all. It is convenient
as a top tool to reduce work or ‘set’ it down, the anvil serving
as bottom tool. G is a ‘heading’ tool, useful in making the
heads of bolts and pins. It is held by the hand at one end







S tea 1n Hammer. 95
while the hot bolt is driven through one of the holes, and, being
retarded by a slight shoulder at the end of the bolt, the head is
formed at that place. The process is shown at B, C and D,
Fig. 104. Ferrules, H, serve to stamp the bosses of small levers.
Of course it must be understood that a good set of tools will
include several different sizes of those above mentioned. They
should all be faced with steel where subject to concussion.
Tongs are shown at Fig. 98, and have several different forms
at the ‘nose’ or ‘bit’ where the work is gripped, such as ﬂat-
nosed tongs (A), round-nosed (B), or angular-nosed (0). They
should be made to take work from a quarter of an inch to
three inches thick, and all of them are more useful if bent out as
at C, so as to admit a bolt-head or collar.
An important adjunct to the anvil is the Swage Block,
Fig. 99. It can be set up in any position, and serves to ﬁnish
several different forms of forging, the holes being for heading
purposes. The swage block is usually made of cast iron, though
cast steel is now often preferred.
The smith having to hold the work in the tongs with one
hand, he wields the hand-hammer with the other, where plain
forging is required, but when top and bottom tools have to be
applied, he is fully occupied with the top tool and the work to
be done, so the hammering must be performed by a helper or
striker. A good-sized forging may be made by this method,
which is called ‘ working double lzanded,’ especially by using a
heavy sledge.
But a striker is sometimes dispensed with by introducing some
specially-contrived, and often very ingenious arrangement to take
his place. The method followed would then be called ‘ working
sz'ngle-lzanded.’ ‘
Fig. 100 shows one of these tools termed a dolly, and its
purpose in the ﬁgure is round swaging, though other forms could
be applied. It is ﬁxed in one of the square holes of the anvil,
and is struck at A with the hammer in the right hand, while the
left hand holds the work at B with the tongs.
Bolts or rivets may be forged single-handed by employing the
block A, Fig. 101. A stock piece, a, is put in the hole in the
block so as to ﬁx the length of the rivet 6. Pieces of round iron


; '
FULLERS
Manama tom. p
' o 0
0 o G _ ‘
FERRULES
Steam Hammer. 97
are cut offof proper length to form the rivet, and being heated, are
dropped into the hole at h. The hammer h is now worked from
the footboard j‘, the blow being delivered by pressing the foot down-
ward on the latter, and
the return of the hammer
ensured by the elasticity
of the sapling of ash,
s, which is bent on each
down stroke of the foot-
board, and in becoming
straight again lifts the
hammer. The correct
form of the rivet head
is given by applying the
cupping tool c, held in
the hand. When the
rivet is ﬁnished it may
be released and thrown
out by striking the foot
sharply on the lever l,
which thus takes the
dotted position, and the
rivet can be then picked a.
up and cooled in water. ’
Steam Hammer " T’I////////
for Smithy. -— Lastly,
the smith requires for
his heavy forgings the
aid of a small steam _
hammer. We say‘ small’ - L1
to distinguish from the '
larger type inuse by the forgeman, but the smith’s
hammer is anything but small. The one illustrated in Fig. 101b,
Plate 11., is spoken of as a 10 cwt. steam hammer, and this means
that the piston and piston rod AA, the tup B, and the pallett C,
together weigh 10 cwts. This, of course, does not take account
of the steam pressure, which at 40 lbs. per square inch con-
H



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98 Force of Ike Blow.
- siderably increases the falling weight. The forces of steam and
gravity being constant, the velocity with which the tup reaches
the anvil may be easily calculated.
Then, if W = weight of moving parts (in lbs.)
v velocity (in ft. per sec.)
g == 32': ft. per sec.
P = greatest pressure on hot iron (in lbs.)
19, = mean pressure‘ (in lbs.)
d = depth of impression (in fraction of a foot)
2
25.. = energy of falling weight.
And if the depth of the impression be measured 5 then,
it
But pd = energy delivered.
Wv2 , _ W212
- 1”’ ' '1’ * at
In a perfectly elastic material P = 216, as shown by the diagram
of work, Fig. row.
The pressure may also be found by a consideration of the time
during which the energy is given up.
Then (if t = number of seconds of time); the momentum
‘iv—7) = ,or and p = g 81‘
In practice v, t, and d are difﬁcult to arrive at, both on account
of the varying rigidity of the material receiving the blow, and on
account of the difficulty of measuring the elastic impression, or
again, of ﬁxing the ratio of yo to P, which is only shown in
Fig. row for elastic deformation; ,o would have a much larger
value in proportion to P in actual practice. Messrs. Massey
state, however, that with 40 lbs. steam pressure:
A % cwt. hammer gives a blow of about 2% tons.
A 5 n u :2 3° n
Referring again to Fig. Iorb, D is the anvil and E the anvil
pallett. F is the valve for admitting steam, opened by a horizontal
movement of the handle L, and G is the regulating valve, which,
requiring to work easily, is balanced by being made of piston

U, 1., ., . PLATE 11.



SCALE OF FEET
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FIGJOLB Mp9,
I0 CyvT. STEAM HAMMER,(b_yMssrs B.&:S.Massqt)
Steam-hammer Valves. 99
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65,.
form. In the drawing, steam is shown entering ,by the mid port,
and passing down the lower cylinder port to raise the piston; at
the same time the exhaust steam from the top of the piston is
passing down the upper port and out at K. :Npw (supposing the
self-acting'lever H is out of gearj, having reached its ‘
c
o
o 0 .
Ioo Heating.
highest position, the valve G is moved upward by means of the
handle J, and, while the exhaust steam from the bottom of the
piston may escape at K by passing through the valve G (which is
hollow), the steam enters by the upper port and brings down the
moving mass.
The self-acting gear allows us to set the hammer for continuous
blows having any desired period, which will go on so long as the
starting valve Fis open. The L-shaped lever H has its fulcrum at
M, and the spring N keeps the valve spindle pulled down so as to
admit steam at the bottom of the piston. While the piston is
rising the tappet P on the tup pushes H to the right, and so puts
valve G in position to bring the piston down again 5 and so on.
If the sector arm Q be moved to the left, the fulcrum M is
thereby lowered, and H is, therefore, turned on its fulcrum
sufﬁciently to the right to be out of the way of the tappet P. The
hammer may then be worked by hand. If quick blows are
required, Q must be pushed to the extreme right, while slower
periods are obtained by bringing Q nearer and nearer to the
extreme left.
If a line of shafting run along the shop, a hammer like the one
in Fig. 102 may be applied with advantage for stamping work,
though it is too slow in its beats for regular forging. Here the
iron strap 5 is made to grip the drum B by the pull of the man at
c, and so the hammer H is lifted by the power transmitted from
the shaft A. Directly the handle is released (namely, when the
weight reaches the dotted position), the strap slips, and the blow
is struck.
Heating.—Good wrought iron will sustain almost any
degree of heat without injury, but the more carbonised steels
have to be treated with great care, for if heated beyond cherry-
red they begin to break up from red-shortness, and cast steel will
overheat very easily. The student may refer to Fig. 87 in
Chapter III., which explains diagramatically the different amounts
of carbon in wrought iron, steel, and cast iron.
In forging wrought iron or steel, the heat should be kept up,
and a new heat taken when the work is getting too cold, for it is
generally admitted that working any metal by cold hammering
crystallises the surfaiie'z‘re'déitvlpg' the blow, and if annealing be not
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102 Welding.
resorted to, the crystallised portion will be left weak and little
better than cast iron. This should be carefully noted in making
connecting rods of steam engines, or indeed any article on which a
great deal depends.
Welding—Wrought iron cannot be cast,* but it can be
welded without difﬁculty; that is, it may be joined piece to piece
by heating and hammering, and work of great intricacy may thus
be formed. The welding temperature for wrought iron is from
1500° to 1600° Fahrenheit, and the two pieces to be welded are
heated to this temperature, which is detected by the iron beginning
to throw out sparks. Two points have to be noticed. The iron
should be, if possible, drawn out so that a scarf may be made,
when welded ; this is shown at A, Fig. 103, and, as will be seen, a
greater surface for welding is thereby presented. But if it be
drawn out too ﬁne, it will burn away when put into the ﬁre for .
the welding heat, and to prevent this it should be left rather thick
at the ends, as at B ; the lump may be easily levelled afterwards.
The two pieces to be welded should both be at their proper heat
at the same time, which the smith ensures by changing their
positions in the ﬁre, so as to advance the one or retard the other.
Withdrawing, he sprinkles them with sand, which forms a siliceous
ﬁlm or ﬂux, and prevents scale by oxidation. Putting them now
together, the smith gives one or two blows to ﬁx them, and he and
the striker then ﬁnish by rapid alternating blows. If the flux be
carefully expelled and the joint well hammered while hot, the bar
will be as strong there as at any other section. Borax is used as
a ﬂux in steel welding.
The scarf weld is the one most commonly practised, but the
fork weld at c, Fig. 103, is often introduced for large work on
account of its greater security.‘
Having thus brieﬂy mentioned the operations of heating and
welding, we shall now proceed to describe the forging of a few
objects.
The making of a Bolt with hexagonal head is shown in
Fig. 104. A round bar A is taken, of suitable length ; it is
heated at one .end, and jumped or upset, namely, is lifted by
* See note at end of Chapter III.

104 Forging Bolt and Nut.
the tongs and struck on the anvil as at B. A heading tool is next
held over a hole in the anvil, and the piece B is reversed and
dropped through the tool. Being prevented, however, from
passing quite through, on account of the shoulder just formed, it
is now beaten by the hammer until the head 0 is formed. The
bolt is then taken out, and the portion c is roughly hammered
into the form of a collar at D. It will now have become cold, and
must be re-heated to ﬁnish the head, which is done in the hexa-
gonal swage B, side after side being presented to the tool by turning
the bolt round, and hammering each time. Finally, it is dropped
into the heading tool once more, as at F, and, after receiving one
or two ﬁnishing blows, a cupping tool f is applied to give the
spherical chamfer.
We may now make a Nut for the above bolt. Of course, it is
almost unnecessary to state that bolts, nuts, and rivets are now
made entirely by automatic machinery, and these examples, there-
fore, are only intended as an introduction to more difﬁcult
forging. A nut can be forged so as to leave the hole, and thus
dispense with after-drilling. This is the case we shall consider.
Fig. 105 illustrates the different operations. Slightly scarf the
bar A, which is to be bent round to form the nut, and must, there-
fore, have the same width as the latter; for example, a three-
quarter inch nut would require a bar about three-quarters of an
inch by three-eighths of an inch in section. Next heat the end of
the bar and bend round the anvil as at B, nicking it through with
a blunt chisel (shown at a in sketch 0). Now, put it back in the
ﬁre to get a welding heat 5 take it out; and, breaking off sharply
at a, lift up the ferrule remaining, on a mandril D, and weld the
two scarﬁngs together; then ﬁnish the hexagon in the swage E.
The nut is not yet complete, however. Re-heating, it is cupped
at top and bottom as at F, and the hole is ﬁnally completed to
exact size by the ﬁnishing mandril G, which is driven through
the nut into the hole it in the bottom cupping tool. The nut
may now be removed and cooled.
Fig. 106 shows the making of a Holdfast for pipes, or pipe
hook. Two beats are necessary. In the ﬁrst a bar is taken, as at
A, and is drawn to a ‘square’ point on the further edge of the
anvil as at B, a turn of 90° backward and forward between each


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106 Forging Eyes.
blow being given by the hand holding the tongs. A second heat
is now taken, and the length of point having been marked off (0)
the remainder is set down at D, on the edge of the anyil. Here
again the bar is turned backward and forward to ﬁnish the edges
in plan E, and the end is chipped off at e to proper length.
Before the work is too cool the part e must be bent round the
beak of the anvil, as shown at F, when the holdfast is complete.
A Single-Eye in the form of an eye bolt is shown ﬁnished
at A, Fig. 107 (page 103). The hole is to be drilled out afterward.
A short piece of round bar is ﬁrst taken of the same diameter as the
collar, and after heating is fullered at B, and set down as at c. On
the second heat the edges are hammered, and the corners chipped
off with chisel as at D, shown in plan. One end of the eyebolt is
thus ﬁnished. Taking a third heat the line E E is marked off, and
the tail of the bolt swaged down at F. Finally, cut off the round
shank to the required length.
We will now describe the forging of a Double-Eye. A in
Fig. 108 gives the ﬁnished form, serving as the end of a tie or
connecting rod, to which it is welded when required. A square
bar is taken (exact length of no importance) rather thicker than
the part marked a, and is ﬁrst heated, jumped, or upset as at B,
and then ﬂattened out in swage block till it assumes the form
shown at 0. Being heated a second time it is drawn out as at D,
partly on anvil, and partly by returning to hole in swage block,
when it is ﬁnished off at the ends by chipping off the corners
shown at E. A third heat is required to bend the T thus formed
round the anvil beak to the fork shape F, and the fourth and last
heat will serve: ﬁrst, to hammer out the octagonal portion; and,
second, to swage out the round part H.
A Pin with cotter is our next forging. After heading at the
ﬁrst heat, like the bolt in Fig. 104, it is then of the form B,
Fig. 109. On the second heat it is cut to the length required,
and the cotter hole marked off. The latter is ‘drifted’ through
by means of the tool c—ﬁrst, with the work lying in a bottom
swage ; and, second, to ﬁnish—by driving the tool through, over
a hole in the anvil, see D. In punching and drifting the tool must
be kept cool by taking it out of the work, and dipping in the
water tank from time to time. A represents the ﬁnished pin. The
P1» (is Collier‘


- U55
3 :92;

108 Forging Spanners.
cotter E needs little description. It may be formed by bending
a thin strip of iron as at F, welding the portion near the bend, and
chipping out the narrow shank.
The student will have already noticed that a good deal of
judgment has to be exercised by the smith in deciding upon the
length and breadth of iron necessary to execute a certain piece of
work, and although this can rarely be achieved with very great
nicety, yet practice enables him to guess it with sufﬁcient accuracy.
As a rule the cubic contents, or the weight of the stuff should be
about the same in the rough as in the ﬁnished piece, some
allowance being made for burning away in the ﬁre, but it is best
to err by having rather too much than too little, and in most
articles the extra stuff can very easily be cutoff. Some, however,
require more exact measurement, as from the nature of their con-
struction the after cutting cannot well be resorted to. Wherever
parts have to be afterwards machined extra material should be
allowed, say from one—sixteenth to one-eighth of an inch, but the
careful smith will always leave as little as possible, and if he is
directed to ﬁnish ‘black’ he should make the work as exact to
dimension as his tools will allow.
Except in the case of the nut at Fig. 105, none of the work
already described has called for the operation of welding. We
shall now, however, pass on to some examples requiring the aid
of this important process.
A common S Spanner is the article we shall ﬁrst consider.
A, Fig. III, shows the ﬁnished forging. A bar is taken of the
same length as the arm, leaving a little extra material for welding.
It is heated and ﬁrst bent to the 8 form (B) on the anvil beak.
straightening by ﬂat hammering on the face of the anvil, and is
next drawn out at the ends as at c. Now, two pieces of rather
thicker bar being procured to form the jaws, these are heated
and bent round the beak, and the corners chipped off and
rounded as at D. Heating again, these jaws are ﬁnished on
the bottom tool and scarfed down as shewn at F. We are now
ready to complete the spanner by welding the jaws to the arm,
at the scarﬁngs already made (see G), and ﬁnish may be given
between the ﬂat face H, and the anvil.--w —~
In Fig. :12, A represents a Shackle for use with chain or
Forging a S lzackle. 109
rope. Some little care should be exercised in gauging the length.
For an ‘inch’ shackle, made out of round bar one inch in
diameter, a length of fourteen inches would be required This


FlNlSHED
WORK





lllIllH WIN

- 1 Earn


‘ ‘I ' ‘ IS‘ Spanner
bar ‘is set down to the form at B, by using the set hammer and
bottom swage b. Two heats, one for each end, are required for
this purpose. Another heat for each end enables us to make a‘
I 10 Forging a Shackle.
scarf of the form shewn at c, by drawing down at the point and
sides. The eyes are next formed by taking a welding heat,
bending round a mandril rather smaller than the ﬁnished size of
hole, and welding with hammer as at D. A ﬂat face is used (E)
to smoothen, and a ﬁnishing mandril is driven through the hole




!'_Zg_-____
Shackle.

as at F. These operations being performed on each eye, we have
the shackle advanced to the stage G. Only one more heat is
now necessary to bend the rod to the proper form round the
anvil beak, and the ﬁnishing stroke is given on a block (H) which
serves as a template to deﬁne the distance between the eyes.
Forging Hoohs. 11 I
An Eyebolt of large dimensions is treated in Fig. 113. A
is the ﬁnished condition. It is such an eye as would be required
for the attachment of a rope or chain, being made of round
section to prevent cutting or chaﬁng. Here we may begin by
taking a round bar of the same section as the part A, and, wrap-
ping it round, scarf and weld it to the form of the eye as at B,
at the same time scarﬁng down the joint again. This done, a
second bar C of thicker section is cut to form the shank, and,
after scarﬁng, is welded to B, giving the appearance D. Lastly,
the collar is put on by taking a piece of square bar of small
section, which may be wrapped round the shank at welding heat
and scarfed at E. The bolt is then ﬁnished off by fullering the
part b, and swaging e, a rough ﬁle being used with advantage
afterwards.
Another and probably quicker way of making the eyebolt, is
to take a bar of the same diameter as the collar and work out of
the solid by swaging down the shank, fullering and ﬂatting out
the eye portion, the hole being punched and rounded off.
As an interesting example of punching and swelling out we
may take Fig. II 3a. Here we have a portion of a Harrow-
frame, and it is desired to form the socket for a common square
tyne. The bar at A is ﬁrst upset, punched, and drifted to the
form at B. It should be noticed that at ﬁrst only a narrow, long
section of drift is used, to avoid breaking the bar. The narrow
hole is swelled into a round one by a suitable tool on the next
heat (shown at c), and the ﬁnal step is the further swelling by
square drift, as at D, carefully ﬁnishing with a ﬂat-face.
Hooks may have the eye formed in the manner described
for the shackle of Fig. 112, or the large end may he ‘jumped,’
and worked from the solid by means of a ﬂat-face tool, either in
the case of hook or shackle, and the hole left to be punched or
drilled cold. The solid method needs no special description.
Assuming a case similar to the one previously described for the
shackle, the bar being ﬁrst round and of the diameter of the
thickest part required, the eye end of the bar is drawn to the
proper diameter for that place, while the opposite end is drawn
down nearly to a point. This is shown by sketch A, Fig. 114.
The eye is next turned and welded, and the hole ﬁnished with



Forging a Box-key. ' I 1 3
mandril either now or afterwards (B). Heating the rest of the
bar the hook is bent to the correct form round the anvil beak C,
being constantly checked by rule and sheet iron template, and the
proper section given at the same time (shown at D D) by means
of set hammer or ﬂat-face. Both these last-named operations
must go together, for the form of the hook will be more or less
spoilt by ﬂattening to the section at D D, and this must be again
restored by bending.
Bolts in machinery are sometimes placed in very extra-
ordinary positions, so that the spanner in Fig. 111 may have to
be discarded, and the Box-key (represented in Fig. 115) used
in its place. It has a socket at A to ﬁt the nut, and a shank at
B, on which a wrench (sketched at c) is placed when required.
The key is forged by making the A and B portions separately, and
afterwards welding them together. Thus, part A is made by
bending a strip of iron, which has been previously scarfed at the
ends, into the form of the hollow cylinder D. This is done on
the anvil beak, and a second heat is necessary to weld it. The
piece B is next formed from a round bar of sufﬁcient section to
give the square when ﬂattened. It is shouldered on a swage as
at E, sufﬁciently small to ﬁt into the ring D. And now the small
end of E and the cylinder D are both heated to welding tempera-
ture; then, being put together as at F, are riveted by striking the
mandril G, and by hammering round as at H. The fourth heat is
required to work out the square J with ﬂat face and anvil, and on
the ﬁfth and last heat a mandril, which may be hexagonal or
square, as desired, is driven intothe cylindrical portion K, and,
the outside hammered until the requisite shape is given to the
hole. Removing the mandril the key is considered as ﬁnished.
Tongs, having to be used almost continually, are soon burnt
away by the ﬁre, and the smith must be able to forge them as
needed. We will therefore describe the forging of the round-nosed?
tongs sketched at B, Fig. 98. The ‘bits ’ that grip the work are
made ﬁrst. For them a piece of square bar is to be set down on
the edge of the anvil until it receives the form A, Fig. 116 ; the
successive operations for this are shown at 1, 2, 3. The two bits
should not be made right (and left-handed, but exactly alike, for
in turning one round axially it will be found to accommodate
1
_ vmaNcr-I

HNiSHED WM‘NC‘




Solid Forging v. Welding. I I 5
itself quite correctly to the other. One heat should be given for
each of these settings down, and during the third the hole (B) is
punched. Next, the handles are to be welded to the bits, and for
this purpose round rods of suﬂicient length are scarfed, heated to
welding, and united in the usual manner c, being ﬁnished care-
fully in round swages, D. The nose bits are yet ﬂat ; they are
rtherefore rounded by means of a top fuller and bottom swage, as
at E, and, ﬁnally, the two half-tongs are rivetted together tightly
F with a hot rivet, the handles being worked backward and
forward while the rivet is cooling, and also during the after
quenching in water. This method ensures a well-rivetted but
workable joint.
The student will notice that in the processes of forging two
‘principal methods are followed, which in many articles merge
considerably the one into the other. These are the forging of the
object (I) entirely from the solid, by drawing down or cutting out ;
and (2) the joining of the parts of the forging by welding. The
former is a process of cutting out or carving, the latter of building
up. Figs. 104, 106, 107, and 108 are examples of the ﬁrst method,
which is the one practised unless the method of welding should be
cheaper, and, as we shall see, is always used if possible in large
objects that have to sustain important loads. Figs. 1 I I, I 13, 1-15,
and 116 are cases where the second method is more useful, for in
Fig. 116 a round bar is attached to work that is easiest forged
from a square bar, and the end pieces in Fig. 112 are manifestly
easier made separately and welded, than they would be by forging
completely from the solid.
Further examples of welding are shown in Fig. 116a. In each
case A is the work prepared by scarﬁng or otherwise, and B the
built up article. The Eye may be said to be merely an example
of ornamental welding, for it would be difﬁcult to ﬁnd a use for it
in practice. The Stud is more commonly met with ; it is prepared
as shown, by scoring the surfaces to be welded with a chisel; less
pressure will then be required, the form of the stud will not be so
[much distorted at the shoulder, and the two pieces are much more
[likely to enter into each other.
The three next forgings to be described will be worked in the
‘solid’ manner, and they will conclude our description of the




S team-H auuner Forging. 1 I 7
methods used by the smith. They will also introduce the use of
the steam hammer, as applied in the smith’s shop.
FINISH ED FORG ING






Fig. 117 is a Single-webbed Engine Crank shown
ﬁnished at A. A slab of iron is required of the same thickness
1 18 Forging C ranks.
and width as the largest boss. Heating to a good white heat, it is:
put under the hammer, and the ferrule B stamps out the shape of
the boss. It is next drawn out by suitable tools, called sets, at
top and sides (see c and D) until it is of correct length to form the
smaller boss, which is ﬁrst set down to the proper thickness, and
then stamped by means of a ferrule, as before. The forging is
now of the form E, and all that is necessary is to ﬁnish by cutting-
off the ragged corners round the bosses, which will require another-
heat—the third; the ﬁrst having been used for the large boss and
the setting down, and the second for the small boss.
A Bell Crank Lever, whether large or small, can be made
in a similar manner to the foregoing. A, Fig. 118, is the ﬁnished
lever. A bar is taken, as before, of the thickness and width of
the boss. It is ﬁrst bent to a right angle—if a small lever this.
may be done on the anvil beak, but if large, blocks would be put-
under the steam hammer, with the hot bar between, as at B. That
clone, the boss is next formed by ferrule, as at 0. Another heat
will now be found necessary for each arm, in order to set down, as
at D D, to proper section, and the ends are ﬁnally out to curve by
means of chisel.
Figs. 119 and 119a represent the forging of a Small Crank
Shaft, say two inches in diameter, such as can be worked by the
smith with the aid of a small steam hammer. A is the ﬁnished
shaft, and has two crank arms forged upon it at right angles to-
each other, in the manner of locomotive axles for ‘inside ’
cylinders. We must, to begin with, have a slab of iron of square
section, sufficiently large to form the crank web when drawn
down. This is seen at B. It should also be long enough to
complete the whole shaft when drawn down and swaged in the
manner to be described. The bar B is ﬁrst to be formed into the
shape shown at c, by heating to a good white heat and setting
down under the hammer, as at D. This will leave the slab of the
same section as the crank web, and, if carefully set down to the
form indicated, the webs will now be in correct position, namely,
at right angles to each other. Of course some care must be
taken, the right angle being tested with a square, and the part
a b in particular should be made of such a length that when;
swaged to the round section it will measure the correct distance .
.FlNlSHE-D wean









1 2 2 Stamping.
between the crank arms. Probably this piece had better be
swaged next (it may require another heat), the forging being
turned round, backward and forward, to produce a good result
(see E). The distance between the cranks should be now ﬁnished
very exactly, by kniﬁng or other means. The ends remain. Here
it is necessary to ﬁrst cut out the superﬂuous material by marking
off at F, punching the hole G, and, while the crank is still hot,
cutting out the rectangle with a knife or cutter (see After-
wards the shaft is rounded by swaging When this has been
done for both ends, and the shaft carefully measured, as well as
tested for axial straightness, straightening if necessary, the work
may be considered complete. In this form of crank (double-
webbed) the pair of webs are always forged solid in the manner
described, and the piece between taken out either by slotting or
turning.
At this point we may as well consider one other form of crank,
which has many advantages. In Fig. 120, A is the shaft alluded
to, and is there shown ﬁnished by turning in the lathe. It is con-
siderably stronger than the one previously described, on account
of the fact that the ﬁbres follow the bend of the crank webs
(represented in dotted lines) while in the shaft of Fig. 119 these
ﬁbres are cut through when the mid pieces are slotted out, and of
course this must weaken the webs considerably. The only
objection to the form here shown is that a great width is required
for the crank itself, and, as this cannot always be spared, the
crank has only been applied on portable or traction engines up to
the present. Properly we should have described this in the space
devoted to the forge, for a larger hammer is required than
commonly occurs in the smithy. A bar of the best Yorkshire
iron, of sufficient diameter to turn down to ﬁnished size, is heated
and placed between the blocks BB, and these are made to
approach each other by blows from the hammer, at ﬁrst gently,
and afterwards more strongly. Lastly, the shaft must be tested
for straightness.
Stamping.-—Where several articles are required exactly alike
in form and dimension they often have to be forged more cheaply,
by the use of stamping tools. The crank last described might
almost be termed an example of this kind of work, and the lever





I-r __ ____-__~
§\\\\
1 ,n\
.._--/'








I
I 24 Case- Ha rdening.
in Fig. 117 could be stamped by means of the tool shown in
Fig. 121, the hot iron being placed in the hollow H, and the
hammer brought down upon it. The ragged portions are after-
wards chipped off the forging. Usually these stamping tools are
made of massive cast iron, but if they are to be used extensively
cast steel will be found necessary. Other examples of work
suitable for stamping are shown in Fig. 121a, where A is a
spanner, B a double eye, c the centre portion of a screwing stock,
D the handle portion of a lever, and E the boss part of the same
lever.
Before leaving the smithy two processes should be explained,
because they are as a rule performed by the smith. These are
the methods of hardening wrought iron and steel. Cast iron, as
we have seen in Chapter I., can be easily hardened at the surface
by chilling, this taking place while the article is in course of
formation. Wrought iron and steel are hardened after the article
is completed.
Case-hardening.—This is the name given to the process
by which wrought iron objects are hardened to a depth of from
one-eighth to three-sixteenths of an inch below the surface. After
forging the work is machined and polished, and is then made to
absorb carbon by being placed in air-tight boxes or cases in con-
tact with some substance rich in carbon, being strongly heated
while in that condition. The method is much the same as that
pursued in the cementation process (Fig. 88), and it will therefore
be seen that the iron at the surface is converted into a ﬁlm or
case of steel, the only difference from the cementation process
being that the heat is only kept on long enough to case the iron
with steel and not to steel it quite through. While the iron is left,
then, hard at the surface the inside remains tough, and is as
capable as ever of enduring vibration. The boxes may be either
made of sheet iron, or may be ﬁreclay retorts similar to those in
use at gas works, and provided with a lid to keep them air tight.
They may be heated as in Fig. 88, and the substance put in
contact with the iron is not wood charcoal, as in cementation, but
animal charcoal in the form of bones; for it is found, why it is
not quite clear, that if nitrogen be present the carbon will unite
more rapidly with the iron. Other substances may be used, such
Tempering. ' 12 5
as 'prussiate of potash, leather or hoof scraps, but the process is
chemically the same. After packing, which must be carefully
done, to prevent the articles bending while hot, the heat is raised
during two hours, the whole kept at a regular temperature for



(A
a 1
0
d
a 3 l
A g ,i- B I
g e
D.
\n I
12100


‘Siam/zed .Work.
about nineteen hours, and then allowed another two hours to
cool. Removing the articles they are quenched in water and
re-polished.
Steel of a mild quality may be hardened at the surface by the
absorption of more carbon.
Such small articles as have to withstand considerable wear are
case-hardened, e.g., radius links for reversing gear.
Tempering is a method of giving to a piece of steel any
required degree of hardness. Properly there are two distinct
processes meant when we speak of ‘ tempering’ a steel tool. The
ﬁrst of these is that of hardening. Here the steel is heated as
I 26 Tempering Colours.
equally as possible to a ‘cherry red,’ and not more; on with-
drawing from the ﬁre it is plunged into a vessel of cold water——
the quickness of cooling has a great effect on the hardness, and
this may be accelerated by moving the article about in the water.
Cracking or warping will also be prevented by this motion.
The steel is now so hard that it will scratch glass. It must
next be tempered or let down to the required degree of hardness.
If the tool be again heated to cherry red, and allowed to cool
slowly it will by that means have become annealed, and will be
at its softest; but if it only be heated to one of the temperatures
in the following table (Fig. 117b, Plate 111.), and then cooled
rapidly, it will take a particular degree of hardness corresponding
to that temperature, and to be obtained at no other. The softer!
tool will be that which is cooled at the big/zest temperature, and
the harder! at the lowest temperature.
The exact temperature which the tool has assumed is ascer~
tained by the colour which appears on the brightened surface, due
to a ﬁlm of oxide of iron formed by contact with the air. There
is naturally some diversity of opinion as to the proper degree of
hardness for particular tools ,' the table given is deduced from one
published by Messrs. Jonas & Colver, of Sheffield.
Tempering a Chisel or DrilL—To make the matter
clearer we will take the case of a chisel for chipping metal. It is
forged out of a steel bar of the section shown at A, Fig. 122, and
is drawn out (at as low a heat as possible, to prevent burning) to
a ﬂat point as at B. This point is now to be hardened and
tempered, while the rest of the chisel is to remain in its natural
condition. Whenever the tempering is accomplished by quench—
ing in water, the preliminary process of hardening must always be
performed, otherwise the tempering would have no effect. In the
case of the chisel, or any tool having a point requiring a particular
temper, the two processes are performed at one heat, but it must
be quite clear that hardening is not therefore dispensed with.
Heating the whole chisel to a cherry-red, the part ab only is
quenched in water, and so becomes very hard. Now rub the
point of the chisel with a stone to brighten it a little, and, as the
heat from the body be travels down towards a, the colours will
appear, the point becoming gradually hotter, yellow ﬁrst, then
93/ 1 2117.1‘
~00LOR—TEMP. —
—USE—
:
E F, o 2 RED |650 HARDENING
L; ONLY
|_ FA_H.
|L PALE 600° T00 SOFT
8 BLUE FUR ANYTHING
O .
SPRINGS
snREw DRIVERS
DARK o mRuuLAR SAWS FDR METAL
0 570
BLUE
coLn cPnsELs PM W1 |.
H
B ' FIRMER GHISELS
m GOLD OHISELS FOR GAST l.
DARK ’ AXES AND ADZES
PURPLE 550
4 com cmsELs FOR STEEL
O
l-ll LIGHT AUGERS
‘J
H PuRPLE 5‘’0
O
YELLOW 0
mm W 520 FLAT DRILLS FOR BRASS
PURPLE TWIST DRILLS
' PLANEIRUNS
BROWNISH o : GOUGES
YELLOW 500 ‘
. EAMERS
UNGH AND DIES
STRAW n YELLow TAPS
I
SCREW-CUTTING DIES
STILL BARKER O
m STHAW 470 BURING GUTTEHS
4 YELLOW
O
MILLING GUTTERS
H BARKER o DRILLS
STRAW 450 PLANERS EoR IRUN
YELLOW
' PLANERS FOR STEEL
HAMMER FAGES
VERY PALE a E E __EE
smw 430 LIGHT TURNING TOOLS
YELLOW
scRAPERs FOR RRAss






FIG H7.B
TEMPERING TABLE
'III EILV‘Id
Examples of T enzperin'g. 1 27
_ through brown to blue. But we require for our chisel the tem-
perature of 550°, which is indicated by a dark purple; as soon,
then, as this tint is seen, the chisel is entirely plunged into water,
and the point is thus made of the correct degree of hardness. A
drill point may be tempered in a similar manner, using, however,
the darker straw yellow for colour.
Tempering a Screw-tap.—Sometimes, when more careful
work is required, the colours can be better detected by laying the


'20 71017111212119 Chis/BL.
A d a 5?. B
I < 3 Lo .
§ Oé» * T“
i _ ._.__ !
I TEMP.4_-90° TEM? 370' >
VERY DARK STRAW YELLOW. DARK BLUE.‘


HOT PL/l TEJl

12 ‘3.
T/emytemng Screw 121132;
article, if small, on a hot plate, which serves to raise its tempera-
ture. Such a case is that of a screw-tap. First the tool is
hardened as before, and next the tempering must take place, but
in such a way as to make the screw threads hard, while the square
piece is left soft. First the square is tempered by allowing the
blue to appear (Fig. 12 3), and at once quenching that part. The
tap is returned to the hot plate, and the very dark straw yellow is
I 28 Furl/"16? Jl/fetlzods 0f Tempering.
watched for; being cooled at that colour we have all that can be
desired. For it will of course be seen that the second part of the
operation being performed at a lower temperature cannot undo
the ﬁrst part which took place on the square head.
By using oil instead of water the hardening process may be dis-
pensed with. Here, as soon as the correct colour is observed,on the
ﬁrst heating, the article is put in oil to cool, and the requisite
hardness thus produced. Why this should be is not at all clear,
and until some of our physicists ascertain the reason for the
difference in oil and water tempering, we must be content merely
to take the facts.
Two other methods of ascertaining the desired temperature
are in use besides the colour test. These are the ﬂashing tem-
peratures of certain oils, and the fusing points of certain alloys.
The ﬁrst is practised by coating the part of the tool with oil, and
holding it over the ﬁre until it blazes off, then quenching in water.
In the second, the alloys are usually of lead and tin, and vary
from equal parts of each metal to complete disappearance of tin
and consequently total lead. A head of the alloy placed on the
tool, may be watched until it melts, and the part then quenched.
Of course, as before, the two operations are required if the tool
be cooled in water, against one if cooled in oil. Watch springs
‘are tempered by the blazing-off of oil.
Gun cores are cooled in oil to withstand the wear of the shell
and to increase the strength of the steel.
It should ﬁnally be noticed that much care is required in
tempering—care not to overheat in the ﬁrst operation; care not
to warp the tool in cooling; care not to crack the tool at the
water level. Some tools will harden best in a saturated solution
of salt, others in a stream of running water. Generally it is wise
to move the tool well up and down during cooling. Hardened
steel may be compared to glass, annealed steel to lead, and
tempered steel to wlzalebone. Our process then when tempering
by means of water is to raise the steel to ‘ glass,’ and then lower
it gently to ‘ whalebone.’ Hardening in oil gives the ‘ whalebone’
without passing through the ‘ glass ’ stage.
In some experiments at the Terre N oire works, four specimens
of steel were heated and cooled in oil, and it was found that
Steam Hammer/for Forge. 129
whereas the average breaking stress per square inch was 35-29
tons before the operation, it had afterwards increased to 512;
tons.
THE FORGE.
We shall now pass on to describe the turning out of very
heavy forgings, which include all articles too ponderous for smith’s
work, and which are consequently made in the forge under a very
heavy Steam-hammer. Fig. 124 is a drawing of a hammer
suitable for general forge work, such as we are about to consider,
but, of course, extra large forgings would require special-sized
hammers.
The hammer in Fig. 124, Plate IV., has a falling weight of
ﬁve tons. After the careful account of the smith’s hammer there
will be very little to say here by Way of description. As before,
the outer valve is for the purpose of admitting steam (being
opened by a screw acting at the end of a lever), while the inner
valve controls the direction of ﬂow, the exhaust passing upward.
The long hand-lever serves to move the distribution valve, and
the self-acting arm between it and the valve reverses the latter
as soon as the arm is moved by the tup on its upward travel.
The Furnace used by the forgeman is very similar to that
shewn in Fig. 85. It is there called a Puddling Furnace, and
indeed ‘ blooms ’ are to be made for heavy forgings just as in the
case of puddling, the only difference being that they are built
from scrap iron instead of white pig. A pile of scrap iron is
heaped on a rough wooden tray, and is then put into the furnace.
Several of these piles being so placed and heated sufficiently, they
are then found stuck together. Withdrawing them, thus adhering,
by means of very large tongs having a balance-weight on the
handle end, and supported at the middle by a crane, the blooms
are put under the hammer and well beaten together to form slabs.
It will be these slabs that we shall use to build up our forgings.
Fig. 12 5 shews an arrangement of furnace and cranes for heavy
forgings.
First we shall consider, in detail, the forging of a Double-
throw crank shaft of large size, the ﬁnished form of which is
seen at A, Fig. 126. The forgeman always requires a staff or
‘porz'er’ to carry his forging, to which, for the time at least, the
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Forging a Large Crank S/zafz‘. I 3 I
latter is welded. It is simply a long tapering bar B (Figs. 125
and 126), supported by a crane chain, and carried to and from
' the furnace by the undermen, while the head forgeman directs
the hammerman, and applies the different tools to the work under
the hammer. The end of the porter is put in the furnace and
made to pick up, at a white heat, a few slabs which have been
previously placed there; putting them under the hammer they
are all thoroughly welded, and the round form of the ﬁrst part
of the shaft obtained by swages similar to those of the smith, but
of suitable size. More slabs are added, and welded, until the
shaft is sufficiently long to take the ﬁrst crank web. The web is
now built up by laying slabs upon it as at c (Fig. 126), the end
being put back in the furnace. Care must be taken in piling
these slabs, both now and always, that space be left between them
by the placing of pieces of scrap, so as to enable them to take a
welding heat right through. Bringing the hot slabs back to the
hammer, they are welded by striking both at top and sides: and
so the process is repeated on both sides, a and b (Fig. 126),
until the shaft has the form D (Fig. 126a). It is then set down
as at E. But the web is not yet ﬁnished. Heating again, it is
ﬂattened out to the shape F, and slabs are again piled on and
welded to the body of the material, the process being repeated
as before for both sides of the web. The object of laying the
slabs on both sides of the web is ‘to keep the direction of the ﬁbre
such that the crank may be best suited to meet the stress put
upon it. By this time the forging, being unbalanced, will be
difﬁcult to turn round; but this is overcome by clamping four
arms dd on to the porter, these being turned by the strength of
two or four men as required. The web is now hammered at top,
bottom, and sides, to correct dimensions, the ragged end e chipped
off by means of a cutter, and the other end f cut down with the
same tool, the extra piece G (Fig. 126a) being worked by sets
‘until drawn out to receive more slabs. The shoulder g, and the
piece G, are next ﬁnished to the round by means of swages, and
. the building of the second web commences. This is carried out
in exactly the same manner as the ﬁrst one, except that it must
be carefully‘ built at right angles; this point, as well as that
of the general straightness of the shaft must be gauged with

ill.


Forging Steel. I 3 3
square and straight-edge by the head forgeman, as the work
progresses.
By this time then our forging has reached the condition H,
and as the sketch A, Fig. 126, shows us a solid collar, for the
purpose of coupling to another shaft, we must add this portion.
Slabs are again piled up as at J, Fig. 126a, heated and welded,
until sufficient stuff has been worked together to form a small collar
K, and then the whole collar can be ﬁnished either by the slab
method, or scarfed bars (L) can be wrapped round the shaft and
thoroughly welded. Finally the collar can be chipped down at M
to the correct length, and cut off entirely at N. There only
remains the porter end 0, which may be ﬁnished by taking off
the handles, and clamping them at the collar end, then putting
the porter through the furnace till it protrudes at the further door,
and after heating cutting it off to the length shown on the drawing.
The shaft is then set aside to cool.
Steel Shafts are forged from ingots (obtained by any of the
processes mentioned in Chap. 111.), and being thus treated from a
solid block, differ in no sense, except size, from the example shown
in Fig. 119. Some makers prefer, after ﬂattening the ingot to the
thickness and height of the crank webs, to set down the central
portion of the shaft, forging each web in the same plane; after-
wards, to turn one web at right angles to the other by the process
of twisting the shaft, but there can be little doubt that this is an
objectionable method, and should never be resorted to. A good
deal of care, in the case of steel, should be taken to get rid of the
blow-holes previously mentioned as existing in the ingots, and as
simple hammering is usually insufﬁcient, cogging is the operation
performed, which consists in partly punching the steel while hot
immediately over any portion where honeycombing is suspected—-
a sort of kneading, in fact.
After the careful description of the crank shaft forging, a short
explanation will sufﬁce for the following articles—Piston-rod with
Cross-kead and a Connecting-rod. Whenever such forgings are
made of wrought iron they are built up from scrap as in the case
of the shaft, such scrap consisting of all kinds of wrought iron,
especially the shearings of plates from the Boiler Yard, and this
being worked over and over again in the manner previously
I 34 Forging Pz'sz‘oriz- rod.
described we naturally obtain a better quality of iron than that
which has been but once puddled. Another point to notice is
that the slabs should all be perfectly welded by good hammering
6efore the forging is actually formed to the required shape, for ''
much working after cutting to proper dimension will cause distor-
tion; while if, on the other hand, sufﬁcient hammering is not
given to the slabs, cracks are sure to show after machining, and
the piece will be dangerously weak.
Fig. 127 will serve to show the forging of the Piston-rod.


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Its ﬁnished form is given at A, the cross~head being solid. with the
rod, and having renewable ‘ slippers ’ of cast iron. Slabs are ﬁrst
piled on the porter to form the cross-head, as at B, ﬁrst on one
side and then on the other; sufﬁcient, if possible to complete both
cross-head and rod. The shoulder of the butt is next knifed out
at c, and the rod drawn down and swaged as shown at D, the
Forging Connecting-rod. I 35
taper given at E, and the whole cut off to proper length. Finally,
the porter is put through the furnace, as in the case of the crank
shaft, the clamps being transferred to E, and the butt end ﬁnished‘
by cutting off at F to the correct width.
The Connecting-rod in Fig. 128 is a little more difﬁcult,
but no new principle is involved. A is the ﬁnished rod. Sufficient
material is ﬁrst attached to the porter to make the forked end
FlNlSHI-D FORCJNG









and about half or more of the rod. This is shown in progress at
B. It is next drawn down by sets and swages to the form c, and
more slabs are piled on to complete the rod and butt (see D and
E). N 0 further description will be needed to ﬁnish the forging,
1 36 Direction if Fibre. .
as there only remains the cutting off of the butt end to correct
dimension, and the severing of porter from forging as in the
previous examples.
Want of further space compels us to close our chapter on
Forging, but sufﬁcient examples have no doubt been given to
stimulate the student, who will now without difficulty" be able to
construct other forgings for himself, albeit .more complicated than
those already given. Of course different workmen have slightly
different ways of arranging their material, and no two will exactly
agree, but that forging will be the best one where the ﬁbre is
disposed so as to meet in the best way the stress coming upon it.
CHAPTER V.
MACHINE TOOLS.
THE pattern maker, moulder, and smith having supplied us
with rough Castings and forgings, it is now necessary to ﬁnish
these articles truly before passing them on to the erector. After
marking 01 measuring-off, certain portions of metal have to be
removed by hand or machine tools. The remainder of our work
will then consist of—Marking-oﬁ; or indicating the ﬁnished outline
by a boundary mark; Mac/lining, or removing superﬂuous
material by automatic or semi-automatic machine power; and
Fitting, which is the ﬁnishing of certain parts by hand power,
usually the chisel and ﬁle.
Machining has always tended to gradually usurp ﬁtting by
hand, and its advance is so rapid at present as entirely to take
the place of handwork for such articles as are to be repeated; in
such instances manufacturers have special machines designed.
Even in unrepeated work a much larger quantity is done by
machine than hitherto, perhaps most of all by the extended use
of such tools as milling machines. '
As so much depends on the perfection of a machine tool itself
(the workmen merely ‘ setting ’ the work and arranging speeds),
a thorough knowledge of these machines is necessary, so as to
appreciate their capabilities and enable us to design work to suit
them.
The next chapter has been reserved for the operations of
marking-off, machining, and erecting, the present being devoted
to the Machines themselves, which may be classiﬁed as Lat/zes;
Planing, Shaping and Slotting Mac/tines ; Boring and Drilling
Mac/zines ,- and ﬁddling Mac/tines.
Of course there are many general varieties of each class, and
each variety is again ‘varied to suit special needs. Thus, as
regards drilling machines, most inland workshops are supplied
I 38 Reciprocating 11. Continuous T ools.
with 'oerz‘ioal drills, but marine shops require also lzorizonz‘al drills
for drilling bolt holes in solid couplings on shafts too long to
stand under a vertical machine. Again, up to a certain size, the
usual form of boring machine is that having horizontal boring
bar; but a vertical bar is preferred by many engineers for the
largest cylinders, to secure a more accurately bored surface, by
thus balancing the heavy boring head. Planing machines
generally have the work bolted to a moving table travelling under
a ﬁxed tool, but some large machines have been made with“
moving tool and stationary work, analogous to slotting and
shaping machines. '
It will be seen, therefore, that it would be a very large task to
adequately describe even every important machine tool. The
only course open is to choose such as are typical of t/zez'r division
of the four before-mentioned types, and ﬁrst we shall give
a few
General Principles.—-Of all the tools enumerated the
lathe was the earliest invented, beginning, according to the
principles of evolution, as a reciprocating machine, that is, it
revolved in either direction alternately, there being no crank
and rod to give it continuous rotation; and the forward motion '
only was effective, the backward revolution being lost. Planing,
slotting, and shaping machines are present examples of this early
stage, as far as reciprocation is concerned. But it 'is not easy to
give these tools a continuous action; reversible tool holders, or
tools, have both been tried, but seem to lack rigidity, and no
doubt the difﬁculty is to be surmounted by a revolving tool, as in-
the milling machine, reciprocation only giving the feed, a similar
evolution to that of the circular saw, band saw, and wood planing
machine, which all began as reciprocating hand tools.
The milling machine has only one objection, the expense of
the cutter, which is also troublesome to sharpen and difﬁcult to
keep to proper proﬁle, and the boss must be ﬁnally discarded.
The latter objection has been met by separate cutters, more
easily re-ground, the stock being retained.
In the lathe, then, we have a stationary tool, and revolving
work receiving a rylina’rioal surface; while the milling machine
has a revolving tool and stationary work taking (by the aid of the
Copying Principle. I 39
feed) a ﬂame surface,- and nothing could be more satisfactory.
If this be the completion of the cycle, as we suppose, then the
recriprocating tools, with lost back stroke, must ultimately give
way.
The Copying Principle is another great principle involved
in both hand and machine tools. All depend for their accuracy
on one or more carefully-prepared copies contained within the tool.
Thus in the carpenter’s chisel the ﬂat back is held against the
wood when paring, and constitutes the copy. The sole of a hand
plane serves the same purpose, its truth or otherwise being copied
on the work, which may be proved by curving the sole, and thus
obtaining curved surfaces.
The copying principle is universal. Take the lathe : the bed
has a plane surface truly parallel to the line of centres, thus
enabling us to produce a true cylinder as our solid of revolution.
A second slide at right. angles to the former gives us a
copy for use in ‘ surfacing,’ producing plane ends or rzglzz‘
cylinders.
The V grooves of the planing machine give accuracy along the
table, while the cross beam or slide ensures truth across it, and so
we obtain a true plane. The vertical slide and the two horizontal
cross slides are the copies in the slotting machine, while the
shaping machine has two copies supplied by the horizontal slides,
at right angles. Lastly, the milling machine has two slides, at
right angles and also horizontal.
As the truth or otherwise of these copies is transferred to the
work, it is of the utmost importance that they should be made
perfectly correct in the ﬁrst instance. 6
The copying lathe and other duplex wood-working machines
are further examples of the principle, but are beyond this
work.
Cutting Tools.-—We will now consider the shapes and
angles required for the tool itself. As a rule wood-working tools
act by wedging, or splitting-off the shaving; and the resistance is
tensile, with some bending. Our interest is with cutting tools for
metal, and Prof. R. H. Smith has shown their action to be totally
different.
The diagram Fig. 129 represents the tool in action. B is the
I40 Cutting Action.
angle of relief, to keep the tool clear of the work 5 A the cutting
angle, and c the tool angle.
The point 0 requires great strength for metal tooling, and as
this makes A very large, ‘paring’ cannot occur, but the material
will be ‘crippled,’ either by compression, shear, or a combination
of both. Sections such as F G will be in compression, and those
parallel to E c in shear, and it will be evident that the drawing of


fig. 129.
action ,of/Caolo nwtal/
the parallelogram E F will show the section E F to be weakened
to the greatest extent, and here the shaving breaks so much as to
curve up the face of the tool. The direction of E F depends on
the comparison of the compression and shear strengths of the
material.
Great heat is generated, due to molecular resistance and
friction. A lubricant of soap and water is used for ductile
materials like wrought iron, contained in a can placed above the
tool-box and led to the tool point by a wire, down which it
Cutting A ngles. I 41
trickles. This cools the tool, and lessens the friction between
tool and shaving. For cast iron and brass these precautions are
not needed.
There has been, up to the present, some diversity of language
regarding the angles A, B, and c (Fig. 1 29). Thus, in the planing tool,
A has been termed the cutting angle, while in the lathe tool C has
been so called. Manifestly the ﬁrst is the more reliable nomen-
clature ; then c may be called the angle of the tool.
Their values were determined by Hart thus :—
For cast iron. For wrought iron. For brass.
O 0
Cutting angle .... . . 54° .... .. 55 .... .. 66
Relief angle ....... .. 3° .... .. 4° .... .. °
Tool angle ....... .. 51° .... .. 51° .... .. 63°
This supposed the least force of propulsion was required. But
if endurance of point be considered, a larger angle is usually
given, as follows :—
For cast iron. For wrought iron. For brass.
O 0
Cutting angle .... .. 70° .... .. 65 .... .. 80
Relief angle ....... .. 3° .... .. 4° .... .. 3°
Tool angle ....... .. 67° .... .. 61° .... .. 77°
In a lathe tool B is termed the bottom rake, and J the up rake,
while a third angle with top of tool, but on right or left side, is
called side rake.
These angles will serve for any machine, and the shape of
tool and shank will be treated in its proper place.
The Screw-cutting Lathe.—Plate V. shows various
views of this, the oldest but most useful tool. The example is
the design of the Britannia Company, and has 10 in. centres, that
is, will accommodate work of 20 in. diameter (called in America a
20 in. lathe). 40in. work can be turned by removing the gap
bridge A, which is bolted down and dowelled, so as to allow the
saddle to pass over it freely.
In all lathes the work is rotated, and the tool ﬁxed in (usually)
a slide rest, which can be moved along the lathe bed. This prin-
ciple, the very foundation of machine-tool accuracy, was the
invention of Henry Maudslay. On account of the various
diameters to be turned, the angular velocity must be capable of
I42 Revolutions of Lat/ze Mandrel.
variation, for the linear velocity at the surface of the work must
be constant. Fig. 133 shows that if ab and a, b, are equal the
angle a, co, must be greater than ac v. i
Let r=radius of work in feet.
V= speed of cut in feet per minute.
R = revolutions per minute to produce V.
V
Then, 21rrR = V and, = 57;,
And as the cutting speeds are, say :—
For wrought iron ................ .. 20 feet per min.*
For cast iron ..................... .. 16 ,, ,,
For steel ............................. .. 12 ,, ,,
We have :—
R 1 ' f ht ' —-——--—3’8
. r n . .
evo ut1ons per m or wroug 1 o = rad. m ms.
. 31
n : ---—.—'—.—_
” ” Cast no rad. in ms.
23
,, ,, steel ....... .. _ rad‘ in ins.
To effect this variation without altering the angular velocity of
the main shaft, cone pullies and back gear are employed.
The cone pulleyc is driven by a belt, from a like pulley on
the countershaft overhead, but the latter is reversed end for end,
so that its small diameter "is opposite the large diameter on head-
stock. As the sum of driving and driven pulley diameters is
constant, the belt will ﬁt any pair, and a change of velocity will be
effected, the highest being due to the smallest pulley on the
head-stock.
But as sufficient variation cannot thus be obtained we use the
spur wheels known as back gear. The mandrel D (Figs. 131 and
r 34) is attached directly to the work by a driver. But the cone
pulley runs loose upon the mandrel. Referring to Fig. I 34, the
bolt E serves to connect the pulley with the wheel F, which is
keyed to D, and by sliding E outward till it engages between lugs
G on the pulley, F and c are united, and the mandrel driven
directly. ., - .
Slower speeds are obtained by releasing E, and allowing the
* Gun metal and brass require a somewhat higher speed.

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144 Fast and Loose Head-stocks.
pulley to run freely on the mandrel, when the latter is driven
only through the back gear (Fig. 131), the pinion H gearing with
wheel J, and the motion brought back by pinion K and wheel F,
thus obtaining a new set of speeds on a slower scale. The dia-
meters on the pulley are here 13", 10%", 83;", 6" ; the wheels J
and F have each 42 teeth, and the pinions H and K 12 teeth.
Supposing the countershaft to make 60 revolutions per min. we
have on mandrel :—
REvoLUTIoNs PER MINUTE
With back gear. \Vithout back gear.
2 4 6 IO 23 46 77 130
which is represented by diagram at Fig. 137; and the workman
chooses such as will give the correct cutting speed.
We have shown that when driving direct the cone pulley and
wheel F are connected; at the same time J and K must be thrown
out of gear. Both are keyed to the hollow shaft L, revolving on
the spindle M, which is supported in eccentric bearings NN. A
‘tommy’ (or short rod used as a key) is inserted at the left end
and the spindle M turned so as to throw the centres of J and K
further from D, and so disengage these wheels.
The mandrel journals are cones rotating in brass bushes (F i0.
134). Of these the left-hand one is hollow, and rests on a feather
key, so that it may be tightened up after wear, by screwing up the
nut P and the check nut Q. The thrust of the work is taken on
the end R when surfacing, and the head—stock is adjusted to
secure parallelism by means of the screws in Figs. 13 5 and 136.
As the fast head-stock just described has an unchangeable
position, the tail or loose head-stock must be adjustable for dif
ferent lengths of work. It is shown in section at Fig. 138, and is
ﬁxed approximately by the bolt and clamp s, after which the work
is placed between the centres, and a ﬁne adjustment given by
rotating the hand wheel T, so pushing out the inner barrel U
(which acts as a nut with a left hand screw), after which the
handle v is used to clamp the barrel securely. Lateral adjust~
ment of head-stock (when necessary) is given by the screw w.
Fig. 139 gives the form of centre to support the work. It is
shown in position in Figs. 130 and I 31, being merely placed in
conical holes of ﬁne taper, and has a ﬂat surface for use with spanner.







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Turning to the Slide-rest and its various feed motions, details
are shown in Figs. 130, 131, 141, and 142. x is the saddle,
having one movement, that along the bed ; Y is the middle slide,
moving across the bed; and the top slide Z has a universal motion,
but by hand, being mounted on a circular table formed on Y; and
thus a feed may be obtained at any angle by turning the upper
plate 2 and clamping the bolts a a.
The movement of x is called traversing or sliding, and the
crossmovement of Y surfacing; these can be combined in any
proportion. The slide rest is actuated from the mandrel in two
distinct ways. The leading screw at the front of the lathe bed is
only used for screw cutting, and is thus preserved from wear at
other times. It is driven by ‘change wheels,’ at the left end of
bed (Fig. 132). These can be changed, so that various rates of
rotation of screw can be effected, relative to that of mandrel,
which comparison ﬁxes the ﬁneness of thread cut on the work.
To facilitate the ﬁxing of the wheels chosen, the intermediate stud
o is supported (Figs. 130 and 140) on a radial arm c, which can
be clamped at various angles, the two wheels on o being fastened
together by keying to a loose sleeve d. The saddle and leading
screw are connected or disconnected by the two half nuts ee
(shown apart in Fig. 141), which are brought together by moving
the handle downward along the dotted arc, when the studs fj‘,
carrying the nuts, are brought nearer the centre by the curved
grooves.
The slide rest is also worked from the back shaft It on the
opposite side of the bed, and the two feeds for traversing and
sliding obtained. It is driven from the mandrel by change
wheels (shown dotted at g, Fig. 131), the intermediates being
carried on the arm c. Some makers drive by belt, which may
slip if the machine is being overworked, but there is no doubt
that wheels give a more deﬁnite feed. Passing to the connection
of shaft with saddle we refer to Figs, 141 and 130. A worm j,
having a feather key, slides along the back shaft, being drawn
along by the saddle. The power passes through an intermediate
worm pinion 2 to the wheel 3, which, being keyed on spindle is,
crossing the bed, rotates pinion 4 on the front side. This pinion,
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I 50 Sguare- Centreing.
obtained. The wheel 3 also gears into the pinion 4 on the sur-
facing screw, and the one feed or the other may be operated at
will on screwing up either of the friction clutches ll by nuts m m.
The wheel teeth at the back are all inclined so as to gear with
worm wheel 2.
These various motions are reversible, for convenience in screw
cutting or traversing—(r) to obtain right or left-handed threads as
required; (2) to traverse plain work in both directions and secure
greater accuracy; (3) to keep the tool in the threads when returning,
a very advisable method where possible. To effect such reversal
three small wheels are used (Figs. 135 and 136), supported on a
frame turning on a stud n. When clamped, as in Fig. I 3 5, a right-
handed rotation of the mandrel will give the same motion to wheel
n; but if changed to position in Fig. 136, a left-handed rotation
of n is obtained. This is done without stopping the machine.
Supporting the Work in the Lathe.--It is now
necessary to show how the work is carried. If a long bar or
spindle, it is ﬁrst centrea’. Being probably somewhat bent, it must
ﬁrst be straightened until it satisﬁes the eye ; and the centre next
marked on the ends, either by centrezng square, as in Fig. 144,
drawing the dotted lines shown, or by conical punch, as in
Fig. 145. The latter, being held vertically, is tapped with a
hammer. The centre is now found, at least for the end portions
(the most important, because rest of bar can be straightened to
suit), it is next punched, with hand centre-punch, so deep as to
just support the bar in the lathe. A ‘square centre’ is next
placed in the loose head-stock; it is similar in shape to that in
Fig. I 39, but is sharpened on four sides only instead of all round
(see Fig. 146). Being hardened it serves as a tool for cutting the
conical hole in the end of the work. Placing the latter between
a conical centre in fast head—stock, and a square centre in loose
headstock, it is revolved carefully and marked with chalk where
‘full’ (that is, stands out more than the average), which if very
bad may compel us to further straighten the bar; then a crotch
tool (Fig. 147) is placed in the rest against the bar, the latter
being rotated rapidly, and the screw in the loose head-stock is-
turned so as to very gradually advance the square centre into the
work. This centre hole must not be larger than necessary, and-
PLATE v.
face p. 750.



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I 52 Driving.
after ﬁnishing a small hole should be further drilled (Fig. 148) to
prevent the work bearing on lathe centre points. This may be :—
For work i" to 5" dia. .................. .. 31.5" hole.
51! 1!! 1__!!
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and the countersink may be three times the drill diameter.
The lathe centres may have any angle at their apices from
60° (American practice) to 90° (English practice), but the square
centre must be formed to give the same angle. Finally, the work
is reversed, and the other end treated in like manner.
Square centreing may appear clumsy to many; it has, how-
ever, proved satisfactory, and is still much used. The counter-
sink may be drilled by lzana’ orace, but not so truly; the brace
must always be used for the smaller hole. Centreing mac/zines have
been devised, but only for comparatively small work. The bar is
centred and gripped by a .chuck ; the countersinking and small
drills being separately advanced.
Driving.-—-The above-mentioned bar is driven from the
mandrel as in Fig. 149. A carrier A grips the end of the work,
and a catch plate B, screwed on the mandrel, holds a stud C, pro-
jecting far enough to strike the carrier and rotate the work. The
carrier shown will take work of varying diameter.
‘Other methods of support are by Face Plate and by various
c/zucks. ‘
The Face Plate, Fig. 143, is here also a large a’og-c/zuck
having four jaws or dogs A A independently movable. It is
screwed on to mandrel, the ﬁt being‘ very accurate, to ensure
correct surfacing across it. The jaws are adjusted by box keys
applied to the screws B B, until the work is centred and gripped,
when the nuts 0 c are tightened, thereby relieving the screws.
The boss of a pulley may be bored in this chuck, the tool
being held in the slide rest, and the traversing feed applied;
while irregular articles can be clamped directly to the plate if the
dogs are removed, and bolts put through the square holes D D.
"Such an arrangement would be that of --a-face-~plate- proper.
Chucks.--Four examples of Whiton’s chucks are shown in
Chucks. ' I 5 3
Figs. 150, 151, 152, and 153. The Independent Chuck (Fig. I 50)
is really a dog chuck. The screws may be turned by a square
key at A, so far as to release the jaws altogether, which, being
reversed, as at B, serve to hold drills when boring stationary work,
or to take a longer grip on rotating work. Fig. 151 is a good
example of a concentric or ‘ universal’ scroll chuck. Applying a
key to the bevel pinion c, the wheel D is rotated, carrying on its
opposite surface what, on reference to front view, is seen to be a


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spiral having three or four turns in its whole travel. The rotation
of this ‘ scroll ’ moves the jaws nearer to or farther from the centre,
hut equally, thus centreing and gripping the work at the same
time. Fig. 152 is a Lever Chuck having a scroll, but no gearing.
A tommy is inserted at E to turn the scroll F, while the rest of the
chuck G G is stationary. All these chucks are fastened to the
mandrel in the same manner, by bolting to a small face plate
screwed on the mandrel. ,
The Drill Chuck (Fig. 153) has the back portion H screwed on
the mandrel, and the front part J carrying the jaws may be rotated;
the scroll is therefore stationary while the jaws are carried round
it. Hand tightening is sufﬁcient for small drills, the surface of J
being roughened for grip; greater tightness is obtained by using







' ‘T We?“
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Expanding M andret. I 55
the key as shown at K; and, ﬁnally, the worm end of the spindle
is used, as at L, for large drills. As the worm only bears on J in
one direction, it is applied at the opposite hole M to release the
drill.
' Chucks that are either independent, universal, or eccentric at
will, are also made,'having combinations of the foregoing motions.
Expanding Mandrel.--There is still another plan of
support for work having a hole through its centre. It is ﬁxed on
a mandrel (or spindle that can be centred in the lathe), of which
several sizes are kept, having a slight taper, one suitable for the
work being chosen ; but a more expeditious tool is the expanding
mandrel in Fig. 154. The mandrel proper is coned at A, and
has three grooves of the same inclination as the cone, in which


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.Mobleis Zia/[warding JlZouwLf/‘eL.
ride keys so tapered that'their outer surfaces form portions of one
cylinder. The mandrel is screwed with right and left hand
threads as shown, and the advance of nut D will push the bars
cc up the incline, so expanding the cylinder to any diameter
I 56 Lat/2e Tools.
within the limit of the tool. D serves also as carrier for the work,
and nut E on the right is for' releasing the keys or for steadying
them. This tool is made by the Britannia Company.
Cutting Tools for Lathes.-—There are various opinions
on the proper shapes of these. Fig. 155 shows the most common,
where A is the plan of a straight tool, B that of a right hand tool,


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Tool Holders. I 57
and c of a left hand tool; D being elevation for all three. Their
uses are there shown, by the dotted cylinder of work at which
each is engaged. Thus A is taking a traversing cut, while B and c
turn the corners of a collar. Top and bottom rake, and tool
angle, are indicated on D, and side rake must be given to all, for
if the tool cuts to any depth, action must occur at the side as well
as at the front. Section E shows the hollow cone required at top
of tool, which is not easy to give in grinding, but may be approxi-
mated to. F is a side tool for boring work on the face plate,
and G is a cutting-off or parting tool. These tools should all be
set so that the point and the top surface of the tool are both at
the level of the centre of the work. If set higher the tool spring
will tend to lift it out of its out, and if set lower will give a ten-
dency to ‘dig.’ The best method of clamping down the tool is
seen in Figs. 130 and 131, Plate V., and in Fig. 142, where two
plates, 1) p, are securely held over the tool by screwing down four
nuts with a spanner. Space is provided between the bolts to
allow for angular horizontal adjustment. The shanks of cutting
tools should be of large dimensions, both for rigidity and for
taking away the heat generated in cutting, otherwise the tool may
be softened. A ﬁnishing cut is given with a tool having a broad
ﬂat nose. If the work spring considerably under the roughing
cut, inaccuracy will result, which cannot be remedied by a single
ﬁnishing cut, so two or three cuts are taken before the ﬁnal one,
and the bending pressure thereby gradually reduced. If the work
be very small in comparison with length, a hack resz‘ is ﬁxed on
the saddle, forming a hearing which grasps the work near the
tool, to prevent undue spring.
Tool Holders have been used for some time, to do away
with the necessity for forging the tool when worn. These are
shanks so shaped at the nose as to grip small pieces of steel, of
suitable section for cutting purposes. They were ﬁrst introduced
by Messrs. Smith and Coventry. Fig. 156 shows several tool
holders having various advantages. A has the best form, though
the cutter is said to slip ; B was designed to obviate that difﬁculty;
and c is similar in principle to B, though slightly different in detail.
The Break Lathe (so called because of a large ‘break’
between bed and fast head-stock to admit a very large face-plate)























T lie Break Lat/2e. I 59
is shown in Plate VI., as made by Messrs. Greenwood & Batley.
The fast head—stock B has a large cylindrical bearing at C, with
adjustable cap, while the pressure of the surfacing cut is taken by
the collars of the thrust bearing D. The face plate requires no
further description than that given for Fig. 143, except to say
that the jaw screws themselves take the grip, and that the jaw
boxes may be unbolted and the work attached directly to the
plate. The back of the plate has an annular spur wheel, driven
by a system of ‘ treble gear.’ We may turn the mandrel through
the four wheels E F G H in simple back gear; or directly, bolting H
to the cone pulley, and throwing out F and G by turning eccentric
bushes ; but if a slower speed be desired G is slid to the right, E
and F kept in gear, while wheel K and pinion M, keyed to the
third shaft L, are moved to engage respectively with pinion J and
wheel N on face plate.
We have, therefore, three alternatives z—Direct driving without
gear; double-purchase ‘gear, E into F, andG into H; or treble
purchase gear, E into F, J into K, and M into N. The latter is
only required for large diameters of work.
The leading screw, lying within the lathe-bed at A, is driven,
by change wheels P, through shaft Q, and wheels R R at- the right
end of bed. By removing the change wheels, the backshafts may
be put in gear, the power being taken from the belt T, passing
thence to the worm shaft U by spur wheels, and across to the rack
pinion, as in the previous lathe. The handle v will pull the lever
w, and clamp the leading screw nuts, while the traversing
motion may be reversed at x. The slide rest has the same
motions as have been described for Plate V., and the loose head-
stock needs no further description. _
This machine is used :—(1) As a screw-cutting lathe with or
without gap; (2) as a face lat/te. For the ﬁrst the gap may be
varied by loosening the bolts which hold the bed Y to the founda-
tion 2 ; and by then applying a lever to boss K to turn a rack
pinion be, so bring the bed nearer the face plate, the standard
d being also removed. The work would be supported between
the lathe centres, and driven by a bolt in the face plate, or by
small drivers as usual.
As a Face Lathe, the gap is widened; and the upper parts
I60 7 Face Lathe.
efg of the slide rest being removed, they are bolted on the
standard at h, which has a circular T groove to receive the
clamping bolts, and admit of adjustment at various horizontal
angles, thus obtaining a traversing, surfacing, or oblique feed.
The position of the standard is adjusted by loosening its founda-
tion bolts, and applying a crowbar to the teeth j j. Feed is given
‘by hand, but can be made automatic as a star ﬁred, or by an
overhead chain. By the former a star piece is keyed to the slide
screw, and a projection .on the face plate catches this at every
revolution, giving it a small turn. By the second,‘ a chain
attached to a crank pin on left end of mandrel, and passing along
overhead pullies, actuates a ratchet on the slide screw, and gives
a small feed at each rotation.
If a face lathe be especially made for surfacing and very short
traversing, the bed is placed across the line of centres.
The Boring Machine.—Figs. 161 and 162, Plate VIL,
represent two views of a horizontal boring machine designed by
Messrs. Buckton & Co. As already mentioned, many boring
machines are made with vertical bars, as for marine engine
cylinders, the object being to balance the boring head, and pre-
serve truth of surface; but if the bar be made very large and
rigid, as in the example, inaccuracy need not be feared. There
are two classes of horizontal machine: In one the work is ﬁxed
on a stationary bed, while the cutters travel; and in the other the
bed and work are advanced, the cutter bar having no longitudinal
movement. The latter is analogous to lathe boring.
Referringto Figs. 130 and 131, Plate V., a cylindrical bar is
placed between the lathe centres, and driven by catch plate.
About half way along this bar a longitudinal slot is made through
_ it, and a projecting cutter securely wedged therein. The upper
slides v and 2 being removed, as well as the bearings g and r,
Fig. 131 (made separate for the purpose), the work is bolted to
saddle x, by bolts placed in T grooves s s, and, as the bar rotates
and gives the cut, the traversing feed advances the work to the
tool.
Boring machines are made on these principles, being, in fact,
lathes specially designed for boring. The bed is made low, and
the fast head-stock high, the loose head-stock dispensed with, and


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Boring .Mackine. 161"
a bearing for the bar used instead. A table carrying the wdrk is
vertically adjusted by a screw, to accommodate various depths of
work.
For large work, however, we have recourse to a machine
similar to that in Plate VII., which is there driven by an engine
ﬁxed to the bed. We will ﬁrst describe it as though driven by
belt from main shaft,‘ the usual plan. The worm shaft A would
be provided with a large cone pulley to take the power from the
main shaft, and to give various rates of rotation to the machine.
The worm B and worm wheel c effect a slow rotation of the
boring bar D, upon which is the facing head L, for surfacing the
ﬂange of any cylinder bolted to the bed E; the tools FF being
shown in position. Each star H catches the stop J after every
complete revolution, and gives a small turn to the feed screw.
Next on the bar is the boring head K, carrying alternately in
notches on its circumference cutters or dummies, the latter to
steady the head in the cylinder and prevent ‘chattering’; this is
seen at Fig. 163. As the head revolves, it is fed slowly along the
bar. Referring to Figs. 162 and 16 3 it is seen that the head has
a nut M'screwed on its inner surface, and sliding in a groove in
the bar. But the screw N engages with this nut, and it follows
that any rotation of N will cause the head to advance, giving the
feed. Such rotation is obtained by spur gear at the right end of
bar, where four wheels P, Q, R, s form a back gear, giving s a
slightly quicker speed than P ; this difference of velocity being
communicated to the screw through the pinions 'l‘ and U. When
required, Q and R may be slid out of gear by unscrewing
nut v, and the wheel w will then be used for hand feed or
adjustment.
To describe the engine: a is the cylinder, and o the crank
shaft, c the steam; entrance, and d the exhaust. A ﬂy wheel or
crank shaft carries’ the crank pin, and the motion passes to the
worm through bevel pinion and wheel f and g; the remaining gear
being as before. We must not omit the ingenious method of
altering the engine speeds: the governor it is driven by a strap
placed on cone pulleys jj, having an ample number of steps.
If we attempt to give the governor a high velocity the tendency is
to throttle the steam and produce a lower speed on crank;
M





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59. I63.


9f Boning Bout

PLATE VII.‘

0F FEETL

'ScALE
MACHINE & ENGINE COMBINED.


BORING
Joshua Buclubon/ & GS’
FIG. I62.

56$ 956 wk
can...‘ oﬁﬁom unnamed
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Doukle- Geared Drilling M aclzine. 16 3
conversely, the effectiof a decreased governor velocity is to admit
more steam and increase the crank speed.
The Drilling Machine.-This, again, occurs under various
forms, as double or single-geared, radial, and multiple drills.
The last will be explained in Chapter VII., being applied to
boiler work; the others we will describe in order.
The Double-Geared Drilling Machine is shown on
Plate VIIL, as made by Messrs. Smith, Beacock, & Tannett.
The back gear is the same as in the lathe; thus the cone-pulley A
,may drive directly by bolting to wheel B, which is permanently
keyed to the mandrel; or, loosing the belt 0 and putting wheels
D and E respectively in gear with B and F, we may have a slower
rotation of mandrel when drilling holes of large diameter; D and E
are put in or out of gear by turning shaft k in eccentric bushes
as usual. The revolutions of the mandrel are transferred to
drill spindle by mitre wheels H and J ; J being ﬁxed to a sleeve K
held between bearings LL, seen more clearly at Fig. 165. The
sleeve K carries a feather key M, ﬁtting in a long key-way in the
drill spindle, thus allowing the latter to rise and fall. Passing
upward, a smaller spindle N is attached by a pin, and forms one
piece with M, while a loose sleeve P, having a rack formed on its -
right side, is held on the smaller spindle by nut Q and check-nut
R. The rotation of a pinion s will thus raise or lower the drill
spindle without affecting ‘its rotation. Steel plates at TT diminish
the wear caused by thrust of drill or weight of spindle.
The feed motion thus obtained is worked by hand or automati-
cally. A worm wheel U, Fig. 164, on rack pinion shaft, is rotated by
the worm on the spindle v, which takes its motion from the mandrel
through another worm and worm-wheel w, driven by cone pulleys
x x, to give varying rates of feed. If we wish to feed by hand,
use is made of the arrangement at Y, shown in detail at Fig. 166.
A race 2 is formed on the boss of the Worm_wheel which drives
the vertical spindle, and a ‘small crank a serves to lift or lower the
worm-wheel, to put it in or out of gear with the worm. The
handle k, whose movement is limited by the groove c, is shown
holding the wheel out of gear, when wheel a’ is used for hand feed '
or adjustment.
Coming to the table e, carrying the work; it is fastened by set
164 Single- Geared Drilling Mac/zine.
screw to a projecting arm f, and provided with slots for bolts, as in
the lathe face plate. The pillar g, which supports j§ has rack
teeth turned upon it, so that the lifting apparatus may always
remain in gear, whatever the position of arm f
The lifting gear is as follows: A spindleg turns a worm gearing
into wheel j, which has on its axis a pinion engaging with teeth on
the pillar g. The handle k, serves either for spindle q, or for
hand drilling when applied to the mandrel. Some machines have
a plain pillar, as in the next example. A very deep piece of work
is accommodated by bolting to the foot or bed, and swinging the
table out of the way.
In double-geared drills the countershaft is usually self-com
tained, as at m ; and the pulley n is driven from main shaft; the
fast and loose pulleys lying side by side, and the fork moved by
handle 19.
The Single-Geared Drilling Machine in Fig. 167
needs little further description. Back gear is dispensed with, and
the cone pulley A keyed to the mandrel. Hand drilling is pro-
vided for by the handle B on fly-wheel c. s is the hollow sleeve
driven by mitre wheels ; and a feed screw at D takes the place of
the rack, being provided with a long key-way, while a key E (shown
black) is ﬁxed to spur wheel F, so that a feed may be obtained at
any height of drill spindle. The feed screw further passes
through a nut G, ﬁxed to the casting H, and a rotation of F will
therefore raise or lower the screw; such rotation being effected
by turning the hand-wheel on spindle J, the latter carrying a pinion
x gearing into F. A socket L in drill spindle receives acylindrical
projection on the screw, in which a race is turned; and a pin M,
passing through the spindle tangential to the race, allows the screw
to lift the spindle without affecting the rotation of the latter. In
the best machines the feed screw is a hollow sleeve.
The table and supporting arm are similar to the last example,
the lifting gear consisting of a handle N and worm P, worm-wheel
Q, and rack pinion, the rotation of the last lifting or lowering the
arm. The rack R is a sort of strut ﬁtted between the top and
bottom collars of the pillar, but otherwise loose. If the table be
moved horizontally the rack is carried round the pillar, and
remains in gear with the pinion in all positions.
DOUBLE GEARED DRILLING MACHINE,
(by smah/ Beacook/é’cTannetb.)


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I 66 Radial Drilling Machine.
The Radial Drilling Machine is most useful for large
work not readily moved, and has been, since ﬁrst designed, much
used for holes in steam cylinders or boilers. The form of bed
depends on the nature of the work, and is sometimes dispensed
with, and a trolley run under the drill. Then the radial arm may
be swung from a wall'or roof stanchion. The machine in Fig. 168
has a stationary table, to the top or side of which the work is
bolted ; and the tool is adjusted over the work (1) by an angular
movement of arm B; (2) a traverse of the saddle c ; (3) a rise or
fall of B. The last is obtained by turning the spokes E, which,
through worm and wheel, rotate a pinion in rack F; and by the
ﬁrst both arm and pillar turn within the bed at X. The mandrel
o is driven directly or by back gear, and mitre wheels H H transfer
its motion to the spindle J, from which again the power is taken
to the horizontal spindle L by mitre wheels K K. As arm B must
rise or fall, K is supported by a bearing projecting through a slit
in the hollow pillar D, and a feather key connects K and J.
The saddle c has bearings M M, and a sleeved mitre wheel N
drives the drill spindle P. A bearing Q supports a short spindle,
to which are keyed the mitre wheel R, spur wheel 5, and cone
pulley T, from the last of which various rates of feed are obtained
as usual; and power is given from L to s by a pinion U, which,
having a feather key, follows the saddle, so as to keep always in
gear.
The drill power passes therefore through ﬁve shafts, G, J, L, Q,
and P, but this is not considered complicated in view of the
advantages obtained. The saddle is moved along the arm by
turning the hand wheel v, which rotates a small pinion, gearing
into the rack w.
Drills.-—Some forms are shown at Fig. 169, where A is ﬂat-
pointed and ﬁts in taper hole in the spindle, the cottera preventing
slip. The method of sharpening is seen at b, c, and d, and notches
ee increase endurance of point. B is a pin-drill, where variation
in diameter of circle cut is permitted by the movable cutter f,
wedged in the slot g, a hole being ﬁrst drilled to receive pin lz.
Cutting angles have been previously discussed.
The twist drill o, no doubt the very best form for accurate
work, is much in favour. A socket j ﬁts the spindle, and takes

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I 68 Slot-Drilling M aclzine.
the larger drills; a second socket k within the ﬁrst is for medium
drills; and a third, within It, ﬁts the smaller sizes. These are
carefully ground to ﬁne taper, and are quite rigid.
The Slot-Drilling Machine (now metamorphosed into
the vertical milling machine) has a saddle carrying the drill
Y t
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~spindle, as in Fig. 168, but arm B is immovable. While rotating,
the spindle also receives a traverse along slide B, taken from a
', leading screw, lying within B, in addition to the shaft L. The
drill thus cuts out a circle that travels along a straight line, known
as a slot. Keyways and cotter holes are examples, and for such
work vertical and horizontal feeds are required.
Planing Mac/zine. ,169
The Planing Machine, as mentioned, is not strictly
economical, because the tool cuts in one direction only, and the
back stroke is wasted. To minimise this loss, and at the same
time reverse the stroke without changing the continuous rotation
of main shaft, ingenious motions called quick returns have been
devised. '
A large-sized planing machine is given at Plate IX., as made
by Messrs. Hulse & Co. The table, stiffened with ribs, and
having T grooves on its surface to receive clamping bolts, slides
in V grooves B B, made true and level, being the copies. Thus the
work travels, and the tool is ﬁxed. The belt pulleys c, D, E are
loose on their shaft, but c and E are technically ‘fast’ pulleys,
because they drive the table, being ﬁxed to pinions F and G. The
strap being on pulley c, pinion F engages with wheel H; and
pinion J on the axis of H gears with K 3 L in turn with M 3 and
pinion N moves the rack P fastened to the table. A slow cutting
advance is thus obtained. At the end of the stroke the strap is
moved from C to E, and then K is driven directly from G, the rest
being as before. Dispensing with one pair of wheels we have
effected two objects—(1) a reversal of the stroke ; (2) a quicker
rotation of N, or quick rez‘um to the table.
When at rest the strap is on loose pulley D, and handle Q lies
at right angles to the bed. Being connected to strap fork through
levers R, s, U, inspection shows that Q moved to the right will give
the advance, and a reverse movement the return stroke. But,
once started, these motions are automatic, thus—Let the table be
returning leftward in Fig. 171, back stop X will at end of stroke
catch lever Y, and move it to the left, shifting the strap rapidly
from E to c, the advance pulley. If the table travel to the right,
stop 2 catches Y and puts the quick return in action. These
stops may be adjusted to give various lengths of stroke.
Two ‘vertical standards aa bolted to the bed have slides on
their front edges, and are stayed by tube 6. A cross slide 0 lies
across them, supported by vertical screws dd, passing through
long nuts at the back. On the slide are two saddles ee, carrying
other slides f], to give a vertical movement to the tool. Screws
a’ a’ are to adjust the cross slide to any desired height, after which
it is clamped by screws gg. A handle turns shaft lz, which is
I 70 Planing Machine.
connected to the vertical screws dd by similar bevel wheels jj,
and the beam is thus kept horizontal; but in our example three
pulleys are used, h being .fast, while mm are loose, and driven
respectively by crossed and open strap. Moving the forks by the
handle l, either strap is placed on fast pulley at will, and the
cross slide raised or lowered by power.
When the work has cleared the tool on the advance, the stop
n, having passed projection r, catches g, and moves it to the right.
These projections are cast on bar it u, which is provided with
teeth engaging with spur wheel v, and thus shaft w will rotate
more or less according to the position of n. Mitre gear transmits
this motion to shaft or, and from it to the feed motions, which
may, by moving n, be varied from 3-17," to 111;” for each stroke.
The wheel 10 is connected with ratchet wheel 14, but is loose on
x, driving only through plate 11, which carries a pawl ﬁtting in
the ratchet teeth; the pawl may be withdrawn, and the feed
motion suspended by turning the eccentric lever 13. On the
return stroke the stop 1), by catching r, will bring back bar it to
its ﬁrst position, without turning x.
The principal feed is that across the table. Screws 8 8 engage
each with one of the saddles cc; and wheels 6 7, when slid to
the right, connect through 4 and 5 with wheel 3 on shaft 2, which
takes its motion from x by, mitre gear 2. A cross feed is thus
given in one direction; but if 6 and 7 are moved to the left, and
3 with them, the direction of feed is reversed; and the inter-
mediate position leaves 6 and 7 at rest.
A vertical feed is obtained when wheels 15 and 16 are in gear,
motion being given to shaft 17, and from it by two pairs of mitre
gear and horizontal spindle to the screws 18 (these screws serve
also for ﬁne adjustment of tool). The bolts 19 ﬁt in.a circular
T groove formed in the saddle, and thus allow an angular
clamping of front'slides 20, when the last-mentioned feed becomes
angular. Using suitable wheels, one tool may be fed horizontally,
and the other vertically or at an angle.
The teol box may also be ﬁxed at a small angle, limited by
the slot 21; and the front or ﬂap is so hinged at 22 that it
may lift during the return stroke and avoid useless wear of tool,
an automatic motion being sometimes provided for relieving the
PLATE IX.


PLANING MACHINE

(by Hats-e 5a 09)

58A LE 0 F FEET

Fl G. 171.
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S/zapz'ng M etc/zine. I 7 1
tool altogether. Special clamps 2 3 hold the tool, having large
square holes to receive it, and the turning of the_set screw serves
both to ﬁx tool to clamp and clamp in tool box.
The tool itself is shaped as in Fig. 172, being so bent back as to
place the point nearly in a line with the hinge and prevent ‘ digging.’
The Shaping Machine is a planer with moving tool and
ﬁxed work, having on this account some advantage for small
articles ; for if a moving


table be employed, its
stroke must exceed the
length of work, so as to
leave space for the ac-
quisition of velocity in
such a heavy mass;
while the moving parts
in the shaping machine,
being much lighter, en-
able us to adjust the
Plan/(211,91
Too/b-


F/gg 172- stroke with nicety, be-
__ sides absorbing less
work. "
The machine in Plate
X. is by Messrs. Smith
& Coventry. The tool
box A is ﬁxed to a ‘ram’
B, the sliding of which in
saddle c gives the cut. The saddle moves along the bed D to give the
feed, and an arm E, cast upon it, supports a rocking lever F,
which actuates the ram through the rod H. The cone
pulley rotates right-handed, carrying on its shaft (which
extends the whole length of bed) a pinion K, giving wheel L a
left-handed rotation. L turns on a stud ﬁxed to the arm E, and
carries a crank pin P, whose throw may be adjusted similarly to
that in Plate XI. A die on this pin slides in a slot M, formed in



the“ oscillating lever F. Referring to Fig. 17415 the umform
rotation of L will give the ram a slow advance when travelling from
a to b, and a quick return from to a, because a6 is a longer path
than ba, as shown by the arrows; the proportion being 23 to 14
1 7 2 Shaping Machine.
in the example. The pinion K can slide on shaft z,-a~n'd so keeps
always in gear with L, being driven by a feather key. - Length of '
stroke is adjusted by the position of P, but position of ram' is
given by adjustment of the nut Q. ‘
The table R, supporting the work (which is bolted to top or-
side as found convenient), may be adjusted for height by the
handle 5, which, by mitre gear '1‘, rotates the screw within the nut
U, ﬁxed to the bracket v. The horizontal position of the work
may be varied by moving v along the bed to the point required.
w is a mandrel upon which hollow cylindrical work may be
placed by removing the loose collar x, and gripping the work
between the cones. The bracket Y steadies the end of the mandrel.
Three feeds are required, each of which may be worked by
hand if desired. The pinion 4 (Fig. 174a) drives wheel g, carried
on a stud e. An adjustable crank pin on g is connected to'the
lever h, which gives, through ratchet d, an intermittent rotation to
the spindle j. Upon this spindle is a worm gearing into a worm
wheel on the mandrel W,- and thus a rotary feed is conveyed to
the mandrel. The ‘latter may be used for such articles as lever
bosses, which are interrupted on one side by the lever arm, and
therefore unsuitable for lathe work. The second feed is a
horizontal motion of the saddle for work ﬁxed on the table. A
crank pin h, on the wheel L, is connected to the ratchet nz, and
the motion transmitted by n to the wheel p. p forms a nut
attached to the saddle, and as the screw 9 is ﬁxed to the bed, it is
evident that arotation of p will advance the saddle along the screw.
The third feed is vertical. r is a bracket ﬁxed to the saddle,
and s a rod sliding in r, as well as in brackets tt carried on the
ram. At each back stroke of the latter the tappet w, on rod
s, is caught by the bracket r, and s moved to the left, causing the
ratchet gear or to turn the screw 3/, and give a small vertical
advance to the tool box. When the ram reaches the end of the
advance stroke the tappet z in turn catches r, moving s back to its
original position. The head A can be ﬁxed at an angle to the
vertical by unclamping bolts 2 2, and reﬁxing, when the last-
mentioned feed becomes angular ; and the position of the tappets
may also be varied. I .
In addition to the above, a fourth movement, enabling us to
ﬁx the tool box at an angle, while preserving the vertical feed, is


PLATE X.

—-_n*_-*' ___-


W _
Quick RETURN MOTION



I2" STROKE SHAPING HINE:
' (by Smith &


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' FIG IMF.3 FIG.‘ I749
f'cwop. 772. '
Slam'ng Mac/zine. 173
obtained by means of the worm spindle I, provided with a handle,
and worm gearing into the segment j, which is pivoted at 3. We
may thus shape a corner or give a feed (by hand) for a concave
surface. .The front of tool box is provided‘ with the usual ﬂap to
relieve the tool during the return stroke, and the tool itself takes
the same shape as thatdescribed for the planing machine.
The 'Slotting Machine is probably the least economical
of ' machine tools. While the planing machine takes simple
horizontal cuts, and the shaping machine tools cylindrical work
lying horizontally, the slotting machine is for the production of
vertical cylindrical and plane services. Though working at a
‘ disadvantage in having to lift a heavy ram, this machine has
served a purpose, and is still used to a large extent. Smaller
work can generally be accommodated in a shaping machine, but
the slotting machine is used for heavier work, and is made more
powerful.
.Plate XI. represents one of these machines, as made by Sir
]. Whitworth & Co. Power being given to the cone A, it may be
passed directly to the mandrel B, or through the back gear at c,
the back shaft being moved to the right (Fig. 17 5) to put these
wheels out of gear, and locked by a pin D. The power is further
taken from the mandrel to the ram through the medium of a quick
return motion. Looking at the front of the ram, and keeping our
attention on both views, the spur wheel E is driven by the pinion
F, and the motion transmitted to the crank disc G by pin H. The
spur wheel turns on the boss J, and the crank disc in K, their
centres being 1% inches apart horizontally. Referring to Fig. 177,
if the spur wheel rotate uniformly it will pass through 10 divisions
while bringing the pin from H to H1, but through only 7 divisions
from H1 toH, and the advance will bear the proportion of IO to
the return 7. As some sliding takes place betweenlpin H and
disc G, a die is provided. The rod L connects the crank disc
with the ram. M, and there are two adjustments; one at N to ﬁx
the height of the ram; the other at P, where the rotation of two
screws is made to move the pin and regulate the throw of the
crank. A brake block Q, bearing on the crank disc, may be
tightened by screwing up the wedge R, and serves to ﬁx the ram
in positions where it might fall on account of its weight.
There are three feed motions, all taken from the cam s,
I 74 Milling Machine.
Figs. 175 and 178, which is connected by a shaft with the disc G.
At every rotation of the cam a vibration is given to the lever T,
which is connected to the lever U (Fig. 179), carrying a ratchet
pawl, and a partial rotation of shaft v (Fig. 175) thus. obtained.
Both levers are provided with slots to adjust the amount of feed.
The table W to support the work, is circular in form, and has
‘worm teeth on its lower rim. It is mounted on two slides x and
Y, which are again supported on ‘the bed slide 2. The shaft v
turns the bed screw g through the wheels e and f, giving a longi—
tudinal feed, useful for cotter holes and such like. Putting f out
of gear by sliding, a cross feed is effected by wheels a and d, the
former taking its motion from v by mitre gear, and the latter '
being ﬁxed on the‘ cross slide screw h, so that v would be
stationary and x would traverse. The third feed is a rotation of
the table obtained by the worm gearing above mentioned; the
wheel d being slid out of gear, and 6 put in, the worm shaft j is
rotated, and its motion transmitted to wheel k, cast on the table.
This motion is analogous to that of the shaping machine mandrel.
It has been customary to attach the tool directly to the ram,
and let the point scrape on the work during its return, giving
useless friction and wear, but it is now recognised that a ﬂap is
advisable, and such a tool box has been shown. A spring on the
front or counter-balance at the back is necessary to bring the tool
back to its work, gravity not being otherwise employable.
The form of tool may be as for previous machines.
The Milling Machine, though in its present form of
recent introduction, has been known for a very long period; but
it was not till milling cutters or ‘mills’ were produced more
cheaply and correctly by emery grinders that the principle could
be sufficiently extended.
Cutter.-—As already mentioned, a rotating cutter is employed
to which the work is fed, and this we shall ﬁrst discuss. Fig. 181
represents a spiral mill for tooling ﬂat surfaces. All these mills
are keyed to a mandrel or cutter spindle, which is either rotated
between centres, or ﬁxed into the catch plate and only centred at
its opposite end. i Fig. 182 shows a key-seating or grooving _
cutter for cutting key ways or as a parting tool. Being ground
both on circumference and sides, it becomes narrower at each
re-grinding, and therefore inaccurate. This can be avoided by
i i I SCALE 0? FEET ‘ i i . i I XI"
I M I SLoTTINe MACHINE m
by Sir Joseph Whitworth a c?)
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Mil/ing Cutters. I 75
the use of the expansible cutter in Fig. 183, which is divided at
a b by a plane slightly inclined to that of the cutter, and has thin
discs inserted to preserve the normal width. If a a were at right
angles to the axis a strip of uncut material would be left on the
work, which is here obviated, besides which, various widths of
grooves may be cut. Further, if required, two mills may be
placed on one spindle, the teeth being interlocked, and a groove
of about twice the former width thereby cut, but it is important
that the mills be of exactly the same diameter, obtained by
grinding them together on the same spindle. Fig. 184 shows a
pair of heading or twin mills for forming the sides of hexagon nuts
or other parallel work, the width being varied by the insertion of
suitable packing. In Fig. 185 A is a mill for grooving a screw
tap, B for ﬂuting a rimer, and c an angular mill for cutting the
teeth of other mills.
When a grooving mill is allowed to cut on its side only, say,
when ﬁxed in a vertical machine, it is termed a face cutter, but
such an application is not desirable.
The steel or " blank’ to form the cutter is turned to correct
diameter while soft, and the teeth then cut. It is next tempered
to a straw colour, and the edges are ﬁnished by grinding with a
small emery wheel of the same shape as the mill 0, Fig. 185.
Great care must be taken to avoid cracking while hardening, but
distortion is now removed by grinding the Izardeued mill.
Fig. 186 represents a cutter for forming the teeth of spur
wheels by removing the interspaces. a is the relief angle or bottom
rake, a side rake being provided by cutting the proﬁle in an arc
eccentric to that of the point path when rotating. Thus 6 is the
centre for formation of the cutting tooth surface, while e is the
centre of rotation. Now d d and e e are curves struck from u, and
sections ion each of these lines would be rectangular, but a
section on d e must take the shape shown at y‘, because dld1 is
greater than e1 e1 as seen in the end view. But as d e is the path
of the point d during the revolution of the cutter, clearance or
relief angle is therefore given at the side, and the cutter is said to
be ‘backed-off.’ Of course this method can only be used with
cutters of tapering proﬁle; it enables us to preserve both form
and width of cutting tool, however much is removed from the
face, and is an improvement on the old cutter, which became

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Milling Cutters. I77
narrower on re-grinding. The space between the teeth is to
admit an emery wheel for grinding the faces.
Angle of toot/z, although important, is still rather in dispute,
principally because the same cutter, to avoid expense, is being
used for various materials—a wrong procedure, without doubt.
Probably some variation on the angles already given is necessary,
because of the higher speed of cut. Experience seems to suggest
the following :—
Cutting angle ................ .. 80° to tangent.
Angle of relief ................ .. 10° to tangent.
Front rake ......... .., ....... .. 10° to radius.
giving a tool angle of 70°. Small mills are made with radial
teeth, corresponding to a cutting angle of 90°. A side rake of
10° should be given, and the teeth cut spirally or obliquely on a
ﬁnishing tool.
Speeds—There is still more variation in practice regarding
these. They can be considerably higher than for other tools,
because each tooth is in contact for only a small portion of the
revolution, and has ample time to cool. The result is the more
highly ﬁnished work that has brought milling into favour. The
following speeds give the result of experience, and are fairly
correct :—
Mllz'ng Speeds in feet per minute ,- and revolutz'am per minute, in
terms of radius (r)" 0f cutter.

v ROUGHING CUT. FINISHING CUT.
Ft. per M. Rev. per M. Ft. per M. Rev. per M.
For Steel ................ .. 30 % 40 l:
,, Wrought Iron .... .. 4o 9;- 5 5 {Ci—:—
,, Cast Iron .......... .. 60 ll; 75 Iii—-
,, Gun Metal ....... .. 80 i5;— 100 i2;
,, Brass ................ . . I 00 £23 I 20 2E—










Universal Milling Mac/zine. 179
The Universal Milling Mae/zine was of American design in the
ﬁrst place, and one of these useful machines is shown in Plate XIL,
as made by Messrs. Tangye.
The mandrel A is driven from the cone pulley B, either directly
or through the back gear, the latter being thrown out by the
handle (I, which turns eccentric bushes as usual. The mandrel
is of large diameter, for stiffness, and revolves in coned bearings
D D, the thrust when using a face cutter being taken by the steel
tail pin E. A strong overhanging bracket E carries a small head
H and centre G, to support an edge cutter, which centre is
roughly adjusted by unbolting H, and ﬁnely by unscrewing the
check nuts. The bracket is usually made round, and that form
has some advantages, but is not so steady. The mill is either
supported between centres, and driven from the catch plate; or
has a shank similar to that described for the drill sockets at
Fig. 169, when it is further steadied by the outer centre G; the
latter is the more common method. A twin' mill is shown in
position. Sometimes tools are ﬁxed in the holes shown in the
catch plate at J, which is thus transformed into a face cutter, but
the points must all be placed in the same vertical plane, so that
each may take its proper share of work.
A vertical slide K, having square edges for rigidity under
heavy cuts, supports a knee bracket L, which carries the table M,
and between L and M are two slides N and P, the ﬁrst for longitu-
dinal, and the second for cross traversing. These swivel on the
circular table Q, formed by their common surfaces, and P is made
of extra length in plan to steady the table, a detail often
neglected. A special point is the improved means of traversing
the table. This is often effected by telescopic shafts with universal
joints connected to the end of the table, and these sometimes act
at such bad angles that the joints in crossing centres cause a slight
dwell, which is reproduced on the work. This is avoided in the
machine illustrated. A small cone pulley R on the mandrel
drives the lower pulley s, keyed to the worm shaft '1‘. This shaft
carries a worm, gearing into a worm wheel g. A telescopic shaft
U is connected to the inside of the worm wheel by a universal
joint, and to the mitre wheels v w by a corresponding joint; these
convey the motion to the screw x, which gives a cross feed to the
180 Vertical Milling.
table. They are ﬁxed in the centre of the swivelling table, and
will transmit the feed motion with steadiness, even when the
table is swivelled up to 45°, say for cutting spiral mills, twist
drills, &c. By moving the hand lever Y the mitre wheel W may
be drawn out of gear, and the cross feed given by hand, if
desired, a catch 2 ensuring the contact of the wheels when in gear.
The longitudinal feed from screw a is rather a setting motion,
there being few cases where other than a cross feed is desired.
The handle h is to raise or lower the table, which it does by
turning the screw e through the medium of the worm gear d.
Other forms of machine are Vertical Milling Machines and
Proﬁling Machines. In the former the putter spindle is vertical,
and a circular feed, as well as'traverse, is given to the table. The
latter is a smaller tool, where a vertical mill is traversed by a hand
lever so as to accommodate itself to intricate forms. Good
lubrication is necessary for all mills, and should be supplied under
pressure from a small pump.





Dill/wing Heads/Cocks.
£291.22
Dividing Head—When milling teeth of wheels, cutters, rimers,
~&c., the work is supported in centres shown in Fig. 189, which
are fastened to a small bed, and bolted to the machine table.
The wheel to be cut is ﬁxed on a mandrel, and held in position
PLAT E XII.




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FIG. I88.

UNIVERSAL MILLING MACHINE’.
(by Tangyeis Machine Tool 6.?)
'08’! ‘d ma!
Dividing Cen z‘res. 18 I
by the carrier A, which is screwed on the right hand centre, and
ﬁxed in spindle B. The spindle B may be turned through any
desired angle by the worm c and wheel D. E is a steel drum
provided with small holes, representing various exact divisions of
its circumference, and the point F can enter any of these, so as to
set the spindle in the desired position. Knowing the number of
spaces in the wheel to be cut, or ﬂutes to the rimer, drum E,
called a dividing plate, can be placed in each position in turn,
and a cut taken. The heads G and H can be either bolted‘
directly to the table, or packed to any convenient height, to
accommodate a larger piece of work ; or H may be bolted to the



c J
790. Zion/[offs Machine Viz'gg
table, G packed, and the centres placed at an angle, as shown by ‘
dotted lines, useful for tapered work. This is obtained by
releasing the screws J and L, when centre K may dip, and B be
tilted between the cheeks of H. B may be further turned at any
angle up to the vertical, for milling cutters of various angles, and
E has a conical socket to hold the mandrel supporting the work.
Similar centres are used when milling spiral cutters or twist
I 8 2 Machine Vice.
drills, but then the spindle must be rotated gradually, by change
wheels connected with the feed.
The Machine Vice is a very useful appliance for Shaping,
Milling, and Drilling machines. It is shown at Fig. 190, and
is .bolted to the table of the machine, its object being the holding
of work too small to be fastened down directly, or to facilitate the
setting and resetting of such work. A great desideratum is that
the latter should bed ﬁrmly on the surface of the vice, accom-
plished in the example by the bevelled jaw plates A A, which pull
the work down at the same time as it is gripped, by sliding on the
bevelled surface. The nut B can be rapidly changed to any
notch, and ﬁne adjustment given by applying a tommy to the screw
C. The jaw D has a cylindrical shank and plate F; it can there-
fore be set at any horizontal angle, and the screw c will still bear
upon it normally. B is also provided with lips at G, to resist
upward pull.
... .4 - - N uw‘w’l‘ ulnnrlr I‘ - .~.--M..._, .-_._.. .- ..
. u- ~“i.>l 0-‘ JIKI'J I
CHAPTER VI.
MARKING-OFF, MACHINING, FITTING, AND ERECTING.
WHEN an engine or machine is ﬁrst projected, a rough
‘general’ drawing is made by the draughtsman, in order to
determine the relation of the several parts; after which the
‘detailing’ takes place, which consists in drawing out each piece
separately to a large scale, and at. ‘the same time classifying the
work—putting all the forgings upon one set of sheets, and the
castings upon others, so as to facilitate the distribution of the
parts to the various shops and avoid delay.
Detail Drawings are fully provided with dimensions, and
have red lines drawn round surfaces that need Fitting or Machining,
viz., such as are required to ﬁt or work together; and the Pattern
Maker and Smith are thus enabled to decide where to leave extra
material. It is the business of the Marker-0f to ‘line out’ the
rough work received from the above men; that is, indicate by a
boundary line the amount of material to be removed by the
Fitter or Mac/zz'uz'st. The work is then ﬁnished and passed on
to the Erector, who carefully puts it together to form the com-
pleted machine.-
The Marker-off’s Tools.—A large plane table or
Surface plate is ﬁrst required. This is shown in Fig. 191, and
its size varies with the average work to be lined-out upon it—
from 4 ft. by 2 ft. up to 12 ft. by 4 ft. It is well ribbed under-
neath to prevent any possible distortion, and is planed very truly,
being better also if ﬁled up and a little scraping done upon it.
The edges should be planed truly and adjacently at right angles,
so that squares may be applied to them when necessary. Lastly,
the feet should stand upon a ﬁrm bed of concrete, and be
adjusted until the surface of the table is truly level, which often
assists the marking-off considerably.
V blocks, to support cylindrical work upon the table, are















193. SOT/{hing Block,
M arker- of ’s Tools. I 8 5
shown at A, Fig. 192; and Cubical blocks are also provided,
of several sizes, but each of known depth and so ﬁgured. They
have. their surfaces truly parallel, and are used to gain greater
height for the Scribing block, as well as for the purpose of
packing up the work (see B, Fig. 192).
The Scribing Block, Fig. 193, is a most important tool.
It consists of an upright pillar A, ﬁxed in a base B, which has
been truly scraped underneath. Upon A slides the head D,
which can be set to any height by tightening the nut H, a pointer
or scriber E being at the same time ﬁxed at any convenient angle
by nut G. Most scribing blocks have no other adjustment, but
in that shown there is a screw at F for further accuracy; while
the head 0 is ﬁrst clamped, and D left free until ﬁnally adjusted
by the screw F, after which D is ﬁrmly tightened and the scribing
done. The scriber has one point straight and the other curved,
the uses of these being shown, where J can be made to ‘ scribe ’ a
horizontal line on the work by moving the block along the table,
and H may serve to ‘ feel’ the height of certain other work. The
scriber is of steel, well-hardened, and must be kept sharp by
rubbing on an oilstone.
The Hand Scriber (Fig. 194) is to the marker-off what the
pencil is to the draughtsman. It is pointed at one end, and
hooked at the other for hanging to the pocket.
Compasses and Trammels must be provided for striking
arcs of various radii, and as some pressure is required to make a
suﬂiciently clear line on the work, both these tools should be
suﬂiciently rigid; the former being supplied, for this purpose,
with an arc and screw, and both tools shown at Fig. 195.
Accurate measuring Rules, with inches divided into eighths
and tenths; Squares large and small (3 in. to 3 ft.); Straight
Edges of different lengths; and Callipers, both for internal
and external measurement, are all necessary tools; while if the
work is too large to mark-off on a table it should be levelled, and
all lines drawn by reference to an ideal horizontal or vertical
plane, necessitating the use of either a Spirit Level or the
Square and Plumb-Bob shown at Fig. 196, the latter being
the only tool in favour with the best workmen, as levels are
known to get out of order so easily.
'1-86 F itter’s Tools.
Of Centre Punches two are required, the larger for mark-
ing main centres only, and the smaller, or Dotting Punch, for the
purpose of making a scribed line more lasting and apparent, by
marking a series of punches or ‘dots ’ along its length.
A light crane arm and Weston block is also of use when work
of large size is to be manipulated.








Fitter’s Tools.—-Most ﬁtting is done at the bench, the
work being gripped in a vice, of which there are two principal
kinds, ‘Leg’ and ‘Parallel.’ The old—fashioned Leg Vice,
made of wrought iron with steel-faced jaws, is still considerably
used, because capable of withstanding a large amount of hard
C/iise/s. " I 87
usage caused by heavy chipping, &c. It is shown at Fig. 197,
and is fastened to the bench by coach screws at A, while the leg
1: serves as a steadiment. Although the pin 0 is a long way
down, the jaw faces are very far from parallel when the vice is
opened to its widest, and then wedges must be inserted to secure
an even grip. To avoid this difﬁculty the Parallel Vice was
introduced, and is now extensively used. It may have either a
simple screw arrangement for gripping, as in the leg vice, or may
have some method of rapid adjustment or instantaneous grip.
The example in Fig. 198 is of the latter class, and instead of a
screw there is a set of levers forming a toggle joint. Referring to
the diagram, AlA are the toggle bars, A1 being pivoted against the
casing c, and A against the toothed bar B, which is capable of
engaging with the teeth in the sliding bar E. The bars are
further held together loosely by the spring D. In order to grip a
piece of work, the handle is ﬁrst thrown back as in the ﬁgure,
and the bar E, being free, is pushed nearly up to the article.
The handle G is next pulled towards the operator. When it
reaches the position H, the bar A1 is released, and the spring D
brings the teeth at B and E into contact. Then, as the handle is
pulled further forward, the eccentric boss J acts on the back of
the lever A1, and, nearly straightening the toggle, forces the bar E
forward with great power.
The proper height to place the vice is an important con-
sideration, and depends on the class of work for which it is
to be used. If this be light, the jaws should be rather higher
than the elbow, to bring the work nearer the eye; but if the
work be heavy, the ﬁtter needs to put his whole weight on the
ﬁle, and the jaws are then placed rather lower than the elbow.
A good average is 42 ins. to the top of the jaws, which requires
a. bench 2 ft. 9 ins. high. The Hand Hammer has a head of
about 2 to 2% lbs. weight (the latter only for very heavy chipping),
and a shaft from I2 to 15 ins. long. It is shown at Fig. 199.
The ‘ face’ is ﬂat, but the ‘ pane’ is usually spherical, for riveting
purposes.
The F itter’s chisel, called ‘cold,’ or ‘ chipping,’ has three
varieties :-—The Cross-cut Chisel, Fig. 200, is for roughing
out work for the ﬂat chisel to follow upon. When in use A is
P- — _-“ by“ 6»









L,eg







_—-
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.1 .
r 1103..
198.
Files. ~ I 89
the elevation, and B the plan view. The Flat Chisel, Fig. 201,
is used to true up surfaces previous to ﬁling; and the Round-
nosed Chisel, Fig. 202, is for chipping out concave ﬂutings;
but the last is more of a machinist’s than a ﬁtter’s tool, the lathe-
man and driller both using it for ‘ drawing ’ a centre-punch mark
or countersink, which has been begun untruly, by chipping a
little to one side of the depression so as to alter the position
of the centre, after which the drill or square-centre is again
applied.
The point of a ﬂat chisel is ground symmetrically on each
side, and should enclose an angle about equal to that of the V
screw-thread, viz., 55°, though a slightly smaller angle may be
used in ﬁnishing. After chipping, the surface must be further
trued by ﬁling.
Files may be classiﬁed in two ways: (I) by the contour,
both in length and in section; (2) by the kind of cut and degree
of ﬁneness. The length must also be stated, measured along
the edge, not including the tang. The cut may be double or
single, the latter being also called ‘ ﬂoat ’ cut, but as this is prin-
cipally used for saw ﬁles, it will not be considered further. Longi~
tudinally, ﬁles may be parallel or blunt, and taper or pointed;
and in cross section they may be ﬂat, t/zree square or triangular,
half-round, round, and square. The ﬁneness of cut is repre-
sented by the terms roug/z, middle, bastard, second-out, smooth,
and dead-smooth, the last four only being required by the Fitter.
Safe-edge ﬁles are those left uncut on one narrow edge, to serve
in ﬁling a surface near a corner, without destroying the truth of
that at right angles to it. Files are either machine or hand cut,
of which the latter are most in favour. It will be seen there-
fore, from the previous information, that a particular ﬁle may be
described something as follows :—-‘ 12 in. hand, taper, ﬁat, bastard,
double-cut, safe-edge ﬁle.’ As the teeth only cut in one direction
‘the ﬁle is analogous to a planing tool.
Scrapers still further true up a surface left by the ﬁle or
machine tool. They are made from old ﬁles, by grinding off the
teeth and sharpening the edges, and have three principal shapes
as shown in Fig. 203 : Half-round (A), useful in scraping a bear-
ing ; three-square (B), sharpened on the long edge for truing up






Surface Plates. 191:
narrow ﬂat surfaces or slot holes 3 and ﬂat (c) used on the end
for scraping a large plane.
Surfaces that are ‘to be trued by scraping must be referred
to surface plates, of which the Fitter should possess two, as
perfect as possible in workmanship; one (A, Fig. 204), of







moderate size, so as to suit the average work to be laid upon
it,- and a lzana’ plate (B, Fig. 204), to be moved over the work,-
which, being supplied with a removable handle, may serve as Za=
ﬁxed plate when needed. Their method of use will be treated
later.
Lastly, Screwing Tackle is required, which consists of Stocks
192 T ups.
and Dies for bolts or spindles, and taps for the nuts in which
these spindles are to ﬁt. Taps are made in sets of three to
each diameter of screw, and to cut V threads of ‘Whitworth ’
pitch; that is, whose pitch per diameter agrees with those in the
table devised by Sir joseph Whitworth, and which is here
appended :--
‘V Threaded Screws (Whitworth).

_ Dia. Threads _ Dia. Threads l _ Dia. Threads _ Dia. Threads
in ms. per inch. In ms. per Inch. In Ins. per Inch. In ms. per inch.
T33 24 I 8 2i 4 4% 2%
i 2 0 1 g, 7 2%- 4 4i- 2 a I 8 It 7 2% 3i- 5 Zi-
s 16 Is 6 3 a 5% 2s
1% 14 It 6 3t 3t 5% 2%
i 12 It 5 3% 3%; s-i 2%-
t 11 It 5 3% 3 6 2%-
i 19 1% 4% 4 3
i 9 2 4% 4i- 2%


Very rarely are taps used beyond 1%; ins. diameter, larger sizes
being screwed in the lathe. The set of three is shown at Fig. 20 5,
and includes ‘taper’ (A), ‘ middle ’ (B), and ‘ plug ’ taps (c).
These are made by forming in the lathe a perfect screw thread
upon a ‘ blank,’ and afterwards ﬂuting to the section shown
enlarged at B, so that‘when the tap is turned right-handed it has
a cutting angle of 90°, and a small relief or clearance angle,
removed with the ﬁle. Next, two-thirds of the length of the taper
tap, and one-third of the middle tap are turned off, after which
all are hardened as shown at page 127. When in use the nut
must ﬁrst be tapped, and the bolt afterwards screwed to ﬁt it.
After drilling to ‘ tapping size,’ that is, to the diameter at‘the
bottom of the screw thread, the taper tap is ﬁrst entered (while
the nut is held in the vice), and is turned round by a wrench D
applied to the square on the top. Only when turned right-
handed is the thread cut, as will be seen on reference to E,
Stock and Dies. 193
Fig. 205; and a left-handed turn will release'the 1.001. When the
taper tap has done its work the middle tap is introduced in like
manner, carrying the operation a little further, and ﬁnally the plug
tap is passed. through to give the ﬁnishing out. After every
stroke forward, the workman releases the tool slightly so as to
avoid undue pressure and perhaps breakage.
A stock and dies is shown at Fig. 206. A is the stock, pro-
vided with handles for turning, and B is an enlarged view of one
of the dies, having a thread upon it in reverse, and four cutting
surfaces at 90°, two to each direction of rotation: so that the
thread may be'cut both on advance and return. The dies are
shown in position in the stock A, being dropped in at e and slid
along : then tightened by a tommy applied to the screw d. The
bolt to be screwed is ﬁrst turned to the outside diameter of
the tap, and then ﬁxed in the vice. The dies are separated
slightly, the stock brought over the bolt as at c, and the screw
advanced. The stock is now rotated until the length of the bolt
is traversed; then, on reversing the motion, a slightly increased
pressure given to the dies ; and so the bolt is re-traversed again
and again, until so cut into by the dies as to show a perfect
thread, and gauge to proper diameter, which may be proved by
trying upon it the already tapped nut, and any degree of tightness
obtained after such trial. At each stroke a slight backward
release is given as before, and oil may be used as a lubricant.
Various sized dies may also be applied to the same stock.
For screws under a is in. diameter the Screw Plate in Fig.
207 replaces the stock and dies, and only one tap is required in-
stead of three.
The pitch of a screw being measured lengthwise from centre to
centre of the threads, let us unwind the latter, both at the top and
bottom of the V groove. The diagram in Fig. 208 will show the
result obtained in each case, and it will be clearly seen that the
angle at the bottom of the thread is larger than that at its top.
But the action of the dies, in cutting, is to ﬁrst mark out the top
of the thread with that part of the die formed to ﬁnish the angle
at the bottom, and it follows that by the time the thread is
ﬁnished, there will be an unnecessary endlong play of_ the bolt in
the'nut. These faults are somewhat avoided by the use of the
o


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OP rHRA‘RD
Grz'na’stones and Emery W/zeels. I 9 5
Whitworth Guide Screwing Stock in Fig. 209. Here there
are three dies, a being the ‘ guide,’ cut so that its ridges just ﬁt
the bolt at ﬁrst, and made to mark out the correct angle for the
top of the thread. b and c are the cutting dies (gradually
advanced by the wedge bolt 0’), and these ultimately give the
correct form for the bottom of the thread. But the only perfectly
true method of cutting a screw is by means of the lathe, where
the tool is ﬁxed in the slide rest and the thread formed by the
gradual advance of the rest coupled with the rotative movement
of the work.
Machinists’ requirements, in addition to the tools men-
tioned in Chapter V. These consist of grinding and sharpening
tools.
The Grindstone, though banished from some shops in
favour of emery, is still so extensively used as to deserve mention,
It is shown at Fig. 210, and the stone ﬁts on a square spindle
having journals at the ends, lying in simple bearings. Large
washers are placed on each face of the stone and the nut a
tightens these. Fast and loose pullies are provided for driving
by power, and a shield c to prevent the water ﬂying about, the
latter being a necessary lubricant. c is a rest for the work, placed
rather high up, and as close to the stone as possible, to avoid
accidents. The direction of rotation of the stone is shown by the
arrow, and the speed is such as to give from 800 to 1000 ft. per
minute surface velocity. It is not advisable to actually run the
machine in water as this tends to soften the stone.
The Emery Grinder is seen at Fig. 211. Its bearings are
longer than those of the grindstone, and its peripheral velocity
much higher, being about 5000 ft. per minute. A plentiful
supply of water is required for tool sharpening, otherwise, with
most emery wheels, the temper would be drawn and the wheel
become glazed. The water is shown in the ﬁgure as coming from
a vessel above the wheel, but is sometimes supplied under pres
sure ‘from a small pump. Glazing is caused by the cementing
material becoming softened by the heat produced in grinding,
though properly the cement should wear gradually and fall away
with the emery powder.
A very useful form of emery grinder is shown in Fig 2I2,

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T wist-Drill Grinder. 197
suitable both for tool grinding on the larger wheel, and ﬂuting,
&c., on the small wheel. It is made by Messrs. Selig, Sonnenthal
& Co., and a small attachment is provided to .carry the wheel
when grinding milling cutters, the latter being then held on [the
)
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spindle of the machine, and the wheel driven by catgut band.
Emery wheels may be used for general grinding and removing of
surplus material and thereby save a large amount of ﬁtting.
Twist-Drill Grinder.--These are of various designs, the
one in Fig. 213 being made by Selig, Sonnenthal & Co. The end
of a twist-drill would be conical in shape but for the clearance or
relief angle. The‘ true surface becomes, accounting for clearance,
.a cone having a helix for its base, and enclosing an angle of 118°.
A section of this cone, then, made at right angles to one of the
slant sides, would give a curve deviating slightly from a hyperbola,
due to the clearance. We will now examine the method by which
this hyperbolic surface is ground in Messrs. Selig’s machine.


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f'OR RIMERS, TAP-5‘ ac.
r01? CUTTER $105.5‘ CUTTER £00 £6‘

Univ/anew Mdling- Caliber G/r/z'zzolllng
BY SEL/G , ,sQ/v/vL'NrH/tz. 8e vcf?-
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T/w/clsb DJZZL Grinder
(By ‘hug, Sonnenthal/ do 6?)


200 Capstan Head Lat/re.
First the drill is clamped in a V groove made in the support
A, and is held in the proper position by means of the plate B
placed at the front end of the groove. The support A rides
on a guide-arm c, which, in plan, is set at an angle of 59°,
or half the angle of the drill. This allows the surface of the
drill point to lie parallel to that of the emery wheel D. The
hand-wheel E serves to bring the drill to the wheel, and F turns
a screw for the purpose of taking up various surfaces of the
wheel so as to produce equal wear. G is a fulcrum, supporting
a rocking arm, which, in turn, carries a horizontal arm H. _ The
end of H encloses the emery wheel spindle, and the other is pinned
to the rotating disc J. It follows, therefore, (that if the disc J be
turned left-handed by taking hold of the handle K, the rocking
arm will deviate to the front, and the centre of the emery wheel
will describe the approximate hyperbola required to be ground off
the drill point, as shown by the dotted lines in elevation. By
ﬁxing the fulcrum G at slightly varying heights by means of the
hand lever L, it is possible to obtain sufﬁcient variation in the drill
curve to suit various sizes of drills; and, as the driving strap is
changed in position, it is kept tight by the jockey pulley N
provided with a balance weight. When using the machine the
workman takes hold of the handles M and K, and pulls K towards
him, and after one surface of the drill has been ground the latter
is turned round in the V groove, and the opposite surface trued
up, B then serving to register the second position with the ﬁrst.
The Capstan or Turret Head—Although we were
supposed to have completed our descriptions of machine tools in
Chapter V, our work would be incomplete without an account of
this very important labour-saving appliance. The lathe in Fig. 2 14
is shown supplied with both Capstan-Head Slide Rest, and Screw-
Copying apparatus, and is designed by Selig, Sonnenthal, & Co.
A is the head, which is capable of holding six tools, to be‘used in
succession on the work in the lathe, and placed in position by
releasing a catch E, turning the head by hand, allowing catch E to
return to its place by means of a spring, and ﬁnally clamping the
rest ﬁrmly by means of the lever D ; all this occupying but a very
short space of time. Of course, it may often be necessary to use
both slides to put the tools in position, as, will be seen, and the

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202 E rector’s Tools.
usual rack is provided for moving the saddle. some distance along
the bed.
Turning now to the screwing gear, J is a rest for the screwing
head, with screw for adjustment, and when in position for work is
held by the handle N. At the same time a lever L, provided with
a screwed die ﬁtting in the threads of the screw M, is placed at the
other end of the shaft H, so that when the screwing tool is on the
work, L engages with the screw M, but if the rest J be lifted and
thrown back, L is at the same time released. When in operation
the screw M is rotated from the mandrel by gearing of 2 : 1, so that
a screw is cut at c, having half the pitch of the copy and of
reverse hand, M being usually left-handed, and c right-handed.
Of course the shaft H is capable of longitudinal motion, and the
piece M, being hollow, can be removed, and another of different
pitch applied, while the die, usually made of copper or soft brass,
does not need special cutting, but will ﬁnd its way into the threads
of the screw.
Lastly, the lathe is provided with a hollow mandrel, which is
very useful for small articles that can be cut from a continuous
bar. An example of such work is shown in progress, being the
making of a small tap bolt. A hexagonal bar is held in a con-
centric chuck, drawn forward to a convenient length, and the
roughing tool g ﬁrst applied, traversing to the front for position.
The bolt being roughed down, is ﬁnished by the tool h, and has its
end rounded by j. Next the screwing is performed by bringing
over the tool in ; and, lastly, the chamferzng and parting are done
respectively by the tools it and l. It will be, therefore, clear that
a great deal of time and labour may be saved by the use of such
a tool where articles have to be made in quantity. All bolts and
studs are turned at such a lathe.
Erector’s Tools—These will include Lifting Tackle and a.
Portable Drilling tool. The latter is known as the Ratchet
Brace, and is shown at Fig. 215 in position for drilling a hole.
The pillar A is clamped to the work, and carries an arm F, which
can be set at various heights, to take the brace and drill B. As
the latter is ground to cut in one direction only (see d, page 168),
the brace is made to enclose a ratchet wheel c ﬁxed to the drill
spindle, which wheel is driven by the spring pawl D, so as only
Ratc/zet Brace. 20 3
to be in action when the handle is pulled towards the operator 3
the back stroke being ineffective. The feed is given by holding
the nut E with the left hand, while the drill is turned right-handed,
the screw thereby receiving a downward advance.
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As a simple Erector’s lifting gear, the Weston Pulley
Block has stood its ground well. The principle is differential.
The upper pullies A B are cast together, and are slightly different
in diameter. They are gripped by the chain, which lies in a
specially-formed groove, and while the upper pullies are once
rotated, the lower or movable pulley is raised by half the
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jacks and Lifting Tackle. 205
mechanical advantage. There is a very large loss by friction
(some 75 per cent), but this resistance is useful as serving to
sustain the weight when the chain is released by the hand.
jacks are useful where overhead support cannot easily be
obtained. Fig 217 shows a simple Bottle Jack, the ‘bottle’
serving as a ﬁxed nut in which the screw rises when turned by a
tommy bar 5 and Fig. 219 represents a more powerfuljack with
worm gear. Here the screw is prevented from rotating by the
jaw d, and is, therefore, raised by the rotation of the worm wheel
A, which acts as a nut. In the example a handle of 14 ins.
radius turns, by means of a worm, a worm wheel of 16 teeth,
enclosing a screw of 1% in. pitch; and a weight of 10 tons is
thereby lifted. The lower jaw d is for loads that are near the
'ground, and the jack may be traversed, when in position, by the
ratchet arm c, applied to the screw 12 at either end.
The Hydraulic Jack is both very useful and very interesting,
and is shown at Fig. 218. It has an upper and a lower jaw to
suit various work, and both are part of the cylinder A. B is a
reservoir in which is placed oil, or water and glycerine. The handle
being moved upward on the fulcrum c, the pump plunger D is
thereby raised, and the liquid enters the pump through the
suction valve E5 on the down stroke it is forced through the
delivery valve F, and exerts a pressure behind the ram 0, thus
lifting the cylinder A. The valves are ‘ non-return,’ being loaded
by springs, and the ram is packed by a cup leather. It being
required to lower, the screw-down valve H is released, and the
, liquid runs back to the reservoir. Screw is for ﬁlling the latter,
and K is an air hole to assist the pump suction. The power
obtained depends both on the leverage and on the ratio of the
areas of plunger and ram, and may be calculated in the same way
as for the hydraulic press, which will be discussed in Part II.
There are a few other small tools of use to the Erector. The
D Cramp A, Fig. 219b, is for temporarily fastening two pieces
of work together 5 and the Key Drift B for releasing keys when
ﬁtting wheels upon shafts. The ﬁle 0 is provided with a special
handle, usually made from a bent bolt, to enable a very large
surface to be ﬁled; and the Square Drift at Fig. 219e is really
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FILE FOR ZARGE SURFACES
539.219. 5.
C/zioping and Filing. 209
drilled and slotted. A Lead Hammer, for use on ﬁnished
work; a Hack Saw; and an adjustable spanner are also
advisable. Round holes are cleaned by the Parallel Rimer
in Fig. 231, and taper holes by means of a Taper Rimer
similarly constructed.


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General Processes.-—-Chipping.—Although hand pro-
cesses cannot well be taught on paper, a general idea may yet be
obtained. We will consider ourselves provided with a cubical
block of metal, and that it is desired to remove a rather large
amount of material from one of the surfaces. We commence by
placing the block on the marking-off table, and, chalking the
edges, scribe a line round as shown at Fig. 219a, to indicate the
layer to be removed. This done we place the work in the vice
and chip with ﬂat chisel a chamfer along the edge of the block,
nearly down to the scribed line, as at B, and make this fairly
straight with a rough ﬁle. Now the cross-cut chisel is applied,
and with it the cross grooves are cut as at 0, each groove being
tried with a straight edge, to make sure it is not carried too far
below the general surface. We are now in a position to com-
mence the removal of the strips that remain by means of the ﬂat
chisel, constantly trying the work with the straight edge, until the
whole is as perfect as the chisel can make it. The position of
the workman and the angle of chisel are shown in Fig. 220, and
practice only will show the steepness of angle required for the
deep cut, and the shallower angle for the lighter cut
Filing—The ﬁle is next applied, and the various ‘cuts’
used in order from bastard to smooth. True ﬁling requires con-
siderable skill, the tendency to the production of a convex surface
being very great. The back stroke needs no pressure, as the
teeth do not then cut; but during the forward stroke all possible
P
' 2 IO - vScraping.
pressure is put on with both hands, and the ﬁle carefully guided
in a perfectly horizontal direction, the position of the hands
being shown in Fig. 221. Comparatively narrow surfaces that
are not to be scraped are generally smoothed by ‘ draw-ﬁling,’ the
ﬁle teeth being rubbed with chalk to compel the small particles
to drop out, and thus avoid the scratching of the work, and a
still further polish given by means of ﬁne emery cloth wrapped
round the ﬁle. The position is shown at Fig. 222. There is
some difference in the grip of the ﬁle upon various materials, it
being greatest on wrought iron or steel, and least on cast iron or
brass, so that a ﬁle may best be used when new upon brass, then
on cast iron, and ﬁnally on wrought iron or steel, for it will grip
the latter when worn on the former; but the reverse method
would not be feasible. During ﬁling the surface should be
constantly tested with straight edge, and when ﬁnishing, a hand
surface plate, being slightly greased with oil and red ochre, will,
on application to the work, at once indicate the parts to be taken
down. The skin of a casting should always be removed, either
by chipping or by pickling in dilute acid, before applying the ﬁle,
otherwise the teeth would be at once dulled by such a hard surface.
Scraping.--If the surface is to be further trued, recourse is
had to the scraper. We will assume that the tool B, Fig. 203, is
to be used. It is held in the hand, as shown in Fig. 223, and
the portions to be removed are discovered by smearing a hand
surface plate with oil and red ochre and applying the plate to the
work. Patches of colour will be transferred to the higher por~
tions of the surface, and when these have been scraped down the
work is cleaned again and once more tried, when the colour
patches will be found larger in number, but smaller in size and
more evenly dispersed. The operation is continued until further
accuracy is hindered by the grain of the material. Then we have
what is known in the workshop as a true plane.
Originating a Surface Plate.—When a new surface plate
is required it is generally copied from a standard plate kept in the
workshop, the method of the last paragraph being employed.
But if no such standard be at hand, or if the truth of our ﬁrst
plate be doubted, it is necessary to use three plates in order to
originate a true surface. These three plates are ﬁrst planed truly

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2 I 2 Screw-cutting in Lat/ze.
by machine, and next ﬁled with a smooth ﬁle to obliterate the
tool marks. We will indicate the plates by the numbers in
Fig. 22 3a. First ( 1) and (2) are scraped and tried by the colour-
patch method, then (2) and (3), and, ﬁnally (3) and (I), the cycle
of operation being repeated until all ﬁt together with great
accuracy. The reason for this method is shown in the diagram.
Thus—(1) and (2) may happen to be convex and concave ; then
(2) and (3) would be made concave and convex. But if (3) and
(I) be now put together, the convexity (or concavity) of both will
be apparent, and may, of course, be corrected. But when all
three ﬁt equally well they must clearly be equally true.
Although ﬁtting processes are less performed now than hereto-
fore, yet all the best work is trued up by the last-described
methods, after it comes off the machine, for however perfect the
latter may be, there is always some little distortion caused by
clamping the work, which, though slight, must be removed if
great accuracy be required.
Cutting a Screw in the Lathe—This cannot be fully
discussed until velocity ratio of toothed gearing has been entered
on, but the practical considerations may be detailed. It will be
clear, from what has been said in Chapter V., that if the leading
screw be connected to the mandrel in such a way as to revolve at
the same rate, a tool of the shape shown in Fig. 224 will cut a
screw groove on the spindle that has been centred in the lathe,
of the same pitch as the leading screw thread. If, on the other
hand, the mandrel were to rotate at twice the velocity of the
leading screw, a screw of half the pitch would be formed on the
work, or of twice the number of threads per inch. Summing up
then, the pitch obtained will depend on the relative velocities of
mandrel and leading screw, a proportionately quicker speed of
mandrel giving a ﬁner thread, and a slower speed a coarser thread.
The consideration of the proper change wheels to be introduced
will be left for Part II., but we may here point out that when
both shafts turn in the same direction the screw produced will be
right-handed (viz., same as its leading screw), and when revolving
oppositewise a left-handed screw will be the result.
The correct section of V thread, as adopted by Sir joseph
Whitworth, is shown at Fig. 225, one-sixth of the theoretical



224.
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2 I 4 Gauges.
depth being rounded off at top and bottom, and the angle being
55°. The rounding at the bottom is given by the tool in Fig. 224,1
but that at the top, as well as the general ﬁnish, is obtained by-
hand—chasing tools. These are seen at Fig. 226, where A is for
the spindle, and B is for chasing the nut; the ﬁrst being held
transversely and the second longitudinally. They are both
carefully cut to correct section of thread.
Fixing a Stud—Studs are used in places ‘where bolts are
inadmissible, because the material cannot be drilled right through.
The stud hole being drilled and tapped, and the stud having been
turned and screwed so as to ﬁt tightly in the stud hole, the former
is entered, and a stud box placed upon the opposite end, as in
Fig. 227. Outwardly this tool has the appearance of the box
key described on page 113; but is screwed internally to ﬁt the
stud, and has a small plate of copper at the bottom of the
socket to avoid damaging the work. A wrench being applied
to the square, the whole is advanced until stopped by the
plain portion on the stud, when the box may be removed by
a sharp back turn. .
Cylindrical Gauges are of great value in securing accurate
work. They are shown at Fig. 227a. A being termed. a ‘plug,’
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and B a ‘ring’ gauge. The ﬁrst is used for testing the accuracy
of a socket, and the second that of a pin, and both are made to
such perfection that the tested pin would be found to ﬁt ‘in its
socket freely, but with no appreciable shake. There are cases
where the ring gauge cannot be applied, and then the ‘ horseshoe ’
Details of Horizontal Engine. 21 5
form is used instead, combining both internal and external gauge.
For interchangeable - work lzzlglz and low gauges are required,
varying in size by a very slight but known amount, and the aim is
to make the work lie somewhere between. the two, so that any
pair of parts will then ﬁt, and the ‘play’ between them never be
more or less'than certain ﬁxed values. .
Details of Horizontal Engine—Having fully described
machines, tools, and general operations, we shall now proceed
to apply the information obtained to enable us to take piece by
piece the various parts constituting a 20 Horse-power Non-
cona’ensing Engine, with automatic expansion gear; and, having
received such parts in the rough condition from the Smith or
Moulder, to follow them through their various stages, until put
together by the Erector to form the complete work. That course
has been thought advisable in dealing with this, the most impor-
tant chapter in Part I, in order to avoid any risk of omitting a
good example; it being supposed that if a student could
thoroughly discuss the whole of this machine he might be con-
sidered reasonably capable of thinking out any new case that
might be placed before him. In order to avoid repetition we will
make a few premises.
The Marker-off either chalks or white-washes his work before
commencing, and obtains the height for his scriber point by
ﬁrst marking the same on the block B, Fig. 192, and then setting
the point to this mark. He should know something of the allow-
ances made by Smith and Pattern-maker, which are usually 51; in.
all over machined surfaces, and in extreme cases 31; in. Bed
plates, for example, warp i in. or even more, and special material
mustbe left on their seatings.
Mac/lining is marked on drawings to indicate all tooled
surfaces; being shown by red lines; but in our case a thick
dotted line will serve the same purpose, thus: v-I-I-n-n.
Further, although such drawings are copiously and fully supplied
with dimensions, these will be omitted in our examples, the scale
being given instead. The sizes represented on the drawing are
known as ‘ ﬁnished sizes,’ and the allowance on machined parts is
left to the judgment of the Pattern-maker or Smith.
_ In drilling, there are at least three various sizes that a hole
may be made, although all ﬁgured the same on the drawings.
2 I 6 ‘ General Directions.
Clearance size is for bolt holes, so that the bolt may drop in
freely; tapping size is that at the bottom of the screw-thread ; and
gauge size, divided into ‘working ﬁt ’ and ‘ driving ﬁt,’ the ﬁrst
having both pairs made to gauge, and the second having its socket
to gauge and the pin callipered to suit the plug gauge.
As regards the drawings; these are classiﬁed as previously
described, but we shall further give each article a number in
Roman letters 5 and in nearly all cases the drawing itself will be
indicated by the letter A, while the various operations take the
succeeding letters of the alphabet. At the close of the descrip-
tions a ‘ general arrangement ’ or complete drawing of the engine
will be given, and we shall thus have followed in nearly every
particular the practical methods of the workshop. One sheet
is omitted, that representing a collection of all the bolts and
studs to be used on the engine. ~ This has been thought unneces-
sary, as the capstan lathe has already been described where these
parts are tooled. It may further be mentioned that there are
always more ways than one of performing the various operations,
both as regards sequence and the tools used, and it may also
follow that each method is equally good 5 in many cases, too,
where the marking-table is mentioned in our descriptions, it
might be found more convenient to scribe the work while in the
machine.
I. Regulator Lever (Fig. 228).—This must ﬁrst be set
upon edge, on blocks, as at B, until level; and a centre line
be scribed all round it. The circles may be struck, just to see
if the stuff ‘holds up,’ and the length of the handle marked
off from these. Now punch all the ﬁve centres. (A method of
centering with scribing block by laying the lever successively on
its four sides and scribing any convenient height is shown at D).
Lay the lever next on its side (c), and pack up until the centres
are quite horizontal, as measured with scriber. Then scribe the
centre line all round, and mark at the same time the thickness
of the bosses, and of the lever ‘itself, as measured from this
centre. Next put in the lathe, and square-centre ; then turn and
polish the handle. Remove and clamp to the table of a shaping
machine, so as to shape across the ﬂat parts ; then clamp on the
lathe face plate as shown at E, for the purpose of drilling the
Regulator Lever. . 2 I 7
bosses and turning them. Of course the boss must be carefully
centred on the plate, and the blocking must be exactly the same


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1.- Leleer for View/e.
thickness. The drill point is placed against the centre of the
boss, and the loose headstock brought up to the other end of the
2 I 8 Bracket for 'Lever.
drill. The latter is then packed 'in the slide rest, and ﬁrmly.
grasped, when the drilling may proceed. ' The bosses are surfaced
to the scribed mark, and to the shaped lever ; the diameter being
gauged by callipers. When these are ﬁnished, the sides are
marked out as at F, and the lever next clamped on an ‘angle
plate’ placed on the table of a planing machine (see G), being
packed at such an inclination that the edge may be planed ; and
four settings are of course necessary. The angle plate is an
appliance which will be found useful for a variety of purposes.
Now ﬁnish off the lever by draw ﬁling and emery cloth. If the
work be too long to allow the bosses to be turned, the latter
are tooled as separate pieces, having a portion of the lever attach ed,
and are afterwards welded to the handle by the smith.
II. Brackets for Regulator Lever (Fig. 229).-—First
centre at the ends as at B, and punch ; then try in the lathe to see
if there is suﬂicient stuff at the middle. Turn the shank to
dimensions, gauging with callipers, and cut the screw thread in
the lathe at the same time ; the taper of the shank being obtained
by setting the top slide of the rest at the requisite angle, and
giving a hand feed to the tool. Polish while in the machine, with
ﬁle and emery, all but the collar, which may be left rough, because
it is to be afterwards cut; the diameter then being made equal
to that across the corners of the hexagon. Now remove from the
lathe, and, setting again on the table in the position B, line out
the ﬂat cheeks of the fork, and shape or mill these. Upon the
tooled surface thus obtained further lining is performed as shown
at c, the centres being. again placed exactly horizontal. Strike
the pin hole and punch. Drill the hole in machine vice to
gauge, and, bolting down to the centre of a slotting or vertical—
milling table D, tool all round with hand and machine feed.
Once more line out, this time for the fork slot as at E, and also
mark a circle for drilling, making sure that the line a is taken for
this, not h. Drill the hole last marked, and take out the rest of the
fork slot in the slotting machine, ﬁnishing by cutting the oblique
portion in the vice by chipping and ﬁling (F). It may here be
mentioned that all bright work is held in the vice between plates of
lead resting on the jaws, and called ‘vice clams.’ Lastly, cut the
hexagon on the collar by dividing out as at G, and ﬁling off the ﬂats.









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220 Regulator Details.
111. Pins and Washers for Regulator Lever (Fig.
230).—Three of these are required, of various sizes, to be made
to the drawing H. Centre for the lathe ; turn to gauge and polish
as at J. The washer is made from a piece of plate, by ﬁrst
drilling the hole, and afterwards turning the rim on a mandrel, as
shown at K. Then, the lever, bracket, valve spindle, and links
are all ﬁtted together; a broaclz or parallel rimer (Fig. 231), of
exact gauge passed through each set of holes to clear out the
irregularities produced in drilling, the pins put into place, and
the split pins marked off a groove being cut in the washer as
at L, to prevent turning and undue wear.
It is advisable to make all pins of steel that have to withstand
much wear, and their corresponding lever bosses, if of wrought
iron, should be case hardened.
IV. Links for Regulator Lever (Fig. 232) are marked
on a piece of plate as at M, which has ﬁrst ‘been planed on all
four sides, then drilled, cut in two pieces, and bolted together.
They are ﬁnished off by ﬁling in the vice, though, if large, they
would be slotted round, or milled. Polish with emery.
V. Regulator Valve Spindle (Fig. 233).—Lay this on
its side, in V blocks, as at B; centre the ends, and scribe the
ﬂats. Then put in lathe and turn to exact diameter, at the same
time cutting the screw. Remove, and tool the ﬂats in a shaping
machine. Now mark off the eye, as at c, and punch the centre;
drill the hole to gauge, and take off the outer material with vertical
milling cutter ﬁtting the curve a. Finish oﬁ‘ in vice and polish.
VI. Nut for Valve Spindle (Fig. 234).—-Lay on table,
and line out for thickness, as at B; plane or shape the ﬂats; mark
off the hole, as at c 5 and, placing the nut in a concentric chuck,
bore and screw in the lathe as at D, so as to ﬁt the valve spindle
easily.
VII. Regulator Valve (Fig. 235).—After cleaning with
rough ﬁle to remove ﬁns, this has only to be machined on certain
surfaces, as shown by thick dotted lines on the drawing A. As
the face must be reasonably true with the lugs, ﬁrst ﬁnd centre of
the latter, as at B, and square a line from the back surface on,
having previously blocked the hole with a piece of hard wood 5
do this for both lugs. To produce this centre line on to the

Regulator Details. 22 I










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edge of the plate, the valve is supported, as at c, on the marking-
table, so that its back surface, our present guide, is level, and the



222 Regulator Valve Box.
just scribed vertical line in contact, both at back and front, with a
line which has been marked on the table. Then set up this line
with square, as shown, so as to mark the centre of the valve plate,
and measure off to right and left the width of the valve. Scribe
also the thickness of the plate all round. Now set in machine
vice to plane the top surface, as at D, with a front tool, and the
edges with a side tool, and be sure that the travel of the tool is
exactly coincident with the scribed lines. The valve is now re-
moved, and treated similarly for planing at right angles to the
former direction. For this the fork is blocked, as at E, and the
centre squared ; next produced upward, as at F, and the width of
valve marked, then planed, as at G. There only now remains the
cutting out of thefork, which is lined by squaring and scribing,
as at H and J; then J is planed out, and H is ﬁnished by hand.
Finally scrape the valve surface very truly, as described in a pre-
vious paragraph. It should be mentioned that when wood is
used to block or bridge a hole, and a centre required, it is ad-
visable to shape a small piece of tin or zinc, as shown at K, to
receive the compass-point.
VIII. Regulator Valve-box, Cover, and Gland (Fig.
2 36).-—-Commence by bridging or ‘spanning’ the two end holes,
and striking the circle representing the diameter of the ﬂanges, as
shown at B ; measure also the length of the box over the ﬂanges,
and mark this. The valve-box is now to be mounted on the face
plate of a lathe, and as the casting is rather long, it must be sup-
ported by angle plates, as shown at c, being tightly bolted between
them, as well as having one ﬂange fastened to the face plate.
Having been carefully adjusted until central, it is turned on ‘one
ﬂange and surfaced ; reversed, and turned on the opposite ﬂange.
Next place the box on a planing machine, as at D, making sure it
is both level and square, packing if necessary, and having scribed
the top seating and boss, measuring from ﬂange centre, plane
these. Remove, and bolt to slotting machine in a similar manner,
as at E, and slot the front face, measuring the distance a in ﬁnish-
ing. It should be noticed that two tools'are here necessary,
cranked respectively to the right and left hand, as at F. Set out
the bolt-holes in circular ﬂange as at G, and drill with clearance
drill. Set level as at G, and, squaring up the centre line, join this
























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224 Regulator Valve Spindle.
along the top, as at H. Then, in position H, scribe and square
the centre d, measuring the distance c from a straight edge at b.
Strike the circle for the hole, drill this tapping size, and tap to
suit the Bracket No. II. To ensure rigidity, the bracket should
have been screwed rather ‘full,’ and be now taken down with
stock and dies until a perfect ﬁt in d. The port is to be marked
off, as at J, with square and straight edge, and measurements from
the square ﬂange, and the edges then chipped and ﬁled by hand,
an operation involving some trouble.
The Cover is to be planed and drilled. Find the centre of
the gland seating as at B, Fig. 2 37, and mark also the centres at
each end; then draw a line across. Set the cover level on the
marking-table, as at c, and squaring up the centre a’, scribe the
thickness of the plate, and mark its width. Set central, on the
planing machine, in a machine vice, or its equivalent, as at D and
E. Level the cover to the scribed lines, and plane the side sur-
faces, aa and bb, as well as the edges. Remove, and square
across for the adjacent sides, as shown at F, using the gland seat—
ing as a guide. Then set in the planing machine, and tool the
edges ; ﬁnish the surfaces cc to the same level as a and b. Now
reverse the plate, and, setting level in the machine vice, as at G,
scribe the gland surface to measure correctly from the surface a b e,
and plane. The cover is next to be marked for drilling, which is
shown at H, and the holes gg drilled to clearance size, it to
tapping size, while j must ﬁrst be drilled for the smaller diameter,
and the stufﬁng-box afterwards taken out with a pin drill specially
cut, as at J. "
The Gland is ﬁrst drilled in the lathe (B, Fig. 238), which
may be done more truly by blocking up the hole with wood
through its entire length, and letting the drill take this out. The
front may be surfaced at the same time. Next place upon a
mandrel as at c, and turn down to dimensions. Remove, span
the centre, and mark off the gland face as at D; then drill the
holes (clearance), and ﬁnish off the edge with dead smooth ﬁle
and ﬁne emery. The cover holes are lastly to be marked off on
the box by tracing through from the cover, then drilled and
tapped. ’
IX. Valve Spindles: Main and Expansion (Fig. 239).




















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2 26 i Eccentric Rods.
As with No. II.,.these are ﬁrst centred, and scribed onthe ﬂat '
cheeks (D); then turned and screwed in the lathe.‘. The hole is
next struck as at E, drilled, and the outer curve milled; and the
fork (F) is taken out last by drilling and slotting. _Broach right
through, and turn the pin-as was described for N 0. III.
The Nuts are best ﬁnished by putting a number of them
after drilling to tapping size, upon a mandrel, which is then
placed between dividing centres on a milling machine, and milled
by ‘means of twin mills (see B). They may be turned axially
through 60° at each operation, and must be afterwards tapped,
and chucked in the lathe for facing and chamfering.
X. Expansion Eccentric Rod (Fig. 24o).—Centre this;
also mark the length between the shoulders, and square up the
thickness of the T end. Turn to the requisite taper by ‘setting
over’ the loose headstock, as shown in plan at J, so that the
front surface of the rod will then be parallel with the lathe bed.
The amount of set-over will, of course, be equal to half the
difference of the two end diameters. Surface also the T end.
Remove from the lathe, lay level as at K, and scribe the cheeks o.
Square and scribe the tee at A to dimensions, measuring from
centre, and strike also the bolt-holes. Drill these to clearance
size, and shape a and h. Then mark out the eye as at L and
mill this with a cutter having the proper curvatures. The rod is
long, but as the milling only requires it to sweep through a semi-
circle, there will be no serious diﬂiculty if it be well clamped. v
XI. Main Eccentric Rod (Fig. 241) presents no difﬁculty
after the previous descriptions.
XII. Intermediate Valve Rod (Fig. 242).-‘-This also
would be tooled by previous methods. The manner of fastening
the pin is worthy of notice. The bearing surfaces of the fork are
but narrow, and it is unwise to allow movement at that place; '
the die, on the contrary, has a good wide surface, so it is there
only that wear should be allowed. After the pin is put in
position, a parallel hole is drilled right through the fork, and
enlarged with taper rimer, the pin for this hole being turned in
the latter with an oblique hand feed. All these pins are of steel,
and all wearing surfaces are case hardened.
The Die is surfaced and bored in the lathe, and afterwards



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228 Guide Bracket.
shaped to dimensions, leaving sufﬁcient excess of width to allow
of accurate ﬁtting to the Radius Link, after which it is case-
hardened and polished.
XIII. Guide Bracket for Valve Rods (Fig. 243).——The
machining is shown on the drawing at A. Set the bracket
vertical by trial with square as at B, and line out the base a.
Scribe also the line b all round the casting, and at the proper
height from a. Lay level on its side as at c; ﬁnd by
measuring the height of the boss and that of the foot centre.
Scribe the thickness of boss. Next shape to these lines as at D,
the boss with a front tool and the foot with a side tool. It
should be noted here that a side tool ought never to be used if it
can be avoided, for there is a great twisting action thereby pro-
duced which is calculated to wrench the tool from its box; but a
good deal is sometimes sacriﬁced to save two settings on the
machine. Re-scribe the line b from the marks left on the side of
the boss, and lay the bracket on its side as at F, packing until the
centres are level; then scribe the heights of the large holes on
both faces and strike the circles. The casting being hollow, the
core-hole must be spanned as at G, in‘ order to strike the bolt-
holes, whose centres are found by scribing a horizontal line and
squaring a vertical one when in the position c, and then bisecting
the right angles obtained. The bolt-holes are drilled as at H, but
the large holes are bored in the lathe, the bracket being clamped
to the face plate, and the latter provided with a balance weight.
This will be understood from B, where the face plate will be seen
dotted, and the bracket clamped in position for boring b. In all
such cases it is necessary to ﬁrst drill a hole large enough to
admit the boring tool.
The Bushes are bored in a chuck, and ﬁnished on a mandrel,
and afterwards driven into the bracket, a block of wood being
placed upon them to receive the blow of the hammer.
The oilcup cover is drilled for the hinge-pin, and ﬁnished by‘
hand, and the oil-holes drilled, and countersunk slightly at the
top. An 5" spiral channel should be chipped in each bush with
round-nosed chisel to allow the oil to ﬂow.
XIV. Eccentric Sheave and Straps (Fig. 244).-—The
cast-iron sheave will be taken ﬁrst. It is of the solid form, being








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2 3o, Eccen trics.
slipped on to the shaft lengthwise. But there are many cases
where it is necessary that the sheave should be in halves for this
purpose, and the machining would be then performed in a very
similar manner to the eccentric straps to be described, namely, by
bolting together the halves before turning. The drawing of the
sheave is shown at A. Lay the casting level on the marking-table,
as at A1, and scribe the various thicknesses; span the hole, as at B,
and strike a circle for its diameter. Grip in the dog-chuck, as at C,
bore, and surface the projecting boss and the face of the sheave,
marking the diameter of the boss in the lathe. As the sheave
has to be chucked eccentrically, the face plate must, of course, be
balanced. Next reverse, and turn the opposite face of the
sheave, this time chucking centrally, as at D, and setting the
already turned boss close to the face plate. Lastly, the outer
circle is struck out, as at E, by re-bridging the centre, and marking
the exact eccentricity on the centre line at x, and the work is
then bolted to the face plate, as shown at F, each portion of the
rim being measured in position, and carefully turned exactly to
dimension, because it must be a correct ‘working ﬁt’ with the
strap. The key-way may be slotted out.
The Straps (drawn at a, Fig. 244) are ﬁrst marked off, as at
A11 and B1 (Fig. 245), with the proper allowance for machining the
feet, and the two are then bolted down together to the planing
table, as at E1. The bolt holes are next scribed and squared, as
at D1, the casting lying level on its side, and these are drilled, as at
E1. The thickness of the feet for the front strap being linedat
F1, and the stop for the bolt head at H, these are cut out, the
ﬁrst with pin drill, as at G (known as ‘ kniﬁng ’ or ‘face-arboring’),
and the second with chisel and ﬁle. Now place face to face in
the vice, and broach the bolt holes right through; then, having
turned the bolts to a good ﬁt, fasten both straps together. Lay
the bolted straps level, as at J, scribe the width, and grip in a
dogchuck, as at K, to face both sides, setting carefully for each.
Leaving the work in the chuck, examine the outer rim for
centrality (for this cannot afrerwards be turned), and mark off
the inner circle for boring, measuring with callipers and rule as
the work proceeds. Remove from the chuck, and scribe the
remaining surfaces—b c d, as at M, measuring from the turned
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232 _ _ Slide Bars and Bracket.
circle, and e, as at N, with scribing block. Shape the former, or
ﬁnish by hand, and plane the latter, as at N. Line out the stud
holes, as at P, though these are preferably marked, or at least
checked, from the already drilled rod. Drill and tap, and bolt to
rod to ﬁnish off the edges by hand. The oilcup must be drilled
and knifed similarly to the cover in Fig. 2 37, and tapped for the
cover nut, after which a short piece of brass tubing is driven in to
form the syphon.
The Oilcup Cover Nut is an example of simple turning
and screwing in a universal chuck, the hexagon sides being milled.
XV. Slide Bars are clamped at sides and end, as at E,
Fig. 237, and the back surface planed, as at A, Fig. 246. They
are then turned over to the position B to machine the front edges.
The width of the groove, being marked, is taken out to correct
depth, ﬁnishing the surface with a ﬂat-pointed tool, and the
corners with a ‘kniﬁng’ tool. The sides of the bars are planed
in a similar manner. The ends are shaped to length, and the
holes marked off and drilled. Channels near each end are'left, in
casting, to receive the slide block lubricant, and are now to be
cleaned out by hand. After polishing all over, the groove should
be scraped to suit the slide blocks.
XVI. Slide Bar Bracket and Distance Piece (Fig.
247).—-The bracket is placed upright on the marking table, as at
,c', and set vertical by trial with square on both sides, measuring
as at aa. Scribe the thickness of foot, and place upside down on
the planing machine, clamping in machine vice; then plane the
foot. Now reverse the bracket, and, clamping right side up, mark
off the height of the bosses, measuring from the foot, and plane
these. Remove, and block up on marking table, as at D and E,
and scribe a centre line all round; then measure the positions of
the stud holes, so as to agree with regard to the square bosses.
The bolt holes are to be marked off by setting the casting as at
F, and measuring with a square the two dimensions shown, the
difference of which will be the distance between stud and bolt
centres. Punch and drill the bolt holes to clearance, and the
stud holes to tapping size. Finally, tap the latter.
The Distance Piece is a simple example of shaping, which
done, the hole is marked off and drilled to gauge.





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Bearings. 2 3 5
XVII. Crank Shaft BearingKFig. 248).—-The bearing
is ﬁrst laid level on its side as at B, the centre line obtained,
and scribed round. The seatings for the brasses are measured
‘and also scribed, after which the bearing is set up as at c (see
both views), and adjusted by line and square till plumb. The
foot is next lined, and the top of the bearing taken from this,
making sure that there is sufﬁcient stuff left in the bush socket.
Now plane in turn the seating sides, the foot bottom, and the
top. Stand the casting again on the marking table as at D, and
ﬁnd the centre of the socket. Square this up, as well as the
socket sides. Scribe the bottom of the socket, measuring from
the foot, and line the bearing centre all round. Square these
lines across as in plan at E, and mark them on the opposite side.
Find the centre of the set screw holes, and measure the foot bolt-
holes from the vertical centre line. Plane out the bush socket—-
the sides with a side tool, and the bottom with a front tool,
ﬁnishing with a ﬂat tool, and the corners with the ‘ corner’ tool
shown at F. Drill the holes.
The Cap or ‘keep’ is set on edge to line the seatings and
scribe the two bolt-holes and oil-hole, as at G, being ﬁrst, how-
ever, planed to thickness on its bottom surface. After planing
also the seatings, and drilling the holes, it is placed in position
on the top of the bearings, and the bolt-holes marked through to
the latter. These are next drilled and tapped, and the studs put
in place. ~
The Brasses are shown in Fig. 249. Being ﬁrst laid on its
side, as at A, the large brass has its width marked and its lips
lined for thickness, and is then planed. The front and sides are
next lined out on all surfaces to dimensions, measuring from the
planed surface, and trying for depth of stuff between the lips, the
brass being meanwhile packed with sides truly vertical, as at B.
The whole is now planed by clamping in the successive positions,
c, D, and E, so that every surface is done, either with a side or
front or knife tool, the depth of the middle surface being gauged
from the lip ; and the small brass F is similarly treated.
The packing plates are next machined, and all is ready to put
together. The brasses and packings are to be carefully smooth-
ﬁled and scraped until they bed perfectly into their places in the









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238 Cranh Shaft.
bearing, and until their top surfaces and the main casting are all
perfectly level. Put on the cap and fasten down, span the bush-
hole, scribe the centre at the proper height, and strike the shaft
circle. Then bolt both bearings, thus complete, to the table of a
Horizontal Boring Machine of the lathe pattern (as mentioned in
Chapter V.). First see that they lie truly at right angles to the
centre line, after which raise the table by the screw and traverse
across, until the boring bar can be passed through and the cutters
(of correct radius) be put in'place. A ﬁnal adjustment is then
given to the scribed lines, and the boring may proceed.
XVIII. Slide Blocks (Fig. 2 50) are planed or shaped and
afterwards lathe-bored to suit the gudgeon.
XIX. Gudgeon (Fig. 25o).—This is centred and turned,
the corner curve being taken out with a tool ground to suit. It
is afterwards laid level in V blocks, and the centre scribed round
for the key-ways. These are then taken out in a slot-drilling
machine, as at H, Fig. 251. Polish the work as usual, and gauge
with ring gauges. -
XX. Crank Shaft (Fig. 2 51).—The forging has been
already described at page 12 3. The markenoff ﬁrst centres the
ends by setting the shaft on V blocks, and then tries with scriber
and straight edge to see if there is sufﬁcient stuff right through ;
if very far out, it should be sent back to the forge to straighten.
. Punch and countersink. Provide large wing pieces of the shape
shown at c, bored so as to freely slip over the shaft. Place the
latter in the position shown at E, supporting on packing and
V blocks. A countersink having been already formed in the
wings at a distance [1 equal to the throw of the crank, this has to
be adjusted until in line with the crank pin, by measuring from
the double plumb line at a a, and by setting plumb the crank
web as at D. Then the set screws are tightened ﬁrmly on to the
shaft, with packing strips underneath of such thickness as to
adjust to the distance [2 with great accuracy. The whole may
now be lifted from the blocks so as to admit the strut bolts d d,
which have their end nuts turned till perfectly rigid. Lift the
crank into the lathe, and place the wings between the centres,
when the crank pin will of course be also central. The object of
the wings will now be seen, for they either entirely or partly

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24o Connecting Rod.
balance the crank shaft, so that it may be driven by a carrier in
the usual way without producing a bad cut underneath the tool.
It is advisable to use two carriers instead of the usual pin and
carrier, one of them being gripped on the face plate centre and
the other to the work, the two being then bolted together so as to
produce a rigid driving arrangement. The crank pin is now
turned to exact diameter and the width measured, so as to be
central between the webs, and ﬁnally polished. The forging is
next placed in the lathe for turning the shaft portion, with the
wings of course removed. The method of measurement may be
seen at E, where a tool or scriber is set at the correct distance
from the crank pin, and is then traversed over so as to cut or
scribe a line for the shaft shoulder. The same is done on the
other side of the webs, and the shaft then turned to diameter,
gauging with callipers. The length is checked with trammels, or
a marked straight edge, and a ﬁnishing tool of broad ﬂat form
passed over all. Polish with emery, and remove to scribe the
key-way as at G, which is milled out by the slot-drilling tool
shown at H. During the last turning operation the crank pin
may be balanced, if found necessary, by clamping the weight F to
the webs, but more often the work is simply driven rigidly with-
out balance. The eccentric key-ways are usually marked by the
Erector and cut by hand, or sent back to machine for slot-drilling,
and are not therefore shown.
The key at A is planed from good steel, and a taper given of
1 in 64, the ﬁtting to wheel being left to the Erector.
The crank webs should be slightly chipped to remove rough-
ness, ﬁled with rough ﬁle, and afterwards painted.
XXI. Connecting Rod (Fig. 252). The large end of the
rod is supplied with a strap enclosing the ‘butt,’ and a gib and
cotter for tightening purposes; and the small end is turned
‘solid.’ The rod is ﬁrst taken and laid fairly level on the table,
as at B. It must be centred for turning by the following
method z—Calliper each round end, and let the difference of
a and b be half the difference of the diameters. Then ‘ feel" and
measure both heights at a 5 add together, and halve. Do the
same for b, and re-adjust till these quantities be the same. Then
scribe this dimension, the height of the centre, all round, as








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242 Connecting Rod.
shown. T rammel between the shoulders, and square up the
vertical lines, as well as the end lines; measured from these.
Next lay the rod ﬂat as at c, and scribe the centre line round in a
similar manner to the last. Punch centres, and place in lathe,
testing with chalk, and square-centreing. Now set the poppet
head over by half the diameter difference, and turn the, taper
portion up to the shoulder radii, as shown at J, Fig. 240. Set
the poppet head trueagain, and surface the ends of the rod, also
the shoulders up to the radii. These last require very careful
turning. They are to be roughed out by means of a combination
of surfacing and traverse feed, and semi-ﬁnished by a broad
tool ground to the curve, the position of which is gradually
changed by turning round the top rest until the whole curve is
gone over piece by piece. The last ﬁnish is given by hand with
the same tool very sharply ground. Of course the work must be
continually tried by means of a sheet iron copy called a ‘tem-
plate,’ shown at D and E, the lathe being stopped at each trial;
and the outer curve of the solid end is to be ﬁnished in like
manner.
Remove from the lathe, ﬁnished, but not polished, and lay on
the surface plate as at F, packing till level. Scribe the thickness
of the butt and solid end, then fasten, as at G, across a shaping
machine having two tables, and shape. Similarly also for the
depth. Return to. the marking table. Scribe the centre line
afresh, and plot out the square hole in solid end as at J ; do this
on both sides, and well dot all round it. This may now be cut
out in one of two ways—(1) a hole may be drilled large enough
to pass a slotting tool, by twist drill and pin drill, and the rest of
the ‘work done by slotting; (2) a probably better method, is to
take out all round by means of slot-drilling tool, drilling, say, a
quarter of an. inch down, traversing all round as at K, then a little
further down, and so on till the hole is completely cut, ﬁnishing
the sides with a milling cutter and the corners with a corner tool.
There is then very little work left for the ﬁle.
Now mark off the bolt-holes at L, on both sides of the solid
end, together with the oil-hole, and the cotter-hole at M. Drill
the bolt-hole from each side, broach through, and countersink
the oil-hole. Take out the cotter-hole in slot-drilling machine,
Cotter and Strap. 243
as above described, until cut right through, when there ought to
be little ﬁnishing with ﬁle. Drill and tap for set screw in butt
end, return the rod to the lathe for polishing, chip off the
centreing pieces, draw-ﬁle, and polish the ends.
The Strap (Fig. 253), being‘forged'v fairly to shape, is ﬁrst
scribed to thickness, and planed. A sheet-iron template is next
provided of the form shown at N, Fig. 253, which is placed on
the forging and the form traced. Finish the contour with
vertical mill or slotting-tool, clamping the work as at o for the
outer and as at P for the inner tooling. The oil-cup is next
marked off as at Q, and the strap clamped to an angle-plate as at
R for turning, boring, and drilling. At the same time the screw
is chased for the oil-cup cover. Lastly, line out the cotter hole
as at s, and slot drill by blocking up in the machine vice as at T,
and, on removal, draw ﬁle and polish.
The Cotter U is ﬁrst planed to thickness from good steel,
and then marked off to length and width. Both edges are then
planed to the marked lines, and the rest ﬁnished very exactly by
ﬁle, with the aid of the gauge template v, great care being taken
regarding the thickness.
The Gib w is similarly marked out, and the sloping edge
planed. The channel is then removed with a shaping tool,
several gibs being bolted together for economy, and the rest
ﬁnished very carefully with the ﬁle.
The Large Brasses are marked off and planed in the same
way as were those for the bearing, Fig. 249, and are then bolted
down very ﬁrmly to the boring table as at x, with liners between
to represent the draw of the cotter, and with bolts lying close up
to the outer surfaces. See their faces are set at right angles to
the boring bar, which is inserted as before, and the work traversed
into position. Bore right through, and ﬁnish the radii with a
specially ground tool, as at Y.
The Small Brasses are shown at a and 2. They are
planed as before, with the exception of the sloping side, which
requires a new setting, as shown ate, and is planed with a side
tool. The ‘ring’ faces must also be left untouched, these being
turned at the same time as the hole is bored, which is done by
bolting the two brasses together, with a wedge between for the

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Crosshead. 245
slant edge, and a liner to represent adjustment allowance, and
the whole chucked in the lathe, as at f. Two settings are of
course necessary.
The Wedge is now shaped to dimension, but not drilled;
the wedge bolt and set screw for the large end both prepared.
The oil-cup cover is then turned and screwed in a concentric
chuck, and milled on the hexagonal faces with a horizontal tool
by placing the work on a dividing plate. All is now ready to put
together. For the small end, ﬁt the brasses in place by smooth
ﬁling and scraping 5 ﬁt the wedge, and mark off the hole for bolt
by scribing through the rod end. Remove wedge for drilling and
tapping, then replace. For the large end, the gib and cotter are
ﬁrst carefully ﬁtted to their holes separately; then the brasses are
ﬁtted to the strap, and the latter to the butt end. Place all
together, and ﬁle the cotter till it enters the proper amount; then
mark off the split pin-hole and drill. Once more replace all
parts, and the connecting rod is complete.
XXII. Crosshead (Fig. 254).—Centre the forging, as at
B, and line the width across the cheeks 5 then turn the side and
end, and shape the ﬂats. Lay now upon the marking table, as at
c (see both views), and scribe the horizontal centre line. Find
the centre for the gudgeon hole, as at a and a, measuring from a
straight edge, and test also with dividers; erect this line with
square, and strike the circle on both sides, also the contour of the
boss. Chuck in the lathe, as at L, and bore the hole, ﬁrst
drilling to admit the boring tool. Remove from the dogs, and
insert next in a large bell-chuck, as at D, the exact position
being found by placing the work between the lathe centres; after-
wards ﬁrmly tightening up the screws, as shown. First drill the
hole as large as allowable, the tool being centred, as at F, and
clamped in the slide rest; and next bore the taper, as at E, by
turning the top slide of the rest to the required angle, the feed
being obtained by a small pulley on the ‘screw, driven from the
countershaft by catgut band. The hole is tested for diameter with .
callipers, and the angle of the rest noticed before removing (this
being afterwards required for the Piston Rod). Now place the
crosshead on the mandrel of a shaping machine, as at G, and shape
all round up to the return curve, the latter being tooled with a












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Piston Rod and Piston. 247
concave feed (mentioned in ‘Chap. V.), and the ﬂat portion with
horizontal feed. Take again to marking table, ‘block level, as at
H, and scribe both fork and slot-hole, measuring from shoulder.
Drill and slot the fork, and slot-drill the cotter hole. Finally, slot
out the key way to suit the gudgeon ; prepare a cotter, and take
out the taper in the hole with round ﬁb ; then draw-ﬁle and
polish.
XXIII. Piston Rod (Fig. 2 5 5).——Centre on V blocks,
and set in the lathe. Then traverse all over the work to the
diameter at C. Mark off the various lengths a, c, c, a’, and put a
centre pop at each place. Turn down a’ to the larger diameter,
and take down the taper at o and d by setting the slide rest, as at
E (Fig. 254), and it should be noticed that if the rest be placed
at the same angle both for rod and hole, the one is bound to
accurately ﬁt within the other. Turn down at a to screwing size,
and chase ; then ﬁnish and polish the whole.
The Nut may be turned, bored, and screwed in a chuck, and
the hexagon milled. Lastly, the rod is ﬁtted into the crosshead,
and the cotter hole marked through to the latter, then slot-drilled,
and ﬁnished with ﬁle.
XXIV. Piston (Fig. 256).—This is to be turned on the
rim,'and bored to ﬁt the piston rod. The latter operation is done
at B, and the former upon a taper mandrel at c, the grooves being
turned at the same time to exact gauge, so as to ﬁt the rings as
truly as is consistent with freedom. The plug holes, 6, left during
casting (see B, p. 30) are to be drilled and tapped, centres unim-
portant, and the plugs are made from a round bar, screwed in the
lathe and parted off to length. They may be an easy ﬁt in the
holes, but must be painted with sal-ammoniac, so as to form a
rust joint. _
The rings are rolled from i-inch brass bar, being received at
the works ready formed, sprung out to a somewhat larger diameter
than the cylinder. The joint is shown at a (Fig. 256), and should
be as nearly as possible closed when the piston is in place.
XXV. Radius Link (Fig. 257).-The forging should be
fairly to shape, being made to template. First line to thickness,
and plane. Make a template exactly to drawing A, with the ex-
ception of the holes, which consist of quarter circles, as at B, with



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.sskadius Link.‘ 249
a little piece ﬁled out at the centre to admit the scriber. Lay
thistemplate on the work, and, trace out. Then drill the holes,
which are to be broached when all the parts are put together.
Remove all the outside material with a vertical milling tool having
a radius equal to that of the return curves, as shown at c. The
inner slot may be cut out by one of three methods: (1) Let
several holes be drilled, as at c, one large enough to take a
slotting tool, and slot all round with hand feed 5 (2) Drill a hole
to take a vertical milling tool, shown at c, and a few more holes
to save the cutter, and mill out the rest, traversing by hand, ﬁhll
one side and then the other; (3) best of all, is the same as the
last, with this exception: the cutter is held in a special form of
vertical mill, called a ‘proﬁling’ machine. Here the bearing
carrying the vertical spindle may be made to traverse any par-
ticular curve by applying to it a copy of the same shape, and its
action is thus similar to that of the copying lathe. The curve
would thus be ﬁnished right off without further ﬁling; and the
ends may be taken out with a double corner tool, then ﬁnished
by hand. The die (Fig. 242) is ultimately ﬁtted to the link by
careful ﬁling and scraping, and both link and die (after broaching
the former) are case-hardened.
XXVI. Governor Pullies (Fig. 258).—-These are to be
machined as shewn upon the drawings. The bosses are to be
bored by chucking in a dog-chuck, and the facing both of boss
and rim done at the same time. Two settings are, of course,
necessary. Next put the small pulley on a plain mandrel, and
the large pulley on an expanding mandrel, as shown at page I 55,
and turn the rim surface in each case with parallel traverse:
then ﬁnish the curve with a hand tool. The large pulley being in
halves must ﬁrst be planed on its joint surface, as in the case of
the eccentric straps at Fig. 245, then drilled for the bolt-holes,
and bolted together for boring. The keys are lastly taken out by
slotting.
XXVII. Governor Bracket (Figs. 259—6o).—This is a
rather more difﬁcult example of lining out, but involves no new
principle, the only precaution of importance being very careful
levelling at every operation. The casting is laid on its side, as in
the ;two- views at B, and‘adjusted until the bush'centres are of the
250 Governor. Bracket.
















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somewhat warped, and absolute perfection therefore unattainable,
so there must be a sort of ‘ give and take ’ until thebest condition
is obtained. Scribe centres of bosses and bush holes. Now lay
the bracket on its other side, as in the two views at c, Fig. 260,
and again adjust the bush centres horizontally. Test the three
bosses until plumb, and the cross line for being fairly level; then
scribe a centre line round the bosses at a and b, and along the
casting to the foot c, which will be afterwards useful for setting
purposes. Scribe also the centre of bush-holes and the lengths
of the bosses, measured from a and b. Set the casting vertical as
at D by trial with square, packing at. the foot, and scribe the
bosses. Then reckon from the boss centres, and scribe the
thickness of the foot and the heights of the bush surfaces.
Centre-pop everything before passing on to the machines; then
shape the foot by packing vertically, as shown at E, clamping to
the side of the table. This done, remove and clamp to the drill
table as at F until the vertical centre is truly plumb, and drill the
upper hole to full size with a drill a’, but do not let the same drill
pass through to the lower hole, or the latter might be drilled
untruly. Commence the lower hole with a smaller drill e, and
ﬁnish with the pin drill f of special shape, and by this means it
will be truly central with the top one ; knife or face-arbor the top
surfaces with the tool shown at g. The bracket is now clamped
to a radial drill bed, as at G, setting by means of the centre line
previously scribed, the holes all drilled to ﬁnishing size, and the
top surfaces knifed. The work must then be reversed to knife
the bottom surfaces, but not specially clamped this time, for
the holes themselves will be sufﬁcient guide. The bolt-holes
may next be marked as at H by blocking the bush-hole, scribing
and squaring. The bolt circle is then struck, each angle
bisected, and the holes drilled at J, supporting the work on
blocks.
The bush for the pulley spindle is simply drilled, and after-
wards turned on a mandrel, then driven into its boss with a lead
hammer. -
XXVIII. Governor Details—The various parts are
shown at Fig. 261, and will be taken seriatinz.
The Spindle A is ﬁrst centred, turned, and screwed, and the
Governor Details. 25 3
ﬂat cheeks lined out. These being shaped, the boss is next
marked off and milled, and the hole drilled, the slot taken out as
in previous cases, ﬁnishing by hand. The key for the mitre
wheel is ﬁnally grooved with a milling cutter. The Sleeve B,
being cast solid, is ﬁrst centred, and the thickness of the bosses
lined. It is drilled in the lathe, and then slipped over a
mandrel to turn, and to screw the end. The ﬂat surfaces of the
bosses are next shaped across, and the space between taken out
with a tool of the exact width. The holes are marked off and
drilled, and the bosses ﬁled round, after which the sleeve is ﬁtted
to the arms 0 by chipping out the socket with cross-cut chisel
and ﬁnishing with a curved ﬁle much used by brass ﬁnishers,
called a ‘riﬂfler’ (see Q, Fig. 262). Mark out key-way for the
weight E, and cut the same by hand.
The Nut for the sleeve is bored and screwed in a chuck, and
turned on a mandrel, and the octagon milled by ﬁxing on a
dividing circle. Drill and tap for the side screw, but only ﬁle
out the corresponding slot in the sleeve after M is put into place,
and the nut advanced to give the requisite tightness. The
Lower Arm c is packed up as at H, Fig. 262, and the fork
bridged; then the centre and the ﬂat cheeks are lined, the fork
centres struck, the lengths marked off, and the centres of the
bosses squared up. Now turn the shank, and slot or mill the
fork to the marked lines. Lay the arm in the position J, and
after scribing the centre line, strike the curves of the bosses and
pin-holes, and scribe the width of the fork. Shape and mill to
the lines, and drill the holes. The Radius Arm D is centred
and lined as at K, Fig. 262, and the shoulder line marked off, as
well as the commencement of the small curve to ball. Set in the
lathe, and turn down the shank. Then prepare a template for
the ball, as shown at L, Fig. 262. First turn to diameter as a
cylinder, and surface the end to length ; then feed at 45°, as at g,
Fig. 262 5 continue to halve these angular feeds until the ball
is approximately spherical, as tried with template, and ﬁnish with
a keen hand tool ground to the ball curvature. Mark the centre
of the ball while revolving in the lathe, and set on marking-
table to get the cross centre, as at M, Fig. 262. The boss is then
ﬁnished as usual, and the hole drilled through the ball. The






















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ma. P19. 262.
2 56 Governor Details.
Central Weight E is fastened to the table of a horizontal’
boring machine, as shown at N, Fig. 262, and bored with cutters
of correct radius. It is next put on a mandrel ﬁtting the smaller
hole, and the outside turned to template. First the ends are
faced, then the diameter turned as a cylinder, and the rest is
obtained by various angular feeds, ﬁnishing by hand. The key-
way for fastening to sleeve B is to be slotted. The Bush F for
the weight, is to be bored in a chuck, and then turned on a
special mandrel, shown at P, Fig. 262, being afterwards driven
tightly into the weight by means of a copper hammer. The
Nuts and Guard G are ﬁrst bored, and afterwards turned on a
mandrel, being replaced in the chuck for screwing. The tooling
of the Lever H may be understood by reference to the regulator
lever No. I., and the studs J J are all examples of simple turning
and screwing. The Lifting Link K, and the Lifting Eye M,
need no special description.
We now come to the Mitre Wheels L. For the machining
of these we may again refer to Fig. 262. Both wheels are made
of gun-metal and are exactly alike, boss included. After boring
truly they are placed on a mandrel, and the ‘ blank’ turned as at
A to a template which has been previously made with great care.
The teeth are then to be cut by means of a milling cutter. A
mandrel is provided which ﬁts into the socket of the dividing
centre shown at D, and the wheel set at such an angle that the
lower line of the tooth, e j’, is horizontal. Looking in front of the
wheel, the work must be set so that one edge of the milling cutter
is in line with the centre. The radius a1 of the cutter at 0 being
made to ﬁt the curve a of the larger end of the tooth, as shown
at B, and the width b1 of the bottom of the cutter made equal to b
at the narrow end of the teeth, a little consideration will show
that the cutter will trim up one side of the tooth in such a way
that the smaller ends of the teeth d will be a little too wide at
this point, as shown at G. After all the spaces have been cut out
as at D and one side of the tooth, the work is traversed forward
and the other face cut as at B, after which the taper c of the teeth
is lined out as at G, using (I) a straight edge of the form shown at
F, page 625 and (2) a template F, Fig. 262. These surfaces are
then dressed off with the ﬁle.
5 tea 772 Cylinder. 2 5 7
XXIX. Steam Cylinder (Fig. 263).-—The various opera-
tions are shown at Fig. 264. The ends are ﬁrst bridged, and the
centre found by reference to the outer curve of the cylinder ﬂange.
Mark temporarily the height of the centre B. Adjust until the
top of the cylinder foot is fairly level, giving and taking with the
three centres at A and B. Scribe the horizontal centre line, B B,
all round, and square up the vertical line, c c; then strike the
circle D for boring. Line the heights of the steam and exhaust
ﬂanges at E, and scribe the thickness of the foot at F; line also
the thickness G of the bosses for the bolts. Scribe the height of
the valve-guide H, using a special piece of bent wire for the
scriber as shown, and mark the heights, J, of the indicator
bosses.
Set the cylinder upside down, as at M, and plane the foot.
Set upright, as at N, and plane the steam and exhaust ﬂanges,
the indicator bosses, and the foot bosses. Now clamp between
angle plates on the planing machine as at P, and if these be
true vertically (as they should be) there will be no diﬂiculty in
packing correctly; but if not, some care must be exercised, and
in any case the centre of the cylinder must be levelled longitudi-
nally. Scribe the steam chest face to correct distance from
cylinder centre, and plane with a front tool, P. At the same
setting the valve face may be planed at Q with long, strong side
tools, right and left, and the valve-guide also ﬁnished.
The cylinder must next be bored. This is done by packing
up, as at K, on a horizontal boring machine of the type described
on page 161, but of a smaller pattern. Bore right through, and
face the ﬂanges by ﬁrst measuring through the cylinder, as at L,
so as to leave an equal amount of seating on each ﬂange; then
alter the tool to take out the bell mouth or larger diameter at
each end. Set the casting on end, as at o, and plane the stufﬁng-
box seatings so as to be level with the cover seating.
All the main faces are now machined, and the rest of the
lining may be done. At v the inner square is scribed on the
steam chest face, measuring from the horizontal and vertical
centres, the latter being squared up with reference to the outer
edge of the ﬂange. Take the material out by hand, or by slotting
tool, very probably the former. The steam chest cover may be
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and the holes scribed through, as at V, and centred. After the

planed in the same manner as the cover at Fig. 237, and the
front and back cylinder covers have been ﬁnished (next example),

holes drilled.

















26o Cylinder and Covers.
they may in like manner be ﬁtted to the cylinder, and the stud
holes marked off (R), both covers being blocked level during the
marking off. Span the steam and exhaust ﬂanges, and divide out
their bolt centres (X) according to the ﬂange circles 5 strike out
also the indicator bosses 8. Mark off the bolt holes for cylinder
foot, as at U U, by measuring from the cylinder centre to a straight-
edge lying across two of them, and otherwise from the cylinder
fronts, giving and taking with the centres of the bosses as cast.
Scribe the centres of the stufﬁng boxes and their studs, as at T,
and square the same from the cylinder centre. Mark the central
holes in cylinder cock bosses according to their position as cast
(see w) 5 the stud holes are better marked from the cocks them-
selves. For the ports a template is provided, and nicked at the
centre lines, so that it may be accurately placed in position. The
horizontal centre is scribed on the port-face, the vertical centre
squared up from the face H, as measured from the stufﬁng box
face after boring; the template is then applied, and the ports
traced through.
Now set the cylinder under a radial drill, so as to drill all the
stud holes in the various ﬂanges to tapping size, and tap them,
either by hand or by machine.
The indicator bosses have a small hole drilled ﬁrst, are pin-
drilled afterwards, half way down, to tapping size, and knifed on
their top surfaces, then ﬁnally tapped. The drain-cock bosses
are treated in like manner, and the cylinder foot bolt holes knifed
on their top surfaces after drilling. Next mark the studs for
drain cocks and valve spindle stufﬁng boxes, the latter as in
Fig. 2 37. Chip the edges of the steam ports to the marked lines,
and scrape the face. Then put in all the cover studs with stud
box, and bolt on the covers to try the ﬁt.
XXX. Cylinder Covers (Fig. 265).—The front cover is
chucked, as at A, until the stufﬁng-box face be true, for this face
is not to be tooled. Set the tool to correct distance from centre,
and turn the rim. Clean up also the front of the cover, measuring
from the slide bar bracket, and mark off the thickness of the
ﬂange, and the circle for the stud holes. If cored, proceed to
bore; if not, drill ﬁrst, and bore afterwards to diameters given,
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262 Slide Valves and Flywheel.
to proper depth. Reverse the work, as at B, and set truly with
the turned face. Turn the inner surface and the smaller diameter.
Now set the cover, end up, on the marking table, as at C, until
the boss is horizontal. Having spanned the hole and found its
centre, scribe the centre line along the boss and on to the cover.
Scribe also the seating for the slide bars and the centres of the
gland studs. Now turn the cover through 90°, by measuring from
a square, as at D, and scribe the centre line across. Mark also
the slide bar seatings, and divide out the stud holes; then drill
the bolts and studs, and slot the slide bar seatings. Lastly, scribe
through the stud holes on to the cylinder ﬂanges. The back cover
is turned, as at E and F, and similarly marked, and the gland
tooled as previously described at Fig. 238.
XXXI. Main Slide Valve (Fig. 266).—Lay horizontal,
as at B, scribe centre of boss and thickness of valve, and plane
both sides. Set up, as at C, till the bosses are level, and scribe
the centre all round; line also the top and bottom surfaces.
Turn to the position D till the boss is quite vertical, and scribe
the centre line round. From this, line the height of boss at top
and bottom. Rescribe the hole for the spindle at both ends,
which is much larger than the valve spindle, to allow for wear of
valve. Next set up on an angle plate in the drilling machine,
as at E, till vertical, and drill the hole right through, kniﬁng at
the same time. Plane the top and bottom surfaces. Line out
the ports by means of a template, and ﬁnish their edges by
hand.
XXXII. Expansion Slide Valve (Fig. 267).--Set level,
as at B, and scribe the boss centres and the face. Square up the
edge, measuring from the centre, and join this along the top.
Next set vertically, as at C, scribe the centre, and line thickness
of boss seatings Drill, knife, and plane as before, ﬁnishing the
edges to template.
XXXIII. Flywheel (Fig. 268) requires very little descrip-
tion. It is simply bolted centrally by the arms to a large face
plate, as shown at A, the boss bored, and both boss and rim- faced.
It is next reversed, the other side faced, and the rim turned, as
in previous similar cases, the curved surface being given by a
careful hand feed.
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264 Bed Plate and Brass Work.
XXXIV. Bed Plate (Fig. 269).—-This is not too large for
a planing machine such as was described at page 169. It is
better to plane the under edge, so that the bed may rest more
perfectly on the stone or brickwork. The casting is therefore set
upside down on the machine, and the ends clamped till the two
side edges are planed 5 the clamping is then removed to the side,
and the end edges planed with a short stroke. The bed being
now set right way up, and held by its lower rim all round, must
next have its seating marked, so as to plane off the calculated
allowance (the total depth is not of any consequence). All the
seatings will be done at once, with a stroke the whole length of
the table. The bolt and stud holes are to be marked off by the
Erector. .‘
XXXV. Brass Work (Fig. 270) must be bright all over
the exterior, and have the interior bored at certain after-mentioned
places. The Oilcup at B‘can be ﬁnished entirely by chuck
turning and drilling, polishing with the very ﬁnest emery cloth.
The Cylinder Cock, A, is cored throughout. The main body
and the plug socket are both turned externally as far as possible,
but the central portion must be ﬁnished with ﬁle, and the corners
cleaned with a rifﬂer. The socket and plug are respectively
bored and turned in the manner shown at Fig. 254, the cock
then placed in the vice, and the plug ground to ﬁt, with ﬁne
emery powder and water, by rotating backward and forward with.
a wrench upon the plug. The screws are chased, and the ﬂange
drilled 5 and the whole polished with ﬁne emery cloth. The union.
nut, after ﬁnishing, is slipped over the copper pipe, and the conical
nipple then brazed to the latter (see page 86).
The Sight-feed Lubricator, D, is the only form now used
for slide valve and piston lubrication. The oil-chamber, a, is.
ﬁxed in any convenient position, and two connexions made with
the steam pipe as shown. Having ﬁlled a with oil, and the sight
feed b with water, the valves c and d are opened, as well as the
two steam cocks, and steam being condensed in the coiled pipe,
forms water, which enters a and displaces the oil, forcing it up-
through the glass sight-feed chamber drop by drop, it being seen
rising through the water in b, than which it .is speciﬁcally lighter.
Reaching the steam pipe, it is carried by the steam to the slide

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267
valve and cylinder; e is a non-return valve, and f a drain cock.
The various parts are bored, screwed, and polished, and then put
together. The steam cocks are cast with a core, and are pro-
vided in casting with a small boss placed on the bend to assist the
~centering in the lathe; this boss is shown dotted.
The Indicator Plugs, c, are next turned and screwed.
Erecting.--We may now collect all the engine parts for the
purpose of erecting, as follows :—
Figs.
I. Regulator Lever .. 228
II. Bracket for Regulator Lever 229
III. Pins and Washers for Regulator Lever 230
IV. Links for Regulator Lever 2 32
V. Regulator Valve Spindle 2 3 3
VI. Nut for Valve Spindle ‘234
VII. Regulator Valve 23 5
VIII. Regulator Valve Box 2 36-7-8
IX. Valve Spindles: Main and Expansio 2 39
X. Expansion Eccentric Rod .. 24o
XI. Main Eccentric Rod 241
XII. Intermediate Valve Rod 242
XIII. Guide Bracket for Valve Rod 24 3
XIV. Eccentric Straps and Sheaves 244-5
XV. Slide Bars 246
XVI. Slide Bar Bracket and Distance Piece 247
XVII. Crank Shaft Bearing 248-9
XVIII. Slide Blocks 250 .
XIX. Gudgeon 2 50
XX. Crank Shaft 2 5r
XXI. Connecting Rod 252-3
XXII. Cross-head 2 54
XXIII. Piston Rod 2 5 5
XXIV. Piston 256
XXV. Radius Link 2 57
XXVI. Governor Pullies 2 58
XXVII. Governor Bracket 259-60
LIsT OF ENGINE DETAILS.
268 Erecting t/ce Engine.
LIST oF ENGINE DETAILs— Continued.
. Fi s.
XXVIII. Governor Details .._. 265-2
XXIX. Steam Cylinder 26 3-4
XXX. Cylinder Covers » 265
XXXI. Main Slide Valve \ .. 266
XXXII. Expansion Slide Valve . 267
XXXIII. Fly Wheel 268
XXXIV. Bed Plate 269
XXXV. Brass Work 27o
XXXVI. Bolts and Studs (not drawn).
The Erector is now to‘be provided with a ‘General Arrange-
ment,’ or complete drawing of the engine, in plan and elevation,
having certain principal dimensions supplied. This drawing is
given in Figs. 271 and 272.
The Bed of the engine is slung, and lifted by travelling crane
into position on blocks of wood, as at a, Fig. 273, and then
levelled with wood wedges and the aid of the square shown in
Fig. 196; the cylinder and bearings then adjusted on their:
seatings approximately. The back and front end of cylinder
bore being bridged with iron bars, the ﬁrst having a small hole-
drilled centrally and horizontally, and the second having a
central notch in its upper edge (see A and B): a strong, ﬁne
string b is knotted and passed through the hole, and carried to‘
the front of the bed, where it is pulled tight and wrapped round
the support 0; the latter being set with one edge agreeing with
centre ‘line of cylinder, as measured from the bearing seatings,
and having notches, ‘as at D, to hold the string at the correct
height. This string constitutes the main centre line, and the-
front of the cylinder is adjusted to suit by tapping the casting-
with a hammer, then ‘clamping ﬁrmly to avoid accidental move-~
ment.
The Bearings are next adjusted. Pass a long straightedge, B,
through the brasses, and support it on level blocks till its upper
surface nearly touches the string. Clamp the large square F upon
E, near the string, and support on block G; then prepare a lath H,
to measure the length from cylinder face to edge of bearing
brasses, and mark distances on the straightedge E, on each side:
Erecting the Engine. 269
of the square, up to the bearing faces (shown by curved arrows).
Adjust bearings till (1) straightedge touches measuring lath;
(2) square touches string along its whole length; (3) face of
brasses is lineable with measure of straightedge ; and (4) straight-
edge exactly touches bearing brass throughout its length. Then
mark the bearing stud holes through upon the bed, and do the
same with the cylinder holes.
The Slide Bar Bracket must be placed with reference to slide
bar length. It is wisest, therefore, to temporarily fasten the front
cylinder cover and the two bottom slide bars. When all are
together, as at d, the bracket is set to central position by squaring
up from its top surface to the string, and the stud holes traced
through.
The Valve Spindle Guide Bracket must also be true with
regard to the spindles, so these are put through the stufﬁng boxes
and the bracket, and the latter adjusted by measurement from
cylinder face on the one hand, g, and from the string on the
other hand, using blocked-up laths at /z. If the spindles do not -
slide truly, a slight readjustment can be made. Examine also for
appearance regarding seating, then scribe the stud holes. The
governor bracket comes to the Erector ﬁtted up entirely with
governors, links, and pulleys. Set up in approximate position,
and measure the distances J from the boss faces to the string,
these being the most important; adjust to these, and also to
distances from cylinder face (e) and crank bearing (K). Then
test, by measurements at K and G, for parallelism of pulley
spindle, and mark off the holes.
The holding-down bolts are lastly marked, all the parts re-
moved, the circles centre-punched, and the Bed Plate either taken
to a radial drill, or drilled by ratchet brace, the former being
preferable. Tap all the stud holes and insert studs; then return
the bed to its erecting position, which need not this time be
level, the main adjustments having been made. And now the
various pieces are to be put in place in the order we shall mention.
First the Cylinder is bolted down, and the Front Cover put on,
the Piston inserted, ‘and the Rod passed through; then the Slide
Bar Bracket, and the Bottom Slide Bars. The Bearings come
next, and when ﬁxed have the Crank Shaft laid upon them, with

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272 Setting Z/ze Eccem‘rz'cs.
red ochre applied to its journals. Being turned round in the
bearings by means of the temporary handles, L, it is lifted away,
the brasses scraped, and the method repeated until a perfect ﬁt is
obtained. The last time the shaft is removed, it is taken to the
marking table to line the eccentric keyways. The angles for each
sheave are shown at M, being known after design, and are there
called a and 16 3 x and y are. therefore found from a table of natural
sines.
For x = radius of shaft >< sin a, and y = radius of shaft >< sin {3.
TABLE OF NATURAL SINES FOR ANGLES UP TO 45°.





Deg Sine. Deg Sine. Deg. Sine. Deg. Sine.
% ‘99872 12 ‘29791 23% ‘39875 35 ‘57357
1 ‘01745 12% ‘21644 24 ‘40673 35% ‘58070
1% ‘02617 13 ‘22951 24% ‘41469 36 ‘58778
2 ‘93489 13% ‘23344 25 ‘42262 36% ‘59482
2% ‘04362 14 ‘24192 25% ‘43051 37 ‘60181
3 ‘95233 14% ‘25938 26 ‘43837 37% ‘69876
3% ‘06104 15 ‘25882 26% ‘44619 38 ‘61566
4 ‘99975 15% ‘26724 27 ‘45399 38% ‘62251
4% ‘97846 16 ‘27563 27% ‘46175 39 ‘62932
5 ‘08715 16% ‘28401 28 ‘46947 39% ‘63607
5% ‘99584 17 ‘29237 28% ‘47715 49 ‘64278
6 ‘19453 17% ‘39979 29 ‘48481 49% ‘64944
6% ‘11320 18 ‘30901 29% ‘49242 41 ‘65606
7 ‘12187 18% ‘31730 30 ‘50000 41% ‘66262
7% ‘13952 19 ‘32556 39% ‘59753 42 ‘66913
8 ‘13917 19% ‘33389 31 '51593~ 42% ‘67559
8% ‘14781 20 ‘34202 31% ‘52249 43 ‘68200
9 ‘15643 29% ‘35929 32 ‘52992 43% ‘68835
9% ‘16594 21 ‘35836 32% ‘53739 44 ‘69465
19 ‘17364 -21% ‘36659 33 ‘54464 44% ‘79991
19% ‘18223 22 ‘37499 33% ‘55193 45 ‘79719
11 ‘19081 22% ‘38268 34 ‘55919
11% ‘19936 23 ‘39973 34% ‘59649





The heights as and )1 above or below centre line have to be scribed
by laying the crank webs vertically or horizontally as at P and N ;
and the distance Q also measured, giving the centre line between
the two eccentric rods. Slot-drill the keyways. Then drive the
sheaves upon theshaft, to which they should ﬁt tightly; put in
the keys, and replace the crank in its bearings. (It may be noted
Setting t/ze Valves. 2 7 3
that the copper hammer should always be used in these operations.)
Bolt down the bearing caps.
Fix the Valve Spindle Guide, valve spindle Stuffing Boxes, and
Valves, also the Governor Bracket with gear complete. Twist the
valve spindles round until the valve screw is placed symmetrically
with regard to the valve; then measure for equal play either side
of the guide bracket. In the case of the expansion spindle, put
in the intermediate rod, and let the lifting link be vertical when
valve is at half stroke. We shall proceed to set the valves; so
to aid us in turning the crank to its various positions, the ﬂywheel
is driven on to the shaft, and there keyed. The governor pulley
can be put on afterwards, being in halves.
It is convenient to ﬁnd the position of the main slide valve by
the aid of a thin wedge of wood, R, which is tried in the port on
the horizontal centre line, and on removal measured. Put the
main slide to open to ‘lead’ at the front of the cylinder, the
amount being known; place the crank horizontal, as taken from‘
the seatings, and put the crank pin to the front, as at s. Now
measure with a lath the length from valve spindle pin to nearest
edge of eccentric sheave.
Set the valve for lead to back of cylinder, place the crank in
horizontal backward position T, and measure the length as before.
The two lengths obtained should differ only by a very small
amount, and, being averaged, the length of the main eccentric
rod can be found. During the preceding operations the expansion
valve can be slid to one side or the other for convenience.
The expansion slide must be set centrally. We ﬁrst move the
main slide to opening position at front and back part alternately,
and each time measure the distances U on the valve spindle. By
setting the spindle to half the sum of the two measurements at U,
the valve will be central. The expansion valve is now moved till
midway between the main valve ports (v v), and its spindle
measured as at U. Set the crank webs upright, as at w, with
straightedge and plumblines. Take the distance, 2, to eccentric,
centre, found thus :
z=radius of eccentric circle x sin ,8;
and move the expansion spindle back at U by this amount ; then
T
274 Templates and f zgs.
‘measure length for eccentric rod between pin of radius link and
edge of sheave. Reversing the crank, as at x, the valve is moved
to the front by the same amount, 2, the length again obtained,
and the .two averaged. In our description of‘ the machining of
these rods we supposed the length already given; but it is always
found for the smith in this way, though often the rods are ﬁnished
in two pieces, and afterwardsvwelded to correct length.
Put the valve rods in place, also the crosshead, connecting
rod, gudgeon, and slide blocks; connect up to crank pin, having
previously ﬁtted the brasses to the pin ‘by scraping, and bolt down
the top slide bar with distance pieces between. Fix the regulator
valve box (previously put together), the cylinder cocks and lubri-
cators, the steam chest cover, and the back cylinder cover, making
all joints with red-lead ‘putty ’ between. The putty is a mixture
of red and white lead, softened with boiled linseed oil. After
covering the. joint surface, a piece of soft hemp line is laid once
or twice round, and the cover then put on. Portland cement or
asbestos discs are also used. '
T he ‘last stage of all is to carry away the parts to their per-
manent position, and bolt down the whole to its stone bed;
connect up the steam and exhaust pipes, and get up steam.
We shall now ﬁnish with one or two general points.
Templates and Jigs—The former have been sufficiently
explained in Figs. 253, 264, and 266. They are used very
extensively in much repeated work, thus saving a great deal
of time in marking off, and they take' a variety of shapes. Jigs
are an extension of the template principle. Instead of thin
plates, castings of an inch or so in thickness are used, supplied
with holes where needed, the object being to guide the drill to its
proper place on the work without the necessity of lining-out at
all. An example of the application of this principle to a cylinder
cover is shown at v, Fig. 27 3.
Hobbing a Worm WheeL—A cutter for forming spur-
wheel teeth was given at Fig. 186, and a method of cutting bevel
teeth at Fig. 262. Worm-wheel teeth can also be cut by ﬁrst
turning in the lathe a worm of the correct shape, and of good
steel. This is then ﬂuted to form a milling cutter, and is termed
a hoh in the workshop. The operation is then much the same as

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Dimensions and W. G. '2 77
that described at page 58. The spaces are ﬁrst cut on the angle
-with a spur-wheel cutter, and the ﬁnish given with the hob by
placing both wheel and worm in position, as at Fig. 72, and
rotating the latter on a milling spindle.
Dimensions. In most workshops the inch is divided into
vulgar fractions in the common way. But in dealing with work
of great accuracy, or where small differences are to be repre-
sented, the above divisions have to be carried beyond sixteenths,
and then become cumbersome. To avoid this difﬁculty, the
decimal system of division has been used for a considerable
period in a few shops, and has proved a great boon, being easily
learnt by any workman, and its advantages greatly valued. We
have spoken of lzig/z and low gauges for interchangeable work.
Where these are used, the drawings are supplied with what are
known as ‘plus and minus’ dimensions. Thus all shafts, pins,
&c., are ﬁgured '002" larger than the size required, an inch pin
being 1'002"; and holes are marked ‘005" larger than their
pins, an inch pin requiring a hole 1'007". There is an under-
stood plus and minus allowance of ‘002" on both these dimen-
sions, so that if a large pin and small hole come together, there
will be a minimum clearance of ‘001", while a small pin in a
large hole will have a maximum clearance of ‘009". For driving
ﬁt, the hole and shaft are ﬁgured the same, and the kind of ﬁt
noted.
It was long ago found advisable to ﬁx the thickness of thin
plates and the diameter of small wires by reference to a table of
numbers, which received the name of the Birmingham Wire
Gauge or B. W. G., and where each number had a corresponding
dimension. This table was readjusted about the year 1885 and
considerably extended, under the name of the New Standard
Wire Gauge, and has been shown diagrammatically in Fig. 274, the
horizontal scale representing a length of half an inch, while the
ordinates are referred to the numbers on the left hand. The
actual gauge is represented at K, Fig. 27 3, being a steel plate
provided with slots of the correct widths.
Split Pins.——Half round wire split pins are made in ﬁfteen
different sizes, the largest being 371,-", a", and T53”, and the
remainder numbered I to 12, corresponding with W. G. The

278 S ,olit Pins.
diameter of eye is equal to that of the pin, and the lengths vary
as follows :—
Nos. 7 to 12 1" to 4" long, rising by 3;".
,, 5 and 6 1" to 4%" ,, ,,
,, 1 to 4 1" to 5" ,, ,,
T53" pin 115" to 5%" ,,
3;", ,, 2" to 5%" ,, ,,
i“. n 2%”110 5%" n
CHAPTER VII.
BOILER MAKING AND PLATE WORK.
WE now enter upon a division of practical engineering having no
direct connection with any previously described processes, ex-
~cepting only Metallurgy (Chapter III.). Boilers, Tanks, Girders,
Ships, &c., are ouilt up by bolting or riveting together plates
previously manufactured at the Rolling Mill, intermediate con-
nections being formed by ‘section ’ bars, rolled at the same place.
Materials.—-It is beyond our scope to give a detailed
account of the production of wrought-iron or steel bars, angles,
or plates, by rolling while hot. Wrought Iron is obtained from
Cast Iron by puddling, as at p. 75, where the process was followed
to the formation of bar iron of different qualities. The bars are
now hot-rolled by passing between pairs of horizontal rollers,
being supported on their way to or from which by a train of
'bearing rollers. Putting the bar through the mill a suﬁicient
number of times (both crosswise and lengthwise), a ﬂat plate
is obtained ; then sheared to rectangular shape. These rolls are
too simple to need illustration. They are very powerful, being
‘driven by a large engine, which is either itself reversible, or the
rolls are supplied with a reversing clutch.
If ‘ Section ’ bars are required, the material is ﬁrst reduced
to a convenient thickness, and then passed through a set of rolls
‘capable of gradually decreasing the sectional area, while lengthen~
ing the bar. Thus any particular section may be obtained, the
process consisting of ‘cogging,’ or roughing-down the bar, and
‘ﬁnishing,’ or giving the true section. In Fig. 275, A represents
a train of rolls for producing |_ or angle bar, a being the cogging
set and o the ﬁnishing set; B shows rolls for plain or merchant
bar; 0 those for T bar; and D for H (aitch) bar. The opera-
tions occur from left to right, the upper rolls being usually
provided with discs riding on corresponding depressions in the
lower roll, and thereby preserving the correct thickness of bar.
280 P/az‘e Material.
Iron plates retain the ﬁbrous quality imparted to the bar,
and are therefore much stronger in the direction of the ﬁbre than
across it. Owing to the secretion of cinder and scale between.
the layers during piling, the ﬁnished plate must be carefully
examined for faults—(1) by eye, (2) by slinging from the four
corners and tapping, when the dull, ashy portions may be de-
tected by the non-vibration of sand sprinkled over the surface.




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Very bad plates are rejected, and the others placed in the scale-
according to quality, thus evolving the various degrees of ‘ best,"
‘double best,’ and ‘treble best3’ terms, however, by no means
sufficiently deﬁnite. The Yorkshire irons are made with great care
and a large expenditure of fuel, being also very carefully selected.
Steel Plates and Bars are rolled similarly. The ingots,
obtained as at pp. 79 to 82, are, after casting, usually broken up,
piled, and re-heated, though ,'some authorities complain that this
destroys the homogeneity for which steel plates are admired, and
prefer to roll direct from the ingot. The slabs or ingots should
Rivet tl/[a terial. 28 I
be well squeezed in both directions when made into plate. Steel
plates are muchmore reliable now than when ﬁrst introduced, it
being clearly recognised that a certain amount of strength must
be sacriﬁced to ductility. They are not, therefore, much stronger
than iron, but much more homogeneous or even in structure,
the particles being so thoroughly re-arranged when in the molten
state. Iron plates, on the other hand, are very various in quality,
even over one plate, because of the processes employed in
obtaining ﬁbre. A test strip, either for plate or bar, rarely gives
an exact determination of the whole, while the contrary holds
with steel. Steel plates are termed ‘mild’ because they have
little more carbon than wrought iron plates; they have some
30 per cent. greater strength than the latter, with twice the
elongation. The prices of both being also similar, it is not
surprising that steel is the only material now used for plate work,
excepting where continuous ﬂame action (as in locomotive ﬁre-
boxes) renders Lowmoor iron or copper preferable. Copper,
though more expensive, and losing its strength somewhat when
hot, is an exceedingly good conductor of heat, and deteriorates
less under the action of ﬂame, lasting therefore longer thanxiron,
while being more efﬁcient.
Steel, then, in a mild, homogeneous form, is the material now
generally used for all plate and angle work. Both steel and iron
are received under the following forms :—

Plates H (Aitch) Bars H
Angle Bars |_ Flat and Square Bars _
Tee Bars T Round Bars 0
Channel Bars 1-1
Rivets are prepared from round bar. If of iron, they should
be of the very best quality—‘Swedish,’ ‘Charcoal,’ or ‘Low
Moor,’ and capable of standing re-heating without deterioration.
Steel rivets have now almost superseded those of iron. The
greater strength of the plates was of little value so long as the
joint (the weakest part) remained much as before, but since the
introduction of hydraulic riveters by Tweddell, and with care in
reheating, there is no objection to steel. The making of rivets
is shown at p. 99.
282 Maximum Sizes of Plates.
Brands, qualities, and sizes of plates—The qualities
of iron have been mentioned at p. 76, ‘common ’ being used for
bridges and girders, and the remainder for boiler work. Mild
Steel occurs in four qualities, thus :—
1. Ship and bridge quality.
2. Ordinary boiler quality.
3. Soft boiler quality.
4. Superior quality (to resist ﬂame).
The brand BT shows the plate has passed the Board of
Trade test, while ‘B: indicates that of Lloyd’s; and there are
other brands representing various makers.
The sizes of plates obtainable vary somewhat with the makers,
the following table being that issued by the Steel Company of
Scotland. The ﬁgures must be kept within the length and breadth
given, but must be checked for area: thus, 14 ft. by 4 ft. may be
the limits of length and breadth respectively, but 4 x 14: 56, and
the area limit is only 28 square ft.
MAXIMUM SIzEs OF STEEL PLATES.


_ Area in
Thickness. Length. Breadth. Square Feet
TIE/2 I 4, on 4' o" 28'
1e 4' 6" 31'
é,’ 2 2' o], 5, o’, 40!
__ I I I!
30:51 25! on 5 3 so’
3 I! I I! I H I
TB- 30 o 5 6 65
I!
% 33I 0!! 6! 0!! 7 2’
5 I! I I! I I! I
1B 35 O 6 3 75
gr! 38/ on 6' 6" 85'
T78]! 40/ on 7 I OH 9 8'
40' 0" 7' 6" 105'
683,, 40/ on 8! 3!! I 15'
n I
in 3 7! or 8! 9!! I 25'
‘g’, 34! OH 8! 9!! I 25'
,, I r/ r n '
1 3 I O 8 9 I 25
1 28’ o" 8' 9" I 1°’
I 7}": 25! OH 8' 9”
Hand Tools. 28 3
Hand Tools, &c.--The boiler-maker and plater require
somewhat different sets of tools. Both men must be able to







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mark out their work although in large shops a separate man is
kept for‘ the purpose. In the latter case the work may be further
subdivided among template-makers, platters, rioeters, and angle-
284 Boiler Smz't/z’s Heart}; and Tools.
iron smz'zf/zs, and even still further under caulkers, ﬂangers, &c.,
the three italicised representing the usual division. _
For Marking-off a large, low table is used, long squares and
straight edges, a scriber, as at Fig. 194 ; wing compasses and
dividers ; a small, very z‘zlg/zz‘ pair of compasses for describing rivet-
hole circles; and in some cases a scribing-block. For scribing
rivet-hole centres, parallel to edge of plate, a compass like that at
A, Fig. 276, is useful, acting like the carpenter’s gauge, while the
wheel tool B, Fig. 276, of 24" circumference, is run over curved
plates to measure their developed length. Of centre punches
there are two, one at c, Fig. 276, for centreing or dotting, and the
other, D, for centreing a hole in one plate to agree with a drilled
hole in another. A small taper rod or pozz’ger is required to pull
plates into line by insertion in their rivet-holes.
The Angle-iron Smith must be able to bend his bars in
various directions, and usually inserts a welding or glut piece
between the parts to be joined, thus making a double fork-weld.
His hearth is built of brickwork, as shown at Fig. 277, coke being
placed on a sliding plate A, which ﬁts under the central well B,
the blast entering from behind. The work is laid on the top, and
loosely built round with ﬁrebricks, then covered with slabs of the
same in cast iron casings, and a good welding heat obtained
without difﬁculty. Reverberatory furnaces are employed for
heating plates; they are similar to that shown at Fig. 85, p. 75,
but have a ﬂatter roof and a larger door for the admission of the
plates. A rivet-heating furnace is smaller, but of the same design.
The Boiler-smith’s tools are not dissimilar to those in
Chap. IV. In addition to the tool c, Fig. 97, a rouna’facea’ﬂaz‘z‘er
A, Fig. 278, is required for ﬁnishing rings. C/zz'sels or cutters,
both curved and straight in proﬁle, and hollow swages, as at E,
Fig. 278, are also necessary. For tongs, the three forms, c, D,
and E are useful—c for lifting angle bars, D for hoops, and E for
rivets.
Plates may be ﬂanged, bent, or straightened by hand, large
wooden hammers being then used, as at F, Fig. 278, three of
which are employed by as many men, who give rapid consecutive
blows ; but these processes are done by machine where possible,
and will be described later.










286 H and-riveting and Caulhing.
The Plater requires three chisels—the ﬂat chisel, Fig. 201,
he cross-cut, as at Fig. 200, and another with curved proﬁle for
chipping the edges of manholes, &c. Hammers are of three
kinds—the ﬁtter’s hammer, Fig. 199, the sledge hammer, and a
riveting hammer with long head and small panes for places where
the sledge or the portable riveter cannot be employed. A
Riveting Gang consists of three men and a boy; the boy
brings the red-hot rivet, which the leader inserts, as at D, Fig.
279 ; another man holds up the dolly, as at A; while the third
man and leader give alternating blows until the cheese head E is
formed. The leader then applies the cupping tool or snap B,
while the striker gives two or three smart ﬁnishing blows with
the sledge C. Work should be designed for machine-riveting
wherever possible, as hand work can neither make the rivet com-
pletely ﬁll the hole or compete in cost.*
Before riveting a seam, the plates, if punched or drilled
separately, are brought into alignment by the podger and bolted
in one or two places; then the drift at A, Fig. 280, may be
applied and forced through by a hammer to clear out the holes.
Though of undoubted advantage if used temperately, the drift
is now banished from the best shops, plates being injuriously dis-
tressed by it when the holes are very untrue. When a joint is
to be broken, the rivet-heads are chopped off by the set B, struck
with a sledge, and the punch c applied to drive out the rivet.
Caulking is the process of making a boiler joint thoroughly
staunch by burring up the plate edges with a blunt chisel or
caulking tool. In Fig. 281, A is the section of a boiler joint,
where-the edge of the outer plate is bevelled at an inclination of
1 in 8. Striking the tool B with a hand hammer a burr is formed,
and the rivet heads treated similarly, as at a. Severe caulking
with sledge diminishes the grip of the rivet and frictional strength
of the joint. To avoid this a fullering tool c is often used, but
there is no objection to caulking if a large number of light blows
be given. A Pneumatic Caulker will be described later. Caulking
is not considered necessary if hydraulic riveting be properly
apphed.
* See diagrams by Mr. Tweddell, prepared for his paper before the North-
east Coast Institution of Engineers and Ship-builders, given in Fig. 301a.
1W ac/cine Punc/zes. 287
Punched a. Drilled Holes—Formerly the holes were
punched in a boiler plate before rolling the latter into cylindrical
form, and alignment then obtained by very forcible use of the
drift. The holes were marked by dipping the end of a short
piece of brass tubing into white paint and transferring to the
plate 3 the puncher could not therefore give great accuracy, and
the plate needed considerable stretching when a pair of holes




CENTRE
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made ‘half moons.’ Later the centre-pop replaced the white ring,
and a ‘ centre’ punch as at B, Fig. 282, was used in the machine,
so that the hole could be punched with accuracy. The machine
punches thus took the successive forms, A, B, c, and D. c was
introduced to avoid distress of plate by giving a gradual shear,
and D, Kennedy’s spiral punch, still better carried out the idea of
c, as proved by actual tests. The bolster is shown at E, to
support the plate while punching; and the size of hole (larger
than the punch) may be found by construction at o, a triangle
288 Crysz‘allz'srzz‘z'on produced by Pzmc/zz'ng.
' being drawn with sides as I :6. Then if a’ be ‘diameter of punch,
and z‘ plate thickness, {ll will be the size of hole in bolster, or
D=d+§
The material removed from the plate is known as the
‘ punching,’ or ‘burr,’ and during the operation a certain portion
is compressed into the surrounding plate, thereby increasing its
density and causing ‘ distress ; ’ the clearance between punch and
bolster hole is to prevent this, which it does partially. The dis-i
tressed area is said to be small, and the distressment relievable by
rimering, annealing, or both. Dr. Kirk’s experiments in 1877 on
the fracture of punched plates, showed the crystalline or weak
portion varying between the two limits at F, Fig. 282. i All this
was removed by subsequent annealing. heating to redness, and
slowly cooling. '
But the question was raised : if the plates require such treat-
ment after punching, and alignment not then obtainable unless
punched after rolling (very difﬁcult with machines as made), why
not drill them at once and avoid annealing? There is no diﬂiculty
in drilling after bending, and further, the holes may be made
through both thicknesses of plate at once, thus securing accuracy
of position. Drilling ‘in position’ is therefore the present-
day practice, and we are not aware of any workshop where
punching is performed except for very thin plates, or for
roughing out man-holes, &c. After drilling, the sharp edge is
taken off by a countersinking tool, or rosebit, to prevent cutting
action on the rivet, caused by expansion and contraction of the
boiler.
Shearing causes the same harm to the plate as punching,
and the edges should always be planed afterwards.
D Cramps as at A, Fig. 219]), are required by boiler
makers for temporarily fastening plates together, or for providing
a hold when slinging. _
Machine Tools, as explained in. Chapter V., are daily
gaining ground, to increase the output, while securing greater
accuracy and cheaper production. - As in the Fitting shop, they
were at ﬁrst driven entirely by belts from a line of shafting, but
the intermittent demand renders hydraulic power more advan-
Geared Punching and Shearing Machine. 289
tageous. Mr. Tweddell advocates the almost universal appli-
cation of hydraulics for plate work, and has fully conﬁrmed his
advocacy of the system, especially where the power has to be taken
about to various places in succession. In all shops Riveting
Machines and Flanging Presses are now actuated by Water
pressure; so also may be Punching and Shearing Machines,
though more often driven by shafting; while Drilling, usually
performed by shaft power, has been successfully attacked by
electricity and water pressure; portable hydraulic drills, under
certain conditions, having proved both efﬁcient and economical.
Punching and Shearing Machines—It is customary
to combine both operations in one machine, as a plate is seldom
punched and sheared at the same time. Fig. 283 shows a good
example of this tool, as made by Mr. john Cochrane, of
Barrhead, capable of either punching, shearing, or angle cutting.
A shaft A has fast and loose pullies at B, and ﬂy wheel at c for
overcoming variable resistance. The power passes, by pinion
and wheel, D and E, to a second motion shaft F, and in like
manner, by wheels G and H, to the main shaft J. The shaft J
has eccentric pins KK formed upon its ends to give a vertical
reciprocating motion to the slides L and M, the former carrying
the punch, and the latter the shearing knife. Dies upon the
pins KK, prevent undue wear, and the fork N prevents the rising
of the plate when the punch is withdrawn. The shearing knife
always moves while the driving shafts revolve ; but the punching
slide L is driven from pin K through the hollow die P and a
cam piece Q, the latter being connected to a handle R. When
R is upright the downward motion of P is transferred to L: but
if the handle be laid on its side, so also is the cam; P then
moves freely without pressing upon L, and no punching occurs.
Thus by changing position of R, the workman has ample time to
set his plate, while the shafts still revolve. The dies are hard
steel, and steel plates in slideM receive the wear. The angle-
shearing knife is fastened to a rocking lever s, actuated from
shaft J by an eccentric T, having ball and socket connection to
the lever. Here, again, the withdrawal of a sliding piece U serves
to stop the motion of the knife, which is necessary with bars,
though not with plates.
U
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Hydraulic Punc/zing and S/zearing Mac/zines. 291
At Fig. 284 is shown an Hydraulic Punching and
Shearing Machine, designed by Mr. Ralph H. Tweddell, of
'Westminster, for performing the same operations as the foregoing
by means of water pressure. In this example there is no reason
why the three parts should be combined except to save floor space.
A cylinder and ram are required for each operation : A for punch-
ing, B for angle-cutting, and c for shearing; there are also the
lifting pistons at D D D. Water being supplied from the accumu-
lator pumps at a pressure of 1500 or 2000 lbs. per sq. inch,
two pipes are connected with each cylinder, one for ‘ pressure ’
and the other for ‘exhaust,’ marked P and E respectively. The
valve boxes at F are supplied with piston valves (worked from
hand and foot levers J and K) to control the supply and exhaust ;
but a constant pressure, on the pistons D D, causes the rams to
rise when water is exhausted from the main cylinder. A
small lever G, moved by ram c when at the end of its down
stroke, is connected to ascrewed rod H, having adjustable discs,
which restore the levers J and K to the horizontal position,
stopping the water supply and the movement of ram 0: this is
known as cut-off gear.. Two overhanging cranes L, L, support
the plates while being operated on.
The Multiple Punching or Shearing Machine in
Fig. 284a, on Tweddell’s system, has been designed to prepare
plates required in forming wrought-iron pipes for conveying
water or oil across country, and known as ‘pipe lines ;’ it is also
useful for ships’ funnels and masts, and for girder work generally.
A shearing blade or row of punches can be attached at will 3 the
latter being shown in operation at A. The punches are set alter-
nately low and high, so’ that the punching resistance commences
gradually, and they are attached to a beam B capable of vertical
movement. Downward motion is obtained by a leftward travel
of bar c, whose lower rollers press upon beam B, while the upper
ones re-act upon inclined planes D, D, D, fastened to the framing.
The working ram E (see enlarged section) moves bar c; water
entering the cylinder F from behind, and connection between
C and E made with a toggle G, to allow for vertical travel.
H is the valve box with piston-valve moved by lever], and the
cut-off is effected automatically by the bell crank K, as

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294 Plate-edge Planing Machine.
previously described. A ﬁxed ram N .on the top of the
framing, has a cylinder M in the form of a girder, to which a.’
constant water pressure is supplied, and the girder is connected
by bolts to the beam B, so that a rise of the latter takes place-
whenever the main cylinder is opened to exhaust. The angle
bar P prevents the plate from lifting, and L is a stop valve.
A Plate-edge Planing Machine is shown at Fig. 285,,
having a long table A, upon which the plate is clamped by-
screws BB. The tool 0 is ﬁxed in a cylindrical box, provided
with handle D resting on stops, so that direction of tool point may‘
be reversed at either end of cut, shown by the arc E; this is.
performed by the workman, who travels on a platform F attached
to the saddle v. The'latter has a hand-wheel and screw G to-
set the tool, while the wheel H, turned by hand, gives vertical
feed. The saddle is traversed by screw J, driven from the‘
countershaft K by gearing: while K is provided with fast pullies.
M, N, and loose pullies L L L. When the forks are in the position
shown, no work is done, but if the straps (crossed and open),
be moved to the right the saddle will travel to the left and
vice versa. Reversal is automatically effected by projections.
P P striking the stops Q Q at either end of the stroke alternately,
thus moving the straps, decision being given by the weight R,
which causes a pressure between the rollers at s. The mid
position is ﬁxed by stops T: and the standards are so arranged
at U that they overhang the work, thus allowing the admission of '
any length of plate. One setting may serve for several plates.
A Band Sawing Machine is a very useful tool in a boiler
shop for cutting out plates of intricate shape, while straight plates,
too thick to be sheared or punched, are cut by a. circular saw"
when necessary. As these are so well-known in their wood--
working capacity, diagrams have been thought unnecessary.
Plate-Bending Rolls, in their most common form, are-
shown in Figs. 286 and 287, the rollers being supported hori—
zontally. These are the design of Mr. John Cochrane, of ‘
Barrhead. The lower rolls A A revolve in ﬁxed bearings, while
those of the upper roll B are lifted or lowered by the screw C, the—
worm wheel D acting as a nut, while the worm is turned by the
spoked wheel E. A A are the driving rolls, and the gearing is very"









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Plate Bending Rolls. 297
powerful, consisting of wheels and pinions F G and H J, the last
being on the driving shaft, while M MN connect the rolls. The
pullies are driven by crossed and open straps, to obtain reversal,
K being the fast, and LL the loose pullies, so that either strap
may be put upon K alternately by a foot or hand lever attached
to the forks (not shown). The plate to be bent is placed upon the
rolls A A, B lowered till a grip is obtained, and the machine set in
motion. When the plate has been drawn nearly through, the


ﬂag. 282 {Si
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machine is stopped, and the wheels EE given a slight advance,
the rolls then reversed, and the plate brought back, and these
operations repeated until B is depressed enough to give the
necessary curvature. When the plate is bent into an entire circle
it cannot be released at the front; so the top of the standard is
made separate at P P, and the bolt Q turned down as shewn
dotted, when portion P P may be swung round horizontally upon
pin R, leaving the bush s upon the roller B. The plate may then
be withdrawn. It should be noticed that the sides of the bush 5
are curved in plan to radii from the pin R.
298 Rolls for bending Section Bars.
- Vertical rolls are often used for long, heavy plates, and are
said to be less expensive in operation, while giving truer ﬁnish to
the end of the bent plate. This last is the principal difﬁculty
with all rolls, the entering edge, to six inches deep, being always
set bybending while hot with wooden hammers. Except for this,
the plates are never heated for rolling, even up to 1% inches in
thickness, for in such cases the radius is proportionately larger.
The weight of plate is eliminated by the vertical method, with less
fear of obliquity of curvature. Long rolls are often slightly bellied
at the centre, to take up spring. For the heavier plates an hydraulic
bender, introduced by Mr. Tweddell, seems very likely to super-
sede rolls. It ﬁnishes the plates to a truer circle from end to end,
and there is no limit to plate thickness, or risk of fracture by too
rapid feed. Butt strips can also be bent truly to boiler curve.
The tool is similar in design to the multiple punch in Fig. 284a,
but the girders are placed vertically, and suitable dies inserted
instead of the row of punches. - .
Plate-straightening rolls are similar in construction, but there
are some four rollers at top, pressed down simultaneously by
connected screws, upon three rollers at bottom, and the plate is
passed through and through till truly plane. '
Rolls for Section Bars (Fig. 288) have their axes vertical,
7 and are placed upon a table A, which is sometimes conveniently
set level with the ground, with a pit for the gearing. They are
driven by the usual fast and loose pullies F and L with crossed
and open straps for reversal. These actuate a worm and worm
wheel, B and C, and a spur pinion D on the axis of c gears with
wheels G G on the roller shafts. Thus E E are the driving rollers,
and H the bending roller, with a screw J to bring its bearing closer
to the rollers E E, effected by turning the nut K. A ring or angle
bar is shown bent to a circle with an outward ﬂange—an inward-
ﬂanged ring being obtained by turning all the rollers upside down,
and other sections by special rollers. Finally the ring is removed
and welded with a glut-piece. _
Flanging Presses—It being always advisable to diminish
the number of joints in a boiler, the end plate is usually ﬂanged
or bent over at the edge to form a ledge for the shell-plate, while
stiffening itself considerably.







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300 ‘Pz'ea'bceuf’ Flangz'ng Press.
Plates were formerly ﬂanged entirely by hand, being moulded
on cast-iron forms by blows from wooden hammers, as at Fig. 278.
This method was slow and expensive, and two kinds of hydraulic
presses are now used, (1) the ‘Piedboeuf’* press for ﬂanging at
one heat, a very effective tool, but requiring separate dies for every
separate kind of work; (2) the universal, or three-ram ﬂanging
machine, invented by Messrs. Tweddell, Platt, Fielding, & Boyd,
and capable of either progressive or single-heat ﬂanging. We will
take these tools in order.
The ‘ Piedboeuf ’ Flanging Press, on Tweddell’s system, is
shown at Fig. 289. It consists of an hydraulic cylinder A con-
taining a ram B, which may be raised on the admission of water
pressure, thus lifting the table 0, on which is placed the lower
die D. A girder E carries the upper die R, being supported by
guides F F, provided with nuts for the adjustment of E. The girder
G supports the central cylinder A, and four cylinders, H H, con-
taining the ‘vice’ rams J ; and as it is necessary to move the
cylinders H H to varying distances from the centre, the pressure
(or exhaust) pipes are trained through three-quarters of a revolu-
tion between their connections at the pipe circuit K K and those ‘
of the cylinder, so that the pipe is not strained materially when
the positions of H H are changed 5 in addition there are sheaths L L
to prevent snapping at the unions. The valve-box M has two
hand levers; N for controlling the vice rams, and P for the
ﬂanging ram. The two dies are shown ready for ﬂanging a tube
plate Q, which has been made red-hot and laid on the lower
die D. The vice rams are ﬁrst advanced until the plate is held
against the upper die R; then the ﬂanging ram B slowly raised
and the plate made to assume the dotted form. The levers being
reversed, the plate may be withdrawn. These presses are made
large and powerful, but are not used for plates beyond 7 feet
diameter, and rarely up to that.
Universal Flanging Press (Tweddell’s system).—-This
very useful machine is shown at Fig. 290. There are two vertical
rams, A acting as vice ram and known as the ‘elephant’s foot,’
and B for ﬂanging the plate on what is known as the ‘ progressive
system.’ A third and horizontal ram 0 gives the ﬁnish, and a
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Uni'z/ersal Planging Press. 303
fourth ram D raises and balances the vertical rams A and B,
having a constant pressure supply; so that the rams A'and B only
rise when opened to exhaust, one or other, or both. Yet a ﬁfth
ram E serves as vice during single-heat ﬂanging. Referring to the
enlarged sections, the ram A is seen to be hollow, riding upon a
smaller ﬁxed ram F. Ordinarily the water only enters the
annular space round the small ram, but on releasing plug G it
passes down the centre tube and then exerts a pressure on the
whole area of the large ram, a variable power being thus obtained.
The horizontal ram 0 is of piston form with atubular continuation
to a smaller piston H, upon which there is a contant pressure, so
the return is effected when G is opened to exhaust. Any special
forms of dies may be applied at J, K, and L, and the guide
bracket M is removable. The valve-box has ﬁve levers, each
working both pressure and exhaust, I for ram A, 2 for ram B, 3
for ram c, 4 for ram E, and 5 for an hydraulic crane to lift the
plates (see A, Plate XIV.) A plate N is being ﬂanged on the
progressive method. It is slewed by crane, laid on a curved
hearth (B Plate, XIV.), and heated for a few feet along its edge,
then transferred to the block P and ﬂanged as described, rams
A, B, 0 being applied in succession. This is done foot by foot
until the heated portion is all ﬂanged ; a new heat then taken,
and the work continued as before. When ﬂanging with complete
dies, the upper die is fastened to the rams A and B, as shown at R,
and the lower die placed on the table. The hot plate being laid
on the lower die, the vice ram E is ﬁrst raised and the upper
rams then lowered 3 the ﬂanging pressure is therefore the differ-
ence of that upon the lower and upper rams. Any kind of ﬂanging
can be performed by this machine by using suitable dies.
Drilling Machines, for boiler work, vary greatly in their
construction. Except for the Radial machine they are all
designed to drill ‘in position,’ and their form depends on the
kind of work to be done. When possible they are made ex-
peditious by the use of more than one drilling head, a necessity
in view of the large number of holes to be drilled.
Radial Drill.—This has been already described at p. 167.
Opinions differ regarding the best construction, but in almost any
form it is an extremely useful tool for boilermakers. An inter-
304 Special Radial Drill.
esting example is shown in Fig. 291, designed by Messrs. Geo.
Booth & Co. for performing a variety of operations. The circular
table A, provided with worm wheel B, may be revolved whenever
the worm shaft c is connected to the driving shaft D by belt 3 at
other times it is stationary. A bracket E, ﬁxed upon the bed ‘ of
the machine, carries a tool F through the medium of the two
slides G and H, each provided with hand wheel and screw, thus
giving adjustment in both directions. When, therefore, a boiler end
plate is fastened to the table through temporary rivet holes, and
_ the worm gear connected up, the tool F serves to turn the outer
edge, and the usual back gear is seen at K. The power passes
through mitre wheels and vertical shaft within the pillar to the
spur wheels L M, and thence through shafts N and o to the drill
spindle, the feed motions being as previously described. The
simple drilling done on this machine is the taking out of
tube holes in the manner shown at B, Fig. 169 3 but large ﬂue
holes are made by using the head P and three cutter bars Q Q
held by set screws with removable cutters, forming in fact a large
pin drill. In all cases a hole is ﬁrst drilled in the plate to receive '
the ‘ pin ’ and steady the cutter, and the radial arm R being long
may be ﬁxed to the bracket s when doing heavy work. But the
most interesting feature to the student is the method by which
large oval holes may be formed, such as those required as man-
holes. A short vertical shaft T is connected to the driving shaft
N by gearing of 2 to 1, the same ratio as that of the bevel gear at
U. At the lower end of T is an eccentric stud adjustable within
certain limits, and a rod v connects this with the saddle. The
shaft T making its revolution in the same time as the drill spindle
an inspection of the diagram at W shows that the cutter will be
compelled, by the movement of the saddle, to mark out a true
ellipse instead of the circle it commenced with, which will be
understood by comparing the numbers 3 of course only one cutter
bar can be used. The tube J may be turned round within the
base X, for ﬁne adjustment, by the worm gear at Y, but the
‘position of the arm R is ﬁrst roughly obtained by releasing the
bolts 2 z. The lifting is effected by the screw a, driven from the
central vertical shaft by spur wheels at &, reversed or put out of
gear at will by the handle 2’ moved horizontally. This machine


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therefore can perform no fewer than four operations—ﬂue-hole
cutting, oval manhole cutting, tube drilling or other single
drilling, and boiler-end turning. '
Although the foregoing is a very useful, it is by no means a
usual tool. The rotating table is more often placed on a bed by
itself, constituting a vertical face lathe.
Drilling in Position.--The [plates of a cylindrical boiler
being prepared and temporarily connected, the rivet holes are
drilled right through the several plate thicknesses. If stationary
machines are employed they must be supplied with a cradle or
bed on which to lay the boiler, so that the latter may be turned
round on its axis, and thus present all portions of its surface
at various times to the drill. Obviously there are two principal
ways in which the axis may be placed, vertically and horizontally,
the latter being used for large marine boilers, while the former is
advantageous when drilling locomotive (‘or Lancashire boilers,
though it has also been employed for marine work. L,‘
Drills with Boiler Axis verticaL—Fig. 292 illustrates
‘this type of drill: and its individual application (the drilling of
rivet holes in the ﬂanges of boiler ﬂues), will ﬁrst be described.
The machine is the design and patent of Messrs. Geo. Booth &
Co., and is very ingenious throughout. The ﬂue is bolted, with
its axis vertical and central, upon the circular table A, and a
handwheel B, being connected to the table by bevel gear c and
worm gear D, serves as a dividing plate, its revolutions being
counted to turn the ﬂue through any fraction of its circumference
between each operation. The saddles E F ride upon vertical
standards G H, and contain horizontal slides J K, for adjustment to
various diameters. l is the driving cone, and power is taken from
horizontal shaft L by mitre gear to the vertical shafts M and N:
from these the various motions are obtained. Thus the spur gear
and mitre gear at o and- P give motion to the horizontal spindles
‘Q R, and from thence by mitre gear to the vertical spindles s T,
which turn the drills U U and vv by spur gear. The vertical
movement of the saddles is given by hand or power. When by
power, a worm on shaft N gears with worm wheel W, which
actuates a second worm and wheel at x, connected with the screw
Y by mitre gear. The mitre wheel on Y rotates within a boss cast
Batler Face DILZLL'ILQ

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Bgach, &. 02

(_by Geo.

scau. or ran
___—_-
308 —- l/Vit/z Boiler Axis vertical.
on the saddle, and has a plain hole, the connection with Y being
by key only. There are two nuts 2 and it upon the saddles, and
the screws b and Y move simultaneously on account of their
union by horizontal shaft ~at a’. When, therefore, the driving
shaft L is rotated in its proper direction, so also are the drills U U
and v v, and a downward feed given to the saddle, as described.
The raising or setting of the saddle involves hand gear, the
capstan e turning the screws through pinion and spur wheel, and
the mitre gear before mentioned : but although the spur wheel is ’
keyed to its shaft, the worm wheel X is not thus secured, and is
only in gear with the screw Y when clamped to the wheel f, while
the nut 41 is carried in ‘a socket, and is adjustable by mitre gear
to alter the relative heights of the saddles. Horizontal adjust-
ment is made by turning the capstans gg, each of which moves a
pinion within a rack, and the bolts 12 ii serve as adjustable stops.
The drills themselves are worthy of notice. The upper ones, UU,
are of the twist shape, but have a conical shoulder at the top,
forming a countersinking bit. The lower drills vv are for counter-
sinking only, and their feed, upward or downward, is obtained by
hand wheels and screws jj. The saddles, somewhat loaded with
all this gear, are coupled to chains passing over pullies kk to
balance-weights behind. In drilling a ﬂue ﬁxed upon the rotating
table, the saddles are raised by hand to approximate height, and
advanced horizontally by the capstans gg; then the stops /3 k are
set. The strap fork is moved on the countershaft and the drills-
rotated, while the feed wheel at X is clamped in gear. The hole
being drilled to proper depth and countersunk, the feed is un-
clamped and the saddle raised to allow the bottom countersinking
to be done by hand feed jj. Withdrawing the tools vv, the
dividing wheel B is operated to turn the ﬂue by the amount of the
rivet pitch, and the next pair of holes drilled as before.
Shells of Locomotive boilers are drilled by machines similar in
general build to that just described. A longer bed is needed,
that the standards G and H may be advanced or separated by
a tommy-bar applied to pinion and rack. An internal dog-chuck
on the face plate grips the shell, and the dividing gear remains
the same. The saddles are materially altered, being similar to
those of the radial drill, excepting that vertical screws are applied
With Boiler Axis horizontal. 309
instead of a rack. The drill spindle therefore lies horizontally,
and might be represented by Q and R, but the screw feed on its
‘other end replaces slides J and K. Some makers withdraw the
drill by power, using a quicker speed.
The larger shells of Lancashire boilers may be drilled similarly,
but are often slung vertically by travelling crane, and held against
a pair of vertical standards, which support the drill spindle at a
ﬁxed height. Such a method is, however, less capable of rapid
and accurate adjustment. If there are two internal and two ex-
~ *ternal pillars, the holes may be drilled and countersunk on both
sides at one operation.
_ Marine boilers are sometimes drilled with axis vertical, on a
rotating table as in Fig. 292, but usually are either laid hori-
zontally, or a portable drill is applied.
‘Drills with Boiler Axis horizontal (Figs. 293 and 294).
--Plate XIII. represents a machine for drilling the shells of
Marine Boilers while laid horizontally. It is designed and made
by Messrs. Hulse & Co. The boiler is placed upon a cradle
‘consisting of four disc rollers A A A A, which can be turned by
power applied to the worm shafts B B, so as to bring any portion
-of the shell circumference in front of the drill. The drill
standards 0 c, carrying the saddles D D, may be moved to various
positions along the slide-bed E, and may also be adjusted, by
‘turning on the hinges F F, so as to lie tangentially to the boiler,
.a condition obtained by the hand wheel and screw at G, and tested
.by the fork H, each of whose prongs should just touch the shell.
There are fast and loose pullies at J, giving power through spun
"wheels K to the principal shaft L, which forms a hinge-pin for the
standards. Within the standard boss, mitre gear connects L with
vertical shaft M, and from thence to drill-spindle N through the
spur gear 0 and mitre gear P. The feed-screw takes its motion
from the shaft at 0, through mitre gear Q, cone—pullies R, worm
and wheels, and mitre wheels T5 and the saddle may be raised
or lowered by the hand-wheel U, the screw being turned as in
Fig. 292. The hand~wheels v V act upon a vertical shaft through
worm gear, and thus turn a pinion within a rack on the inside of
the bed for adjusting the horizontal position of the standards.
The shaft L, besides driving the drills, also rotates the rollers of
310 Portable Drill.
the cradle. Bevel wheels W X connect L with worm gear at Y,
and the worm shaft 2 moves the shafts B B in its turn through
mitre gear at a. The drills are put in or out of gear by clutch
handles b b, and the clutches at dd turn the cradle rollers in
either direction according to whether W or X is put in gear, while
a central position of handle e puts them out altogether. After
adjusting the standards by means of G and H, the drilling pro-
ceeds as usual, the outer countersinking being done at once by
the tool, 21a, Fig. 316, while the rosebits, 21b, are used for the
internal countersink and changed at each drilling. When two
boilers are drilled at once, the coupling at f is disconnected, but if
one long boiler is being operated, the rotating gear must act as one.
So much for the shell. The front and back of the boiler, so
far as the seams are concerned, are drilled by a machine of
similar appearance, but the standards are rigidly vertical instead
of being hinged, and the cradle is turned through a quarter circle
in plan; that is, the front of the boiler would be seen in Fig. 294,
while the side view would appear at Fig 293. When the lower
seam has been drilled, the boiler is rotated through half a circle
until the upper seam comes into position, the other holes having
been previously taken out under the Radial Drill.
Portable Drill.-—This machine being much less used than
formerly, we shall only brieﬂy notice it. It exists under two
types—the bracket or standard type, bolted to the plate through
holes already drilled by it; and the slung type, well represented
by Borland’s Drill in Fig. 295. In either case the driving gear
(by rope) is similar. Referring to the ﬁgure, A is the driving
shaft, and the cord is held taut by weight B, while the power is
taken off by pulley C. A second endless rope D drives the drill
spindles in opposite directions, and the feed is given by worm
gear. Being slung within the boiler, two opposite holes are drilled
at once, the one pressure forming a reaction to the other. The-
feed is supplied either automatically or by hand, and the machine
is capable of drilling shells 9 ft. in diameter. The safety chain
avoids accidents in case of breakage of the rope.*
Multiple Drill.--In addition to the machines already
described, there is one—the Multiple Drill—which has always.
* See previous remarks on portable hydraulic drills, page 289.


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DRILLING MACHINE I
FOR MARINE BOILER SHELL.

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3 I 2 Multiple Drill.
proved of great service for ﬁrebox work. Its modern form is
shown in Figs. 296 and 297, Plate XIV., as originally designed
for some of the Irish railway shops, and made by Messrs. Hulse
& Co. With it six stay-holes can be drilled at one operation, or
each drill employed separately at will. If a plate only is to be
operated on, it is laid on the high table A, but if the ﬁrebox is
previously built up, then A is removed, and the lower surface B,
of the trolley, used instead. The trolley is run under the drills
either by a hand wheel placed on the square at D, to turn the
hind rollers through bevel gear, or by spokes at c which rotate a
pinion a within a rack B, one method or the other being variously
convenient. F is the cross slide, raised or lowered by the screws
G G, coupled by horizontal shaft H; and the drill brackets J J are
moveable along the slide by the application of a ‘pinch-bar’ to
the ridges at K. L is the driving shaft and M the feed shaft.
They are connected by the feed gear, viz., worms and wheels at
N and o; and the feed shaft is provided with levers P P, attached
to the drill spindles by links at Q. The drill spindles R R are
driven from L by bevel gear s s, and the springing of the two
shafts L and M is prevented by the brackets J J, which support
them both. The bevel wheels on the spindles have clutches T T,
actuated by the balance handles U U, so that any or all of the
drills may be put in gear at will. The balance weights v v are
attached to the levers P P, to relieve the weight of the drill
spindles, and the set screws W W are tightened against the rod X
to ﬁx the centres of the drills after adjustment. If only some of
the drills be required, clutches T T are disconnected and the
drills withdrawn, feed gear being stopped entirely by releasing the
clamping handle Y, which unites the ﬁxed plate 2 with the loose
worm wheel 0. The method of operation, then, is to (I) lay the
plate on the table in position, and bring the work under the drill
by turning the spokes c ; (2) adjust cross slide F for height, and
drill brackets for centres by pinch-bar at K; (3) ﬁx by set screws
W w; (4) start shaft L, and pull down the clutch levers U U;
(5) bring drills down to work by handle b; and (6) put feed
motion in gear by clamp Y.
The drilling being done, unclamp the feed, raise drills by
handle b, change the strap to loose pulley, and set to another row



< -. _ ' 'PLATEXIV.
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Stationary Hydraulic Riveter. 3 I 3
of holes. Considerable economy results from the application of
this machine, which is very well designed in Plate XIV.
Summing up, the great desiderata in boiler drills are rapidity
of adjustment and withdrawal of tool, and where possible the
introduction of multiple drilling.
Hydraulic Riveting Machines.—It is to Mr. Ralph H.
Tweddell that the honour of introducing hydraulic riveting
properly belongs. No other method is now used, if we except
recent pneumatic and electric contrivances, which are not as yet
much employed: but steam riveting is entirely obsolete. The
advantage of hydraulics for riveting is very great: it is a power
that can be conveyed to great distances without appreciable loss,
it can be stored till wanted, and the steady and known pressure
on the rivet-head, coupled with the increase due to absorption
of the momentum of the accumulator weight at the moment of
closing, is just the action most desired.
Large Fixed Riveter.-—This machine, on Tweddell’s
system, is shewn in Fig. 298. The standards A and B are securely
connected by two bolts at c, and well designed to resist the
stresses caused in closing. A supports the cylinders, while B
serves as ‘dolly,’ carrying the tail cup M, and presenting a
nearly ﬂush top surface, for the purpose of getting into corners.
The riveting cylinder v, carrying the heading cup, rides upon
a ﬁxed ram T, and within Y is placed the ram U, which advances
the annular plate~closing tool v. The auxiliary ram X, of piston
form, receives pressure on either face for advance or return:
and the tank D, placed 20 feet above the top of the machine,
supplies the cylinders T and U with low-pressure water. The
pipe E carries this water to cylinder T, and the branch pipe R
passes to U, the check~valves Q and s in each case preventing
return excepting through the exhaust pipe L. The latter com_
municates with each of the piston valves, P, o, N, as does the
pressure pipe J; P being connected to the back end of the
cylinder X, through the pipe a: o with the cylinder U through
pipe A : and N with the cylinder T: while b is a constant pressure
pipe connecting J and the front end of X. K is a stop valve, and
2 an overﬂow pipe.
We can now understand the action of the machine. The




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Portable Hydraulic Pir/eter. 3 I 5
boiler seam being placed between w and M,-the rivet heated
and put in from the side M, lever H‘ opens valve P to pressure
and'a right-hand advance is ‘given to the ram x, due to the
difference of area of its faces. This pressure, assisted by the
head of water passing from the tank, through the check-valves
Q and s, carries forward parts U and Y.’ When w and v reach
the rivet and plate respectively, lever G admits pressure water at
0 through pipe A, to advance the ram U, thus pressing the
plates ﬁrmly together between tools v and M. And now valve
N is opened by lever F, and pressure given to T in turn, thus
bringing forward the cylinder Y and the cupping ‘tool W to
close the rivet, the pressure obtained being due to the difference
of areas of the rams U and T, part of the water from U passing
into T through pipe J. The pressure should be kept on the rivet
until it cools somewhat, to secure a tight joint, and the three
levers are then moved to exhaust, when the pressure c pushes
back ram X, bringing U and Y to normal position, and lifting the
water up L into the tank. '
Fig. 298 shows all the latest improvements introduced: the
plate closing (in 1880) and the use of low pressure water to
ﬁll the cylinders (in 1890). The latter is very interesting, and
greatly economises high pressure water, which is only used as a
ﬁlm on the back of the tank water, as it were, the ﬂuid being
practically incompressible. The plate closing apparatus prevents
‘collars ’ being formed on the rivet between the plates. In a
Ioo-ton riveter, 60 tons are applied for cupping, while the
remaining 40 tons hold the plates together, but ultimately the
whole 100 tons is applied to the rivet-head and plates.
Portable Hydraulic‘ Riveters.—Although Mr. Tweddell
introduced hydraulic riveting in 1865, his invention of the port-
able machine did not occur till 187I, since which date Messrs.
Fielding and Platt, who then took up its manufacture, have
been associated with him in the design of nearly all his later
hydraulic machine tools. There are two forms of the portable
machine known as the ‘Direct Acting’ and ‘Lever’ types re-_
spectively; their present construction being shown in Figs. 299
and 300. Referring to the former, frame A is a rigid casting,
supporting a cylinder B with direct-acting ram c. There are three
3 I 6 Portalzle Hydraulic Rir/ez‘er.
diameters on the ram 3 c and v to obtain two powers, while w acts
simply as guide for the cupping tool F. When the smaller power is
required, water pressure is admitted to the annular area D, but if
plug E be unscrewed it acts also on the back of c, the pressure then
being due to both areas 0 and D. K is the valve box, containing
the piston valve Q, capable, by means of the passages within it,
of connecting the annular chambers N and M, or of opening M to
L, where the pressure-water enters. G is the returning ram, upon
which a constant pressure is exerted through pipe H, and space N
communicates with the exhaust pipe J. The handle P acts on the
valve lever 0, so that if the latter be moved to the left, space M is
uncovered and pressure-water enters cylinder B; but if 0 be moved
to the right, spaces N and M are connected, and the cylinder
water passes out to the exhaust pipe. The machine is slung by
chains R R from a pulley T, provided with worm gear; by turning
which from the hanging chain T, the frame may be set at various
angles to the vertical within the plane of the paper. Studs also
are ﬁxed on the frame at the centre of gravity of the whole, on
which are placed the slinging pieces XX, and the worm-gear at
s turns the frame in a plane at right angles to the previous move-
ment: universal adjustment being obtained by the combination
of the two motions. The space between the cupping tools may
be adjusted by the insertion of longer or shorter dies, or by pack-
ing collars; and the method of riveting needs no further
description.
Taking now the lever machine at Fig. 300; A and B are the
levers, the ﬁrst carrying the piston E and the second the cylinder
D, while both are connected by the pin or fulcrum c. To avoid
another joint the curved cylinder was devised by Mr. Fielding, as
well as special tools for its perfect machining: two enlarged
sections of it are shown. The pressure pipe is coupled at J,
where a sheath attached to the union preserves the pipe from
injury by sudden bending, and the movements of the machine
are not interfered with, for the water passes through a swivel joint
at K, through the coiled pipe M and the swivel N, then through
the pin at N and the arm Q to the fulcrum pin 3 another swivel R
and a short pipe T connecting c with the valve box. .U is the
exhaust pipe, led away as required, and the piston valve H is












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5GALE. OF FEET. J‘fCT/O/VS 0F’ CYLINDER.
318 i Locomotive Boiler S hop.
moved by a lever (not shown), to open the cylinder to pressure or
exhaust; while a constant pressure passage from T communicates
with cylinder G, so that the small ram F brings back the piston E
whenever D is opened to exhaust. The fulcrum is at the centre
of gravity of the whole apparatus, and the levers are supported,
directly by the‘ arm Q and secondarily by the arm P, in such a
way that they may be swivelled upon centres C, N, or K, securing
perfect adjustment to suit the work. The worm gear 0 ﬁxes the
position round the axis N, and the drawing shows the latest
method of hanging this riveter.
f The choice of one or other of the machines described depends
upon the nature of the work. The direct-acting machine has the
advantage of rigidity, but the lever machine can be applied more
easily, and reachesymore rivets, being therefore useful where the
character of the work is constantly changing, and the rivets less
accessible. '
'We may now direct the student to Plate XV., which shows
Tweddell’s system of Hydraulic Machine Tools applied in a
Locomotive Boiler Shop. A is a Fixed Riveter, similar to that in
Fig. 298, but without plate closer. The handles at 5 work the
crane B, which lifts the boiler: D being the lifting cylinder, C the
slewing cylinder, and E the traversing cylinder, each ‘supplied
with multiplying gear. F is a smaller crane, where the jib is
lifted direct from the cylinder. K is a crane for portable riveters,.
the trolley s having a ram for vertical adjustment of riveter, the
horizontal position being obtained by hand. The pressure pipe
- on K is jointed for horizontal movement of J, and the pipe at J is
coiled to give spring during vertical movement. Of the portable
riveters, G and N are of the ‘bear’ type, the former having one
and the latter two supporting arms; P and Q are ingenious
applications of this type, and R is an example of the ‘lever’ form
with very long levers. The small bear at L, H, and M has been
devised for ﬁreholes and foundation rings, being swivelled from
' two arms, and the toggle gear at o adapts the ﬁxed riveter to
i ﬁrebox crowns. T is a Forging Press for stamping purposes, and
1° U the ‘ Piedboeuf’ Flanging Press, detailed at Fig. 289. Crane v
is used'with this ‘press, and the Travelling Crane W covers the
centre aisleof the shop. The striking difference of the cranes
































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Marine Boiler Shop. 319
required is very apparent, the importance of ample provision for
lifting being a point upon which Mr. Tweddell constantly insists.
Plate XVI. represents the interior of a Marine Boiler Shop.
B is a Stationary Riveter, exactly as in Fig. 298, and a circular
pit c admits a large marine boiler when riveting. As it is difficult
to obtain nicety of vertical movement in the travelling crane D,
an intermediate cylinder or Hydraulic Adjuster, E, forms a very
useful adjunct. The Progressive Flanging Machine F was shown
at Fig. 290, and the crane A lifts the plate to or from the ﬁre. A
plan view of the latter is given at G, where the dotted lines show
the plate being heated. H is the Locomotive type of Marine
Boiler, much used for the smaller boats, the riveting of which is
performed as in Plate XV. A Marine Boiler is given at J, having
the furnace mouth riveted round with a small bear K, which also
joins the ‘Adamson’ ﬂues at L. At M the boiler is being closed
by a powerful bear-type machine, having plate-gripping tool, and
hung from the travelling crane through the medium of the
adjuster N. The last-ﬁnished ﬂange is here turned outward, as
advocated by Mr. Tweddell, to secure good machine riveting
throughout; but as many makers prefer an internal ﬂange, to
save cargo space or reduce weight, the riveter at P has been
recently devised. It is slung from its centre of gravity, and the
free arm lowered into the boiler, as shown dotted. When raised,
it serves as ‘dolly,’ and can be adjusted in length to suit various
diameters of boilers. A hole must be left at Q, to be covered
afterwards by the plate carrying the central nest of tubes, the ﬁnal
riveting of which is performed by hand.
The diagram in Fig. 301 shows the arrangement of hydraulic
tools on Tweddell’s system applied to Shipbuilding. A is a keel
riveter, supported by parallel motion and balance weight, so that
it may be raised or lowered to reach the keel in any position, yet
remain with jaws vertical. The gunwale riveter at E is similar in
construction. H shows a small travelling jib crane, carrying a
bear machine for riveting the combings of hatchways. J and K
are hydraulic winches, and G a punching or shearing machine. D
is another jib traveller carrying the large lever riveter c for ﬁnishing
the double bottom, and the machine B, supported by a crane with
two movements, is for riveting the keelson. ‘ A special carriage F
320 Hydraulic Shipyard Tools.
carries the stringer plate-riveter, and J is the pressure main which
supplies all the machines through ﬂexible copper piping. This
arrangement is now carried out at many shipyards, and the drawing
explains the advantages of portable riveters more clearly than




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would pages of description. Indeed, the Forth Bridge, all the
great bridges of India, and the Tower Bridge, could not have
been riveted up without these wonderful machines.
The pressure used in the hydraulic mains for boiler shops, &c.',
is usually 1500 lbs. per square inch, but is sometimes exceeded,
being often 1700 lbs.

















































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322 Pneumatic Caulher.
Pneumatic Caulker.--This, an American invention, was
ﬁrst introduced in 1890. As shown in Fig. 302, it is being made
by Messrs. Crossley Bros, and is said to do the work of three or
four men. E is a jacket held in position by the cylinder J,
screwed into the nose-piece F. The caulking chisel G is loose,
but placed within F when required. The piston contains a piston-
valve P, vibrating at right angles to the piston’s axis, the slide
hole being closed by slips 0 o, dovetailed into K. The starting
valve R, when in the position shown, allows the compressed air,
after entering at L through a strong indiarubber tube, to pass-
through the piston by T and U, then harmlessly out by the
passages v and W; but if R be pressed down the passages v W are
closed and the machine operates in the manner to be described.
Key X allows the piston to slide vertically, but prevents axial
rotation. Y is a passage from T to the piston, and T and U being
formed by ﬂats in s, are not in communication with each other.
There are two passages from the piston to U, seen in plan at z 2,,
while in the piston itself one passage j communicates with the top
of the cylinder and another h with the bottom. In addition, two
holes d d1 are made in the slips 0 o, and grooves e e,, f ﬁ are in
connection with these holes at certain times. One other point
must be noticed—the hole g is the exhaust outlet when in
working order, but-M ﬁts the hole in the nose-piece so that air
cannot escape when the piston is at the bottom of its stroke.
If, however, K be lifted to the top position M, it will be found just
of a length to disclose an annular space round the curvature N,
and the air“ is free to pass out at g. -
Having noted all the parts, we can now describe the working
of the tool. The workman, after placing the chisel G in the nose-
piece, holds the former with his left hand against the seam of the
boiler as at H, while with his right hand he grasps the boss s,
pressing the head R upon it, thus practically closing the passage
U. The air passes through T and Y, but cannot get further.
Hole d1 is now in communication with passage e, however, so the
air enters the valve chamber from the right and moves P to the
left. This allows the pressure to act through h on the botto'm\of
the piston, and the up stroke is made. While this air exhausts ‘at
g, the hole d, being now in communication with f, the valve is





























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324 Tale Expander.
vibrated to the right‘, and the pressure air passes through j to the
top of the piston, bringing the latter down again. Once more P is
moved to the left, and pressure exerted on the bottom of the
piston; but the imprisoned air at the top must escape somehow,
so it passes through 21 to U, using the latter as a receiver, the con-
tents of which are exhausted when the piston again reaches the
top position, and Z is in communication with k. The air pressure
is from 10 to 50 lbs. per sq. in., and a free blow is given the tool
in the downward stroke, while the piston is cushioned by the
imprisoned air at the top on the upward stroke, making it easier
for the workman to hold the tool. e1 is a relief at one end of the
valve, while air enters at the other end through c‘; and f1 bears the
same relation to f. i
: Tube Expander.—Boiler tubes must be sufﬁciently ductile
to withstand the rough treatment to which they are subjected.
The earliest metal employed was copper, but that was expensive.
Brass is now extensively used for the smaller, and mild steel or
wrought iron for the larger tubes. A new material, ‘Red Metal,’ is
being introduced, and appears to possess excellent properties,
being intermediate between yellow brass and copper. In all cases,
as a test of ﬁtness, the material must allow of being doubled up,
and having the ring enlarged till capable of slipping over a tube
of the original diameter. The treatment which tubes receive in
the boiler shop consists in their expansion to ﬁt tightly in the
tube-plate holes, and beading at the ﬁre-box end. Although
large tubes are often lap-welded, smaller ones are solid-drawn, or
forcibly rolled upon a pointed mandrel, as in Fig. 303, the latter
being long enough for the whole tube. The process reduces the
ductility of the material, so the tube ends must afterwards be
annealed, while the rest of the tubes should be perfectly straight
and uniformly elastic. - _
A Tube Expander is shown in Fig. 304. A is the smoke-box
tube-plate and tube : B the body of the tool : c three rollers dropped
in between B and the cover-plate D : E an adjustable gauge to ﬁx
the position of the rollers with respect to the tube-plate: and F a
taper mandrel provided with a tommy bar G. The action is simple 3
the rollers are rotated by rod F, which is at the same time pressed\
forward till the tube is well expanded to ﬁt the tube hole. Mr. I






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326 Tube Beader, Cutter, drc.
Yarrow recommends the roller shown at a, and advises that the
hole in tube plate should be rimered to the same taper as the
mandrel F.
Tube Beader (Fig. 305).—H is the body of the tool, con_
taining three jaws at J capable of sliding radially, and moved out~
ward by the taper part of bolt X. when nut L is tightened up.
This is done when the header is put in place, the disc M serving as
steadiment. The collar N holds three rollers, placed at such an
angle as to do the work efﬁciently, and a ratchet wheel 0 is keyed
to N. P is the feed nut, and the ratchet arm Q rides loosely on N,
the latter being driven by Q, like the drill in Fig. 215. But there
is one depression b in the rim of the feed nut P, so that when Q
has, by its vibrations, brought N round by one revolution, the feed
nut is automatically advanced by a small amount. The ﬁrebox
ends of the tubes being excessively strained by the great variations
in temperature there occurring, beading protects the‘ joint, while
the ferrule R, in addition, secures the rigidity not obtainable by
simple expanding.
Tube Cutter.—As it is impossible to gauge the length of
the tubes accurately beforehand, the tool at Fig. 306 becomes
necessary. Three bearings s s s, capable- of radial sliding, support
hard steel discs T T T, which are the cutters. The tapered bolt U
advances these bearings outwardly when tightened up by the
_nut v ; this may be termed the feed. The tool body w has a
square at X and an adjustable gauge at z, by which the cutters
are set. The gauge being ﬁxed, the tool inserted, and nut v
screwed up, a spanner on X rotates the whole. Then v is
tightened, the operation repeated, and‘ so on till the tube is cut
through.
Ferrule EXtractor.—-As tubes have to be withdrawn and
replaced, and the ferrule is the most troublesome portion to
remove, the extractor at Fig. 307 has been contrived to meet this
difﬁculty. The washer b is ﬁrst placed against the tube plate;
then the set screw d released to allow the jaws e f to enter.
When all are in position the screw d is advanced to press the
jaws against the tube, and the nut' g then tightened with a long
spanner and the ferrule drawn out.
are supplied by Messrs. Selig, Sonnenthal & Co.
All the four foregoing tools " 1
‘1
Electric Welding. 3 2 7
Electric Welding.--This important process, ﬁrst intro-
duced in 1885, has proved of great advantage in satisfactorily
uniting pieces unattachable by ordinary means. Among these
articles are boiler plates, which must be our apology for intro-
ducing the subject here. Wrought Iron, or in a less degree Mild
Steel, were the only materials previously weldable, and even then
the joint had but 70 per cent. of the strength of the solid material
-—-—a serious matter with crane chains, where every link is welded.
Scale might form between the weld, the heating could not be
:seen openly, and might neither be even nor thorough ; objections
all absent in electric welding.
Electric energy consists of two factors—electromotive force
‘(or pressure) multiplied by the current (volts x amperes). If
this energy pass through a good conductor, nothing is observable
in the latter; if a bad conductor be presented, the current will
not pass; but an z'rzo’q'ﬁrem‘ conductor will allow some of the
energy to pass, while the rest is converted into heat on account
of the resistance, the amount of heat energy produced being
equivalent to the electric energy destroyed. The metals we most
desire to weld are in the class of semi-conductors, and there is no
difﬁculty in raising their temperature to welding point by the
electric are 3 but the heating effect of a current is independent
‘of the pressure or potential, depending only on the quantify of
.currem‘, and it follows that the energy from the dynamo must be
transformed, so as to obtain a low voltage with a high ampérage.
Every one knows the galvanic battery and induction coil, where a
current of low potential becomes one of high potential after
passing the coil, though at a sacriﬁce of quantity, the energy
‘remaining the same. Transformers serve the same purpose,
ib'eing similarly designed, and it depends which side of the trans-
former we are on as to what amperage we obtain.
There are two processes employed in electric welding, the
" Thomson’ and the ‘Bernardos,’ named after Professor Elihu
Thomson and M. Von Bernardos respectively. The ﬁrst con-
:sists in using the pieces to be united as the poles, and the second
.in using one of the pieces as the‘ negative pole, while the positive
pole is supplied by a rod of carbon, held in the hand in the
manner of a soldering bit. The electric energy isv obtainable in
3 2 8 Electric Welding Processes.
either case by one of two methods—(1) from an ‘alternating’
dynamo, the ‘current’ being increased by passing through a.
transformer; (2) from storage or secondary batteries, which take
their energy from continuous dynamos. The welding apparatus
is not thereby altered. A general diagram in Fig. 308 shows the
direct method combined with the Thomson process, where A
is the dynamo, B the transformer, and c the welding apparatus. '
Two wires are clamped in position at D, and end pressure put on -
by the screws,'the current switched on at E and regulated at F. .
The ends of the wires are previously brightened, and a ﬂux of'.
powdered borax interposed. After welding, the bar or wire is.
removed and hammered to size.
Energy remaining the same, the following examples willa:
show the variation in ratio of potential and current for VaIlOllS-i
purposes :—
. 1. For arc lighting: 1 2500 volts at 10 amperes.
2. For incandescent lighting: 100. volts at 250 amperes.
3. For welding: _ % volt at 50,000 amperes.
4. For welding : % volt at 100,000 amperes.*‘_
No. 3 would weld steel bars 1% inches in diameter in less than
two minutes, while No. 4 would do the same in one minute, ab-
sorbing 35 H.-P., but only for a short time. The great advantage
of electric welding lies in the local character of the heating, which.‘
prevents the spoiling of a ﬁnished piece of work.
We will now turn to the Bernardos process, shown in Fig. 309.-
It is there worked by accumulators—the method most preferred.
The batteries being charged from a shunt-wound dynamo, they‘
are connected to a switchboard A, so arranged-as to throw them--
out in sets of ﬁve. From this board the current passes through
resistance coils for further regulation, and then through the‘
welding tool B, the pieces to be welded, and back to the accumu-
lators. Fifty cells are usually employed, and, if two boiler plates.
of about {F inch thick are to be united, the tool carries a very
* NOTE.—-Only strictly correct in the Thomson process, where energy‘
absorbed is due to true resistance. The Bernardos process uses the arc, and‘.
energy is required to produce light, viz., to volatilise the carbon and render it;
incandescent : amounting roughly to 30 volts in addition.


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33o Cornish and Lancashire Boilers.
hard carbon about 2 inches in diameter, which is held in-a copper
sheath, guard F serving to arrest sparks, and protect the hand,
while the handle is formed of non-conducting material, and the
workman views the operation through a dark blue glass held in the
left hand. Various applications are shown in Fig. 309. At C a
lap-joint is being welded; and at D plates are welded while on
end, a carbon cup holding the ﬂuid metal being gradually raised
as the weld progresses. An interesting application is seen at E,
which may be termed an electric forge, where the circuit is com-
pleted by resting the tongs (having non-conducting handles) upon
the roller, and touching the carbon with the piece of work. The
intense heat of the are forms alloys scarcely known previously,
while, with nearly similar metals, the joint is always as strong as
the weakest one.
Having described the various tools and apparatus used by
the Boiler-maker and Plater, we will proceed to examine the kind
of work to be performed by these men, and the structures which
they are to build. We will consider Boiler Work ﬁrst.
Cornish and Lancashire Boilers. -- These are only
dissimilar in the number of their internal flues. The Cornish
boiler has but one, while the Lancashire boiler is provided with
two, so we have considered a drawing of the latter only to be
necessary. This is given at Fig. 310, where B is a longitudinal
section: A and C end views. A is an internal view of the front, and
B of the back plate. The front plate is ﬂat, being fastened to the
ﬁrst shell plate by an angle ring a; but the back-plate is ﬂanged at
b. The shell plates are numbered from the front thus : 1st, 2nd,
31d, &c., and as their dimensions would be about 3% feet by
25%} feet, giving about 89 square feet area, they may each be made
in one piece, as will be seen on referring to the table of maximum
sizes (p. 282), where a é-inch plate may be 40 feet long, 8 feet wide,
or 105 square feet area. We are enabled, therefore, to keep the
joint near the top of the boiler, out of the water space, and easily
reached after the boiler is set in brickwork. The front and back-
plates are stayed from the shell by ‘gusset’ stays dd, which are
oblique plates attached at each end by a pair of angles ; and are
further supported by the longitudinal stays mm. The fire-bars
being lard in the ﬁnes at if on supports, the heated gases pass



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through to the end k1, thence by brickwork ﬂues, along the bottom
of the boiler to the front, again to the back end by the brick side
ﬂues, and away to the chimney. The internal ﬂues are therefore
at a greater heat than the‘ rest of the boiler; this, producing
expansion, necessitates the introduction of elastic portions. The
ﬂues, moreover, are in danger from collapse, for a cylinder,
although strong when pressed from within, is unstable when
pressed from without 3 so strengthening rings are applied at various
distances along the circumference. But as joints have to be
formed, on account of the great length of the ﬂues, it is customary
to make provision for elasticity lengthwise, and rigidity of cross
section also, at these places, the most usual method being by the
introduction of the Adamson ﬂanged seam at e. This joint has
the advantage over other methods, of shielding the rivet heads from
ﬂame, and a slightly projecting annular strip is placed between the
ﬂanges for caulking purposes. The space between the tubes
being small, the seams are made to ‘ break joint’ longitudinally,
so as to be easily got at when necessary. Conical ‘Galloway’
water tubes are sometimes inserted, as at D, for intercepting the
heat more satisfactorily, the smaller end being passed in at the
larger hole. The ﬂues are joined to the end plates by angle
rings, and their diameters decrease at k,, the connection being
formed by the conical portion l. The manhole edge at f is
strengthened by a riveted ring, always added when a large hole
is removed; and the mudhole n is similarly treated, a portion of
plate being left all round, on which to place the internal door.
Holes are cut for various ﬁttings, as at a, g, and la. The circular
seams are single riveted, but double riveting is used for the
longitudinal joints, because any boiler receives but half the stress
longitudinally that it does in a circumferential direction.
F ox’s corrugated ﬂues, shown in section at E, are extensively
used for the furnaces of many boilers ; taking the place of the two-
pieces jj, while F is equivalent to the portion 12. The corruga-
tions give not only strength and elasticity, but a larger heating
surface.
The proportion of length to breadth in the boiler shown is the
largest allowed; more often the length is about two-thirds of that
given.
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The Marine Boiler. 333




















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The Marine Boiler, as at present constructed, is shown
by the two views in Fig. 311. The number of furnaces depends
on the size of the boiler ; in this, a large example, there are four,
334 The Marine Boiler.
A A. The combustion chambers are also vaﬁously divided, there
being from one to four per boiler; two are shown at CC, each
having a plate C, to split and assist the draught. The heated
gases, rising from the ﬁre at A, pass through the combustion
chamber G and tubes D, to the uptake, which is placed at E to
cover the tubes. The boiler is cylindrical, but with large ﬂat
ends which require a good deal of stiffening, for ﬂat portions in
all boilers are weak. There are two belts of shell plates 1;,1- inch
thick, the ﬁrst H and the second J, each being, on account of its
large circumference, divided into three, and connected by double
butt-straps, with treble riveting, as in plan at K. The division is
uniform and is seen on the front elevation ; where F F F represent
the joints of the ﬁrst, and B BB those of the second plate. The
circumferential seams are double riveted, as at L L, and the man-
hole is placed at M, with strengthening ring. Sometimes a
separate dome is connected to the top of the second plate, but
just as often the steam valve is applied direct to the boiler ; in any
case the dome is simply a horizontal cylinder with dished ends.
The front and back-plates are divided into three, N, o, and P show-
ing the parts of the front-plate, while Q, R, s are those of the
back-plate. N, P, Q and s are each % inch thick, but R is only 5} inch,
and o is inch. They are all ﬂanged and riveted as shown, 0 1
being cut out a suitable shape to take the nests of tubes, while R
is rectangular. Where three plates overlap, the middle thickness
is drawn out as shown at 51, which is a plan of the joints TT.
Longitudinal stays, for the steam space, are supplied by bolts
U U, having large washers to distribute the pressure. The plate 0
is necessarily stiffened by double thickness at the seams, but there
are also stiffening plates vv riveted on the inside, and stay ‘tubes
W W, shown by their nuts, support both plate 0 and combustion
chamber tube-plate X. The other tubes, ferruled at the ﬁrebox
end, and expanded at the uptake end, act also as stays. The plate
P is stayed by bolts at YYl, and the manholes are stiffened by
riveted plates at z. The three bolts marked Yl pass right through
to the back-plate s, which is further strengthened, together with R,
by screwed stays at a, which are bolts screwed their whole length
and ﬁtting into holes tapped in the plates. The combustion
chamber back-plate 5» inch thick, shown at G, is a simple ﬂanged
T he Loeomotz've Boiler. 335
plate; but the tube-plate x, -}-% inch thick, is throated to ﬁt the
furnace ﬂue. The top and side plates, % inch thick, are in three
pieces, with joints at Me, and wherever three thicknesses super-
pose, the mid plate is feathered, as at d. Screwed stays 1i- inch
diameter, 7 inches apart, are ﬁxed between the chambers at e and
at the sides, while the roof is supported by girder stays which
each consist of two plates resting by their ends on the roof seam.
Between these plates are passed collar bolts, which, after being
screwed into the roof and fastened by nuts, are tightened against
special washers on the girder. The furnace ﬂues are of the Fox
pattern, ﬂanged to the throat plate as shewn.
The Locomotive Boiler (Fig. 312) was the earliest form
of multitubular boiler, and has served as pattern for many other
steam generators. The ﬁrebox A is cubical and of %” copper-
plate, thickened at the tubes to -}-i3;”. The back plate D is ﬂanged,
and dished round the ﬁrebox hole to the form shown, the tube
plate 0 being also ﬂanged. The top and sides are in one piece E,
and all these plates, being ﬂat and weak, are supported from the
outer shell by screwed stays riveted over. The latter are 5%"
diam. and 4" pitch, and must be of copper, to avoid corrosion
:by galvanic action, which frequently occurs next the ﬁrebox plate.
The shell top and sides are in one plate H, cut out as shown at
H1; the throat plate F is ﬂanged to join the barrel and the ﬁrebox
shell; and the back plate G is also ﬂanged. The foundation ring a
serves as a distance or closing piece when fastening the shell to
the box, and a similar piece is required at 2, called the ﬁrehole
ring. Mudhole bosses b b are welded on the solid plate, and
‘tapped for tapered screw plugs. A hole is cut in the top of the
shell at v for a double safety valve, and the plate stiffened by a
wrought-iron valve seating. From angles on the shell roof at w
are hung the sling stays X X, supporting the girder stays Y, the
latter being solid forgings, and the stay bolts taking the form of
tap bolts. T is a stiffening angle for the shell back, and P P are
expansion brackets which rest on the engine frame. The ﬁrebox
tube plate, besides the ordinary‘ screwed stays, has four palm stays
at s s, which are seen in detail at 8,. Two plates, K and J, form
the boiler barrel, and each makes a complete circle, the joints
being shown in plan, well out of the water space. The dome L








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The Vertical Boiler. 3 37
vis welded from one piece of plate and ﬂanged over as shown, a
stiffening ring being placed round the hole in the boiler, and an
angle riveted within the dome to support the regulator pipe.
The tube plate Q is attached to the boiler shell by angle R, and
‘the smoke-box plate wrapped round as shown; but as the latter
is not considered part of the boiler, we shall not discuss it further.
A hole is cut in the tube plate at M to receive the copper steam-
pipe, which is expanded to ﬁt, and the tube holes are spaced as
at the ﬁrebox end, excepting that they are all lifted higher by a
small amount to clear the barrel plate. The circumferential
seams are all single riveted, and the longitudinal seams double
riveted. It will be noticed, in the end views, that the ﬁrebox is
contracted, because it must ﬁt between the engine frames, but
after rising clear of these it may be enlarged.
The Vertical Boiler appears under several shapes. The
chief difﬁculty has been to keep the heated gases in the ﬁrebox
sufﬁciently long to allow of their yielding a reasonable amount of
‘their heat to the water. Bafﬂe plates, bent ﬂues, cross water-
tubes, have all been used, but the most effective construction
seems to be that which imitates as closely as possible a short
locomotive boiler. It should be so built that a man can get
inside for repair or cleaning. The drawing at Fig. 313 shows
Wailes & Fraser’s patent boiler, a modiﬁcation of Cochrane’s,
having the advantages required. A is a dome-shaped ﬁrebox,
and B a connexion to c, the combustion chamber. The shell is
a vertical cylinder, made of three tiers of plates, and having a
dished roof E stayed by four gussets F F. A manhole G com-
municates with the combustion chamber for the purpose of
getting at the tubes, and the ﬁrehole is at H. The tubes J are
expanded into the tube plates, and the smoke‘box K is affixed
afterwards. This form of boiler is found very efﬁcient, but rather
.too rigid to withstand the deteriorating effect of expansion and
contraction.
The 'Tubulous or Water-tube Boiler differs totally in
design from any of the preceding. Fig. 314 shows a sectional
elevation of the boiler, with its brickwork setting. A number of
comparatively small lap-welded tubes at A are inclined over the
:ﬁre, and connected at their ends by zigzag chambers at F and H,
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T/ze Tuoulous Boiler. 339
termed headers, which ﬁt closely together. Every header is
connected by a tube a, with a collecting chamber a at each end
of the receiver G; and all the tubes are expanded .into their
respective sockets, the necessary holes at a’ being closed by
covers of ‘mudhole’ pattern. The water rises to the centre of
the receiver, which therefore serves both as dome and part of the
boiler. There is a cleaning hole at e. I is a cylindrical mud
collector, while K, L, M, and N are soot doors 5 and the draught,
shown by arrows and dotted lines, is compelled to follow the
tubes, by reason of the division walls C and D, and the position of
ﬂue E. The receiver is held in place by the girders P P, bolted
to the brickwork. The headers are usually of cast iron, though
wrought-iron ones have been recently constructed, and plates Q Q,
with ﬁrebrick distance pieces, serve to stay and support the tubes
intermediately. The chambers a e are ﬂanged and welded from
wrought-iron plate, the tubes are of wrought iron or steel, and the
receiver of steel plate.
These boilers have been much favoured recently by electric-
lighting engineers, on account of rapid steam-raising properties,
and immunity from accidents due to the small diameter of their
tubes, with relatively great strength; but they require consider-
able cleaning and repairing.
Geometry required by the Boiler Maker.—This is not
of a difﬁcult kind, but involves one or two intersections of solids,
and development of the contact line upon either of the solids
when their surfaces are laid ﬂat. He must know the relation of
circumference to diameter of circle, thus—
Circumference = diameter x 1:‘
22
and 71' = 31416 or ~7-
and the diameter of a boiler should be measured (for develop-
ment) to the centre of thickness of the plate.
The intersection of cylinder with cylinder is given at Fig. 315,
and the method of developing the plane surface: A and B repre-
senting a dome and boiler respectively. Taking the dome in
plan, divide the circle into, say, twelve parts, and number as
shown. Calculate half-dome circumference, and lay out as at
c D, dividing into six parts by vertical lines. Project lines up
34o Geometry.
from plan to meet boiler circumference, and carry these along
horizontally to cross the vertical lines at c D; the serpentine
curve, being then traced through the numbers obtained, will
represent the developed intersecting line. This may be repeated
on the second half of the plate, and allowances made for ﬂanging
and welding. The boiler hole is developed by stepping-off the
three distances, Ii, Izl, and H, with dividers, and measuring them
from the vertical centre line in plan to give a, o, and c respec-
tively, the remaining four segments being symmetrical. The
length of plate is found by calculation. "
Intersections of oblique cylinder with plane, or cone with
cylinder, are rarely required 3 but cone with plane is ‘sometimes
necessary, as in funnels for American locomotives, or conical
ﬂues such as that shown at L, Fig. 310. The latter has been‘
chosen as an example, ‘and the form of plate developed at K,
Fig. 315, J being the ﬁnished ﬂue. The drawing 1 having been
made, the outer lines are produced to meet at f; and the dotted
circles struck, with g f and j f as radii. Upon these are measured
the circumferences at d and e respectively, and allowance made
for welding and ﬂanging.
If the set-squares at hand he not long enough, the marker-off
should be able to set out a right angle by the measurements of
three sides of a triangle, it being easily remembered that the
proportions 3, 4, 5, for base, perpendicular, and hypotenuse in
turn, will serve his purpose, as can be proved by the 47th proposi_
tion of Euclid’s ﬁrst book, thus :
32+ 42= 52 or 9 +16 =25
The length of arc, chord being known, is sometimes required,
and may be obtained as follows :—
Let c=the half chord.
r=radius of arc.
a = half the angle subtended by the are.
c .
Then -=s1n a.
r
The angle a being found from a table of sines,
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342 _ S citing-out a Marine Boiler.
Setting-out a Marine Boiler.--We are now in a position
to detail the method of setting out the plates and putting together
of any form of boiler previously described. Taking ﬁrst the
Marine Boiler: the Draughtsman must make a list of the plates
required, taken from the drawings, for ordering purposes, giving
each a marginal allowance, which will vary from i in. to gin.
all round according to thickness of plate. This is necessary, for
the shears at the Rolling Mill leave a rough edge and distress the
plate. Referring to Fig. 311, the plates N, P, Q, and s would be
ordered as ‘ sketch plates ’ ; coming in roughly sheared to the shape :
G and X might also be cut down at the mill; but the remaining
plates would be ordered to the nearest rectangle. Care must be
exercised to remember ﬂange or lap allowances. The Fox tube
is rolled by special machinery, so must also be ‘ordered out.’
When received, it must be carefully gauged at every ring, and if
found to be more than a gin. oval, must be rejected.
Supposing all the plates have been received, we will refer to
the sketches in Figs. 316 and 317, taking the Front plates ﬁrst.
I. Front Stay Plate—This is received roughly sheared, as at
1. It is painted with whitening and marked off to drawing, as
shown by dotted lines, keeping a near the edge to avoid much
planing. Then the curve b is cut out by band saw to give an
edge for the ﬂanging gauge 2. Flange to gauge, by the pro-
gressive method, Fig. 290, the ends being set as at 3, by the
horizontal ram. Being now considerably strained, the plate is
placed in a furnace, and uniformly heated to a dull red heat ; on
removal it is laid on a ﬂat table, and straightened by wooden
hammers, then allowed to cool slowly. The edge 1a is next
planed on the machine in Fig. 285, and a bevel given by setting
as at 4, the angle being 1 in 8 ; often this is given to outer edges
only. The long edge is planed with a stroke the full length,
and the ﬂange 5 with short strokes, the position of the stops Q,
Fig. 285, being altered for the purpose. The ﬂanged edge is
milled as at 6, with a conical cutter, to obtain caulking inclination,
a suitable table being provided to give a curvilinear feed.
The rivet holes are now drilled to the extent of one in every
six, measured along the pitch line, for use in holding the plates
together while drilling in position. In this case the holes along














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344 Front Plates.
1a are to be marked from the tube plate; but those along the
ﬂange are obtained by laying upon the latter a very thin steel
strip 7 prepared with marked holes, and of the exact length of
the ﬂange. After marking through, the ﬂange holes may be
drilled in a Horizontal Drill, and the plate holes in a Radial
Drill. The holes for the stay bolts are marked off to dimension,
as shown at U, Fig. 311, and drilled with clearance for the bolt.
II. Front Tube Plate—The Plate is ﬁrst marked as at 8, and‘
part 8a cut out by Band Saw. The pieces 9a are next drawn out
to a tapering wedge as at 31, Fig. 311, after which the parts 9&-
may be removed by Band Saw. Flange 96 to gauge; anneal
and straighten. Plane edges 9d and go to a bevel, trimming the
corners by chipping, and mill the ﬂanged edge as before. Set
out all the plate rivets as at w, v, and Y, Fig. 311, and the tube
holes. Prepare a steel strip the exact length of the ﬂange, and
pitch the rivets upon it; then mark through to the ﬂange one-
rivet in every six, leaving the corner rivets. (N.B.—It should be
remembered that the corner rivets, where three plates overlap, are
always better drilled absolutely ‘in position’) Now drill all the
plate rivets under a Radial Drill, and the tube holes at the same-
time, making ﬁrst a small guide hole for the pin drill 10. The
stay tube holes are made to tapping size, and the other tube holes-
to gauge. The ﬂange holes are drilled in a Horizontal Drill, and
the stiffening plates (v, Fig. 311) marked from the tube plate and
drilled separately.
III. Bottom Front Plate.-—-Whiten the plate as before 3 draw‘
centre line, line 11a, and strike curve 11b. Set out the centres
of the furnace holes, and strike a circle on each, smaller than the-
ﬂue by the ﬂanging allowance. Drill a small hole for drill‘-
steadiment at the furnace centres, then lay the plate on the drill
in Fig. 291, and take out the large hole by the trepanning tool 12.
Heat and ﬂange, as at 13, each of the furnace holes, and after‘
cooling lay on the marking table to test the original lines, which»:
have drawn a little 3 so the curve 111% must be re-struck, and cut
by band saw. Flange to gauge, including the setting of the
ﬂange ends 3 anneal and straighten. Mark out line no’ and cut
out with band saw; plane also the edge no. If possible, give
the bevel at a’ when cutting, but if that is not convenient, ﬁnish
Bach Plates. 34 5
by milling or chipping. Mark the ﬂange rivets, one in six, with a
special steel strip, and the rivets along the seam a d, one in six,
from the tube plate. Set out the centres for stays Y Y1, Fig. 311,
and mudholes z 2, as shown at 14. Next prepare the stiffening
plates 15 by marking out, sawing, cutting the oval hole by the
special method shown in Fig. 291, and drilling the rivet holes.
Place the stiffening plates in position, and mark through all their
holes; then drill all holes by a Radial Machine, and cut the
mudholes by the appliance in Fig. 291. The edges of the furnace
ﬂanges are tooled in the same machine by ﬁxing the plate hori-
zontally on the table and revolving the tool Q Q, as at 16.
IV. Top Bach Plate is prepared in the same manner as I.
V. Bach lldiddle Plate—This must be lined out as at 17,
with a and 6 parallel, and the curves struck. The rest may be
understood from II. After planing a and h, and setting out the
stay holes, the latter are left to be drilled till all are bolted
together.
VI. Bottom Bach Plate (18) is treated in the same manner
as I., but the stay holes are all drilled in position, as in last
example.
VII. Front Ring Plates—There are three of these, all equal
in length. They are lined, as at 19, with long set squares, then
planed, the long edges to a bevel, and the short edges square;
next taken to the Rolls, Figs. 286-7, and put through in the
manner previously described. But many Marine ﬁrms prefer to
work with Vertical Rolls, believing that besides supporting the
weight, the curve is obtained more squarely with the long edge.
In ﬁnishing the short edge, a greater pressure is given to secure
accuracy of curvature, and partially avoid the necessity of bending
with hammer. Now mark off the rivet holes to suit those already
drilled in the ﬂanges of the Front and Back plates. To this end
the steel strips are again used, and, being very thin, do not differ
appreciably in their outside and inside circumferences. The
positions of joints T T must be found with relation to the butt
joints F F (Fig. 311), and the centres of T T marked upon the
front long edge of the ring plates. Then the steel strips are
applied, and the holes marked to correspond with the ﬂanges.
Of course these strips must be all carefully numbered, to avoid
346 Ring Plates.
mistaking the one for the other. The rivet holes, one in-six, for
the back long edge must be set out so as to bring the joints
F and B (Fig. 311) into exact relation with each other. B B are
therefore marked upon the Front Plate, and two methods occur
by which the intermediate holes may be traced: one involving
the use of the thin strips, and the other being the placing of one
plate upon the other, on blocks as at 20. The latter method
seems preferable, because all the holes may be marked on the
back edge of Front Plate, one in six drilled, and then traced
through to the Back Plate, VIII. The manhole is next marked
off, with its rivet holes, but is not cut out till in position. ‘The
butt strap is prepared by planing; heating and pressing to correct
curves between dies ; then marking off all holes, but drilling only
three on each edge. It is next applied to the plate, these holes
marked through and drilled.
VIII. Bach Ring Plates—These are also in three, and of
equal length. They are marked as in the last example, and if
care be taken, the horizontal joints of the Plates II. and V. will
be in line with each other. This is a necessity, so it is advisable
to keep the vertical centre line of the boiler well in view, on all
these Plates I. to VIII., during the whole of the marking off.
We may now bolt together the whole of the shell plates
through such rivet holes as have been drilled, and place the
boiler upon the cradle A A, Figs. 293-4, Plate XIII. The drill
spindle is adjusted as there described, and all the holes in the
ring plates drilled right through. There are two principal forms
of rivet holes required, as shown at 37 and 38, the former being
for machine and the latter for hand-riveting. In 37 the arridge
is just taken off, while 38 requires a deep countersink, but both
may be given by the tools 21 (a and b). 21a is applied from the
outside, and withdrawn when the hole is ﬁnished. 21b is then
passed through from the inside of the boiler, and fastened in a
special slot as shown. Its teeth out left-handed, so the machine
need not be reversed, but the backward feed is given by hand,
and the depth gauged by a mark on the drill. All the shell rivets
are like 37, excepting those in the back ﬂange, and even they
may be machine-riveted, as will be shown. The manhole, is taken
out by drilling holes round its circumference close together, then
Furnace and Coinlnzstion Chamber. 347
ﬁnished by chipping. The bolts being clamped, their holes are
also countersunk, being ﬁrst rimered to ensure exact correspond-
ence. The rivet holes both at front and back of boiler are next
drilled by placing the latter on a cradle, which allows the ﬂat
plates to stand vertical, and'face four drill standards supporting
horizontal drills on suitable saddles. The boiler joints being
truly level, the rivet holes may be easily drilled, as well as the
stay holes in the back, the latter being made to tapping size.
IX. The Furnace Tnhes (22 and 23) are usually obtained
rolled, ﬂanged, and cut to correct shape, an allowance being left
at front end for turning. They may be ﬂanged, however, under
the machine in Fig. 290, as shown at 24, using special dies. Mark
off all the ﬂange holes, as at 23, and drill all those at h, one in
every six at e, but none at the corners a’.
X. Combustion Chamber Throat Plate—This is ﬂanged to the
shape shown at 25. A rectangular plate being procured, the
centres of the furnaces are found as at 26, a hole trepanned, and
the ﬂanging of the throat done at one heat, as at R, Fig. 290.
The rest of the plate is lined as at 27 and the corners cut, the
sides e, f; g, and h being ﬂanged progressively until the whole ﬁts
a cast-iron block or template. This is of course an. operation
involving great care. Now the portions 25a and 25b are sawn
out, ﬁnishing the plate with the exception of the taper ends,
which are drawn out by heating and hammering on the cast-iron
block. After milling the ﬂange edges, the rivet holes 23b, con-
necting with the Fox tube, are marked from the latter, and drilled
separately; and the ﬂange holes carefully spaced out by reference
to the top corners and the furnace centres, but only one in every
six drilled now, and none through the taper portion.
XI. Combustion Charnher Bach Plate (28).—-T his must be
lined out and ﬂanged progressively to ﬁt a cast-iron block, and
the ﬂange edge then milled. The stay holes are drilled in
position. '
XII. The Cover Plates for the Combustion Chamber are now
edge-planed, rolled, and bent hot with hammer, until they exactly
ﬁt the ﬂanged plates, as shown in Fig. 311. There are three of
these plates, one for the roof, and one for each side; and the
holes already drilled in the ﬂanged plates must be traced through
348 Riveting t/ze Boiler.
upon them. The inner laps at the joints 5 b 3 must of course be
tapered, but no holes are yet drilled there, or through any of the
tapered pieces.
Fix all plates of both chambers, including Fox tubes, with
temporary bolts 3 and, laying each upon its back, drill with
Horizontal Drill all the rivet holes, as spaced on the cover plates.
Mark out and drill to tapping size the stay holes in the mid cover
plate of one chamber only, and drill also the holes for the girder-
stay bolts. Set up both chambers in position as at 29 by bolting
through the rivet holes, and blocking below. Obtain level position
with great exactness, then draw horizontal tube centres by
squaring from the roof, and the vertical lines from the middle
plates. They are afterwards drilled to correspond with II. The
mid stay holes are marked from one chamber to the other by a
punch 30, of the same diameter as the tapping size of the holes,
and afterwards drilled by Horizontal Drill.
The Girder or Roof Stays are now out out by band saw, being
clamped together, and are next ﬁtted to the roof, as shown in
Fig. 311.
The Band Saw is a very useful tool, but requires some
attention to keep it keen. The tool at 31 is a roughened steel
helix, rotated by gearing to sharpen the saw teeth as the band is
advanced.
Riveting the Boi1er.—The Front and Back Plates may
now be put together in a Fixed Riveter as at 32, and the ring
plates attached by the same machine up to the condition L,
Plate XVI. But the Back Plate must either be put in by hand
or semi-hand process, or by the machine at P, Plate XVI. The
combustion chamber (after riveting up) is ﬁrst inserted, and laid
loosely within the shell. Then, if hand-riveting be used, the rivet
will appear like that at 38, the ﬂat ﬁnish being obtained by very
quick consecutive blows from riveting hammers used by two work-
men, while a third ‘holds up’ a cupping tool within the boiler.
The hammering is continued on both sides after the rivet is cold,
as a sort of caulking. A pneumatic hammer is employed in
some works, as at 33, where a lever vibrates from a crank plate
driven by a belt, while the hammer end is provided with a
pneumatic dashpot or cushion, giving a ﬁnish like 36. The


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holding up may be obtained as at 34 or 35, by pressing on the
levers there shown.
But the boiler may be ﬁnally closed by machine, using the
methods at P or M, Plate XVI. The former is adapted to
internally ﬂanged boilers, the tube plate being cut in three pieces
at the stiffening plates. After the ﬂange has been riveted, the
various tube plate rivets may be closed by the usual Lever Riveter
with long arms, dropped in through the furnace holes. The best
result is obtained by a boiler designed as at M, Plate XVI.,
and this should be employed whenever the ship designers
permit it.
The Combustion Chambers are put together as at 39 and 40,
but the back plates are riveted by hand, with rivets like 38, unless
the ﬂanges be made as at M, Plate XVI. The chambers and
furnaces are next put Within the boiler shell, and the latter closed.
They are slung as at 41, carefully blocked and bolted in position,
then clamped at the front. Placing the boiler on a cradle, before
horizontal drills, and on the machine in Plate XIIL, drill the
stay holes through into the Combustion Chamber to ensure exact
alignment for the screw threads. All stay holes, including those
between the chambers, are now tapped, as at 42, by a tap whose
threads a and b are continuous.
The Screwed Stays are prepared on the machine at 43.
Stay a is coupled to spindle b, which revolves by gearing c,-
screw b has the same pitch as die nut d, and prevents the forma-
tion of unequally pitched threads on the stay by ‘drawing’ or
uneven pressure. The stays, having a square on their ends, are
now placed in the boiler with a wrench, a nick being ﬁrst turned
at each end to represent their exact lengths; so that having been
advanced to correct position, a sharp twist will break off the
surplus material. Nuts are now added, and the stay ends
trimmed up.
The boiler being still upon its cradle, the rivet holes at the
furnace month are set out and drilled by the machine at 44.
The drill bracket may be revolved on a horizontal axis by worm
gearing, and this, coupled with the rotation of the boiler, will
enable us to drill all round. The riveting-up is shown at K,
Plate XVI.
Stay Tubes. 35!
The Stay Tubes must next be screwed. They are either
formed with a plus thread at one end and a minus thread at the
other, as at 45, or both ends may have a plus thread. The ﬁrst
involves less labour, while the second is stronger. The tapping
machine is shown at 46-7—8. First the tube is cut to length, and
placed within the bushes a b e. After a and e have been adjusted
till the trammel at (whose length represents an exact number of
threads) ﬁts their thread grooves, the set screws are tightened,
and the spur wheel e, being rotated, will also turn the tube and
‘the bushes. At 48, the end view of ﬁ are seen two screwing and
two chasing tools, the one pair being withdrawn while the others
are in operation, and the two pieces ff are united by a back rod
gand a shaft h. h is again provided with two arms jj, which
hold copper dies resting on the bushes a and e. It follows,
therefore, that when the machine is in operation, the tube turns,
and the screwing tools advance to cut the screw on the tube ends
of the same pitch and with a perfectly continuous thread, as
obtained by means of the adjusting trammel a’.
The Tube plates are next tapped. A short tap of the usual
form is used for the front plate, but after that is done, a long tap
like 42 is inserted to screw the back plate, a being the tap and b
the guide screw. Of course, as before, the two threads must be
continuous. The stay tubes are inserted with a square drift and
wrench 49, while the plain tubes are expanded at the uptake end
and ferruled at the opposite end 5 then cut off by the tool at
Fig. 306. The ferrules at 50 and 51 are found most effective for
marine work.
The Manhole seating is now ﬂanged. A ring is cut out of a
solid plate by trepanning, and then bent over blocks by hammers
to the shape M, Fig. 311. Of course this occupies both time and
labour, and probably a method of machine ﬂanging might be
suggested. The stiffening plate being also provided, both pieces
have their holes marked from the boiler, are then drilled, and
riveted to the shell. The longitudinal stays are prepared and
screwed, their washers turned, and all bolted up in place.
The seams and rivet heads are ﬁnally caulked, and the boiler
tested—(1) by hydraulic pressure, to 2% times 5 and (2) by steam
pressure, to 112» times the working pressure.
3 5 2 Setting-out Locomotive Boiler.
Setting out other Boilers—The general methods given in
detail for a Marine Boiler are equally applicable to other boilers,
some little variation being necessary to suit the particular form.
The Locomotive Boiler was given in Fig. 312. The back shell
plate G, the throat plate F, the ﬁrebox tube plate 0 and back
plate D, and the smokebox tube plate Q, are all ﬂanged at one
heat, between full-sized dies, under a Piedboeuf press (Fig. 289) 3
then the edges are ﬁnished by planing and milling. The ﬁre-
holes in D and G are struck out and trepanned, also the holes T
and M. The barrel plates are marked off and planed to dimen-
sions 3 the dome hole L closely punched round its circumference,
but the piece only removed after bending; and the corners of the
plates heated and drawn out taper where necessary. These
plates are next rolled to complete circles, with overlap as shown
in plan at J. The ﬁrebox-shell cover plate must have its developed
outline marked out upon the provided plate, including the set-off
at H1 and the hole at v. H1 must then be cut out by band saw, or
by a combination of punching and shearing, ﬁnishing under a
vertical mill in either case. The remaining edges are planed,
and all ﬁnished with a bevel for caulking. The hole at v is
punched in the same manner as L, with the piece left as a
support during rolling. The cover plate may now be bent care-
fully to ﬁt the ﬂanged plates. Heat and taper all mid feathers
or plate ends that have to lie between two other thicknesses.
Prepare the ﬁrehole ring 2 and foundation ring a by forging from
wrought-iron bar and welding; forge also the girder stays Y and
the safety valve seating v, both being steam-hammer work. The
last is bent to the shell curve, then planed underneath and
surfaced on top. Weld the mudhole bosses o b on the plates,
either by roughing the two surfaces to be joined, or by shoulder-
ing down the boss and riveting through on the inside. Bend the
angles w w and ring R in the machine at Fig. 288, the ring being
welded with a glut piece. Forge the sling stays and pins at X,
and cut off the angles P and '1‘ with circular saw. The dome
plate is rolled into a cylinder and welded, then the ﬂanges at top
and bottom are formed by heating and bending over special
blocks with wooden hammers, and the stiffening piece is cut from
solid plate.
Drilling and R iveting. 35 3
All the plates are now prepared, and must next be marked off
for drilling. First the tube holes are carefully lined on the two
.tube plates, and cut out by pin-drills in a radial machine. Then
the outer plates may have their seam rivets spaced out, and one
in every six drilled, always omitting the corner holes, or those
where three plates overlap. The various parts may now be
tbolted together, and all the rivet holes drilled and countersunk.
Thus K and Q-being connected, the tube plate rivet holes may be
done in a radial drill; adding plate J, the circular seams may be
drilled, as described at page 308, including also the holes in the
dome hole stiffening piece, and those for the smokebox plate.
The dome ﬂange is marked from the boiler and drilled separately.
Bolting H to J, the ﬁrebox shell may be drilled round its circum-
:ference in like manner, but those on the ﬂat sides would be done
under a radial or multiple drill, the latter being preferable. The
barrel is now disconnected from the ﬁrebox shell, and the ﬁrebox
bolted to the latter; then the whole shell placed on the lower
table of the Multiple Drill in Plate XIV., and the stay holes
drilled right through both plates to secure accurate alignment.
All remaining holes are now made, such as those for the angles T,
W, and P; for the seatings v and M; for the palm stays at $1; and
for the guide stays at E.
The operation of riveting is clearly shown at Plate XV. The
barrel and shell are closed by ﬁxed riveter at A and o, and the
ﬁrebox partly by 0 and partly by portable riveter. Then the
smokebox plate and the ﬁrebox are each fastened to the boiler
shell by portable machines, as shown at G, L, and H. Finally, the
dome may be riveted as at P, so there is no occasion for hand
work on any part of the boiler. Note that the angles w, T, and P
must be riveted before the ﬁrebox is put in.
The tubes are ﬁxed by expanding at the smokebox, and heading
and ferruling at the ﬁrebox end, using the tools in Figs. 304 and
305 5 and the smokebox ends of the tubes are then cut off by the
tool in Fig. 306. The screwing of the stays will be understood from
the marine example, but in this case their ends are riveted over by
hand after ﬁxing. The mudholes are tapped to suit the plugs, the
guide stays screwed into place, and the steam pipe M expanded
into the plate. The boiler is lastly caulked throughout and tested.
A A
354 S etting-out Lancashire Boiler.
The Lancashire Boiler (Fig. 310) may be next considered
shortly. The back and front plates are turned, trepanned, and
drilled throughout, with the exception of the rings a, b, p, and 9,
these being marked afterwards from the angles. The shell plates-
are prepared as before and drilled in position with axis vertical,
two by two. The angle ring a is also drilled for the shell, and
the holes at b for the ﬂange; then all are riveted together in
batches of three, with a ﬁxed machine, and the batches connected
by hand, or by the method at 34, Fig. 317. Next the ﬂue plates
are rolled, welded, and ﬂanged as at 24, Fig. 316 ; turned on
machine, Fig. 291 ; drilled in position by machine, Fig. 292 ; and
riveted together, with caulking strip between, by a portable riveter.
The plates j and h, are to have the angle rings p and g attached,
but the plates themselves are ﬁrst bolted to the other tubes, and
the whole tested with a long wooden lath to see if it will make up.
to the same length as the boiler shell; then the end tubes turned
down accordingly. The general straightness of the tube should
be tried during riveting, and adjusted by varying the thickness of
the caulking strip. Now the rings of holes—a, b, p, o—may be
marked on the end plates. First the holes at p, g, and a are-
marked and drilled. Then the shell is laid horizontally, the ﬂues
blocked up in place, the back and front plates put on, and bolts-
put in the rings a, ,b, and 9; when the holes in the shell at b may
be traced through to the ﬂange. Removing the back plate to-
drill the ﬂange holes, the gusset stays are prepared with their‘
angles riveted on, and are placed within the boiler. The back
plate is once more bolted on, and the whole boiler lifted on to a
trolley, which can be run under a radial drill, the latter being
preferably hinged on a wall or shop pillar so as to be at a
sufﬁcient height while presenting no obstruction beneath. The
holes g, h, and f are cut out by drilling, and those in the shell,
for the gusset stays, lined out by squaring from the end plates,
then drilled. Entering the boiler, the workman places the stays
in position, and marks off the remaining rivet-holes in the end
plates. Removing the back plate again, the gussets are taken
away to drill, then all are replaced for riveting.
The gussets, the ﬂange b, and the rings p and 9, must be
riveted by hand, but the ring a may be done by machine.










PLATE SECTIONI





l I l l l 1 L l L J l L l l
‘i Q 5 i Y 0 9 \0 u 11 r5 m ‘5 \5 \
QCA E. or FEE-T
£17010 RopfePxtuwgml

356 Girders and Skins. I
Prepare the longitudinal stays and manhole- seating 3 put in place,
with ﬁttings 3 and test the boiler as before.
The Vertical and Tztoulous Boilers present no further‘ difﬁ-
-culty. Taking the ﬁrst, the shell is built-up separate from the
ﬁrebox and chamber. Machine riveting can be used for most of
‘this work. But when putting together, the foundation ring is the
only other part that can be done by machine ; all the rest is hand
work. The tubes are expanded into the tube plates as before.
The Tuoulous Boiler has its tubes cut to length and expanded
into the headers 3 the chambers a b ﬂanged and welded 3 while the
making of G will be understood from previous descriptions.
As further examples of Plate Work, we illustrate a Girder at
Fig. 318 and a RoofPrinczjoal at Fig. 319; but these are simple
‘in comparison with boilers, as far as their practical construction
is concerned. The Box Girder has its plates and angles sheared
to dimension, the holes then marked off, and usually punched.
The angles A and web plates B are ﬁrst riveted, and next con-
nected to the booms c c; so it will be clear that no hand-riveting
whatever is necessary. The Roof Principal needs no explanation.
The ﬁrst application of portable riveting to bridge erection
was made by Mr. Tweddell in 187 3, on the Primrose Street
Bridge, London.
Ships are now built of steel plates and angles, whose dimen-
sions are carefully got out by the draughtsman in the ﬁrst place.
Much more drilling is now done than formerly, though a con-
siderable amount of punching prevails, and the plates are usually
sheared. The keel and framing are ﬁrst erected, and the plates
then adjusted and marked from these. As regards the riveting
up, nothing could show this better than the diagram at Fig. 301.
Of course there are many plates too long to be reached by the
machine, but this diagram shows what an extraordinary amount
of work can be performed by these wonderful ‘ Portable Riveters.’

PART II.

SYNOPSIS OF LETTERING ADOPTED IN

THIS PART.
CAPITALS.
A Area in square feet.
Bm Bending moment. [efficient of discharge.
C Modulus transverse elasticity in lbs. per sq. inch: Co-
D ‘ Larger diameter ’ in inches.
E Modulus direct elasticity in lbs. per sq. inch.
F Total stress in tons per sq. in. : F ° Fahrenheit.
Flbs Total stress in lbs.
Fn Tractive force to overcome friction : in lbs.
G Weight of a cubic foot of water: Centre of gravity.
H Height in feet: Total heat.
H.P. Horse power per min. = 33000 foot pds.
I Moment of inertia {2 (area x 1'2) I Ioule’s equivalent.
K Modulus volumetric elasticity in lbs. per sq. inch.
KP Speciﬁc heat of a gas in foot pounds at constant
L Length in feet. [pressurez K. at constant volume.
Lh Latent heat.
M Poisson’s ratio.
N Number of revolutions per min.
O Coefﬁcient of bending stress. [in lbs. per sq. foot.
P Total pressure in lbs.: Effort, or force applied: Pressure
Ptons Ditto in tons. 2 I
Q Concrete of formula for struts = 7r : Water discharge
R Radius in feet, [in cub. ft. per sec.
R" Larger radius.
Rt Reaction at supports. [heat
S Range of stress variation in Wbhler formula: Sensible
T Number of teeth.
Tm Twisting moment.
'l‘n Greater tension in belt or rope.
T° Final temperature.
U Work put in.
V Velocity in feet per min. : Volume in cub. ft.
W Weight or load in tons: Resistance, or force removed.
X Number of bolts in ﬂange coupling, cylinder cover, &c.
Y Concrete of formula for beam deﬂection = 4—————;UE I.
Z Modulus of section (in bending).
Zt Ditto (in twisting).
Synopsis of Lettering. 359
SMALL LETTERS.
Area in sq. ins.
Breadth in ins. [constant
Contraction coefﬁcient for gun coils: cylinder clearance:
Coefﬁcient of velocity.
Diameter in ins., or ‘smaller diameter.’
¢§§~6nﬁ
_ f Stress per sq. in. in tons (generally): acceleration in ft. per sec.
ft, ﬁe, f5, fb Stresses in tension, compression, shearing, and bearing,
_ in tons sq. 1n.
jlbs Stress per sq. in. in lbs.
J‘; Lateral stress.
fo Modulus of rupture (in bending).
_fh Hoop stress.
g Acceleration of gravity in ft. per sec.
h Height in inches.
2' Intermediate radius of thick cylinder.
.1’
h Pitch of bolts in terms of bolt diameter.
1 Length in inches.
on M ass in lbs. = 2
n Number of revolutions per sec.
, p Pressure in lbs. per sq. in.
#0115 Pressure in tons per sq. in.
p" Pitch of screw or riveted joint.
4
r Radius in ins., or ‘ smaller radius.’
s Side of square in ins. : speciﬁc heat.
1 Thickness of plate: time in secs.
t° Temperature, or rise of temperature, in deg. F.
tn Lesser tension in belt or rope.
Work removed.
Velocity in feet per sec. : volume in cub. ins.
Weight or load in lbs.
Width of one link in rivet calculations.
Coefﬁcient in Wohler formula. [twisting).
Distance of furthest ﬁbre from neutral axis (in bending or
I
u
71
“22!
w!
.x
3'
a
360
a (alt/2a).
,8 (oeta).
y ( gamma).
6 (delta).
17 (eta).
6 (them).
K‘ (kappa).
3; (mu).
7:‘ (
p (rho).
' o‘ sigma).
1‘ (tan).
¢ (Mi)-
0) (omega).
Synopsis of Lettering.
GREEK LETTERS.
Small Letters.
Coefﬁcient of linear expansion in degrees Fahrenheit :
various angles.-
Various angles.
speciﬁc heat at constant pressure
speciﬁc heat at constant volume‘
Deﬂection per inch length: ﬁfe“ = ditto per foot.
Efficiency. '
Angle of torsion.
Coefﬁcient of jet contraction.
Coefﬁcient of friction or tangent of friction angle.
3‘1416 or 27”: ratio of circumference to diameter.
Radius of curvature in bending: coefﬁcient of resist~
Various angles. [ance.
Absolute temperature in F °.
Angle of friction.
Angular velocity.
Ratio of
Capitals.
A Total deﬂection in inches.
Aft Total deﬂection in feet.
2‘. ‘ Sum of.’
, SIGNS. .
‘Varies as.’ H Parallel to 3 with ﬁbre. '~
Greater than.
Less than.
+ Across ﬁbre.
PART II.-—-THE0RY AND EXAMPLES.

CHAPTER VIII.
THE STRENGTH OF MATERIALS, STRUCTURES,-AND
MACHINE PARTS.
OUR intention 'is to treat of the cohesive strength of the
materials used in Mechanical Engineering, of practical testing to
obtain strength constants, and of the use of the latter in propor-
tioning machine parts, so far as may be done.
Load is the total effect of the external forces, and may be
‘ dead ’ or ‘live,’ concentrated or distributed.
Stress is the ‘cohesive force called into play to resist the
load.
Strain is the deformation produced by the stress.
Kinds of Stresses.——Only three simple stress-strain actions
are possible: tension (pulling), compression (thrusting), and shear
(cross-cutting). Bending is a mixed action, and local compression
produces a_ hearing stress. Fig. 320 shows the distortions and
fractures produced by these various stresses.
Elasticity is the property of regaining original shape after
distortion; very apparent in an elastic body, but scarcely per-
ceptible in a rigid one. In 1676, Hooke propounded the law
‘ut tensio sic vis ’ (as the tension, so the strain), meaning that
stress and strain are proportional, if within the elastic limit of the
material.
Limit of E1asticity.--A bar being subjected to an increas-
ing stress (of any kind), will receive also a proportionately increas-
ing strain (of the same kind) until the elastic limit is reached,
after which the strains increase more rapidly than the stresses till
rupture occurs. Showing this by a diagram, Fig. 321, o is an



a compnessigrv
, %t
l.
t
C ‘SWEAR, , F TORSION





ing. 320 .D/L'sl‘omfz'om e. F/IW


' 6. Egg‘ . 321
STRESS

\
P
/ Gen‘emé fer/n
/


3.
j


. .95.
g. A , .SZness -- xSZraz'n
. ‘t -
. Q; g; Dmgr/omu

o g .S‘TR/l/N ' i F 6
Elastic Moduli. 363
origin from which stresses are measured along 0 'A, and strains
along 0 B. E is the elastic limit and o E is a straight line, showing
proportionality of the co-ordinates. Plasticity begins at E, and
increases in perfection up to s, the curve being interrupted at Y,
the yielding or breahing-a’ozoni point (or commercial elastic limit),
while the lowering at B s indicates rapid contraction of sectional
area at rupture (see A, Fig. 320).
If W = load in tons at B, a = original area, and a1 = con-
tracted area: a -
W . . . .
7; = stress per sq. 1n. estimated on original area.
and ‘I = stress per sq. in. estimated on contracted area.
“1
The ﬁrst is used commercially, and is shown at B, while the latter,
the strictly scientiﬁc result, is given at B1, and the plastic curve is
thus corrected. The curve from B to s is not considered reliable.
Compressive stresses do not materially distort the specimen,
so the curve requires no correction. The primitive elastic limit
occurs at E, after which a permanent set is given to the bar. This
limit may be altered artiﬁcially.
Modulus of Direct Elasticity, or Young’s* modulus,
'(E) is a number giving the ratio of stress and strain within the
elastic limit, and is practically the same for tension or compression.
- stress sq. in. in lbs. ftlbs fclbs
: strain per inch length _- 5t 66

Modulus of Transverse Elasticity, or Modulus of
Rigidity (C), serves ‘similarly for shear action thus:
_ shear stress sq. in. in lbs. __ fslbs
_ shear strain per inch length _ <55

55 will be understood by reference to Fig. 322, being the strain
between two shear planes an inch apart.
Modulus of Volumetric Elasticity (K) compares stress
and diminution in volume, thus:
stress sq. in. in lbs. fvlbs
_ decrease in vol. per cub. inch _ 6,.

* Dr. Thos. Young, Foreign Sec. Royal Society, 1826.




364 Poisson’s Ratio.-
TABLE OF ELASTIC MoDUL1.
Material. E. C. K.
.. 0 000 000 12 000 000
Cast Steel 3 , , , , 30,000,000
Forged Steel 30,000,000 13,000,000
Steel Plates . 31,000,000. 13,000,000
Mang. Bronze... . . . . . .
. . 0 o 0 0 00 000
W I Bars 29, 0 ,0 0 1 ,5 , 20,000,000
W. I. Plates 26,000,000 14,000,000
Copper 1 2,000,000 . . . 24,000,000
Gun Metal 13,500,000 - Cast Iron 17,000,000 . 6,300,000 14,000,000
Brass 13,500,000 Muntz Metal 14,000,000 5,2 50,000 Water ... 141,000,000

Mechanical treatment may raise these ratios: for tempered steel
E= 36,000,000 and C = 14,000,000, while for rolled or drawn
copper E = 15 or 17 millions respectively.
Poisson’s Ratio (M) is a constant to determine the lateral
effect of direct stress. If a bar, as in Fig. 323, be extended or
compressed, it undergoes lateral contraction at A and expansion
at B. Then, within the elastic limit:
Direct strain = lateral strain x M
8, or 80 = 51x M
_ TABLE OF PorssoN’s RATIo.

Material. '‘ ~ M.
Steel 3'25
Wrought Iron... - 3'6
Cast Iron 37
Copper 2'6
Brass ... 3'0


Nature of Shear Stress.--If the bar in Fig. 324 be sub-
jected to shear strain, any square a 6 cd becomes arhombus a e cf,
Nature of Shear Stress. .365





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g TENS/0N A .._. J
4'1; me ' ..._.._-._.-,s.-, i
- J/heaw - lei‘
l condinsssrorv ‘
- _ _ .fzrezuu. —————-—-— '
59 —--——-~— . !
5

. i \\ Lazcemz concraeaon & cazaeaa'on.
@/ w _by_ Pollssort’s Ram). 2L3;
7


f. n
‘9 FoRc £3


of Jizeovr-Jlrgo's 1729' - 324*-
.the diagonal ch being shortened and ad lengthened, each by the
same amount. Then because stress or strain, the stress ft:
stress j}, and these are components of the stress fs, having
366 Diagram of Work done.
directions at 45° to the line j}, The diagram h jhl being drawn
parallel to the stresses will give their value, and
fc2 +f.2 =fs2
ﬁorﬁ=—]:°:= ,\/2 1 414
Nature of Tensile and Compressive Stresses—On
account of the cup or wedge fracture exhibited when a specimen
is broken by tearing or crushing, and for other reasons, Prof.
Carus-Wilson argues that rupture takes place by shear stresses
at 45°, either wholly or partially. Certain it is that the three
stresses are intimately connected, and assist each other in de-
stroying the cohesion of the particles. 5
Work done by Uniform Forces—The unit of Work is
a foot-pound, or one pound exerted through a distance of one foot. _
One pound acting through two feet, or two pounds through one
foot, are each two foot-pounds. Hence :
Work = pressure >< distance
= pounds >< feet = foot-pounds.
These forming a product may be represented by an area, for
length x breadth = area, and A, Fig. 325, is therefore the diagram
of work with uniform force : '
Work done = pounds >< feet = o x x 0 Y = area A.

Work by Variable Forces is shown ‘by diagram at B,
Fig. 325. As the body moves from 01 to 5, the pressure varies
as 01 X1, 2 b, &c. Now, work done between 01 and 1 can neither
be 01 X1 x 1 ft. nor 1 a x 1 ft., but must be the average of these,
or 01 f x 1. In like manner the other dotted rectangles show the
work between the remaining intervals, and their addition,
Area 01 X1 bY1 = work done.

Work done in Deforming a Bar is found at r, Fig. 326.
Divide 0B into ten parts, and erect a perpendicular between the
divisions. Measure these ordinates in tons, then ‘
Total of ordinates
10
and mean load x extension”: work in inch tons.

= mean load in tons,

Resilience. 367
Resilience is the work done in deforming a bar up to the
elastic limit; 2, Fig. 326, is the diagram, where B A is the maxi-
mum elastic load, and o B the corresponding strain.






VAR/ABLE
ronc
l :- "]d _—__E
UNIFORM FORCE I j I '
. X. I l ‘
X e I i I I
I Q I | l r 16
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O ‘ nsa-r' y Q I- 2 .3 4 Y
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Dn'czgr/g/m, of I’Vbrk, wnmmcuuform or
I war/labia F119’. 32.5
K i //'
g, / HA _ - ,q//
2 I l’)
E K I 2 l
2 I I
I 5 }
g (l ) I Io 0 I
o , l 2 I
‘Q l ‘9 I l
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. , ,4
i“ t : k I g :
_V l l l l Tl‘ a. l 1 I. -' I l B
O .EXTENSIONS m’ was 5 0, EXTENSIONS w ms.
-( 111401315) “(Rename/j

326.
Work done=area A0 B=C D x o B,
or generally,
Any work within } : ﬁnal load
2
. . . >< total strain =-j-[>< A (inch tons)
elast1c 11m1t .2
368 Impulsive Stress.
Stress caused by Impulsive Load.—When a body
moves with a given velocity, its store of energy (or work capacity)
‘ac/v?‘ '

ft. lbs. (see p. 98). If this be absorbed by an elastic
2%’
material, we have:
work stored = work given out
1
is; = —;—s x Aft (within elastic limit)
= mean stresslbs x Aft (for all cases)
and mean stress = $5
in lbs. per sq. in. ZXA

which is applicable to steam-hammers, pile-drivers, ﬂy-presses, gun—
targets, &0.
If the fall of a weight deﬂect a beam, or stretch a crane chain,
then—-
work stored in weight l _ work done on material
’ _
in inch lbs. in inch lbs.
lbs

F
zv (/t+A)= 2
and Flbs is the greatest total stress, or the steady load which would
produce the same A.
Stress caused by Heating and Cooling.——Experiment
shows that the expansion or contraction by heat or cold of a bar
xA






fl
Fiance caused- by [Lea/5. 327.
of given material, is a regular quantity for each degree of tempera-
ture. When measured per inch length or breadth, and per degree
Fahrenheit, it is given in the following table :—
Heat Stresses. 369
COEFFICIENT OF LINEAR EXPANSION IN DEG. F (a).


' Material. a.
i .
1 Strong steel '00000 63
,, ,, tempered ‘00000 73
Mild steel ‘00000 57
1 Wrought iron... ‘00000 66
Cast iron ‘00000 62
Brass ‘0000 105
Copper ‘00000 95
Bronze ‘0000 111


If t° == rise or fall of temperature, a t° == expansion or con-
traction for every inch, and
Each inch is increased by a t° ins.
lbs
But strain by mechanical means is-é =ZE-
bs
'Then if a t° =j-AE.
f lbs : E a to
and total force of expansion on walls, as in Fig. 327 at A B, is
Flbs = E a l‘ a
Necessity of Testing to obtain Unit-strength Con-
stants.--It has been hoped that the cohesive strength of the
various materials might be obtained solely by chemical analysis,
but continued experience seems to show more and more the
necessity for direct mechanical tests to obtain the strength per
square inch in tension, compression, and shear. Certainly it is
wise also to refer to chemical composition in stating the quality of
a material, in order to know how far it is safe to heat or otherwise
treat the same.
Testing Machines—One machine generally serves for
tension, compression, and bending experiments, the pulling
shackles being changed to suit. Possibly machines may ulti-
mately be designed to test by combined stress, and thus verify the
theoretical formula on which we at present rely. In small machines
B B
3 70 Testing Machines.
the pull is exerted by turning a screw directly or by gear, but in
large machines hydraulic power is employed, while the load is
always measured by a smaller weight attached to a lever or system
of levers, in steelyard fashion.
Cement Testing Machine.-—Michele’s machine will illus-
trate the above details, the load being applied by worm gear at B
to the specimen H, a cement briquette, and the pull measured by
the weight and lever C, or Danish steelyard. The arm D varies
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very little, but the arm E increases to the maximum F or some
shorter distance, during the experiment; the stress therefore varies-
‘as this arm and the pointer is left at its furthest position after
rupture, while the weight returns about half an inch. The scale
is graduated to represent the full load upon H.
Horizontal and vertical testing machines are so named from'
the direction of the pull, and each has its particular advantage;
the former is represented by
The Werder Machine, extensively adopted in Germany,
and shown in Fig. 329. C is the specimen to be tested, and B an
adjustable washer between shackle and crosshead A, to allow-for
length of C. ' Ram D moves to the right by water pressure from
hand pumps, and the pull is given through the bolts EE, for»
tension at C, or compression at G. The load is measured by the

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372 Werder and W icksteed T ypes.
weights J and lever H, the shorter arm of which is F, the pressure
being received on knife edges {16" apart (or much smaller than
shown), and a leverage of 500 to 1 thus obtained. A spirit level
is used to ascertain the horizontality of the lever H.
Professor Kennedy's Machine—Messrs. Buckton & Co.
have made a machine to Professor Kennedy’s requirements, em-
bodying the Werder principle with improvements. In Fig. 330,
A is the hydraulic ram in a ﬁxed cylinder, and B a sliding frame
carrying an adjustable crosshead E. T shows a tension experiment
and c a compression experiment, the load being resisted in either
case by the crosshead F, and its effect transmitted through the
rods GG to the system of levers. H corresponds to H in Fig 329,
but a second lever M is here applied, with a jockey weight L to
avoid the trouble of changing weights. L is traversed by hand
gear at M1 and carries a pointer at Q, while K is a spring stop,
and J a hand gear for adjusting the position of F by turning the
screws GG. In this machine all the operations are within control
of one experimenter and the specimen well in view 3 in addition
there is, during compression experiments, a shorter length of parts
between cylinder and weighing levers than in any other machine
(except the ‘ Emery’), as shown by the thick lines in the ﬁgures
N, o, and P, thus giving less recoil on the knife edges at rupture.
The Wicksteed Machine, also by Messrs. Buckton, is
shown at Fig. 331, as designed by Mr. Wicksteed to Professor
Unwin’s instructions. A is the steelyard weighing lever, and B the
jockey weight, which at a leverage of 50 to 1 exerts 50 tons pull
upon the specimen. Additional weights up to 1%; tons at C exert
another 50 tons by means of 40 to 1 leverage. The knife edges
are shown in detail at D, Fig. 332, being 20 inches long from
front to back 3 and the weight B is moved by screw a, either by
hand at E or by power at F, through the shaft o and gearing a’,
the connection of the strap e being made immediately below the
fulcrum. The lever is kept horizontally between stops HH by
admitting pressure water to the straining cylinder J through pipe
R, and the load is relieved towards the close of an experiment by
running back the jockey weight. The pressure water is obtained
in Professor Kennedy’s machine from the Hydraulic Power
Company, in Dr. Garnett’s new Wicksteed machine at the Durham


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College by town’s water acting through the Intensiﬁer in Fig. 333,
and in the usual Wicksteed machine by means of the ‘Quiet
Compressor ’ in Fig. 332. Crossed or open straps at j drive a
A lternati'z/e Fulcra. 37 5
shaft h, connected by spur gear with nuts ll, which turn within
the bosses nz on, and thus advance the screws n n. The latter are
connected to the ram p by crosshead g, and thus a very even
pressure is given to the water, which ﬁnally passes to the straining
cylinder J, Fig. 331, through pipe R. The pump may be worked
by hand if necessary, or the strap fork moved by hand lever s if
power he used, and a cut-off gear at t puts both straps on loose
pulley when either end of the stroke is reached. The shackles
w and v, Fig. 331, are adjusted to suit the specimen by turning
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loose gear, from v downwards. Enlarged views of the shackles
are given at v, Fig. 332, to clearly show the gripping wedges,
slightly convex on the inside and roughed like a ﬁle.
Mr. Wicksteed’s alternative fulcra, as designed for Professor
Hele-Shaw, are shown in Fig. 334. Fulcrum A is employed for
heavy tests, and B for lighter tests, which are thus made with a
greater degree of sensitiveness. The lever knife-edges are level,
but the support 0, which can be put in or out of position by worm-
gear, is higher than support D, as seen at (2). This gives enough
clearance for vibration either at (I) or (2), and the lever takes the
position E F when changing the centres.
The Emery Machine has obtained great favour as an
instrument of precision. Professor Unwin says of a 75-ton
:machine: ‘Every half-pound of load was precisely and instantly
imeasured, whatever the stress the machine was exerting.’ It is
376 Emery Mac/zine.
only fair to say, however, that Professor Barr, in referring to a.
Wicksteed machine (May, 1888), said 1 lb. additional had been
indicated, with a load of 43 tons. Referring to Fig. 3 3 5 : A is the
straining cylinder, having water admitted beneath its piston for‘
tensile, and above it for compressive tests. Adjustment for length
of specimen is made by simultaneous revolutions of the nuts 0 c,







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through hand-gear B, to move the cylinder, and the water pipes
have swivel joints to allow the motion. To measure the load, the
hydraulic support at D is employed, which consists (see enlarged,
section) of a sealed sac of soft sheet brass J, ‘005" thick, con--
taining alcohol and glycerine, and supported by' a dwarf piston
F, and cylinder E1. The pressure compels the plates to ﬁll con--
centric channels at J J, while further support and closure is given-
by the rings at H. The ‘ yokes ’ M and N take the hydraulic support‘
between them; and the crossheads o and P in turn act on the
yokes, the ﬁrst for compression, and the second for tension. Thus.
the load, being applied on the straining cylinder, is felt at J, and
transmitted to the liquid, through pipe R, to the second sac at Q,
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termed the ‘reducer,’ and from thence to the lever weighing
apparatus. The movement of F is only '001”, but the reducer and
support areas being as r: 30, the movement of piston s is
378 T lzursz‘on’s T orsz'on M (whine.
‘001 x 30= '03", or 300,000 lbs. on the specimen become 10,000
on the block T1. Instead of knife edges, very thin springy plates
are used, forced into grooves, as at v, and the pressure on T1 is
decreased by levers U and W, till the vibrating pointer Y is reached,
the connection from W to Y being by a much thinner plate in
tension. As the lever system gives a ratio of 20,000 to 1 between
the motions of a and T, it follows that inch at a will give a
movement on the support D of T16 x 81-0 xgflob =WIZW, inch, and
the total multiplying capacity of the weighing apparatus is 600,000.
Very small weights (about T16 oz. per ton of load) are therefore all
that are necessary to keep the levers horizontal, and these are
placed upon lever W by handles and rods at H. Where the pipe R
enters the sacs J and Q, the plates are depressed and held in
position by a ring, as at G. i
The parts M, N, o, P are balanced by means of springs which
can be very nicely adjusted, and not only are the various resist-
ances reduced to a very small amount, being the bending of light
springs through inﬁnitesimal distances, but these are all allowed
for in the calibration of the weighing apparatus. Two hand-wheels
are placed at p and at e, the larger opening to pressure and exhaust
respectively, while the smaller wheels adjust the openings Within the
larger plugs, so that the ﬂow may be regulated between I foot per
min. and ‘002" per hour; and r is a reversing valve for changing
ﬂow to top or bottom of cylinder. The Watertown arsenal
machine, U.S.A., is an Emery machine of 357 tons capacity.
Professor Thurston’s Torsional Testing Machine is
designed for twisting stresses only, and was ﬁrst made about 1874.
Fig. 336 shows its construction. A is the specimen, held in
shackles, the twist being applied by worm-gear B, turned by hand.
The load is measured by a pendulum weight c, as in Michele’s
machine, and a diagram obtained autographically, in a manner to
be described later.
Shackles for Test Specimens should be carefully
designed to give a perfectly axial strain, or the amount of ultimate
load will be affected. The Wicksteed tension shackles have
already been described at Fig. 3 32. Of other tension shackles in
Fig. 337, A is Professor Unwin’s, having spherical seats screwed to
the ends of the specimen, a very good plan ; and B was used by
Sir John Anderson, with split sockets a to connect the shackles
Test S hachles. 379
to the specimen b, held in place by a slightly ‘conical ring c.
Compression shackles are shown'at Fig. 338. A, and B1 are to take
small specimens in a tension machine, and the arrangement at c1


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Strain Measuring. 38 I
shackle h, a very good axial thrust is obtained. Professor Unwin’s
shackles at B1 receive the testipiece between a hard block e, and
spherical surfaces d, and the parts are shown separately to make
their construction clear. The Emery machine is provided, for
compression, with spherical nuts A and B, upon which lie convex
plates or tables D and c, and the hard seatings E F receive the
thrust. c and D are adjusted to the specimen by means of the
handles J J. In the shearing shackles at Fig. 339 (designed by
Mr. Wicksteed for Professor Hele-Shaw), a knife A adjusts itself
so as to give equal pressure at B and c, while the specimen is
nicked down to localise the strain. The torsion grips at A, Fig. 3 36,
have sockets to receive a square bar turned down in the mid portion;
and Fig. 340 illustrates a pair of bending shackles where knife
edges BB are adjustable for various lengths of specimen, and the
shackle A is formed so as to indent the bar as little as possible.
Strain Measuring—At ﬁrst it was considered sufﬁcient to
know the breaking load in tension, then Mr. Hodgkinson showed
the necessity for compression tests, and Mr. Kirkaldy lastly
pointed out that the contraction of area at fracture was not to be
overlooked. Now it is considered imperative to know the
breaking load and elongation (usually given per cent., or extension
x 100), and advisable to obtain both load and extension within
the elastic limit. A stress-strain diagram, as in Fig. 321, will show
the whole life of the bar, and can be obtained in two ways: (1)
by noting load and extension at several points during the experi-
ment (the latter being measured by instruments of more or less
precision), then plotting a diagram to these dimensions; or (2)
by compelling the machine to make an autographic diagram.
Taking (I), the simplest method is to make a centre pop near
each end of the specimen, and measure the distance between
these by means of dividers; a better result is obtained by the
use of a standard rod (1 (Fig. 341), and wedge gauge D, placed
between clamps A and B on the specimen; and very great accuracy
by the aid of an extensometer. Such an instrument is absolutely
necessary for the ﬁne extensions within the elastic limit, and Fig.
342 shows a very effective form devised by Professor Unwin. A
is the specimen to which Tee brackets c and D are clamped, both
of which carry spirit levels F and J, while D in addition supports
the measuring pillar G. Within G is a ﬁne screw carrying a







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384 - A z/tograp/tic A pparatus.
micrometer disc K having 200 divisions, and the strip M is divided
into inches and ﬁftieths. Whenever the zero mark on K comes
round to M, the divisions are read upon M only, but if Kbe turned
by one of its divisions, the ﬁftieth on M is further divided by 200,
and the advance is 5:11“; x 3% = 1%55”, which is the accuracy of
the machine. In practice, J is ﬁrst levelled, and F raised till level,
by advancing the screw against 0, and the length obtained both
before and during the experiment.
Autographic Test Diagrams‘ show many details in the
curve not obtainable by other methods. Among the earliest were
those of Professor Thurston, obtained by the machine in Fig. 336*
Paper is laid on the drum b, while a specially-formed guide a’
compels the pencil c to move proportionally to the arm D in a
direction at right angles to the plane of the latter, thus repre-
senting the load; and the extension, measured in degrees, is given
by the rotation of the drum itself relatively to the pendulum.
Although Mr. Wicksteed has obtained good diagrams by using
the pressure water to represent the load, the method is not con-
sidered advisable, in view of the resistances, which may be variable.
Better results are obtained by the apparatus in Figs. 343 and 344.
The ﬁrst will be understood by comparing with Fig. 331. The
rotation of the jockey-weight screw being proportional to the
load, it follows that the screw-turning gear may also be used to
rotate a paper drum G, and thus represent stresses, while a pencil
L may be moved vertically by a wire from the specimen, to show
the extension. B and H are cone pulleys which drive the drum
through worm gear, and at the same time allow of change of load
scale; and" the wire is returned upon itself before leaving the
clips J K so as to mark the extension to twice the natural scale.
A is the hand wheel‘, connected to the countershaft B by belting,
and c is the auxiliary shaft, which turns screw F through spur gear.
To avoid errors of belt slip between 0 ‘and H the gear in
Fig. 344 has been introduced. Here the screw is turned by mitre
gear through shaft A, and a pencil 0 represents the load, being
traversed by screw at E turned by worm-gear D. At the same
time the drum B is rotated for extension by a wire F from the
specimen, and a hammer weight G releases the wire when rupture
* The writer’s attention has been called to Mr. Cawley’s apparatus used in
japan, which probably antedated the above. Fig. 3466 was obtained from it.
S tress-strain Diagrams. 3 8 5
occurs. This apparatus has been applied in Professor Hele-
Shaw’s machine.
Stress-strain Diagrams, as obtained principally by the
previous apparatus, will now be discussed (see Figs. 345 and 346).
Most experiments have been made in tension, and our list of
compression and shear diagrams is therefore but meagre. In
every case the authority has been cited, and where possible the
unit stress and length of specimen given.
Deductions.—Mild steel and good wrought iron have long
' plastic extensions and considerable contraction at rupture (see
c, F, G, L). Stronger steels are less ductile, as at B and D,
while steel castings, A, are very short, though the strength may be
higher than shown. Cast iron, Q, has really no elastic stage,
though Hodgkinson ﬁxed an apparent limit, but brass, o, is
better off, and is much more plastic. N is a very ﬁne diagram
for aluminium bronze, showing great ductility and high elastic
limit. Torsional and transverse diagrams (s and R) are not
essentially different from tension in character, but compression
diagrams take quite a different form, v being a typical example,
the plastic portion tending always to curve in an opposite
direction to that of tension. T is an experiment on long pillars
held loosely in sockets to prevent bending; and diagrams Q, T, U,
and v have all been plotted.
Raising the Elastic Limit.--If the load be carried a little
beyond the primitive elastic limit and allowed to remain, say, for
24 hours, then removed, the bar will shorten slightly; but on re-
stressing, a new elastic limit will be found at a little higher load
than that just removed. Repeating the experiment‘ beyond the
second limit, a third limit may be found, and so on until the bar
breaks. All this is beautifully given by diagram M, and also by
diagram 5, one plastic curve bounding all the limits, and it is
clearly shown why English engineers consider the breaking load
the only reliable test of a material.
Local Extension.—In Fig. 347 a test strip has been taken
12" long, and divisions marked across it at one inch apart, then
the actual extensions within each inch measured, and set up as
ordinates on the line A B ; c D E is the curve showing distribution
of extension, and is seen to increase very greatly towards the ﬁfth
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inch, where fraction occurred. This indicates the necessity of
stating elongations somewhat as follows :——‘ 28‘2 per cent. in a
length of 8",’ or ‘ 2 5'8 per cent. in a length of 10”,’ meaning ‘282
or ‘258 of the original length 3 and the breaking stress should be
measured as maximum load -:— original area.
Diagrams showing the elastic line have recently been
drawn by Mr. Thos. Gray, of America, by means of the double
apparatus shown at Fig. 348. The paper drum is rotated by
worm gear, as in Fig. 343, to give the load, and there are two
pencils H and c, both connected to the specimen by wires 3 but
while A is connected to 0 through the single lever B and gives an
ordinary diagram, D gives motion to H through the triple set of
levers E, F and G, and thus the stroke of H is very greatly
magniﬁed. Three diagrams are shown, where the higher curves
are drawn by c, and the lower or elastic lines by H. Of course
two extension scales are required.
Admiralty Test requirements are given in the following
table :—

_ Tensile breaking stress in .
Material. tons_per sq. m. of Elongation.
original area.

. 22 H
W. I. Ship Plates (1st class) 3 18 +
w. 1. Ship Plates (2nd ,, ) j l'r
W. I. Section Bars 22
, . 21 ll
‘W.I.-Boiler Plates 218 +
KSteel Ship Plates 26 to 30 20 °/° in 8"
,, Castings (intricate) 28 minimum 13% °/o in 2"
,, ,, (Roller Paths an 36 to 40: yield point I 1} O/ . 2,,
16:0 _ Pivot Plates) at 18 min. 3 ° m
52 1’ H (G‘iggrféfililgfgff }28 minimum 18%°/° in 2”
8 Steel Rivets 27 maximum 2 ,, Forgings (general) 28 to 3 5 28 to 24 °/° in 2-"
g ,, ,, (Piston Rods) 32 to 35 28 to 24 °/o in 2"
, , Roll 5 nd 0 - n
L; ’ ’ ( R (3i eraPaths) ( 38 to 45 22 to 16 /o in 2
L1. ,, Plates-
28 to 32 20°/o in 8"
Gun Metal (ordinary) .. 14 minimum 7% °/° in 2"
,, (for hydraulics) ,, 3% °/° in 2"

Manganese Bronze 28 25 °/° in 4











s
5:45
U
35-4 - . .
g3?’ Basin/lawn
r5 _Qf_
x_ -
” 4 Extelwwn/
A E
r '2. 3 4 5 6 7 8 9 IO M :2
Pg. 347.


[jlmlimmi
ZORD


Double 7166i Danny/nuns dc 341d
390 A dmz'mlty T ests.
(Lloyd’s tests for Boiler Steel are the same as for Admiralty
Ship Plates.) '
Hot tests for angle bars are shown in Fig. 349 at A, B, c, and D ;
for T bars at E and F ; and for channel bars at G. They consist in
a bending of the ﬂanges in either direction, or a complete ﬂattening.
@Aczibc @ .aaa%»qp
ﬂocmmitcy Taws for Ralled/ Bars. 119.349
Cola’ tests are obtained by notching and breaking to observe
the fracture. Sometimes, as with armour-plate bolts, a tensile
fracture is obtained by dropping a weight of one ton through
30 feet, and rails are often bent by a falling weight to imitate
the conditions of practice.
Rivets should sustain hammering while hot till but %" thick,
and punching crosswise with a tool of their own diameter, without
cracking in either case.
Wcihler’s Law.-—In 187 r, Herr Wohler conducted experi-
ments on variation of stress, and showed conclusively that the
range of variation was a factor in lowering the breaking load, so
that a bar under variable stress would break much more easily
than if an unchangeable load were applied. His experiments
were so conducted that the test bars withstood two or three
million changes of load before breaking. Prof. Unwin, who has
given great attention to endurance tests, deduces the following
general equation:
f,=-Sé+ It/f12—xSf2
where f1= original breaking stress in tons sq. in.
S=stress variation in terms of f, in tons sq. in.
x=a constant deduced from experiment
__ 1'5 for Wrought Iron and Mild Steel
__ (2'0 for Hard Steel )
Wo'hler's Law. 39 1,
Taking x== 1'5, .three simple cases may be deduced:
(1.) A steady or dead load:
' (2.) A simple live load, or ‘suddenly-applied load,’ viz., one
removed and replaced continually and instantly, but without
velocity.
S =f2 — o I
and f2 =1; + Jff- I'Sfifi
Simplifying, squaring, and solving the quadratic obtained :
f5 = '6f1
(3.) Reversal of stress, or alternate compression and tension
of equal value, as in rotating shafts.
S is from—f2to+f2=2f2

and f2=27f’+~/A2—I'5><2121‘1
f2=%~f1
:Summing up, we have for:
Steady load j;,=f1
Live load f5= ‘6]’, for Wrought Iron: '8 f1 for Steel
Reversible load f2: 1} f1 for Wrought Iron: i f;l for Steel
‘or roughly, the strengths are as 3 : 2 : 1.
Factor of Safety.--The working stress must not only be
‘within the primitive elastic limit of the stress diagram, it must
:also be further reduced on account of stress variation, and still
further because the working conditions can rarely be all estimated;
‘the correction for all these being made as follows:
breaking load or unit stress
Safe load or unit stress = factor of safety
' If a foundation factor of 3 be used to cover uncalculated
‘effects, and to keep within the elastic limit, then, by Wohlerz
A steady load requires a factor .......... .. 3 '
A live load requires a factor .... .. 3 x 2 = 6
A reversible load requires a factor 3 x 3 = 9
39.2 Factors of Safety.
And the following table, deduced from practice, .is fairly explained :
FAcToRs OF SAFETY.


Material. . . I]? 5:51. Live Load. Moving Load.
Wrought Iron and Mild Steel 3 5 to 8 9 to 13 ‘ ‘
Hard Steel .. 3 5t08 10 to 15
Bronzes 5 6 to 9 10 to 15
Cast Iron and Brass .. ' 4' 6 to 10 10 to 15

Average Stresses adopted in practice.-We must now‘
sum up the results obtained in testing, as given by the best
authorities, and form a table of breaking and safe stresses. But.
as there are high and low qualities for each material, and samples:
of each quality vary so much, our tabulations can only be the-
averages of many averages. _
Breaking Stresses.—-Thus cast iron may vary from 5 to 15-
tons per square inch in tension, 22 to 58 in compression, and 4
to 5 in shear. Wrong/it iron breaks at from_15 to 30 tons in
tension, and 10 to 22 tons in shear. The strength of steel increases~
with the carbon it contains, but as a rule 8 its elongation is.
simultaneously decreased. Steel plates should have but % per.
cent. Cementation steel reaches very high strengths, varying
from 40 to 67 tons per square inch in tension, some samples of'
tool steel yielding 88 tons 3 and tempering increases its strength.
Steel castings bear from 15 to 34 tons with reasonable elongation.
Copper depends on mechanical treatment. Cast, it supports 10
tons; rolled into plates, 14 tons 3 and drawn into wire, 20 tons.
Brass has 8 to 13 tons per square inch tension, and gun metaif
10 to 23 tons.
There is some difﬁculty in collecting good results for com-
pression. If the specimen be ductile it ﬂattens out, and then,
as Rennie said, ‘the resistance becomes enormous.’ Brittle.
materials are more easily dealt with. Besides, tension has been‘
looked upon as a sufﬁcient test for all materials, and thus ‘the:
compression and shear columns are in many cases vacant. In such
cases we may take compression = tension, and shear = ‘7 of tension.
Breahing and Safe- Stresses. ‘ 393
The safe stresses given in the table are those usually adopted
in English practice, and have a factor of 5 or 6 on the breaking
stress. - Continental engineers take the elastic strength as their
guide, but its unstable character prevents its adoption as the
standard in this country. In deciding upon the working stress, the
designer should, however, consider well the following four heads :—
I. Elastic limit—Some idea of its position should be obtained.
Compare E and Q, Figs. 345 and 346, a higher proportionate stress
being allowable in the former.
2. Variation of stress.-—The condition of loading should be
found with care.
3. Unknown actions—Endeavour to ascertain to what extent
these occur, and whether they form an important part of the total
load.
4. Quality qf material—If possible, a test for all material
should be insisted on, both for ultimate load and elongation:
preferably also for contraction of area and elastic strength. This
will enable the designer to ﬁx his working strength with great
exactness.
TABLE on THE AVERAGE BREAKING STREssEs OF MATERIALS AND SAFE STRESSES FOR
ORDINARY LIVE LoADs (1N ToNs PER sQ. 1N.).


In Tension. In Compression. In Shear.
Material.
Breaking. Safe. Breaking. Safe. Breaking. Safe.
Steel (‘crucible cast’ for
strong forgings and
tools)... 45 8 80 8 -— 5
Steel (mild, for general
forging) 35 7 —- 7 —— 5
Steel Plates (and rivet
steel) 3o 6 —- 6 24 5
Steel (for castings) 3o 5 —- 5 —— 3%
Manganese Bronze 3o 5 - 5 31}
Wrought Iron (forgings) 25 5 22 4 20 3%
géiosphlpr Bronze... 25 4 —- 4 —— 3
2
roug t, Iron Biatesijlm a8 } 4 __ 4 I6 3
Muntz Metal 22 31} - 3% -— 2%
Copper 13 2 26 2 II 11}
Gun Metal 12 2 -— 2 — 1%
Brass 11 15 —- 11} -- 1
Cast Iron 7% 13; 45 4 5 I


3,94 Classzﬁcqatz'qn ‘of Stress Action.
The quantities in this table are given in tons, because ‘the
numbers are thus more easily remembered, and because it is ‘the
Engineer’s language. Fig. 350 shows them diagramatically.
foals 05A :0. 'iv.

_ ﬂuecagajinessw ﬁr Materials 350.
The Proportioning of Structures and Machine
Parts by- Calculation.--T he equality of action and reaction
is the starting point in constructive calculation. Whether the
load be applied directly or through a lever arm, the external
forces must balance the internal stresses, and we have for the two
cases: ., I
(Direct action). Total load = Total stresses.
(Lever action). Moment of load= Moment of stresses.*
which are our general strength equations.
Classiﬁcation of Stress Action.-—Practical cases of
simple or compound stress may be arranged under ten-
heads :- ' i -
* A moment : force x lever arm.'_
Tension S tress-,A ction.
Kind of Stress.
39.5.
Some Cases.

1. Tension .. Lifting rods, chains, bolts, ropes, boilers, pipes
. and cylinders, boiler stays, ﬂywheel rims.
2. Compression All short pillars.
3. Shear Punching and shearing, rivets, pins, cotters,
coupling bolts, keys. ' -
4. Torsion (momental shear) Short shafts, spiral springs.
5. Bearing ... Plate edges on rivets, cotter edges, and canti-
levers.
6. Bending (momental com- Beams, axles, boiler end plates, slide bars, teeth
pression and tension). . .
of wheels.
7. Bending+Tension Crane books.
8. Bending+Compression Long pillars, boiler ﬂues, ships’ davits, con-
necting rods. '
'9. Torsion + Bending Long shafts, crank arms.
. Torsion + Compression...

Propeller shafts.

will give total stress.
Tension Stress-Action.—-Unit stress x area of section
Load
W
Therefore :—
Total stress.
ﬁa.
In the case of steam or water pressure the load is unit pressure x
area pressed upon, and
p x area of boiler or piston, in square ins. = ft a.
Of course ﬁ may be either ‘breaking’ or ‘safe,’ and W or /> will
vary in like manner. -
Example I.——Find safe load for following sections, at 5 tons per
square inch. (1) 3 ins. dia. (2) 3 ins. dia. with i" cotterway. (3)
3" tube with 2’_’ hole. (Eng. Exam., 1892.)


(I) a=1rr2 = %2 W=fa=29'73 tons.
(2) “=F7’2 “ 2%" =55? W=fa=35'35 tons. "
(3) a = 11'7’12--1r722= 55 W== 1964 tons.
I4
396
Tension Examples}
Example 2.——With 6 tons static stress for W.I., ﬁnd (1) dia. of
bar to carry 20 tons 3 and (2) the dia. when in addition 30 tons are
suddenly applied. (Eng. Exam, 1886.)
W __
(I) W=fa,anda=7=3‘33 .‘.d=2\/g=2‘06"
(2) f = 3 tons for the live load a

__-_-_
-- —10
Area for live load = 10.
n a: dead as ='3'33

Total area = I 3'33
_—
And d=2 ,\/51=4‘12".
'R'
Example 3.——Find the total stress on a W.I. crane chain 25 feet
long, when a load of 20 tons drops through 6 ins., the stress per square
inch not exceeding 5 tons. (Eng. Exam, 1886.) '

Putting all measurements in tons and feet,
2 000000
E = —~———-———9’224;J = 12,945 tons. But E =‘g and 5 =*E}—c
. a_../:L:=5____X 25.__.
.. A —- E 12945 - 00965 ft.
W (H + A) =5 X A
20 (‘5 +‘00965) = F x ‘5 x ‘00965, and F= 2114'73 tons.
Example 4.—A steady load of ﬁve tons produces a deﬂection of
half an inch. Find the height a weight of 2 cwt., must fall to produce
the same deﬂection. (Eng. Exam, 1888.)
F
W(H+A)='2“><A
2 1 5 1 5 1
-— H — =- - = ______ _ n
20 +2) 2X2 andH (4 20)10__12.

Example 5.-—Find the dia. of a pump rod, the bucket being
20 ins. dia., and the water pressure 25 lbs. per square inch. (Eng.
Exam., 1889.)
316mm x area of bucket =ﬁ a
2 x 22 x 10x 10 x 2 —-——
_5__________._=5_-_22. and r: J'2232=‘5",
224ox7 7
. d=1"
Strengzfk of Chain and Ropes. 397
The Strength of Chaim—Both sides of the link resist
tension, so taking f = 4 tons safe :
W=2 X'rr r2><4=z512 1'2
but r = W=6'28 d2 tons safe load.
MIR
Sir Jno. Anderson deduces a simple rule from the above :
. - - 2
(gillleilghj-t-El = safe load in tons.

. . 8 8
Thus an mch chain bears X = 6'4 tons.
Strength of Ropes.--For w/zz'te hemp ft=é ton safe. But
. . circ.2
as all ropes are measured by their circumference, and area = 4”

Strength of hemp rope = x all.“

= '04 circ.2 (tons).

I/Vz're rope has its members stated by their W.G. Referring to
page 276 the total area may be reckoned: then ft: 11% tons safe
for iron or steel.
Strength of Pipes and Cylinders, pressed internally.
Imagine a hemispherical vessel A, Fig. 351, hung by a string, and


Qty. .251.
pressed internally; then, as the vessel moves neither to right or
left, it follows that the total pressure on the curved surface in
direction F is equal to that upon the ﬂat surface. The ﬂat surface
is called the ‘ projected area ’ of the curved surface.
398 i T lain Cylinders.
(ﬁrst Case, min Cylz'rza’ers.)--A boiler, or thin cylinder a 6 ea’,
Fig. 351, tends to tear along the joints a b and ea’. Examining a
strip 1" wide we obtain:
Internal load on = { safe strength of ~two sections of
projected area. plate (in tension).
pwnsxzrx I=ﬁ xztx 1.
pwnsr = ft 2‘.
Suppose the plate tends to tear at aring section as at e f, then:
ptonsxme =ﬁx zvrrx t.
pm 7' = 2}}, t.
From this we ﬁnd that

Stress on longitudinal section = t
and stress on transverse section = %
so there is no fear of a boiler bursting at a cross seam. The
above supposes the boiler plate to be equally strong throughout.
But as the seams, whether welded or riveted, are much weaker
than the ‘solid’ plate, a multiplier (11) must be introduced on the
right side of the equation to reduce the quantity and show the
strength at the joint.
strength of joint
strength of solid plate
01’, 1) per cent-=17 X 100

q = efficiency =
For lap welded joints, 1; == '7
For single riveted joints, 1; = '5 }roughly
For double riveted joints, 1) = '7
and the formula for boiler or pipe strength becomes
ptonsr : 14;: in
Example 6.-A copper steam pipe 12" dia. is to resist an internal
pressure of 160 lbs. per sq. in. Find its thickness, if n for brazed.
joint = 80°]o
‘From above formula lio» x 6 = 2 x tx '8 t = ‘267 ins.
2240 -'_"—
T hich ' Cylinders. 399
Example. 7.--Find the bursting resistance of a cast-iron pipe $- in.
thick and :0 ins. diameter. (Eng. Exam, 1887.)
pwnsr =f, (there being no seam)
15mm =1; =75 ton = 1680 lbs. per sq. in.

Second Case, Thich Cylinders.-If cylinder thickness be small
in comparison to diameter, the stress at the inner surface is
practically the same as at the outside. But this is by no means the
case with very thick cylinders. Then the following formula must
be applied, devised by Lamé:
11' or 2 .. ~/ﬁ t???“
7 a’ Jﬁ _ptons

and the stress varies throughout the thickness, the hoop tension
f, being found at any intermediate radius 2' by the following
formula: -
_ — ptons72 (22+R2)
fh 1“ “ms -
Example 8.—A cast-iron hydraulic cylinder is 6" internal diameter,
and loaded with I ton per sq. in. pressure. Find (1) the thickness,
and (2) construct a curve showing the hoop tension throughout the
thickness.
-‘_}_=,\/f+ptons= A/I 25+I : 5 ._. R”=9 and Z.____6n
r Vf_ptons -————
The section of the cylinder is shown at Fig. 352, and the ordinates

JZQZ%EZ;9i
.Gytmdelzs.
\.
\s
\ \s ‘-
\\\\
y§§§§: ~ _gzg.352.


at abcd e fg show the hoop tension at the various rings, found as
follows: I x9 (81 +9)
at a, ﬁx: 9 (SI—9): r 25 tons
Similarly at b, ﬁ,= '76 ton, at c = '5 3 ton, at d = ‘406 ton,
at e = ‘332 ton, atf= ‘283 ton, and atg== '25 ton.

400 Gun Coils and Cast Cylinders.
The curve is an equiangular or logarithmic spiral. Large
guns are built of coils shrunk one over the other, so as to put
the inner tube in a state of compression. The pressure of the
explosion then tends to equalise the stress, by slightly adding to
the outer tension, but more than removes the inner compression.
\Vhen cold, a coil is slightly smaller than the core it is to envelop,
according to the following rule: .
Diminution of coil dia. =w
inside dia.
where c for the outer coils = ‘00133
c for next inner coils = ‘00108
c for next inner coils= ‘00083
Let an outer coil be 17" outside and 12" inside, then
Diminution= 14.5 x Mix ‘00133 = ‘0233"
The same effect is produced in cast-iron cylinders by casting with
a cold-water core, and thus much less thickness is required. (See
Figs. 289, 298, 299, 300.)
‘ Casting Rule ’ for Steam Cylinders, Bro—With the
usual steam and gas pressures, the previous formulae give so small
a thickness that the metal would not ﬁll the sand mould, so an
empirical rule must be adopted to enable the cylinder or gas pipe
to be cast, thus:
=‘18
This will represent the thickness for steam chest and other parts,
but the cylinder body should be about 7% in. thicker, to allow
for reboring, and the ﬂanges should also be stiffer.
Tensile Stress induced by Centrifugal Force.—
When a weight zo, attached to a string, is swung in a circular
path, it exerts a pull upon the string represented by "
2
F1bs==§€i lbs. (21: actual velocity of weight)
In a grindstone or ﬂywheel this centrifugal pull exerts a tension
between the particles of the material, which we shall examine in
Strength of Fly Wheel Rim. 401
Fig. 3 5 3. R is the average radius (radius of gyration) of the
rotating ﬂywheel rim, a/zb. If w=the weight of a cub. inch of






the material, 2011 is the weight of the darkly shaded solid, and
its centrifugal force,
2011 v2
Flbs = ____
gR
But every such solid in the circumference acts radially as at A,
Fig. 351, and the ﬂywheel tends to burst at a d, as the boiler did
at it, Fig. 351.
Centrifugal force per
( safe strength of
sq. in. of rim
} X Prolected area = l strip section at a b

‘RI/2712
xzr=2flbslz
0"
<5
w/zr/2x2xrzR rem/112
and ﬁlbs.= =
gRxz/z g
“1E
then v== 1'64 ,v/L
‘22'
For cast iron, 20: '26 andflbs: 1'25 x 2240
/1'25 x 2240
Safe v=1'64/\ _26
170 ft. per sec.
DD
0.0
I.‘
0000
Q...
0..
Q.
.08.
402 Strength of Bolts.
This velocity is reckoned for radius R, which for a ﬂywheel may
be taken at the centre of the rim, but for a grindstone
R2+Ri2
R___.\/ 1 2 z
where R1 and R2 are its radii at pin and rim respectively. A
much less velocity (about 80) is adopted in practice.
Strength of Bolts—In an ordinary bolt with V thread,
the nut being deep enough, the bolt must break by a combination
of tension and torsion, '13 of the bolt area being devoted to resist
the latter, according to Unwin. In practice both are allowed for
by putting a small value on the safe stress—3 tons per sq. in.
for Wrought Iron, and 4 tons for Steel, estimated on the area at
thread bottom. Cylinder covers must be bolted very tightly, and
an initial screwing stress often resisted also, so the working stress
may be:
W. I. Steel.
For 3 feet cylinders .... .. 3 tons .... .. 4 tons
For 2 feet cylinders .... .. 2 tons .... .. 3 tons
For I foot cylinders .... .. 1%t0ns .... .. 2 tons
The diameter at thread bottom may be found from p. 213
and p. 192. Thus a g" bolt has a thread '1" pitch, and depth of
thread= '1 x '64= '064.
Dia. at thread bottom: '75 — 2 x '064=Lz_
. 2
and area at thread bottom = Elf—Ii- = '304
No faced joints, except very small ones, should have bolts
less than 212-" dia., or they may be broken merely by screwing up,


£19. 3541.



and their pitch should not be greater than six times the bolt
diameter. To secure the best strength conditions, the shank
should be turned down, as in Fig. 354, to the diameter at thread
bottom.
Strength of Bolts.
403
STRENGTH or BOLTS (WHITWORTH V THREAD).


Dia, of Sectional area at Safe load Safe load
bolt in ins. _ thread bottom. at 4 tons per sq. in. at 3 tons per sq. in.
i ‘027 ‘108 ‘081
*3‘ ‘068 ‘272 ‘204
§ ‘121 484 '36
a} ‘203 ‘812 ‘609
=2 ‘304 1 ‘216 ‘91
g ‘422 1‘688 1 ‘26
I ‘554 2'216 1'66
1% ‘697 2'788 2'09
Ii ‘894 3'576 2'67
1% 1'06 4'24 3'18
e 1'3 5'2 3'9
1% F472 5888 4'416
Ii- 1'753 r012 5'25
1% 1'985 794 5'955
2 2'31 9'24 6'93
2g- 2‘66 1064 7'98
2% 2‘925 11'7 8'77
2% 3316 13'264 9948
2% 3732 14'928 11196
2% 4‘173 16‘692 12‘519
2%- 4‘463 17'852 13'389
2% 4'944 19776 14'832
3 5'45 21‘3 16‘35





404 Cylinder Bolts.
In cylinders, if D = dia. of cylinder
D1 =dia. of bolt circle, a’,L = dia. at thread bottom
kd1=circumferential pitch, d = dia. at thread top.


a1 2
Number of bolts=Z-Z?,-1 and strength of one bolt =J—Ct—7rZ-1—
Total strength = total load.
71' D1 fr 4112 _ 71' D2 tons
119’. X 4 _ 4 p
_ _1_ 25253.12.’
d1 _ 22 k k D1
. . ‘ d1 + ‘0 5
But d1=‘9d-— ‘05 (empirically) d= _9
Example 9.---A cylinder 24" dia. has a steam pressure of 100 lbs.
per sq. in.: bolt circle, 28" dia.: and circumferential pitch to be six
times bolt diameter. Find bolt diameter and number of bolts required.

_7 100 24x24_.
d1_22X6X2240x3X 28 _ 584
d.__'_§8_4i°_5=
'0,sa ‘”
9 74 vi
Checking, we have :
Strength of bolts = total load
100 x 22 x 144
2240 x 7
and number of bolts = 20.
‘91 x number =

Finally pitch = 523-: = 4'4" or six times bolt dia.

Compressive Stress-action, pure and simple, exists in
few cases. The calculation is made similarly to tensional stress,
and may be applied to all short columns (whose length is only
ten or twelve times the diameter). Thus:
W=fca.
Strength of Suspension Lz'nh. 405
Example Io.——F ind the thickness of a short, hollow, cast-iron
column of 18" outside diameter, to sustain a live load of 80 tons, plus
a dead load of IOO'tODS. (Eng. Exam. 1888.)
Equivalent dead load = 100+ 2 x 80 == 260 tons
260 = 7 a and a = 3714 sq. ins.

But a=1rR2—-7r r2=37'14 orZ; (8I—r2)=37'I4
and 7’: V6924: 8'32 i=9 — 8'32: '68"

Shear Stress-Action rarely occurs alone, but pins and rivets
are thus calculated: W = A a.
Strength of a Suspension Link (see Fig. 355).-The
strength of one thin link in tension, at a and e; the shear
I


Strength 9! Slay/tension Link;-
355.
strength of the pin a’; the strength at h ; and the bearing stress
on projected area of e, should each equal half the load:
(I) (2) (3) (4) (5)
W J2
z =ﬁ (ea-e) i=1?’ =jw=fbee
4
Let ﬁ=1, fb=IJ§, andfs=%.
By (4) and (5) rxht =15 dt and 12’: '66h
By (2) and (4) I(w~a’)t=rxht and w==r66b
d2 '—_‘__
By (3) and (4) {i4— = 1 ht and t = '26!)
By actual tests d1 =12’ ' = '66 I)
and the thick link must be 2 t in thickness.

;_ 406 _ Strength of Rzjvetea’ foz'ntsx,
Example IL—A wrought-iron suspension_ bridge chain supports
I 5 tons. Find its dimensions and draw the joint to scale.

,—
Here ft(&_><'266)' =i5 and b ='\/I_I-5_3 _‘3-4

d = '66x3'4 = 2'24" d1 = 2'24

' w = 1'66x 3'4 = 5'64” .t = '26x 3'4 = ‘884"

and the whole is drawn in Fig. 355.
Strength of Riveted Joints—A boiler plate ma'yr'b'ze
supposed to consist of similar links to the above, but with some
redundantmaterial between (see Figs. 3 56- and '3 57). The joint



MEL/.95.
\ Double wéodcdﬁ


may give way by (I) shearing the rivet, (2) tearing the plate
between rivets, (3) cross-breaking at (2'1, and (4) crushing by
reason of too thin a plate. -~ ~. ' I ' ' i' ‘
Single Riueti'ng : Size of Rivets: ‘407
i In a Single-riveted Lap Joint,'ias in Fig. 356, shear
strength of one rivet, = tensile strength of plate between two
rivets, - 7 Tan H
or B7 =fr (? *5)’
which is our general formula. But the rivet (up to‘ 1” plates)
bears a deﬁnite proportion to the plate thickness, thus :
a’ = 1'2 ../t before riveting ‘
d1 -'—-' 1'3 .,/t after riveting, and t = ‘6 d12
Also steel plates and rivets are the usual practice, where f5: 5 and
ii‘: 6-_ Putting these in the formula, we have
"5x22'xd12; ,,_ _. 2'
—7?I¢—6@ e964
pitch = 1 '09 + d1

which shows that the space between rivets is a constant quantity
for all plates up to 1" thick. Also lap= 3 times a’.
SrzEs OF RIVETS AND PLA'rEs (IN INCHES).

Plate thickness. N/l Rivet. Rivet hole.
{a _ '56 21% '73
ii ‘61 ii '8
T73- '661 -}§- '86
a '7 ' i ’ '9I
at '75 as ‘975
a; '8 - 1 '04
k} '83 v‘ 1 1'08
ii ‘866 ' ' r1%- ‘ 1'1 2 5
it' 9 Ira ‘ 111
i '93 It I?
g- '96 1% 1'2 5
1 1 1i 1 '3
1;;L 1‘06 1% 1 '3
1%; 1'1 1% 1 ‘3 I


408 Eﬁciency : Double Riveting.
Efficiency of joint has been already mentioned, and its
value,
__strength of pierced plate p” - d
_ strength of solid plate p”

for single riveted joint,
1'09


. 'r =: = ' 6 60
with 1% plate, 11 1.09+_8 5 or 5 /o
c _ _ . O
and with 1 plate, 17 _ 109+“; __ 45 or 45/o
Strength of Double-riveted Lap Joint (zigzag) can
easily be discussed by reference to the ‘virtual links ’ in Fig.
357. Clearly plate A must equal one rivet, while B equals two
rivets, in strength. So the centres at A will be 1‘09 +d1, while
those at B (called the pitch),
3b"= 2 (1‘09)+d1= 2‘18+d1
———_2
and C = \/A2—(€)
The distance from rivet centre to plate edge will be 1%d as
before, deduced from practice

. 2'18
and the efficiency ‘)1 — n _ 2' =, o
For% plate-_—————2_18_l__8 73 or 73/o
,, _ 2'18 __ o
For I plate—m— 625 or 62%)
Example 12.——Find the various dimensions of lap joints for 483"’
boiler plates; (1) single riveted, and (2) double riveted.
(1) d = g" and d1='8 or 31%"
p”= 1‘09+a’= Ill."
lap = 3x ‘8 = 211%”


and the joint is drawn at Fig. 358.
Rivet Head. 409
(2) e" = 2'18+d= 3"
diagonal centres = 1%"
cross centres = 3-57 _ 2-22 : 1126'"
121» = 2.1V. 1.8. = 3.3.,’
and the drawing is given at Fig. 3 59,
(it WW.



| T g '
S'- Q“
N 15”
r+r-—’|
—__ _ _ _-—' -—___-


I‘:


Example I 3.—Find the pitch of a single-riveted lap joint where
d=-Z;”, f5=7800 lbs. and f,=ro,ooo lbs. (Eng. Exam. 1886.)

Id2 II
800x22 ,, I,
7 4_—__><8>:<87x7= 10.000 (pk-s): e = P813 or 1+}
Contour of Rivet Head.—Fig._ 360 shows how to draw a
cup or snap head, and a countersink. Mark out plate thickness
and rivet diameter. Divide GB, by guesswork, into four equal
parts, and at centre G strike arc D F. Lastly, with centre F and
radius A E strike the cup curve. Both snap head and countersink
have a diameter of 1% a’. _
Strength of Chain-riveted Lap Joint—The same ele-
ments are required as for zigzag riveting, for the same links have
to pass. Centres A, Fig. 361, may be 1'5+a’1, and the angle a
.410
C/zain Rz'veting.
should not be too large. The efficiency will be reckoned on the
pitch line as before, because the joint is weakest along that line,
i / e N
0°. \§§S Lil__Tw_' 41T_

‘>
__.}. _

















Rivet? Jihad. chm-mm Lap/Joint
m9. 360. Fig. .361.
‘XXVI/Ill!
ass M§§§§§§§$ nnnnnnnzmkenn§§s|m§§sn§s§
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BUTT JOINT








the links being most crowded there.
be arranged to take place preferably on the pitch line.
All the seams given may have two butt straps instead of a lap,
and the dangerous bending action thereby removed, see Fig. 362.
The fracture should always
l
.Treble- Rizieting. '41 I
As each rivet is then in double shear, and twice the previous
\ strength, the pitchmay be considerably increased, but this cannot
be taken advantage of, except perhaps in the thickest plates, or
staunchness would be affected,
A Double-riveted Butt Joint with two Coverplates
is shown in Fig. 363, designed to use the'full strength of rivets.
Of course the links will'be twice the width of a lap joint,
1)": 4 (1‘09)'-l-d1==4'36+d1
,and diagonal centres=2 (1'09+d)= 2'18 +d.


The butt strap might be %t in thickness, but is safer at :Z—t. It
might have to be thicker and should always be examined separately,
as one plate equal to the two straps put together. The overlap
may also have to be increased as at 2d.
The Treble-riveted Butt Joint at Fig. 364 is taken from


j jh .'.~- ' ' >h‘
‘ _‘ 0 "_'_'~ fun.
\ J j l . l s I A
Alvgr ' £5 [57,,“
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. l_ I . . r1. / A‘M“ _ l.
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= , ‘l , j I l ‘I ‘.\
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\=/éd c= 7-22' . 5-
D,+Dzanecugooda.s?'4, _ ( 8
drug each J'l'r'ap- a!‘ &C .
Jﬂengﬂc 0/ liable—riveted, Butt Joint 1219. .364.
actual marine practice. Using the general formula (page 407), and
. remembering that 5 rivet strengths must pass at the pitch line:
Proportioning as a lap joint, width of one link: ‘838"-
and p”= 5 (‘838)+ 1'28 = 5'47"

proportioning as a butt joint, width of one link= ‘838 x 2 = 1'676”
and p”=5 (1_'_676)+1'28=9‘66”

412 Stringer Plate.
an intermediate value being taken. Next, the butt straps must
pass 2% rivets each at D1 and D2, or D1 + D2 must pass the same
strength as C. But
Plate at C = 7‘22t.
and ,, D1+D2=5‘94x 1'25t=7'4t,
or the links are most crowded at the pitch line.
Taking now the joint as designed,
Strength of pierced plate= (8'5 - 1'28) 1'28 x 6 = 55 tons.
5 x 22 x 1'28 x 1'28
7 X 4
Strength of ‘solid plate: 8'5 x 1‘28 x 6 = 65‘28 tons.
and 11=63i8=8425 or 84% ‘Z

Strength of rivets= x 5 x 2 = 64‘34 tons.



Tie Bar or Stringer Plate, Fig. 365, is an important de-
duction from the last example. By compelling the joint to break




TQ ebcu"
2:
ASLIZL'rZgQT
arm 1 ‘5335 (nsour)
r\ /\~/‘\[mt;_/\ _.
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preferably at A B, the plate is only weakened to the extent of one rivet.
The strips must not be bent abruptly, however, and the butt straps
should always be examined separately, and their thickness in-
creased until the links are narrowed sufﬁciently for all to pass;
thus %t is required in the example.
VALUES OF 11 FOR VARIOUS THICKNESSES OF PLATE AND VARIOUS Foams OF ]01NT, USING STEEL PLATES AND
STEEL R1vETs, AND FULL STRENGTH OF BUTT JOINTS.



'sazanazagﬂ'g f0 ejqnl
Single-riveted Single-riveted butt, Double-riveted Double-riveted butt, Treble-riveted Treble-riveted
Dig, lap. with 2 straps. lap. with 2 straps. with 1 strap. with 2 straps.
t 5511'. 44' ,, __ e.’ ., _ w." ., ., 31/’. ., w': .,
= I rlvet. - 2 rivets. — 2 rivets. =4 nvets. - 5 IN. = 10 rivets.
1% '73 I '99 '59 2'18 '75 2'18 '75 4'36 I '85 5'45 '88 19'9 '93
3 '8 1'99 '57 2'18 '73 2'18 '73 4'36 ; '84 5'45 '87 19'9 '93
171; '86 1'09 '56 2'18 '71 2'18 '71 4'36 I '83 5'45 '86 10'9 '92
11,- '91 1 '09 ' 54 2'18 "70 2'18 '70 4'36 1‘ '82 5'45 '85 10'9 '92
1% '975 I '99 '53 2'18 '69 2'18 '69 4'36 l '81 5 '45 '84 19'9 '91
43; 1'04 1 '09 '51 2'18 '68 2'18 '68 4'36 '80 5'45 '83 10'9 '91
H; 1 '08 1 '09 '50 2'18 '67 2'18 '67 4'36 '79 5 45 '83 10'9 '91
-} 1'125 1'09 '49 2'18 '66 2'18 '66 4'36 '79 5'45 '82 10'9 '90
h‘; 1'17 1'09 '48 2'18 '65 2'18 '65 4'36 '78 5'45 '82 10'9 '90
If; 1'2 1'09 '47 2'18 '64 2'18 '64 4'36 '78 5 45 '82 10'9 '90
1% 1'25 1'09 '46 2'18 '63 2'18 '63 4'36 '78 5'45 '81 10'9 '90
1 1'3 1 '09 '45 2'18 '62 2'18 '62 4'36 '77 5 '45 '80 10'9 '90
1%,, 1'3 1'034 '44 2 '068 '61 2 '068 '61 4'136 '76 5 '17 '79 10'3 '90
It 1'3 '976 '43 1 ‘958 ‘6° 1'952 '69 3 '914 '75 4 '88 '79 9'96 '88
11% 1 '3 '915 '41 1'859 '57 1'859 '57 3 '799 '74 4'62 '78 9'25 '87
1'3: I '3 ‘873 ‘40 1 ‘756 '57 I'756 '57 3'512 '73 4‘39 '77 8'78 '37



2117
4I4 Examples.
Remarks.--In cooling, the rivet exerts great grip on the
plate, giving frictional strength to the joint, but caulking
diminishes this, so it is not allowed for. Rivets over 6" long‘
would break in cooling, so must be hammered up cold.
The formula for boiler strength, ptoris r=ﬂ n, can now be used
to better advantage. Construct a table showing tand 17 under
all conditions, and after ﬁnding tx n from the formula, choose
such values of each as will meet thecase when multiplied. Such
a table precedes this page, where the pitch has been taken at its
largest value in every case. This must be decreased to secure
staunchness where necessary, as with the thinner plates in the last
column.
Example I4.—A steel Lancashire boiler 8 ft. dia. is loaded with
100 lbs. per square inch. Find 2‘, and indicate the joint you would
use.
100x x12 '

ﬁtonsr=ﬁzﬂ 0.0 I. Single riveted lap joint t1; = g x '50 = '375
2. Single riveted butt joint 9 . _
3. Double riveted lap joint i t" : T6— X 69 = 382
4. Double riveted butt joint in = 116 X -83 = '363
Something between (3) and (4) would have to be adopted; say
(4) with it” plate and spacing like (3) for staunchness.
Example 15.——Two lengths of mild steel tie rod 7"x 1” are to be
connected with double butt straps. Determine dimensions and
efﬁciency. (Hons. Mach. Constr. Exam, 1893.)
d1= 1'3. Centre to edge: 1'5 x 1'25 =I'875
w” for one rivet, in double shear=2'18
7-~1'3= 5'7 width of pierced plate : . ' . =3 rivets say.
Checking we have :
2><22><1'3><1'3><6><3
' 7 X 4
Strength of pierced plate = 5'7 x 6: 342 tons
Strength of rivets =

= 366 tons
Strengths of Shear Sections. 415 8
Strength of cover plates = (7 — 2'6) x 2 x 2 x 6 = 39‘6 tons
Strength of solid plate='=7 x 6:42 tons








Strength of Pins and Bolts in Shear.-—An allowance
must be made for partial bending, as follows :
For round sections . 4- safe stress = at
For square sections .4— safe stress = §fs
For diagonal sections .4— safe stress = ~§-fs
Strength of Cotter Joint—Fig. 367 shows this joint con-
necting two lengths of pump rod. It may break (1) by shearing
the cotter 5 (2 and 3) by crushing the cotter 5 (4) by tearing the
socket 5 (5) by tearing the solid rod; and (6) by tearing the
pierced rod. Supposing all to be made of equal strength and
of forged steel, where ﬁ=7 tons, f8: 5 tons, and fb= 14 tons,*
we have: '
(1) Strength of cotter for shear: 5 x 2 x bt = 10 b t

(2) ,, cotter for bearing on pierced rod= 14 a’, t
(3) ,, cotter for hearing on socket == 14 (D2 — d,) t
_ 22 11
(4) a: socket: 7 X 7 X 4 (D12 _ “712) = _2' (D12 " ‘1712)
* f1, may be much greater than 12 if the material be well sustained all round.
416 Strength of Cotter joint.
(5) Strength of solid rod=7 X

22 d2 =I_I_d2
x4 2
7
22
(6) ,, pierced rod=7(7X4d12—d1t)==€-d12—7d1t
(7) Strength at b2 for shear: 5 x 2 x 122 d1 = 10 b.2 dl

129.362

Equating, we obtain :

By (2) and (5) 14 d1t=525d2 and d1t=‘393 d2 .... .. (8)
B 6, , 11 11 ,, _ —-—-——
y(ar(d(<5g>} _2-d12—7d1t=-2-d~ Hal: ,\/1‘5d2=1'22d(9)
By (2) and (5) 14 d1t==55 d2 = ‘322 d .......... .. (10)
By (1), (5), and (10) 10 bt=-I;I- d2 b= 1'71 d ....... .. (11)
By<4>and<5> §<D.2-4.2>=i§-e D.=./"_2-542=1'64<12>
B Sland 5), _ .
y((9) and (10)} ‘4(D2-2'.)t=52-I-o’2 ..
1
By (7) and (5) 10 b2 d1=-;- a’2 _b_2== '45 d .......... .. (14)

D2=2‘44d or 2d1 (13)

The values at (12) and (14) are both unreasonably small, and
are increased in practice to D1 = 2 d; and b1 =b2 = 5} b= 1'28 d.

S trength of Shafts. 417
Example 16.—-A foundation bolt with square head (Fig. 368) is
secured by a cotter. Find D, h, and t in terms of d, where ft, 72, and ft
vary as I : 2 : 2 respectively. (Hons. Mach. Constr. Exam. 1886.)
Following the previous calculations:
D=I'o8 d, [2=I'44 d, and t='363 d.









Torsional Stress-Action unallied with bending occurs
only in very short shafts. In any case the two actions must be
separately considered. Fig. 369 shows a shaft under twist, the
external load being caused by the couple dx [2 e, while the in-
ternal resistance of the shaft is shown by the couple e ><fg.*
External moment=moment of resistance of section
where Z,, the modulus of section, is a number depending on the
size and shape of the section.
Strength of Solid Round Shaft.--Let 7' be the outer
radius of a solid shaft, Fig. 370. Imagining the section divided
into concentric rings:
Total stress on outer ring =7“S x 221' x t ( I)
But fs diminishes towards the centre because 55 decreases:
. 2'
Total stress at any other ring r1=;1fs x 2 71'7'1 x t (2)
* A couple is formed by a pair of equal and opposite forces, and can pro-
duce turning effect only, being represented by ‘ one force x total arm.’
EE
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all- steiimtmnftitmimamtw- - 1
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_ H . _ he; gum
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Itlltllltlllwmr s .r.
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.a b
_

Round and Hollow Shafts. 419
(1) may be represented by the lamina at a, and (2) by that
at b, and the total of the stresses on all the rings will be given by
the pyramid. Again :
Moment of stress at ring r =a x r
Moment of stress at ring 1‘, = b x r
Moment of all the stresses = contents of pyramid x average arm
= (base >< % height) x (% height)

. . 2wrxr J3
Moment of reslstance of sect1on = f5 -—3—— x 2 r = f$7-_2_
. d 'n' d3
and uttlnor — = r = __
( p D 2 > S( 16 )
Strength of Hollow Round Shaft—Fig. 371 shows a
shaft of diameters D and d, externally and internally respectively.
At radius R" the stress is jg, but at radius r it is proportionately
less, being but fs The strength of the hollow shaft will be
found by deducting the strength of shaft d, as stressed, from the
strength of a solid shaft D.
Moment of resistance = moment of solid shaft — momentof core
71' D3 d 71' (l3 11' D4 — d4
Bias-(‘Elie =fR(_D )
Strength of Square Shaft.—In this case we shall not
use the previous methods, but shall adopt a construction which,
although requiring careful drawing, can be employed for any
section, and is therefore general. In Fig. 372, A B c D is the shaft
section, divided into concentric rings as before. Erect perpen-
diculars on E D to represent the length of every ring, and bound
these by the ﬁgure E o L F D. J F = 71' s, and F E is a straight line,
while the lengths between F and D are found by stepping off each
set of four arcs with dividers. Now the stress will be greatest
Ztt'D, and will decrease gradually to zero at E, and the product
(fs x ring area) will proportionately decrease, so the total stress
may be obtained by imagining f, to be constant, and each ring
to have a value represented by the circumference decreased


420 S guare S liafts.
according to its distance from D, the point of greatest stress.
Thus, if the ring K L be projected to D N, and NE joined, the
length KM will represent the virtual length of the ring if fS be
constant. Treating every perpendicular similarly, we obtain the
curve E P D, and the shaded ﬁgure is the virtual stress area, or
area of equal stress. Now cut out a copy of the shaded ﬁgure in
thin cardboard, and, hanging loosely from a pin in two different
positions, as at w, mark plumb lines from the pin in each case
upon the paper. The crossing point will be 0, the centre of
gravity, or centre of all the stresses, and the arm = ER. Next,
ﬁnd the area of the ﬁgure. Divide s into 10 parts, and measure
everything in terms of these parts. Divide DT into 10 parts, and
draw horizontals from the middle of each part 3 then measure
their intercepts on the ﬁgure. Adding all these ﬁgures
(‘13, ‘44, ‘82, 8:0.) and dividing by 10 we get the mean width
2445, or ‘2445 s. The height DT measures 22‘12 parts, or
2‘212 s, so the area = height x mean width, and
Moment of resistance of section = jg >< stress area >< arm

=fs >< height >< mean width x arm
=fs X 2'212 S X ‘2445 5x ‘435; -_-fS(-235 33)*
St. Venant showed, however, in 1856, that Coulomb’s ring
theory was not strictly applicable to any but circular sections,
and gave the following:
Moment of square section =fs(‘208 s3) or ‘88 of { fs('23 5
because the greatest stress does not occur at the corners. To
illustrate St. Venant, Thomson and Tait have imagined the shaft
to be a box full of liquid, which, if rotated, would leave the latter
behind somewhat, and the apices would cause two stresses——
tangential and centripetal—to act on the particles, the former
only being of momental value.
"' Generally Tm=f8£ Zr :51? and 1:21 y, where I is the polar moment
of inertia (see p. 429).
Rectangular Shafts. ' 421
Strength of a Rectangular Section was given by St.
Venant as :
52/22
Moment of resistance of rectangular section = '2944 ‘Tia?
while the pure ring theory would give '1666 hh J and
the discrepancy increases with the ratio 2 n
Thus if h: I" and h: 2"
Tm= '5266 ton ins. (I) by St. Venant; and '745 ton ins.
[(2) by ring theory,
and (I): '7 of the diagram value ( 2).
If 6= 1'' and h=4"
Tm= 1'142 (I) and 2'747 (2) respectively
or (I) = '41 of diagram value.
Hexagonal shafts may be found directly from diagram.
Strength of Shafts by Direct Experiment. —The
following experimental ﬁgures may be used by way of correction.
Moment of any shaft a’1 or s= Figure in table x (d3 or 33).
MOMENTS OF SHAFTS I" DIA. AND I” SQUARE IN TON-
INCHES (ELSWICK EXPERIMENTS).

Round. Square.

WroughtIron... 5'35 6'83
Cast Iron... 5'31 6'78
Steel... 8'92 11'6
Yellow Brass 2'45 3'15
Cast Copper 2'15 274


A factor of IQ is to be used for short shafts and of 16 for long
shafts, to secure stiffness. Strength is rarelythe sole criterion.
Example 17.—-Find relative weights of two shafts of equal strength;
the one solid, and the other hollow with a hole half the outside dia-
meter. (Eng. Exam. 1892.) '
422 Strength of Coupling Bolts.
Moment solid shaft = moment hollow shaft.
. 3 __ _
1'. 3_ l D4_d4 - =N/D4-(15T5l4
fsl6dl _f516( D "d1 ' 1)
_ 3____ 3__
Let D=I. Then d1= ,\/I 1118 =\/%= '979


Weight of solid shaft __ 11'7’12 _ '9792 _ 1.2 7. I .
Weight of hollow shaft — 7r(R2— r2) _ 12- (5)2 _ ____._7 '

Example 18.-—Find the relative strengths of shafts :—
2%" round, 3-3" round, 3" square, and 5" x 2" rectangular.
Moment of 2124' round or 11.6— d3 = ‘1963 x 1562 = 3'066 say 31.
,, 3%" ,, o< ,, = '1963 x42'87 = 8.415 say 84.
,, 3" square <x'208 s3 = '208x 27 = 5'616 say 56.
I’ I’

Strength of Coupling Bolts.-Fig. 373 is the face view of




a ﬂange coupling. As the bolts and shaft must be equally strong:
and allowable stress==Z f,
Moment of bolts = moment of shaft
é 7rﬁx) = 2133
(4f; 4 )7 ‘7216
"=~/¥%=wt/i-Z§
Strength of Keys. 42 3
Example 19.—Determine the diameter of the eight bolts of a ﬂange
coupling; the bolt circle being 23" dia. and its shaft I4".——(Mach.
Constr. Hons. Exam. 1887.)
d = ‘577

I43 _ ..
8 x 1 1%; _ 3'15
Example 2o.—-Compare the diameters of two shafts, their mean
twisting moment being equal : in one (A) the ﬂuctuation of moment
is between 141— and Z- the mean; and in the other (B) between twice
and half the mean. (Hons. Mach. Constr. Ex. 1886.)
Stress o: Tm
'. In shaft (A) : by Wohler formula :
1
— - —- 5
A = 255+ VM 1'5 X at oqf. = "/_——f12_75f2f"1
Squaring and solving quadratic : f, = '59 f1
Similarly : in shaft (B)
I ‘ 1
f. = + ~/f.’— 1'5 X 1512f. and/2:441‘.
The diameters must now be made to meet greatest Tm.

3_
a
Tm=f,1i: and d o: also let mean Tm= I.
16 j;
3.__
Then for (A) e a 1'284
_ 3 59 or as I : 1% roughly.
2
andfor B d or —= 1'6
( ) _ .44 5
Strength of Sunk Keys may be investigated, though ﬂat
heys (A, Fig. 374) and saddle heys (B, Fig. 374) cannot be satis-
‘5 / / r ; \\
//-
\\ \ xylrelggk ,’ A B 9,; /
a‘
\ .
\\\. re
wan
-, ' WY
/75~
Zeal?
\“
s
ZZQLL 74- Beg/.2.
factorily determined. Referring to Fig. 375, we must make (1)
bearing surface at h, (2) shear through adl, and (3) shaft d, all of
equal strength. Taking fb : fs :: 2 : 5f,

424 Angle of Torsion.
Moment of shaft=moment of key bearing=moment of key shearing
d3 lilo’ d
sire = f‘ 2' z - = f‘ "1.
(3) (I) (2)
By (3) and (1) ix ‘1963 d3 =Z/zld lzl= ‘2944 d2 (4)
nld d
By(1)and(2) 34LT=332Z .-.7.=23 ....... ..(5)
'Letb=‘3d Then by_(5)/z='75x‘3='225d
By (4) lzl= ‘2944 d2’ and l=1'3d


In practice the following rules are adopted :
‘ t.=1e+-,1,~" and/i=%d+%"
'2 944 2'2
Then l- {3+ 3%
Angle of Torsion, or the angle through which one endof
a shaft turns relatively to the other under a given stress.
_ shear stress fslbs fslff
- ———-. = -— and 8 = —
' shear strain .5, s C
Referring to Fig. 376 and putting 6 in circular measure ( viz. 32-)
lbs
6 = 2; for every inch of shaft length. Substitutingfsf for 55



If a weight w produce a twist 6 (Fig. 377), then
A ' 2fslbsl" - 1b 1rd3 ' 1b ,1'6zvr2
H=r%_ Cd But'zuQ—fc’ S’_1_6_ .aridljs‘s'z 1rd3

Strength of Helical S ﬁrings. 42 5
2fslbs‘lri2 _ zze/r2x I6 lr2 writ
cc - mace = or
This can be referred to radius r (Fig. 378) if in be increased.

'. A = x 10'18
Notice that strength Tm 0: d3, while stiffness % 0: d4.
Example 21.—The angle of torsion of a round W. I. shaft is not
to exceed one degree for every 3 feet of length, and the stress to be
within 8000 lbs. per sq. in. Find diameter for each condition in terms
of Tm: and its actual value in each case. (Hons. Mach. C0nstr., I889.)


22 _
forsfigness A_10'I8xwr2l 77360: 10'I8xa’x36 wr
— C d4 5 10,500,000 d4 2
_ _ 7><'10'I8><'36><360 3— __ 3,-—
' £14— 22><2><10,500,000><2"/w7 "M
f 1(2) th “is J—T— 3— 3—
ors reng ear—fS .16 __ 2'2: WVwr=~185 x/wr

2fslbsl 22x2 _ 2x8000><36
C a’ or 7X360—IO,SO0,000,Xd

Again, 6 = a’l=2'54”
. . 3 _ _
Equating to previous result, 2'54 = '21 54 V'wr w r= I 1'83 lb. ms.
3
And. a’,='185 \/11'83 = 2'18"

Strength of Helical (Spiral) Springs.--In the round
wire spring (Fig. 379) the pull is exerted axially, and any
section a’ is in torsion. . .
.i lbs 7’ d3
20 r --fS I 6 '
Extreme elastic stress for steel= 89,000 lbs.
89,000

and working stress = = 29,600 lbs.
For square-sectioned steel (Fig. 380),. I
’ zel ri=jfslbis ('208- J3)

‘and for rectangularv sections,
. 62 h2
w r =f~=1b5('2944 X l
V61 + 112 .


426 Deﬂection of Helical Springs.
Deﬂection of Helical Springs—This may be found by
imagining the wire uncoiled, and treated as a straight shaft.
Let Z: length of wire from A ‘to B, and n =number of coils in
that length (Fig. 379).





£29. 360.
£169. 379. ~E'elxical/ .S/ux'ngs.
2fslbslr_ zwr 16 x 211'?” r_ zonr3
[=27r7'72, andé= Ca, - 7rd3cd -Cd4 64
N.B.—This is for round wire only. For square wire,
20 n r3
and for rectangular wire, w n 7.3
A= ——. 24
b3 h'*
C ( 62 + 112)
The above formulae have been thoroughly tested with
C = 12,000,000 lbs. and found reliable with that value. The curve
of work during extension or compression is found as for a bar
(Pase 367>- ,
Bending Stress-Action.-—Fig. 381 represents a model
devised by Prof. Perry to show the'stresses occurring in a beam.
Supposing w very heavy and beam 1 so light as to be negligible,
Bending S tress—A ction. 427
w causes a bending moment or turning effect round A equal
to W x l, and also exerts a downward pull to be balanced by
weight W1, so that w = W1. The latter is called the shearing
force, and is felt on every vertical section of the beam. W1 and
w really form a couple with the arm l, and this can only be
balanced by another couple = (t or c) x A B, a tension being felt
in the upper ﬁbres and a compression in the lower ones, shown
respectively by the link A and strut B.








383.
IZ/ceory_g¢ 3,6607%‘.

The case we have examined is that of a cantilever or overhung
beam. Fig. 382 shows a supported beam or girder, and the
bending action is here reversed, the lower ﬁbres being in tension-
and the upper in compression. Taking a bar of indiarubber, and
measuring both before and after bending, it will be found that
c is thereby shortened, t lengthened, while n is unaltered 5 n is
therefore termed the neutral line or axis of the bar.
Position of Neutral Axis—The bar in Fig. 383 is bent
to an entire circle, and has A B for neutral axis, with ﬁbres B c
428 Position of Neutral Axis.
in compression and B D in tension. The stresses will be zero
at B and increase towards c and D as shown, forming a couple,
(J or F) x G H, to resist bending, where J = F.‘ Consider two
small areas at and a5, and let p=radius of curvature at neutral
line. Then:
Length before bending = 2 71‘ p
Length of ring at after bending = 2.71’ (p +yt)
Length of ring ac after bending = 2 v‘ (p -yc)
Strain on ﬁbre at=21r(p+yt) —27rp =24-i-yt
and Strain 0nﬁbr€dc=21rp—27r(p—yc) =21ryc

But A=jg generally 2 wry =f2€p andf=El (1)
E a
Total stress on a small area = f a = i-
. E ‘ a .
Total stress on area B1 D1 = sum of ——L—5 for all portions of B1 D1
p
and Total stress on area B1 01 = sum of c for all portions of B1 01
E yc a
p
'But these are the forces F and J,
E E - E .
2 43-1523‘ = 2‘. M and as -- 1s a constant,
P P P
2ytat=Eyc ac ...................... .. (2)
or Moment of tension area=moment of compression area.
But centre of gravity of a lamina or centre of ﬁgure of area is
such that the moments on either side are equal. Therefore the
neutral axis of any bar passes through the centre of ﬁgure of its
cross section. '

Moment of Resistance. Again,'in Fig. 383.

Moment of stress on a =_fa xy= Eya x y'
Moment. of all stresses on a section
E a E
=2-(——y——— xy) =—-Eay2
' ' '- PC I i p t I 0
But 2 ay2 15. the moment of inertia of the section: I
._ - Moment of resistance --=_ I-Ep—I (in terms Oflp) .... .. (3) I

Moments of Inertia. 429
MOMENTS OF INERTIA OF AREA (WITH was As sHowN).








FoR BEAMS. FOR SHAETs.
Section. I y I y
all-41
7F ' _
' {it Ms ;, » 1212 (524.42) Jew/12
Rectangle I ——- - 12 2
‘L 12 2
14—-b _ ' 4 _
i M3 e i M/z
Square ‘L -—I 2 5 6
,4
Square 5 S ,J;
The same general formula
Hollow 3 _ 3 holds for shaft moment as
Rectangle w H for beams,
2_ 2
or Square thus Tm =f£
J’
_ 6 e3 2 [Z
Triangle £- 36 3
1-5-4
__f 71' a“ '17 4'4 ‘j,
Circle 64 '2‘ 32 2 I
_ .J- ‘‘
Hollow ‘ 11(D4 _ d4) 12 7r (1)'1 — a“) 9
Circle 64 2 32 2
Hexa on it h
g -—_4 5 h r3
5 ~/ 3 7‘ ——— + h3 7'
I6
I’
Hexagon r



4 30 Moment of Resistance.
We may also represent the moment in terms of the limiting
stress f (sometimes ﬁe, and sometimes ft). Then:
- Bending moment = moment of resistance
B1m = f Z ...................... .. (4)
and Z is known as the modulus 'of section.*
Let y = distance of furthest ﬁbre from axis :
E E I
By (I) f= 7,1 by <3) B... = 7;- and by <4) Bm=fZ-
I
Then fZ=-—EI and —-EyZ=---EI Z=- .... .. (5)
p _ P P 3’
and Bm=f)-I;
The value of Z can now be found; thus,
. h h3 h h l 2
for ' rectangular sections f Z = f ' = f -_Z



I? T Z 6
. . 'R'd4 07 1rd3
and for c1rcular sectlons f Z - f H -,- g _ f K2-
Graphic. Solution for Moment of Resistance.—
Taking, ﬁrst, a rectangular section (Fig. 384), draw the neutral
axis AB. Then CD will be the line of limiting stress, and the
value of any horizontal ﬁbre E F to resist stress will be found by
projecting to CD and joining cD to N, thus obtaining the in»
tercept GM. Every ﬁbre being thus treated, the sum of the
virtual stress areas‘ will be the areas 0 D N and H j N, which
each make one force of the couple when multiplied by the
limiting stress
Moment of resistance (generally) = one force x total arm

Moment of rectapgular section = f { aroera Ii]; >< arm‘ K L
h h 2 h h2
= - x -h = --
f( 4 l 3 f 6
Unsymmetrical sections are treated at Figs. 389, 390 by this
method, which can be applied to any section.
* Z = virtual area >< arm. (See Figs. 384, 38 5.)
Moment of Inertia, and Stress Area. 431
To ﬁnd Moment of Inertia of any Beam Section.- .
Proceed as in the last construction and ﬁnd Z. Then Z =)%
and I =Z y.* So for rectangular sections
_ bh2 X h __ bh3
6 2 12

Stress areas for circle, hollow circle, triangle, and hollow
rectangle are shown in Fig. 385, being found as in Fig. 372
(mean width x The centre of gravity of each area is obtained
by cutting out in stiff paper and hanging up in two different
twee“;
LI If 0!‘ LIMITING 5












\
£49. 384. _ .385-
positions to mark two plumb lines, which will cross at G. For
the triangle the neutral axis must be drawn at the height, a line
of limiting stress drawn across the apex, and another below, at an
equal distance from its axis. Projecting and converging, we shall
obtain the areas shown, which must be equal. The results are as
follows:



Moment of resistance of circle = f ‘0982 d3
. D4 — d4
n ,, of hollow circle = f '0982 D
1. ,, of triangle =f'0185 bh4
s _ 3
.7 ,, of hollow rectangle=f'1666 B H ﬁll

__ H
" See also note, page 430.
432 Finding Centre of Gravity.
Centre of Gravity of -Area by Calculation or
Graphics.—-Let A B c D (Fig. 386) be the area. Draw any
line B c, and perpendicular limiting lines at E and F. Divide.
B 0 into 10 parts, and erect perpendiculars abcdefghjh at
their middle points 3 also mark point P so that P B = half a
division. Then take moments round P thus: (length a x 1),
(length b x 2), (length c x 3), 810. Then :
addition of moments = addition of lengths x K
reckoned in added moments
‘ and K( divisions ) : added lengths
Then HG is found, containing the centre of gravity. By turning
the ﬁgure through about 90°, and repeating the process, L M is
also found, and N is the centre of gravity of the whole ﬁgure.









541 4
£ // F . L
j . , 2 1°
l y ‘i’
i /'"'X
i b 0 e, di- 9 _I' C I 5;
ll ' l J‘
i_‘ziclt\'t's‘zbn ‘k -\ w
i(‘ w V)
M.


'2 £49 387. _
The graphic method at Fig. 387 suits some cases better.»
The area is ﬁrst divided up and its separate parts calculated:
AB= 5'31 : CD= 1'8 : and EF being a trapezium is cut into
triangles of 2'69 and 1'86. Next mark centres of each of these
areas at zv, x, y, and 2. Set off the weights to scale upon LM,
join to any point N, and drop perpendiculars through 20, x, y, and 2
on the area. Now commence at any point P in 2 P and draw
PQ H LN, PR H YN, RS H xN, so I! wN, and ﬁnally oU H NM,
giving U, which, produced upward, cuts the centre line HZ in G
the centre of gravity, and K is then known.
Economical Sections. 43 3
Economical Sections.--It will be seen in Fig. 384 that
half the material is incapable of resistance on account of its
location near the axis, being only affected by shear, which is,
however, but a small effect. We are therefore driven to the
conclusion that ‘solid’ beams are uneconomical (seen also in
the solid circle and triangle in Fig. 385). The hollow circle and
hollow rectangle are an improvement, but the best results are
obtained by distributing the material near the line of limiting
stress, and thus the well-known H section (F ig. 388) is arrived
at for wrought iron, where fc =ft approximately, while the modiﬁed
T section (Fig. 390) is adopted for cast iron where fc >ﬁ.


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Assuming that the vertical web is for the purpose of resisting
shear, we may ﬁnd the moment of resistance by an
Approximate Methoa’.——The direct strength of the ﬂanges
forms a couple whose arm may be taken as the total depth of
the beam (as the web has been neglected). Let a = area of
either ﬂange,
Moment of resistance of H section =fc aC h or ft at h
whichever is the lowest value.
In cast iron;3 = a? or & roughly, and the ﬂanges must have
areas in inverse proportion. .
Exact graphical solution may also be found, and we will take
a few cases.
F F
434 Rolled Beam.
Momental Strength of Wrought Iron Rolled Beam
(the section being given at Fig. 388).—Referring every ﬁbre to
GB or DE we obtain the shaded stress areas. As these change
in contour very abruptly, it isbest ‘to divide into 20 parts to
ﬁnd the mean width '6895._ Then '6895" x 2'75": 1'896 area in
sq. ins. The arm may be found by calculation or by hanging up
the paper area from two positions, the ﬁrst method being shown
in the diagram, and the result found as 2'33" on either side‘.-
Then .2 = area >< arm, and >
Moment of resistance =f>< 1896 x 4'66 =f8'835
= 4 x 8835 = 35'34 ton inches


In such beams ft: 5 tons and ]‘¢= 4 tons, so the lowest value
has been taken. By the approximate‘formula,
Moment =fcach = 4 x 1625 x 5'5 = 3575 tons ins.
Momental Strength of Steel Rail (Fig. 389).—-By
cutting out the section and hanging it, the neutral axis is found
at 1'56" from bottom and 1'69 from top; the limiting line is
therefore BC. A second limiting line is drawn at DE, also 1'69
from axis, and every ﬁbre now referred to BC or DE, and the
stress areas obtained. Cutting these out, their centres can be
found, giving the arm 2'5”, and their areas by dividing each
into 10 parts vertically. Then (mean width x height) gives
'751"x1'69”=1'27 for top area, and '867”><1'56"=1'35 for
bottom area. It is very difﬁcult to get them exactly equal
graphically, so the average 1'31 sq. ins. must be taken. Then

Moment of resistance = f x area >< arm

= 6 x 1'31 x 2'5 = 1965 ton inches.

Momental Strength of Cast Iron Beam (Fig. 390).
—-—CD A B is the beam section, whose axis is found at E. Draw
perpendiculars F G and M N. Set off H G= 1i and M 14:4,
representing ft and fc respectively, and draw H J and KL through
axis, giving F J as 2%— and LN as 2%. This shows that if fc be the
limiting stress the tension ﬂange would be stressed to 2% tons,
or dangerously; while ﬁt at 1% tons would only stress the com-
pression ﬂange at 2% tons, or safely. ft is therefore the limiting
stress, and A B the limiting line below E, while a corresponding
Plate Gz'rder. 357
line P'Q is drawn at equal distance above E. Then as before,
after drawing stress areas:
‘Upper area = r256 x 4-56 = 5-7 } _Y .
Lower area = 2102 x 2'44 == 5'2 “_ 5 45 average
and Moment of resistance =ﬁ >< area >< arm

= 1%x57'45 x 535 = 36'45 ton inches
or by approximate formula = 1;} x 6 x 518- : 418 ton inches.








T tin/w K
i . ‘_-_%__ C,
l—Lld l-zscx q-ss = 5-7 } 5 5
11:’ 1"07-1 Z'III-I = 5'2 queue-E
AREA
I e a 5cm: //6
i _ Fag. 390.
i “ 231.11 Y c ___L N MZL¢
A’ LINE or L1 ‘17/ "6 5m!“ 76:5‘,— ' L l g" _l -
K— —— -—6 — ‘tiff’: *- le’" Ccwl- b77077, Beam

Momental Strength of Plate Girder (Fig. 391).—The
rivets must be deducted in tension ﬂange, but they aid the


0



g! I - k \l gm.‘ l I‘ g\

I




°>l



'5‘ rwo n/vzrs
~79-l6
:b w 1c
SCALE ’8 “Tag/g; ‘a EIE
.2 ‘l
Moment q‘ Plate Gzrrder'. FAX/93$”.
resistance in compression. The centre of ﬁgure i's'then found
by taking moments of the parts round A.
436 Modulus of Rupture.
Moment Of diminished section = moment of I rivet+moment of zrivets
{a- (b+c)}x = b x arm+c>< arm
(1'394>< 8‘5)+(49‘16>< 11'25) = n
68:28 — (13'94+49'16)
j‘c being limiting stress (see below), B c and D E are reference
lines, and the areas are found as before.
andx=
Each stress area = 26'35 and arm = 21'12
For W. I. plate girders ﬁ= 5 and f,= 4
For Steel plate girders jt= 6 and ﬁ= 5
The reduced j}, being an allowance for buckling.
Moment of resistance =fc >< area >< arm
-= 4 x 26'35 x 21'12 = 2226 ton ins. for W. I.
= 5 x 26'35 x 21'12 = 2782 ton ins. _for Steel.


Value of f in Beams.-If a ‘solid’ beam be broken
across, and f found from the momental formula, it will be found
much greater than ﬁ. Our ‘bending theory must therefore be
imperfect, and indeed takes no account of lateral adhesion in
the ﬁbres. We must meet the case by the formula
)2 = 0ﬁ
where ]‘O is the stress found by transverse experiment and called
the modulus of rupture, while O we shall call the bending coeﬁicient.
It varies with the beam section. Thus :
In sections . or . O is greatest, being about 2
In sections I or I O is less, being about 1%
In sections I O = 1
And depends also on the material, as seen in the following table,
compiled from various experiments.
TABLE 0F BENDING CoEFFIcmNTs (0) FOR RECTANGULAR SECTIONS.

Fir '52 to '94 Wrought Iron- 1'21
Oak '7 to 1'0 Forged Steel 1'47 to 1'6
Pitch Pine... '8 to 2'2 Gun Metal 1'0 to 1'9
Cast Iron 1'57 to 2'3

And our beam formula becomes
Bm=OfZ
Bending Theories. 437
In general the value of 0 may be an average one, some
regard being paid to the section, but ]‘o =' f in H beams. In
practice this method, or its equivalent, is employed to ﬁnd the
safe load, f (safe) being put for f Some writers condemn this
method, holding that the increase of strength is beyond the elastic
limit, and therefore untrustworthy. Mr. Robert C. Nichols’ theory
is that the elastic limit may have been passed in tension, though
not in compression, when an apparent increase of elastic strength
occurs, and ‘that the stress areas have the appearance shown at
Fig. 392; but the author himself witnessed an experiment on a



bar of forged steel where the stress diagrams were plotted both
for bending and tension of the same material. The elastic line
being perfect, j‘o was found to be 24 tons, while f was 15 tons,
giving the bending coefficient 1'6 in the table. The theory of
increased strength is adopted by Sir Benjamin Baker, and was
ﬁrst upheld by Mr. Barlow.
We have now completed our investigations of moment of
resistance, and shall proceed to consider the left side of the
bending equation.
Bending Moment and Vertical Shear.--In long beams
the shear is small in comparison with bending stress, and is fully
met by the surplus section. For the distribution of shear stress
may be shown to be parabolic, as at f; (Fig. 393), or greatest near
.438 Bending Moment and Shear.
the axis, while on the contrary the greatest bending stress is
furthest from the axis, as shown at A.
%]Z x area of section = total shear
3 total shear load on section
and)‘; : ‘é' .
area of section

In very short beams this stress should be considered, till
ﬁnally, in rivets and pins, the shear is almost pure. We will now
examine the distribution of Bending Moment and Shear Load
under various conditions of support and load. ‘ .
I. Cantilever with Concentrated Load * (Fig. 394).—A B is
the beam and W the load, the latter having a leverage over










tar-w ;._reiteL.t_vr-_=_m___j_
' . r/ / y 7 -
l i l M, L" A Z,Q_L_E_ I Pl 5
/ a r-at' 1.1.1
4 F 111'“
.. I. j . d?‘ j
l uul/ let/2;!
A 2W
a, 5 NDINGl 4 MoMI 6
wt 9 4 I
v_v_L 16
'2 Fag .sos
: SHEAR/Na FORCE c sue-name FORCE

e-W"
\


‘section A of W x l ton feet: at section D of W x ;3;l, and so on.
The Bending Moments at various sections may therefore be repre-
sented on the base line a h by downward ordinates, thus :
AtA=Wl><1 atD=Wl><g
At c=Wl><§ atE=Wl><-i
and at B = nothing; and these ordinates are shown at f, g, h, j,
and h. >
The ShearzngForce is caused by the reciprocal action of W and
Rt, and will equal W upon any section ‘between A and B. For
regularity we shall always consider the force on the right side of
* Weight of beam is not taken unless stated.
Cantile'oers. 1439
' t/ze‘section only, so here the shear ordinates are drawn downward
on. the line a o, and equal W in‘ every case.
’ II. 'Cantileoer wit/z Uniformly Distributed Load (Fig. 395),
the load‘ being represented by the weight of the beam. Con-
sidering the beam hinged successively at A, B, c, D, and E, the
loads on the right may be successively concentrated at their
middle points, and the Bending Moments become:
I
AtA= Wnxg =Wlx-Z— ocr6=42
a 9 32
Z, 8
W l . I ‘I
Atc: =WlX-8— Oi 4=2
AtD= V—vxf -='wzx_I_ 0t 1212
4 8 32
and 'at E = nothing, as shown by diagram, and as the ordinates
vary as the square of the abscissae at a o, the curve is a parabola
with o as vertex. '
S/zean'ng Force on right of section A=W, at section B = %W,
W W . .
and at c D and E, -2—, -—, and‘ nothmg resp'ectwely, as shown by
diagram on a1 t1. 4 '
III. Girder with concentrated load at centre and ends merely
. . W .
supported (Fig. 396).--React10ns W111 each equal —-2—, WhlCh we
shall use in estimating the moment. Rtlbalances Rt2 round W
as a pivot, and the stress at E, is due to one or tile other, but
. W .
not to both. Then calling each reaction —2— the Bendzng Moments
will be:
AtB=WX—l— =Wz><i cc 1
2 r6
8
Atc=—V!x-Z- i=Wlx£ ocz
2 4 8
W 3 ._ s_
C13
AtE=-V-\-r><—{ =Wlxi 0:4
2 2_ V 4
and similarly between J and E.
440 Girder ‘with Concentrated Load.
The Shearing Force is found by a deduction of weight and
reaction. Considering always the right‘ side of section, the force
is constant from A to E, and is that part of W which balances Rt,
W ,1 ,
or -2— downwards. From E to J it is a constant equal to Rtz
upward. At c1 the forces change suddenly from + to —. If
the weight be hung as at M N there is no shear stress between.
. . . W
M and N, but if the link K L be adopted the shear stress 18 ;-
right up to the centre line on either side.
\ l
.Rflji— —— —- —- —-é -—— —— -—~ — ~71ERZZ', 'l‘Rlz' E2 ’
III 181 [ll]
1) EFG‘ H




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6 BIS/VD ma MOMENT

UCNOING n... . ‘ . ‘

l
_ 1131.. l l
sworn/me fanc: J‘, ‘7' - - a, . "4 SHEAR/Na FORCE a’
a we =1; a», Re,
.. E . . _
1 no. 396. £49 -__~3 2 7.

IV. Girder with concentrated load at any point—Taking
moments round J, we have
Rtxl=W (l—x) ‘and Rt=‘-Y—(€Z:-Jf2
W (l - x)
l
diagram is made up of straight lines ac, cb, as in the last case-
The Shearing Force is found from the reactions as before.
V. Girder supported at ends and loaded uniformly (Fig. 398),
Bending Moment at E = x, and the rest of the
. . . W .
the weight of the beam representing the load. Reaction = 3- 111.
each case. The Bending Moments are the subtraction of the
weight moment and reaction moment at every ‘hinge,’ as shown
diagrammatically : ‘
Girder with Uniform Load. 44]
W l W l 7
AtB"(2"‘§> “(WE—6) -W"';;5 ‘I 7
A....(§Y.1)_('1.2) :Whi O...
2 4 4 8 -32
__ W 3 _ 3 3 )_ 15
AtD—(Z (I IS
W l
AtE=(Exg) -(——x—) =Wlx i or 16
2 2' 2 4 8
and are similarly found between H and E, all being shown on
base a h. Drawing f k horizontally, the intercepts between h f
and a f are seen to vary as in Fig. 395, and the curve is therefore
a parabola with vertex at J‘.
The Shearing Force is found by deducting upward and down-
ward forces on the right of each section. Thus:
W
AtA== W—;= Wxé or 4
w
AtB=ZW- = Wxi or 3
s I s
W
AtC=§W———= W><i 0c 2
4 2
_5 _‘_Y_ _I.
AtD-8W 2_ W><8 0t 1
W W
AtE= -———-——= 0 or o
2 2
__3_ 1L. 5 _
AtF—SW 2- W><8 or I
T
AtG= E—-VY—=—Wxi or-2
4 2
W W 3
AtH— -g-—'-2"'-— Wxg (I—s
AtJ= -Y=-Wxg 0c—4
There is no force whatever at the centre.
VI. Beam ﬁxed at both ends and loaded in the centre (Fig. 399),
weight of beam neglected. The beam will be deﬂected to the
dotted shape, Ac and G J acting as cantilevers, and CG as a
supported girder. From 0 to o the Bm is upward, and from
2,42 _ ' Bearers-ﬁxed 2a- an M..-
A to c and G to] downward, being .zero at c and G, the points
of contra-ﬂexure,in this case at l from the ends. The Bending
Moments are ' - , . _ a _ g
1
At E = generally = -Z- =W l x5 upward
‘ W l - 1
At A and J = (W l) generally == z- X Z= W l x g downward
and the diagram is given on base a h.
Shearing Force is the same as Case III.









' V21‘? __ L___.__f't=%"/t V/i
[ stale slt'lslals" / '
q" 18+¢i9i5lr+8F0¥| 4
w
9: Lyon l
t P29. 398
"it—137*’ -" viL—Tﬁ-o I
k ' L ‘:17 I I l ‘1
.r "1. '’’t7 al 2| it? b
9 5' . t-
'6 )3 I WI. \ aewonvcje, Moms ‘w!
1 a)" v1.‘ | 3—
8 l
a drive/~66 Moue/vr I b |


NI;
1
F7 . - l '
a’! i A ' |
v_v - ‘5715491410 rage; * SHEAR/‘NC J,
z q, TL’, Q to CE 6,
2
VII. Beam ﬁxed at both ends and loaded uniformly by its own
weight (Fig. 400).—The points of contra-ﬂexure, C and G, can be
proved to be '211 l from either end. Then Bending Moment
_ Wl '578Wx'578l _ 1
at E— generally --——-—8——-——= 04176 Wl or 21- W1
and C G is a parabola drawn upwards. '
The moments on A c are composed thus:
For concentrated load "289 W; Bm: '289 W x '211 l= '06098 Wt
'211 Wx'zrr l
2
These added give '083 W'l or
and for uniform load on W; Bm= = '02226 Wl
Drawing no on base ac and the parabola he on base no (see
Beams ﬁxed at one End. 443
Case II.),_it will be found that the total ordinates from to vary
as the square of their distance from g, proving that kgl, is a
continuous parabola.
‘ ' ~The S/zearing Force at A consists of
. I ‘ i _ W
‘289 W+ ‘211 \/ =—2— and at c= ‘289 W
and the diagram is a straight line.








I
l
59. 1, 40/.
- l
E
. J/lMm/vc I
r"
C ETA/DING '6 MOML'NT l
l
I






FORCE
| Fgg' .400.‘
VIII. Beam ﬁxed at one end, supported at tile ot/zer, and loaded
by its own weight (Fig. 4or).-—A J is in the same condition as the
part A G in the last case, and the point of contra-ﬂexure is there-
fore’ ‘267 Z from A and ‘733 Z from J. Bending Moment
.. W; . . W . l
._ _ At E= generally=l§§—§X——7§§~ = ‘06716 W!
A At ag== ‘3665 W x ‘267 l='= ‘09785 W!
1. . .‘ . . 6
and Atgf: 267Wx 2 7i

=‘I W!
='<>35644W1} 335
2
; -j Shearing ,Force at A=a1 a’1 + d1g1= ‘6335 W, and at J=o1f1
= ‘3665, W. _- The curves will be found. continuous in both
diagrams. _ s v .
Combination Diagrams are shown ‘in Fig. 402 based on cases
. already discussed. The ﬁnal shaded areas, Bf and Sf, are found
444 Combz'ned Bending Moments.
by superposing the results due to the separate loads, having regard
to the signs + and - . The cases are as follows :
(1.) One distributed and two concentrated loads on cantilever.
(2,.) One concentrated and one distributed load on girder.
(3.) Maximum diagram for rolling load.
(4.) Three concentrated and one distributed load on girder.



: u i J ['—¢T:l I: i.’ G?‘ Cg Cs
“— ' 1 _
clog’? @ 5 @ﬁ. .. I
u A;




man. I


:11?’ I I’ )7”, 117





\\








§\\\\\\\\\\\\\\\__. ‘
(1)


~\\\\\\\\\\\\:
&\\\\\\\\\
k\\\\\\\\\\\\\\
2\\\\\\\\\\\\\‘
a


\\\\\\\\'\'\“\=


Combined 3W Jllbrnenb
d’: Shearing .E'o‘rw Diagrams.
The distributed load is more conveniently placed on one side
of the base line, and the concentrated loads on the other side,
in the superposed diagram. All are well lettered" to show the
relation between diagram and load. In Case (3) the load must
be placed over the successive numbers, and diagrams obtained for
every position, as in Fig. 397, then the bounding curve will be
the maximum, and the ﬁnal Bm will be a parabola. I
Fig. 403 shows a continuous beam on three supports, loaded
by equal concentrated loads, W1 and W1, and uniformly by its
own weight, W + W. The contra—ﬂexure points are practically
the same for each case, and the diagrams can be obtained from
previous considerations. The following table is very useful for
continuous beams :—
Continuous Beams. 44 5
TABLE OF REACTIONS ON SUPPORTS FOR CoNT1NUoUs BEAMS, AS FOUND
FROM CLAPEYRoN’s ‘THEOREM OF THREE MoMENTs’ 1N TERMS OF
W1 THE UNIFORM LoAD 0N EACH SPAN.


2 Spans | |
2 19 32
I 8 8 8
3 Spans I I I I
i 11 ll _4_
IO 10 IO IO
4 Spans I I l I I
H .33 38 i? L‘.
28 28 28 28 28
5 Spans I I I I I I
15 43 37 37 43 I5
38 38 38 38 38 38
6Spans I I l I I ,l I
41 118 108 106 108 118 41
104 104 104 104 104 104 104


7 Spans I l l l
56 18.1. 131 1503 213. L31 181 i8
142 I42 I42 I42 142 ‘I42 I42 142
8 Spans I I l I I I l l I
1.5% £1.43 37_4 323 E9 392 .374 4319 LEE
388 388 388 388 388 388 388 388 388
QSPanS I I I l l I l I I I
E’? 901 5I1 5_3_S _5£9 _52_9 §3_5 5I_I_ 601 209
539 5.79 539 E39 539 539 539 E59 % 539

Culmann’s Funicular Polygon (Fig. 404) is a ready means
of solving such a problem as (4) Fig. 402. Culmann of Zurich
proved that the bending moments are there proportional to the
ordinates of a polygon obtained by hanging the same weights to a
loose string hooked at the supports. Taking the loads in Fig. 404,
B c is drawn to scale, and represents the weights taken in order
shown. Mark a point E any distance x ft. from c B, and join to
c, M, N, and B. Draw from any point F, FG c E, o H H M E, H] H
N E, and J K H B E. join K F, and draw E L H K F. The shaded
polygon is the curve of Bending Moment, and
B,n = vertical ordinate in lbs. x x’ (lb. ft.)
‘
446v Cnlmann’s Theorem.
' Project $1‘ from ‘1., UV from c, wx from‘ M, Y'Z from N, and
a h from B, and ‘the curve of Shearing Force is obtained, measure-
able by load scale. Also s a = Rt, and T v = R,,.
x~--------.1:_--~_----___.t /
, t .w Rt,‘ ‘5| “Rt
11 .w A 1 W id)“; wt "I; l











7/
s




‘
J8
YB
92
3






\
“\\\\\
Ix
Y z
A Parabola may be drawn by the method in Fig. 405,
which consists in dividing A B and BC into an equal number of
parts, and joining the divisions of A B to ‘D by lines cutting the‘
divisions of B c, then tracing the curve through the crossing
points.
We will now take some examples to illustrate the equation‘ of
Bm to f Z. The shear diagram is. not often required in practice,
but should be made for trial. '
Example 22.—The following beams are proposed for a central load
and given span: (1) a bar 4" deep by 2" wide; (2) a bar 3'8” dia. ;.
(3) a bar 3'5" square. What are their relative strengths? (Eng.
Exam. 1885.)
Wl
Bm=fZ or-4—=fZ .'.WOCZ
(I) Z-%_ 2X16 —5'33 <><I
_ 6 _ _6__ _
a . . . .
(2) Z=_g-:—=2—z—X—3—§—:—§’-f—X§§=5'388 06 1'01
s3 ' >< ' >< '
(3) Z: *6" = 3'—--——S 365 35' =7'I45 0< 1'34
Examples on Beams, 447
Example 23. .——(I) A beam 2' long x_1" square is broken by 2 50 lbs.
at the centre. (2) Find the breaking load for a beam IO ft. long,_
to" deep, and 6" wide, with the load 2 ft. from one end. (Eng.
Exam. 1886.) a ' ‘ ' ' ' ‘ ‘ '
For (I) (keeping l in feet'and in ins.)









._V_V_l_ Q3 _f_.W'16_250><2><6_
. 4 _ 6 _46/12_ 4XIXI-_7SO
For (2) by Case IV., Fig. 397 ~
Bm_ ELL) 1: W232 =§
' 1 IO 5
- § _ 5/‘2 _ bkz><5__75o><6xloox5
.. 6 andE—f 6X8 ...._. 6X8
7 = 4687 5 lbs. = 20'9 tons.
A i 0 u_________2ww5__
/ \ "
'/// “-h\\\ R
i / ‘1, \\\\\ 10d+ 50 "Z
2 / // _\ \ :ftofgo
3/ 'll l i
l 8'" YJM-ﬂ ‘Hugh/r ‘
4
B 4 .s z , <5 I B‘... of PuLLeq_hL¢b.S'cpa:,:;dL -.
. 7 ~\\_


//
""”’/J// 75’ 7
£9406 a
Example 24.—A shaft pulley is 8’ from one bearing, and 2' from
the'other. Weight of shaft=zoo lbs. ' Weight of pulley: 50 lbs.
Total belt tension (downwards) =_ 100 lbs. Draw bending moment
diagram and ﬁnd loads on bearings. (Eng. Exam. 1888.)
' W l _ 200 x 10
‘ Bm of shaft weight = T — ——-—g—— = 250 lb. ft.
Reactions due to pulley and strap = 1% x I 50:: 30 lbs.
and 186 x 150=120 lbs.
'. 5 of pulley weight and strap pull= 90 x 8 or 120 x 2:240 1b. ft.
El: 100+ 30 = 130 lbs.
R2 = roo+ 120 = 220 lbs.
ﬁ And the diagrams -a'—re shown at Fig. 406, Bf being the combined
gure.
448 Examples 012 Beams.
Example 25.—-Find the safe central load in the following cases by
the approximate formula.
(I) Wrought Iron Plate Gz'rder.—-Each ﬂange, 10" x é"; angles,
3%” x 3%" X i"; total depth, 3 ft.; span, 28 ft. ; ft or fc= 5 tons.
(2) Wrought Iron Rallea’ Cantilever, H Section—Each ﬂange,
4%" x 32;"; depth, 8"; overhang, 8 ft. ; ft or f¢==5 tons.
(3) Cast Iron Beam—One ﬂange, 3"x 1%"; one ﬂange, 9"x 1%";
depth, 12"; span, 20 feet.
(All from Eng. Exam. 1891 and 1892.)

.1. .1.
(I) W___4flalz=4><5><(Io><2+r3><2)><36=24,64 tons

28x12
a s
(2) 4X5>8<>4<21:8X8 =4-7 tons
(3)/Z ac = 3 x 1% ><4=I8 tons; andﬂat=9>< r—gx ri=r7 tons

tons = I7 cwts.
Example 26.—Find the depth of an~engine guide bar 10'’ wide
and 4 ft. span. Total piston pressure=25 tons; length connecting
rod==twice stroke; and greatest obliquity supposed to occur with
guide block at centre of span. j},=5 tons.
(Hons. Mach. Constr. Ex. 1892.)
Draw crank and rod to scale, Fig. 407. Then the forces are as
at A, and the triangle of forces, drawn parallel, as at D. Then
E : F : : r : 4.
D = N/FZ—E2= ,JIo- I =3'87
E __ press. on bars x 25
I
_ ._ _.____.__.______._ ’ —__ -—-—- = 6'
But D plston press. and press on bars 3, 87 46 tons

. 2 ___________
Then l¥=jg ﬁg‘ and_@: , /.W.__ZX6_ ,/6,4635.4X_l2_><_§=i
4><tfo_ ‘N’ ' 4x 10x5
Example 27.——-The girder stays of a combustion chamber are 21”
span, and spaced 8%” apart (see Figs. 311 and 312), the section being
rectangular, 5%” deep by 1%" wide. There are two bolts to each stay,
7" apart (Fig. 408). Find the greatest stress in the stay when steam
pressure: 225 lbs. per sq. in. (Hons. Mach. Constr. Ex. I891.)
Axle Example. 449
Each bolt supports 7 x 8% x 225 lbs. = 5'8 tons.
Max. Bm at B, or B,=R.>< 7" = g X 5-3 X 7=27 ton ins.
and Max. Bm at Bf = 27 + ~25 =40; ton ins.









0 x6
Bm =fZ andf= f-léi/zz— : 4'9 tons.
25m _ A I hi 55>‘ 1'7};
Z= . -ﬂi-—1-—"1
r/// W1 I ~ '
l: I I 1 529mm | '
. I‘ I E I] I
l
,f—ZZZMW _ , . . 1 +3....
4'4. i ".
‘ll?

Example 28.—An axle is loaded as in Fig. 409, with 5 tons at G.
Find greatest Bm; Bm tending to fracture each journal; and deduce the
diameters at these places, taking f,=5 tons. (Hons. Mach. Constr.
Ex. I879.) - '
Rt1 = 5x 5=2'14 tons R? = ‘71 x 5=2'85 tons
Bm at G = 2'14 x 4 x 12 = 102'72 ton inches

B.n at A = ‘1% X 102'72=6'42 ton inches
B... at B = 536 x 102'72=8'56 ton inches
7rd3 3________
Bm—Fz— (“at B): \/8 56><32><7:4_4S,,
-—-—- 22 —-
3 s
and a’: ,\/L:r32 and d (at A) = ___6‘42 iii—2 X 7 = 405”
Now in circular beams i area goes for bending, and g) goes for
shear (see Fig. 385).
G G
4.50 ' Beam Deﬂection.
Total shear at A =1‘, >< area left for shear
2'14 =fs x '6 x 12'6
fs = '28 ton, and similarly j; at B = '3 ton at A, so both journals‘
are safe for shear. 3
Finally, a’ (at G) = A / Bria-Saw = 10'15"
Deﬂection of Beams.—Take a supported girder, as in
Fig. 410, of uniform section, and imagine it deﬂected into an arc
of radius p. Bisect A B at G. Then D c B is similar to A 0' B,



\\i / _' W
\1/ [4,9411
because 6 is common, while a and a are right angles. If A is
small,
I l l2
p:—::-—:A andA=—
2 8p
EI I
But Bm=-—— and p =1}—
P Bm
_l2B,,,_z_e_/__l_X l2 _ wl3
_8EI_ 4 8EI—32EI
In reality the arc would not be circular but similar to FG, and
its deﬂection would be less;
wl3 . . . .
A=E§—E—I for a girder of uniform section, with central load,
and this will hold if the elastic limit be not exceeded.
Taking two cantilevers back to back, as in Fig. 411, we must
substitute for w and l in the above formula 2 w and 2 l respec-
tively; then,
For cantilever with } A __ 2 w x (2 l)3 w l 3
concentrated load 48 E I = 16 X 48 E I

Resilience of Beams. v 45 I

DEFLECTION FOR UNIFORM BEAMS, WHEN Y=“—;U-é—2.
Cantilever with concentrated load i 16 Y
Cantilever with distributed load 6 Y
Girder with concentrated load I Y
Girder with distributed load 51
Fixed beam with concentrated load 5} Y
Fixed beam with distributed load g Y
Beam supported one end, ﬁxed other central load gf-Y
Beam supported one end, ﬁxed other distributed load {-5- Y


3
w . on
A or m and stiffness or 73—
and the practicable‘ allowable deﬂection is, for cantilevers -1—"
80 9
and for girders 115" per ft. of span.
Resilience of a Beam is equal to half the proof or elastic
load multiplied by the corresponding deﬂection (see p. 367). For
a girder with central load,

wl3 4]‘1b5o/z2 e123
A—_48EI Lv_ 61 andI_ 12
2
,_ w wl3 r6flbso2lz2l3rz
.3 = A ='— = __
Resilience 2x 2x4815:I 36Z296E&h3
jibsolzl
18E and 0: all!
Flat Surfaces in Boilers are best calculated by the Board
of Trade empirical rule.
C (t+ I)2
s — 6
where s= surface supported by one stay, in sq. ins.
t= plate thickness.
100 when stays have nuts and large washers.
C = 60 ditto, but exposed to ﬂame.
36 stays riveted over and exposed to ﬂame.
Safe steam pressure p =
4 2 Beam Examples.
- Beams of Uniform Strength.—If rectangular beams be
proportioned to their bending moment at every section, the depth
or width will vary as follows, easily proved by equation :—
. Case I. - Depth 0: parabola.
Co‘gsltgnt ,, II. ,, 0: triangle.
,, III,, IV. ,, or two parabolas.
breadth \ ,, V. ,, oc semi-ellipse.
with ’ Case I. Breadth or triangle.
,, II. ,, 0c 2 convex parabolas.
Constant ,, III., IV. ,, or 2 triangles.
depth ,, V. _ ,, oc 2 concave parabolas.
Example 29.—~A beam of oak, supported at the ends, 2’ long, 2”
broad, 2” deep, supports 400 lbs. safely, at the centre, and its de-\
ﬂection is '06". Find safe load at centre, and deﬂection of a beam
of oak 16’ long, 9" broad, 14" deep, (I) with ends supported; (2) with
ends ﬁxed. (Eng. Exam. 1882.) -

- 2 3
Taking Z in feet and bit in ins. W OE 5?- and A Qc 2
Samplebeam,W 0C 2X2 =4 A CI ic—2)—.;<L88-=zoo
New beam, W1 oc (E—IIZ-ig—I-l = 1102
(1) Supported; W :W1 :: 4 : 1102 and W1=420—XZI—192=11,0201bs.
A : A1:: 200: 1600
A1 or Li:lI><—-625—§=16oo and A _1600><'06__ 8,,
9 9 1-—'__—200 "' 4
W! W!
(2) Fixed; Bm(r): Bm(2) 1; T = -8—- and A (2)=% A1

W2 = I 1,020 x 2 = 22,040 lbs. A (2) = = ‘096

Example 3o.—A beam of uniform section is supported at the ends
and loaded centrally. Find the ratio of depth to span that the deﬂec-
tion may not exceed ﬁlm; of span when f= 8000 lbs. and E=.28,ooo,ooo.
(Hons. Mach. Constr. Ex. 1887.)
l
Comhined Bending and Tension. , 45 3
3 19951
zol3 wl_ bszl __
andas—zf-fl 72, w_ kl
“BB1
__ 8fll3 =_f_l_2_ and_l_____ 8oooxl2
F48hlEI 6hE 1000 6><28,ooo,oooh
_l___6><28,000_,2__00_31
h 8000x1000 1

Combined Bending and Tension Stress-Action.—
Let the bracket in Fig. 412 support a weight W. There are two
\
4
J i .
l l/VE 01-’ (M41 f/NG 8&6}


ADI‘!
I
45142.22?






6"“








'1‘
l u
. _ | Q “ u:
. 11:11. ; is 15 44 512%
“gill/lip” Q “LL i.
\ .I _ ‘ r."
I | .
i 413- ‘ L/NEI/ 0F L/IJIITING $318555
actions upon the section: bending due to moment Wr, and ten-
.sion by direct load W. Then-
(1) Bending action: W r=j¢oZ andﬁ=1gf
W7’ Wr
01’ ftO=—Z— andft=26
. ' W
(2) Tensile action: W=ﬁa andﬁ=_a_
W Wr
Highest tensile stress (on inner edge of hh) = F, = ;+-Z—(-)
0= 1 for H sections, and 0= 2 for solid sections.
Strength of Crane H00kS.—-In these, theory and practice
'are considerably at variance. The following table is regularly
' l
is
454
used at Elswick, and has been well tested, the diagram being
given at Fig. 413.
Crane H oohs.
CRANE Hooxs (ELSWICK PRACTICE).









Tons. A. B. C. D. E. F. G. H.
% 3i% 2% It It I i i it
i 4% 2% lib 1% lib ii i% i
I 4% iii 1% I%% 1%’ i % f%
1% 4% 2i? It‘ 1{% ~If% I t 8
"2 5i 3 2 1% Ii IFB ii {b
3 5% 3% 2% 1% If% 1% I i
4 5i% 3fb zfb 1ft 1% lib I {b
5 6f% sit 2% 1% IFB Ii IFB B
6 6%% 3% zit Ii 1% 1% 1% it
8 1% at? 3 1% 1% 1% 1% it-
10 8% 4% 3f% 1% 1% 1% 1% %
12 8%; 4f% 3% 1% 1% Iii lib %
15 9%% 4% 3% ' Slit '2 Iii 1%% ii
18 10% 5th 4%% 2% 2% 2% 1% it
21 11 5% 4% 2% 2% 2i 1% %


Taking O = 2 we will examine three hooks.
21 tons hook: a=9'23", ?‘=5"t
f.=
at 1
9'28
21 x5-
6'2 x 2

Z=6'2
= 2'26 + 7'66 = 9'92 tons.
5 tons hooh: a=3'95, r= 2'97, Z=1'32
ﬂ=—5— +L7= 1'27+5'62=6'9 tons.
1 ton hooh: a=2,
f.=
3'95 1'32x2
r=2'15, Z= '5
.I. +m15=
2 . :5x2
'5 x 2'15 =2'65 tons.

' 8 Examples, in Tension + Bending. — 4 55
As 3 tons is sufﬁcient for ft in a crane hook, it is diﬂicult to
account for the ﬁrst two examples. Certain it is that 0 increases
with the beam section, but only a large value would satisfy ‘the
ﬁrst case. ' '
A hook within the author’s knowledge was straightened with
11 tons, and ‘upon examining by the above formula j‘t came out-
to 2964 tons breaking, which seems very reasonable.
Example 3I.—-A longitudinal steel boiler stay, 20 ft. long and 2"
diameter, supports a ﬂat area of 15 ins. sq., having on it a pressure of
120 lbs. per sq. in. Find the greatest stress in the stay due to its own
weight and the steam pressure. (Hons. Mach. Constr. Exam. 1890.)
Weight of stay w = 20x 12 x 3'14 x '29 = 2185 lbs.
Steam pressure P = 15 x 15 x 120 = 27,000 lbs.
wl 1rd3 _ 14w! __
Bin—~8— -fI,—3? andﬂ—mT-8342bs.
' ﬁa = 27,000 and f,= = 8598 lbs.
Total stress =ﬁ+ﬁ = 8598+8342 = 16,940 lbs. = 7'56 tons.
Example 32.—A piece of T iron consists of a web 4" deep and
%" thick, and a flange 2" wide and %" thick. Compare its strength
under ‘longitudinal pull for the two cases (I) with line of action
through centre of web depth ; (2) with line of action passing through
centre of ﬁgure of the T. (Hons. Mach. Constr. Ex. 1888.)
See Fig. 4I4.
Find neutral axis by taking moments round A : k=1'75". Draw
lines of limiting stress and ﬁnd stress areas.

~10 Z = areaX arm = ‘6875 x 3205 = 2203
a = 3 sq. ins. and r = '75"
_ W Wx '75 __ _ .
C353 (1) fmax — 3 + 2.203 —
Case (2) fmax = = '33 W
' 0
Strength (1) '33
_______—— : —-— : 0
Strength (2) _67 or as I 2 roug y

Combined Bending and Compression Stress-Action
is calculated by the same formula as for tension and bending, by
substituting fc in the direct stress.
456 , Faz'rbaz'm Cranes. and seas Davz'ts.
Example 33.'—-Fig. 415 shows a ‘Fairbairn’ crane. Draw the
bending moment for all sections, and design a suitable section at A B,
taking fo= 5 tons. (Hons. Mach. Constr. Ex. 1887.)
Bm diagram is given in Fig. 415, using centre line of jib as base
_ line. At each section the
Moment = W x horizontal arm to section.




-F[a.nqer
‘975 12,1.1/ 2|
"8 ) {valzrT/QA’VJ 1+
1.15 o‘ u
. | a, E
I E t z
k t3/4,‘ W17‘ Q
145' __ _ _ _ _ (v
/ ‘ i I '
'5" __ _‘ ’l
‘ a’ '31 l '
l
Q44... Q l /0 rofvs
Java/Na | ,
MOMENIS __._ - _./.5 __r__..J
IN I
rail-arr l l
/50 _ _ __L
..__.__.______W __
Section at AB can only be obtained by trial and error, and has thus
been found in Fig. 415. Checking by approximate method :
Area of two angles, one ﬂange, and
portion of web between angles
Z = alt = 16x24 = 384 and total area = 45 sq. ins.
r = 15x 12 = 180".
, i _ IO 10 x 180
-- flux—2'5“ 384XI
)» = 16 sq. ins.

= '22+4'7 = 4'92 tons.
Ships’ davits are similarly calculated, but their sections ‘are
like that of a crane hook.
Strength of Pillars and Struts. Although these fail
by compression and bending, the action is not so simple. Struts
of ten or twelve times their diameter are reckoned for direct
crushing only, but longer pillars bend before breaking. Euler*
devised a formula to give the greatest load consistent with
stability, that is, beyond which the bar could not restraighten.
2i:
Let "[2_I=Q.


* Pronounced ‘ Oiler.’
Long Columns: by Euler. 457 _
EULER’s F0RMULAE FOR LONG CoLUMNs.



One end ﬁxed the 71-2 E I
, = l :
other free w 4 l2. iQ
Both ends free but w_1_r2 E I _
load guided _ 72 _ I Q

One end ﬁxed the 2 E I
other free, but 22/ = 2 2r— = 2 Q



2
load guided 1
Both ends ﬁxed, ,_ 112E1 _ Q
and load guided 2f _ 4 l2 _ 4

@- |:-:-:~:r- 2513- s—.\._



A factor of safety of 5 must be employed, and I can be found
either from table or graphically (see p.432). The neutral axis for
I must be taken across the greatest width of section.
Euler’s rules do not compare favourably with experiment, so
engineers prefer Gordon’s formulae, which are a modiﬁed form of
those made by Hodgkinson from his experiments. They give
458 _ ~Gordon’s Formula. -
the breaking stress only,
Then :
( 1) For pillars with both ends ﬂat‘and carefully bedded :
. a
f breaking- I + M2

(2) For pillars with both ends jointed or imperfectly ﬁxed:
fbreaklng = m

l
r= . : and values of a and h are as follows :
shortest diameter ‘

ToNs.
GoRDoN’s CONSTANTS.



I)
For solid or hollow round C. I. pillars 36 1%,;
,, solid rectangular C. I. pillars 36 ii solid rectangular W. I. pillars 16 361,";
it Pill?lrs of L T l'~'l -l- or H section, W. I. 19 was
' 'ld t l 1
)9 solid round Pillarsj ml S 66 30 11°F
strong steel . .. 5 1 6.6
- . 'l t l _ 1
7! solid rectangular pillars{ ml d S ee 30 211???
strong steel 5 1 WW


Some results from these formulae are shown in Fig. 416, and
will be found handy for reference. A factor of safety of at least
6 must be used, and 10 or 12 in the case of moving parts.
Then:
breaking x area of section
W = f tons
factor

Claxton Fidler says a pillar strength cannot be an absolute
quantity, but may be anywhere between Euler and Gordon's
results.
and an arbitrary factor must be applied.
Bﬁﬁﬁlfllvé‘ 877?!“ 70%;‘ P47? JV. IIV.


Stress”
in; Pillar;

éy Gordan? formulaa
4/6'.
HOLLOW OR
504/0. REC m/vsuL/m _ .



















OR ROU/V0,
6887' I. PILL/1R6‘.
.5 1° 25 30 65 4° ‘5 so 55 6° 65 7O 75 80
RATIO OF LENGTH To 009.
SOL/D RECTANGULAR
WROUGH T / RON
701v: PER 80. IN
P/L L RES
0‘
BRL'ﬂK/NG
RATIO OF LENGrH .TO DI4‘
460 Pillar Example.
Example 4o.-I—'Find the diameter of a steel connecting rod 10 feet
long for a maximum load of 70 tons. (Hons. Mach. Constr. Ex. 1886.)
a 30 42000 d2

fbg: 1+4br2= I +‘ 4 X l_“" = 14ood2+4oo
1400 a’2
W ___ fbgx area
IO
2 2
'- 70 42000“, Xzzxd , and solving the quadratic,

: (1400 d2+4oo) x 7 x 4 x 10
d = ,./54‘5 = 7'4" at centre
For the small end W =fc a
1rd2 -———-~ ,,
'. 70 .= 4 x T and a’ = ,,/22'27 = 4'7 at small end.
The rod must be tapered as shown in Fig. 417 to meet the bending
stress in the large end, due to pendulum motion.
II
.Te-I-"H-‘l-r-wlwe- "_mw


[4 ’gg' . 412
Strength of Furnace Tubes.-—No satisfactory theory of
these having been propounded, we are driven to the adoption of
empirical formulae obtained from experiments. A tube pressed
outside is in a condition of unstable equilibrium, and fails by
bulge or collapse. For plain tubes '
By Fairbairn’s rule, modiﬁed by Unwin, { __ 3,500,000 ("2
the factor of safety being about 3 ° _ /”a’”
90,000 x t"2
' Wm’
These may be set against each other and checked by the simple
formula '
By Board of Trade rule
Sooot”
d”
p, = collapse pressure, pw= working pressure (both in lbs. per
sq. in.), t= thickness of plate, and a’=diameter. The ticks
show feet or inches. ‘
Board of Trade rule p“, =
Furnace T ubes. 461
For Foxi’s corrugated tubes,
Board of Trade rule 1)..
where d is least diameter.
14,000 t"
d”
Combined Torsion and Bending exists more or less in
all shafting.
In pure bending: ﬁ= #3722,
__
32
. Tm
and In pure torsion : f,: m
16
Combining these into one direct stress f.,, we have
B + J B 2 +T 2 . . . _
f. = m w m Wl'llCh Is the stress caused by a twisting
I6
moment Bm + ~/Bm2 + Tm2,

or a bending Bm + A/Bm2 + Tm2
moment of 2
In combined bending and torsion:
(1) Equivalent twisting moment = BIn + l\/Bm2 + Tm2
B... + ~/B...2 + "11,2
2

(2) Equivalent bending moment =
The ﬁrst is most used. Let the shaft in Fig. 418 be under two
pulls, D1 and W. Bm due to W is found by Case IV. and set oﬁ‘
at DE. Bm due to D1 is shown by the diagram 01H; where
‘G J is formed by the balancing force at G, and action shown
at v. MPN is the total Bm, having regard to sign. Twisting
only occurs between W and X, and is drawn at QSRT to the
same scale as the Bm. Now combine M OPN to form the
equivalent diagram ahcdefg, every ordinate of which is obtained
from the auxiliary diagram Y. Thus, take Bm on MN and Tm
of! QR, and, placing them at right angles, join the hypotenuse;
then turn Bm round into line with the latter, and measure off the
total ordinate upon a g. The total shaded diagram thus obtained
462 Combined Torsion and Bending.
is the equivalent T,,,, and the darker diagram, half of this, is the
equivalent Bm.
Example 41.—In Fig. 419 are some dimensions of a crank shaft.
Let P= 1 ton when at right angles to plane A C B, Tm being balanced
by a couple M at D. Find greatest Bm+Tm and diameter of shaft
when j§=6 tons. (Hons. Mach. Constr. Ex. 1893.)









_Ri_____
The end view shows how P1 must be introduced to make the
couple P P1 complete. Then P1 produces a Bm of %g- X 12 = 5'45 ton ins.
as in diagram, and P gives a Tm of 5 ton inches.
'. Greatest equivalent Tm= 5'45 + J34'7 = I 1'35
3 3_—____ _
and d: ~/_'|£1_6= /\/_____—__.II.35X I6X7=3'8650
'17 22


Combined Torsion and Compression. 463
Examﬁle 42.-—The crank in Fig. 420 is acted on by a force W,
which causes a Bm on the shaft equal to half the Tm, Find a and h
in terms of a’, so that all shall be equally strong. If d = 2", ﬁnd the
sizes. (Hons. Mach. Constr. Ex. 1889.)


‘Tm = Wr ‘and Bm=Yv2—7—’
Teq = Bm+ ~/B,..2+Tm2=-V§271+ N/(Ylf 2+(Wr)2=1'618Wr
2
3 . 3
'. 1'618 Wr='fswlg and W=Iirji (I)
2 6h2 3 _ 2 h3
W3r-f~6- and h—g .. Wgr-fi—é (2)
. 3 3___
Substituting (1) in (2) w=fizi and h= e/I'29 a'3=I'09 0'
rx3 16
‘ a
“i§=% ~"___a=1'57<>8¢
Then ifd= 2" h = 2'18” and a = 31416”.
Combined Torsion and Compression Stress-Action.
-—When a shaft is under thrust and torsion at the same time, the
stable load for the former is, by Euler:
772 E1
[2
and, if both actions be considered, according to Professor
Greenhill:
11'2 E1 Tm2
wl - 72“ ' tin
with which a factor of 5 must be adopted.
Braced or Framed Structures—We commence these
by stating two rules:
Rule L—[f three oblique forces keep a hody at rest, their direc-
tions meet at one point.
Bale 2.—-Their proportionate value will he shown hy the respec-
tive sides of a triangle drawn parallel to the forces.
Let A and B (in Fig. 421) represent two forces in direction
and magnitude. Completing the parallelogram, R is the resultant,
464 Reciprocal Stress Diagrams.
which can only be balanced by one single force, R1, equal and
opposite to R, so that triangle ACR represents the values of A, B,
and R1, and all three meet at E.
G is the force diagram, or triangle offorees, drawn parallel to
the forces, and notice that the arrows must follow round the
triangle in one direction. '

ﬁg. 421.
100/IV 7 0f ﬂirt /C/9 I' ION




Let forces A, B, c, D, E, balance at F (Fig. 422). Drawing a
and o parallel to A B, g is the resultant. Combining G with c, It is
the resultant. Similarly, j, the resultant of A, B, c, and D, will
equal E, and meet at the starting-point. Hence: [f a murder
of forces keep a oody at rest, their relative magnitude will oe shown
by a polygon, w/zose sides, taken in order, are drawn parallel to the
forces. If all the forces are known but two, those two can be
found from the polygon of forces.
Maxwell’s Reciprocal Stress Diagrams.-—The force
diagram of a framed structure will consist of several polygons in
' juxtaposition, representing the stress caused in the members by
the action of the loads. It is known as the reciprocal stress
diagram, and the extension is due to the late Professor Clerk-
Maxwell, though found independently by Mr. W. P. Taylor-
The method of lettering invented by Mr. Bow is not the least
S imple Case. 46 5
important part of the system, which we shall now illustrate by a
few examples.
Simple Roof Truss (Fig. 42 3).—~(1) State all the external
forces (loads and reactions). The rafters divide their weights
equally at at and ac respectively. The reactions must balance
the direct loads at h and c, and the load at a in addition, so that
Rt1 = 13'9 and Rm: 161. The ceiling weight does not affect the
truss directly.


‘we MM-rm-ml -- b 1
Whwh does rwt/Loumuy ‘(r-w ML 6,1,“ bu. d



. ' F, '1 FORCE
I , ‘FT-lo o locwb of ulna/Mm 15
44-—— ---,z ' l Rafar -
// 1i) cw2< I I 591:; _ Z
I D I l‘ c ' A 'C
r J6? I/'/
z/- /6-/
-l
\ / =blO'JJ'g'l5'9 _ __ V____ ___>‘ R
\' — — -—@— ores-ave qfcLkZl-ng \
A "— c /’ E 0
_ c
- \IIIAQ 4III
F E K
. I, f. /
Fgg. 423. a A _, c
(2) Assign a letter to each cell. Of these there is but one, the
triangle A.
( 3) Place a letter in each dim'sion of the external space, as
formed hy the lines of forces. These are at B, c, D, E, F in the
ﬁgure.
(4) Draw the force diagram for every set of radiating forces.
Take the four forces at corner c, each deﬁned by the spacial letters
thus: FB, Bc, cA, AF. (Adhere to one method, preferably a
right-handed rotation.) Set off vertical FB in force diagram=
5 cwt.: and BC = 16'1 cwt. Draw (:A to bottom member hc.
Then AFmust be to ac, and must meet at starting-point F.
The steps are clearly shown by the ﬁgure at G. Notice that the
arrows must follow round in the force diagram. The novice may
imagine a dotted circle round each set of forces to avoid con-
fusion caused by seeing two arrows on one member in opposite
directions. The reason of the latter is explained at H, where the
same pull is felt in opposite directions on the walls. If the
H. H


+ _
466 Suspension Bridge.
polygon does not properly close, the arrows may not be in the
right direction, and a new examination must be made.
Next take the point a, and draw the triangle FA, AE, EF in
the manner shown at J. EF should measure 15 cwts. Finally,
draw the polygon EA, Ac, cD, DE for the point b, as shown at
K, making CD = 139 cwts. and D E = 10 cwts. And the stresses
in the members may now be measured off, marking + for com-
pression, and — for tension:
+ in AF = 14'5 cwts.
+ inAE = 10'4 cwts.
— inAc = 9'5 cwts.
Thick and thin lines also represent compression and tension
respectively.
Suspension Bridge Chaim—A free uniform rope or chain
hangs ‘in a catenary curve, which is, however, so nearly like a
parabola that the latter is always substituted for simplicity in
practice. Taking the chain in Fig. 424, supposed weightless, but
with loads at even distances as shown, the forces at L and B are
necessary to keep equilibrium, and the chains will be in tension as
shown by the arrows. Supposing reactions to be 3% each, the
triangles ABc, AcD, AEF, &c., are drawn in succession. Then
the distribution of load may be found for cD, D E, EF, &c., and
the stresses in the chain also measured.
Warren Girder with Symmetrical Loads—First,
Distributed on lower boom (Fig. 425). The cells are equilateral
triangles, and the girder has been much used for American
bridges. Loads being 1, 1, 1, reactions are 192+15, and the
force 1% at J causes compressions in 11 B and 1-1 A, but tensions in
A J and AB. The force diagrams are drawn for points 1, 2, 3, 4.
5, &c., and the total diagram is given in the ﬁgures JKGDA.
Measuring the latter, we ﬁnd the stresses to be as follows :—
InAHandHG=1'73+ InHBandHF= 1'73+
,, BA and GF = 1'73 — ,, 5 HD = 2'31 +
,,cB and FB=0'58+ ,,AJ and GK=0'86—
,, Dc and ED = 0-58 — ,, CM and LE
2'02 —
Warren Girder. 467
Second, let a Warren girder be loaded centrally on top hoom.
The diagram is found at Fig. 426, and can be easily followed.
Warren Girder with Unsymmetrical Load (Fig. 427).
—The load is placed on the top boom and the force diagram shown
















below; but may be worked for other conditions. KM is, of
course, W, and ML {-6 W, and all the ﬁgures should close
at B. If W be placed at each apex successively, and a separate
diagram found for every case, we may, after examination,
ﬁnd the maximum stresses due to rolling load. Then Fig. 425
468 jio Crane.
gives stresses due to bridge-weight, and 427 those due to loco-
motive, 81c. Tabulate the stresses so as to ﬁnd the maxima,
thus:


ROLLING Loan Maximum lil’e
' load. Stress T l
Member due to 9m
. dead maximum.
1st 2nd 3rd 4th 5th _ load‘
position position position position position +
AH ol- ono In. on‘ ‘no qu- cao one +
BA .. _
&c.



After which the bars are designed to meet the stresses, either as
ties or struts. A lattiee girder is shown in Fig. 426, being two
Warren girders superposed.
Example 43.—-The post, tie rod, and jib of a crane (Fig. 428) are
I 5, 45, and 50 feet long respectively. Find all the stresses, (1) with
barrel on tie rod ; (2) with barrel on jib, with a load of 5 tons. (Eng.
Exam, 1887.)



56027,; D
C D
Reaetions.——Load produces both turning effect and downward pull,
resisted by equal horizontal forces at o and e, and by 5 tons upward
force at c. That at o is supplied partly by bending strength of post,
and partly by balance-weight. Letter the truss.
First, suppose the weight hung from a as a ﬁxed point. Draw
B C in stress diagram = 5 tons, and complete triangle B CA. Passing
to o, E A must be a pull to produce equilibrium, and B A E is the force
triangle. Finally, forces at o are shown by polygon A C D E A, and
stresses are :
on AB = 15- on CA= 16'66+ and on AE = 2'77-
Redundant Members. 469
Also EB = C D = 1474.
and weight couple = righting couple
Tons. Feet. Tons. Feet.
5 X 44'92 = 1474 X I5
22 I ' I = 22 I ' I
Case (1). Stress in tie rod from a’ to a becomes — I 5 +5 = 10 tons —
Case (2). Stress in jib from e to a becomes + 16-._2;+5 = 21% tons+ .
other stresses being unaltered. The advantage of Case (I) is obvious.
If the barrel be between a’ and e the stress must be resolved on the
two members. As the load varies from nothing to a maximum, the
righting lever of balance weight should be half the maximum.
Redundant Members are such as receive no stress in
force diagram, but contribute usually to resist buckling. In
Fig. 429, the cross-members connect the weak strut B with the


/


E69. 430.
strong tie A, but otherwise receive no stress. In Fig. 430, A is
redundant, but receives stress from the instability of strut B.
Example 44.—-A crane is constructed as in Fig. 431. ~Draw stress
diagram for internal and external forces. (Hons. Mach. Constr. Ex.
1888)
5 Ir £49". 4"- 9'1‘
b
D =




The crane is shown at a, and the stress diagram found at b, com-
mencing with the weight E D.
470 Roof Trusses.
Roof-truss with Five Cells—Two cases have been
worked in Fig. 432.
Case (1). Vertical load due to :
(1) Weight of roof and rafters, between two
principals. = 2 W
(2) Weight of snow on ditto.



AUXILIARY
FORCI
DIAGR/‘IM


e w- draw—{—
-ZL in‘,
l

\
B \ Chi/ha 1. J
JX-QEJSEQ DU; 70 VERTICAL
LOAD L I/<\3\\0P~
\ it til



5 w/ND - PREJSURE \JTAESSA'S

Taking each side of roof (1) + (2) must be distributed as
T3,; W, %% W, and T37; W at the three points respectively, making
reactions = total load, 2W; the forces are then as given; and
after lettering the spaces, the stress diagram is found as below.
Case (II). Oblique load due to wind pressure. Considering
the wind to blow horizontally (rejecting vertical load), exerting a
Wind Pressure. 47 I
rorce of from 40 to 60 lbs. per sq. ft. (according to the exposure)
‘upon the area (h x width of bay).
Total force Pt = 50 x h w’, say, in lbs.
Then Pt must be resolved upon ac to ﬁnd P,,, the normal
:pressure, so that: Pt X k
Pn t0ta1= at ,

and this force is distributed at a, d, and c as PH, g— P,,, 136 P,,.
In iron roofs the expansion is usually allowed for by ﬁxing one
‘end (a) and leaving the other free (h), which allows us to say the
reaction, R,,, is vertical. Now Rtl, Rtg, Pn are three balancing
forces, and must meet in one point X, found by producing Pn to
meet Rt, produced. Then joining a X, the direction of Rt1 is
found, and the amounts RH and Rt2 further obtained from the
auxiliary diagram. If the wind blow from the right, Pn is exerted
on oh, and x will be above instead of below h (Case 111.). Both
II. and III. must be examined, though we only have space for
the ﬁrst. Take the lettering as in 1., with the exception of the
additional external space L, and draw the stress diagrams as
shown below.
Finally, tabulate the stresses and add those of Case I. to the
maximum in Case II. ; then design the members to suit.
Framed Structures of Three Dimensions are such
.as include a solid instead of an area. They must be solved by a
step-by-step process, taking each plane in succession. We will
‘explain by means of an example.
Example 45.——A sheer legs (Fig. 433) is formed of two fore legs
145’ long and 60' apart at the base, and a back leg 170’ long attached
to a nut having a travel of 40'. The maximum overhang is 40’, and
“load 100 tons. Find the stresses in the members, (I) and (2), at each
end of the nut stroke; (3) when the load is directly over the base
"plates. (Hons. Mach. Constr. Ex. 1888.)
Case I. Nut at D.—Taking ﬁrst the plane ADB, the diagram P
:shows stresses
in AB = 174 tons, in AD = 82 tons.
Turning to the end view, the stress of 174 in AB must be resolved in
each leg, as in diagram Q, giving stresses
in ah and ac, each = 88 tons.
472 T lime-dimensioned Truss.
Case II. Nut at E.-—R is the ﬁrst diagram and S the second,
giving stresses
in A1 B = 92 tons, and in a o and at each = 47 tons.
l
I00



I
60

3w: or TONS
l l I | l . I .
o 40 5‘0 60
Sana: or 70:48

I I ‘ b ‘
|



Case III. is worked entirely from the end view. 100 tons is to be:
distributed on the fore legs, causing no stress in the back leg. Then.
by diagram T, stresses are
in ao and at each =51 tons.
CHAPTER IX.
ON ENERGY, AND THE TRANSMISSION OF POWER
TO MACHINES.
WE commence with a few deﬁnitions and explanations.
Force and Mass.--Engineers use ‘ gravity’ units for these:
the unit of force being 1 lb. and of mass 32'2 lbs. (g) or:
to
mass = —
8
Velocity is estimated in feet per second. If unzfor/n, the
distance travelled (s) depends both on rate and time occupied:
thus, 3 = to (distance = time x velocity)
shown graphically at A, Fig. 434. The diagram B shows
similarly the distance travelled with variable velocity, given by
the curve, the area being measured as at Fig. 326, Chapter VIII.
Acceleration (f) is the increase of velocity during each
second. Uniform acceleration is produced by any constant
force, the latter being measured by increase of momentum it
produces.* Momentum = mass x velocity.
Force producing acceleration = —— x f
g
Uniformly Accelerated Velocity—A body starting from
rest at o (c, Fig. 434) has its velocity gradually increased by the
amount f during each second t, and the ﬁnal velocity is 4 f But
the total time is 4. Therefore ﬁnal velocity,
Z)=ft.....(1)
and the distance is shown by the area, as at B, or :
n
s=-2-t=,13~ft2.....(2)
Substituting value of z‘ from (I) we have :
v2
s= z—j-r andzl == 2fs.....(3)
* N ewton’s second Law.
474 Velocity.
With an original velocity v, the distance is found by adding the
two areas at D, Fig 434.







A B _ _ C J’)
. v i
v 6 JP
, v f . ‘i a,_ _r_ aha,
I 2 5 4.1605 _j 4_ I 2 J a”; ‘o’
0 -> z: 0 —-+ b 0 _--> c was
'1“ 'F __"‘-"““““1‘1F
I ' I .
Iv. l F’t Ma
r‘(— -l*- 1,1 _‘LE car—Legs"
l . ‘ o
0" . . LL , ascer- M464.
0 _> 5m,- o ____9 t -— -__._.__
Uniformly Retarded Velocity is a similar case to D, the
ﬁnal velocity and total distance being found by subtraction of
areas, as at E, and are v1 — v2 and s1 — s2 respectively.
Collating results, with v1 as original and v2 as ﬁnal velocities,




U. A. V. U.A.V. with original velocity. U.R.V.
Z'zzff z’2=z’1'|"ft 7/2=7}i_'ft
s= .5712 s= tv1+5ft2 s=tv1—-§-ft2
v22: 2fs v22=v1+2fs v22=v1—2fs
Exanaole 4o.—-A locomotive and train weighing 100 tons start on
a level, and attain a speed of 60 miles per hour within one minute.
What was the mean pull exerted ?

_v__ 60><528o=3§
From“) f_ t — 1><6o><36oo 15
and Pull in 165. = 231: 10° X 224° X 22 = 10266 lbs.
-——_- g 32 x 15
or 4'6 tons, neglecting friction.
Conservation of Momentum.--Two balls, A and B,
Fig. 435, raised simultaneously, are allowed to fall, strike, and
rebound. The duration of shock is called the impact, and it is
Energy Forms. 47 5
found that the added momenta of the balls is the same whether
before or after impact, a fact useful in many calculations. In the
case of ordnance the total momentum is divided at explosion,
Momentum.
i769. 4435.


equally between gun and carriage on the one hand, and the shot
and charge on the other.

Highest velocity _ (weight of shot and charge) x I ‘I x (muzzle velocity)
Of recoil _ (weight of gun and carriage)

the quantities being in lbs. feet and seconds.
But if; = pt (p. 98) mean force of recoil = 3%? and
c5 6

maximum force = mean force x 2.
Energy is the capacity to do work—Potential Energy is
latent till some small change occurs to give it actual value: thus
the chemical energy in coal requires a small starting heat, and the
water in a high tank may be released by opening a small valve.
Kinetic Energy or energy of motion, is always visible, except in
the case of molecular movement merely.
EXAMPLES OF ENERGY FoRMs.
I‘ Raﬁggidyflght (sohd orjlEnergy of position.
2. Clock spring wound up : (
bent bow I Elastic Energy.
3. Compressed gas: J
. Nerve Energy: (Capableofmuscularexertion.)
That due to separation of positively
and negatively-electriﬁed bodies,
as in frictional electricity.
Electrical Energy : (
( Due to separate existence of
Potential Energy.
or #-
elements, as in gunpowder
L 6. Chemical Energy:
and coal.
476
7
8.
>2 9
no
2 10
1:1
.2
3 11
.E
M 12
I3
. Electrical Energy :
. Heat Energy:
. Chemical Energy :
Nature’s Stores of Energy.
EXAMPLES OF ENERGY FoRMs (continued).
(When in motion.)
e.g., the wind, heat engines.
As in machines.
The current in motion, as in
Voltaic and Faradaic elec-
tricity. .
Being molecular motion.
When combining, on account
of afﬁnity of elements.
The vibration of the ether
causing light and heat.
. Muscular Energy:
Gas expansion :
. Mechanical Energy:
l
l
. Radiant Energy :
The true energy is that only which is aoailaole, by reason of a
certain
difference of ‘ pressure,’ ‘ head,’ or ‘ potential,’ as measured
within fullest attainable limits.
II.
III.
IV.
V.
VI.
VII.
VIII.
NATURE’S SToREs OF ENERGY.
{
Direct from sun: probably sustained
by meteoric impact.
Due to fall from mountains to sea.
Due to difference of pressure caused
by sun’s heat.
Due to chemical condition of separ-
ation.
Heat Energy :
Water Energy :
Wind Energy:
Coal Energy :
l
Petroleum or oil -
Energy : {Dltto
Tidal Energy : Due to moon’s attraction, principally.
(1.) Due to separation of kind, as in thunder
clouds, and untractable: (2.) Due to very
small differences of potential in both an
and earth, and valueless for large oper-
ations.
Due to sun’s action on growth of
plants.
Electrical Energy : '
Food Energy : (
All these, excepting VI., are due to the sun’s heat, which has
grown
due to
coal. forests and daily evaporates water. V. is probably
a condensation of the once glowing earth.
C onsernation of Energy. 477
Conservation of Energy.-In every system, the total
energy, however changed in form, remains constant. This is
- shown by every fact we possess, and although impossible to prove
directly, its rejection raises absurdities. Stated generally,
Kinetic Energy + Potential Energy = Constant.
But in its more useful form for the engineer : in any machine,
(a) (b) (C)
- _ useful work work lost by
Total energy deposlted ‘— given out resistances,
unless some portion is stored for future use, as by a spring. The
most usual form of (c) is frictional heat, and we are quite certain
that more work cannot be received than was ﬁrst deposited, which
at once disproves the sanity of perpetual motion machines, de-
pending as they do upon a surplus.
Transformation of Energy.-Thus, generally, potential
energy becomes kinetic, and nice oersa, the simplest example being
a pendulum which is alternately stationary but raised, and moving
but fallen. Coal, potential in the mine, becomes kinetic, as
heat, in the boiler; and kinetic, as mechanical energy, in the
engine. Chemical energy becomes electric in the galvanic
battery, and heat energy electric in the thermopile ; while water
may turn a dynamo through a turbine. A locomotive brake
block converts mechanical energy into heat, and many other
examples will suggest themselves.
Numerical Estimate of Various Energies—A raised
weight may do work in falling. Therefore its
energy in foot pounds = '20 H (potential)

When reaching the ground its velocity will be—
____.__ {)2
a: ,g/zgH andH=;—ér
Substituting this value in the ﬁrst formula we have—

. zoo . .
energy In foot pounds = 2 (kmetIc),

which may be applied to all cases of moving bodies, whatever the
cause of their motion, for we may always suppose that the velocity
has ‘been caused by gravity, a strictly tenable artiﬁce.
l
478 Numerical Estimates of Energies.
When the moving body rotates round an axis like a ﬂy-wheel
rim, the linear velocity
N
v = 211'7'72 andn =—
60
Energy in foot pounds = W = '0001714 w R2 N2
where w is the weight of the moving body or ﬂy-wheel rim. Here
energy or w R2 N2

Example 4I.-—A ﬂy-wheel of a 4 H.P. engine running at 75 revs.
per m. is equivalent to a heavy rim 45” dia. weighing 500 lbs. Find
(1) ratio of its kinetic energy to the energy exerted in a revolution,
and (2) greatest and least number of revs. when the ﬂuctuations of
energy is 41- the energy of a revolution—(Hons. Mach. Constr. Exam.
1887)
(1) Energy per rev. = M29
75
Kin. energy of fly-wheel = '0001714 w R2N2 = 1682 foot pounds.
Ratio j F ly-wheel En. 1682 _ .955
= 1760 foot pounds.
(2) Let v1 = highest vel. : v2 = least vel. : v = mean vel.

Thenyl-_;lZj-2-=vandv1+v2=2v = zﬂ'RN x 2=29'436
60
Fluctuation =;%_(v12 —- v22 = 17—22 I and (‘I/1 — 7/2) (711 + 7/2) = £7269 + 7764
b
1760

'. v1 —v2 = 1'92 ft. per sec.
: 4 X 7764 >< 29'436
But (v1 -— v2) + (v1+v2) = 2v1 v1 = = 15678
and (v1+v2) — (v1 — v2) = 2712 v2 = = 13758
60
Finally N = R v = 5'1 v

2 1r
Highest revs. perm. = 7995 and least revs. = 70'16
The energy of a spring or compressed gas is the average force
multiplied by the distance moved : thus—
Energy of compressed : initial pressure in lbs.
spring in foot pounds 2
Energy of compressed __ mean ordinate of total expansion or stroke
gas in foot pounds _ pressure curve of piston in feet

X extension in feet
Prime Movers to Transmitters. 479
A unit of heat will raise I lb. of water through 1° Fahr. when
near 39°, its greatest density 5 and Dr. Joule found by experiment
that
One unit of heat = 772' 5 5 foot pounds of mechanical energy.
Thenumber 772 therefore is spoken of as Joule’s equivalent (J).
Electrical energy may be estimated in terms of mechanical
energy as follows :
Energy in foot pounds = '7 37 E Q.
where E = Electro-motive force in volts.
and Q = Quantity in coulombs.
Lastly, Chemical energy is measured by its heating effect,
found by careful experiment. Thus, 1 lb. of average coal will
give out 12000 units of heat when completely burnt, and these
may be further represented in foot pounds.
Prime Movers are machines which obtain Nature’s energy
at ﬁrst hand for transmission of, or transformation into mechanical
energy. Such are: Heat Engines, Water-Wheels and Turbines,
Windmills, Electric Engines,* and Tidal Motors.
Power is direct or controlled energy, as distinguished from
the free energy of Nature or that, say, of a bullet. The term is
more usually applied to mechanical energy or the mechanical
equivalent of other energies.T It should never be used to designate
a force.
Transmitters of Power remove the mechanical energy
of a prime mover to a distance, or change the components and
perhaps the whole form of the energy. The following is a list :—
L Linkwork: Connecting rods, coupling rods,
cams and levers.
2. shafting: { Lines of shafting, with clutches,
couplings, and bearings.
3. Spur gearing: I For connecting parallel shafts.
4. Bevel gearing: Connecting shafts at various angles.
5. Worm gearing: Connecting shafts at right angles.
- _ I Connecting shafts at various angles,
6' Belt gearmg ' l but chieﬂy parallel. D
7. Rope gearing (cotton) : For high speeds.
* By voltaic battery. + Rate or intensity of Power : Horse-Power.
480 Horse Power.
8. Rope gearing (wire) : Low speeds.
9. Pitch-chain gearing: Instead of (6) : positive driving.
10. Friction gearing: Instead of (3) and 1 1. Compressed air : For storage and for mines, &c.
12. Hydraulics : Water power for storage.
13. Electrical transmission : May be conducted in any direction.
Comparison of Agents.--The work a prime mover 0r
transmitter can perform in a given time may be referred to the
standard Horse-power, or 33,000 foot pounds exerted during one
minute. Then for any agent,
foot pounds done in one minute
33,000
In this way the following results have been estimated :

Horse power =
Horse Power of Various Agents.


Ft. lbs. H.P.
per m. per m.
A man raisin his own wei ht verticall
during a dagy of eight hoiirs ......... i 4350 .1318
Ditto, pushing and pulling at capstan 3180 ‘0963
Ditto, turning a winch ...................... .. 2700 ‘081 8
Horse pulling a cart . . . . . . . . . . . . . . . . . . . . . . . . .. 26150 '7924
or a man performs T16 to g, and a real horse T85 of a horse-power.
Theory of Machines—A machine is an assemhlage of
parts whose relative motions are fully constrained, and its purpose
is the transmission or modiﬁcation of power. The time-honoured
method has been to refer all machines, however complicated, to
six simple cases,*9 each consisting, according to deﬁnition, of more
than one part. They are:
I. The Lever : bar and fulcrum.
handle and barrel upon axle: equi-
l r .
2' The V‘ heel and axle ' { valent of continuous lever.
3. The Pulley I block and tackle: continuous lever.
4. The Inclined Plane 2 sliding plane and resistant base.
5' The \Vedge, ditto: equivalent to double inclined
' plane.
. , screw and nut : equivalent to con-
6' The Screw ' { tinuous inclined plane.
* Called (wrongly) ‘ Mechanical Powers.’
S imple Machines. 48 I
.and they can all be placed under two divisions—levers and
inclined planes. There is always a point P where the power is
deposited, and a point W where it is removed,* and the Principle
of Work states that
Work put in at P = work taken' out at W
meglecting resistances. But as work = force x distance,
W _ d
P ' i"
'where d = distance travelled by P, and D that travelled by W.
This is the underlying principle, and our investigations on
:machines are for the purpose of ﬁnding the comparison of the
.distances or speeds at P and W, for by inversion we shall obtain
'the relation of the forces W and P. The ﬁrst is the principle of
virtual velocities, and the second mechanical advantage. Then,
generally,
P><d=W><D, or
7.
vel. P force W Vt
vel. W _ force P : Mech' Adv' P

The Lever is shown under various forms in Fig. 436. By
moments:
W a
= WA . . = — = -
Pa and Mech Adv P A
The Wheel and Axle, Fig. 437, is reckoned similarly,
and its
a handle
Mech. Adv. = A = ‘ m
A train of gearing in Fig. 438 consists of two pairs of wheels,
a handle, and a barrel. The advantage of the ﬁrst pair would
‘*be 2 : of the second pair 5% : and of the wheel and axle if: So
1 .
‘the total 2
W a1 a_,_
a
Mech. Adv. 13- = A X A’; X A2
* The old letters P and W being retained, are meant to represent the forces
and also the points of application. Rankine called them eﬁbrt and resistance
respectively.
I I
482 Levers and Equivalents.
which can be easily proved by the levers shown below. Generally,
then, for toothed gearing with wheel and axle,
W followers wheel rad.
Mech' Adv’ P _ drivers axle rad.
the wheels being estimated by teeth, radius, or diameter.
<--A--',L~———a‘————2 tt--—-~ee--—--_¢p








Belting is a substitute for toothed gearing, as shown in lower
diagram, 21 crossed belt giving the same direction of motion as one
pair of wheels. N .B.--If revolutions only are required, the wheel
and axle does not enter into the calculation. ’
The Block and Tackle (Fig. 439).—-Neglecting friction,
the cord has the same tension throughout, and there are (in case
shown) six pulls on the weight, each equal to P.
No. of cords
Mech. Adv. ‘1 = -6I- or generally = I
P
W_
P
r-ilN
In any movable pulley M, because W only rises half
the height of P, as shown.
Inclined Plane and Screws. 48 3
The Compound Wheel and Axle is given in its most useful
form at Fig. 216, p. 204. P is the hand, and W hangs from the
lower hook. While the upper pulley makes one revolution :
W P’s dist. 1A 2A
Mech. ‘F = == 77-A_77B - 2
The reason W rises only half difference of circumference is that
the lower pulley is‘ movable.

PRACTICAL FORM






The Inclined Plane and Wedge are shown in Fig. 440.
While P moves through h, W is lifted through h, and
W h
Mech. Adv. i; = 72
Gr, a body being held on the plane by the three forces P, W, & R
(the latter belng normal), the relation of the three may be found
by the triangle of forces, Fig. 421. -
The Screw exists in combination with the lever, as in
Fig. 441 (see also pp. 206-7). If P make one rotation,
_ P’s dist. __ _2_1r_r_'
_ W’s dist. — p"

Mech. Adv. ‘g
484 Screw Cutting.
Example 42.—Arrange the gearing of a single purchase crab so
that 60 lbs. on a 15” handle may raise half a ton from a barrel 10"
dia. (Eng. Ex., 1891.)


Mech d _V_V_ _ follower handle _ 1120
' a v' P _ driver barrel rad. _ 6o
_ follower _ ‘1120 x5 _ _6 _
'driver_6ox15_9— 1
So the pitch line diameters may be 6" and 3732” for pinion and
wheel respectively, as in Fig. 442.
Example 43.—A shaft A has a spur wheel of 120 teeth, which drives
a pinion B with 1 1 teeth. On shaft B is a wheel of I 32 teeth driving
a pinion C of 10 teeth. Lastly, on shaft C is a wheel of 48 teeth
driving a pinion D of 8 teeth. A turns at 2 revs. per m. Find speed
of D. (Eng. Ex., 1885.)
The wheels are shown in Fig. 443.
vel. D _ followe_r_s_ __
120 x 132 x 48 = 864
vel. A - drivers 11 x IO x 8 1

D makes 864 x 2 - 1728 revs. per 111.

Example 44.—Two men at a crab exert 60 lbs. each on a 16"
handle. The pinion has 12 teeth, the wheel 72 teeth, and the chain
barrel is 12" diameter.‘ Find the load raised, neglecting friction.
(Eng. Ex., 1888.)
Mech. adv. W followers >< handle _ 72 x 16 = 16
P = drivers x barrel rod. — 12 x 6 I

_W: 16 x P = 16 x 120 = 1920 lbs.
Example 4'5.—ln a Weston block the diameter of the large sheave
is 10”, and that of the smaller 9". Find the load raised by a pull of
50 lbs., neglecting friction.
§V_ 2A _2><Io 20

W = P X 20 = 1000 lbs.

Change Wheels in Screw-cutting.—General principles
are explained at pp. 147 and 212, it being shown that:
Kinematics of Machines. 48 5
Revolutions of mandrel : No. of threads per inch. on mandrel
Revolutions of leadingscrew N o. of threadsperin. onleadingscrew

in order to cut a deﬁnite pitch. This may also be stated as

followers at L. S. end __ pitch L. S.
drivers at M end _ pitch M screw
or the pitches and wheels are in the same ratio, which ratio, being
found, must be accommodated by a suitable train.
Example 46.—-In Plate V., the leading screw being i” pitch, and
the wheels in the set rising by 5 at a time from 20 to 120 teeth, it is
required to arrange wheels to cut (I) a screw of 10 threads per inch,
right-handed, and (2) a screw of 1" pitch left-handed.
L.S. __ _'_ __ 15
M" '— a. _ '5' _
Putting 30 teeth on n (Fig. 135) into 75 on stud (b, Fig. 140): 30
teeth on stud into 90 on L.S., we have,
7_5__>i_9_2 : _I_5 and the handle at n
30 x 30 2 must be down.

(I) pitch ratio
wheel ratio =
u ' 1.4-8. 6
pt h t -_- = :1
(2) 1 c ra 10 M 4
Putting 45 teeth on L5. and 60 teeth on n; with any intermediate
on stud (say 60) we have,
H Isle:
3 and the handle at it must
4 be up.
Kinematics (of Machines) is a method of attacking
machine problems devised by Prof. Reuleaux, and anglicised by
Prof. Kennedy. We shall proceed to discuss its principles.
Pairs.-—The constraining parts are termed pairs because
they always occur in sets of two. Of these there are higher and
lower pairs. The former connect by points or lines, but the
latter by their whole surfaces.
Three kinds of lower pairs are possible: I. Sliding, as a
piston and cylinder. II. Turning, as a journal or pin. Ill.
Screw, including all screws and nuts. Complete or closed pairs
have their motions fully deﬁned: incomplete pairs require further
closure, as at Fig. 444, where gravity is not for the moment
considered.
wheel ratio = i5- =
""_"""'— 60
486 S lider- C ranh.
Kinematic Chains—A link is formed when two pairs are
connected, as in Fig. 445, and three or more links form a chain.
The Slider-crank Chain, Fig. 446, is the simplest of
these, the ﬁxing of each link in succession producing several


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useful contrivances as in Fig. 447, variety being obtained by
inversion or change of the ﬁxed link, and by alteration in the
relative lengths. Thus:
1. Fixing A 0 gives Direct acting engine.
F. . , Oscillating engine:
2' Dung B C ” and Quick-return (M, Plate X.).
. . Whitworth’s uick-return Fi . 1 ,
3' Flxmg A B ” i Plate XI.).Q ( g 77
4. Fixing block 6 ,, Stannah’s pendulum pump.
Prolonging C B to D making a straight line.
5- Fixing AC (and Scott-Russell’s straight-line motion,
H
twice its length)
Double Slider-Crank, and Quadric Chain. 487
Closed chains have their relative motions fully constrained by
chain closure or force closure. The ﬁrst occurs at 3, 5, and 2,
Fig. 447 3 when cdrives at 3 and 5, and A at 2. But at I and 2,
with c as driver, and at 4, dead points occur which must be over-
come by ﬂy-wheel or other force closure, unless an arrangement
like m be employed, which shows coupled cranks at right angles,
or chain closure. Gravity is often the closing force: e.g., planing
machine table, and many journals.
The Double Slider-Crank Chain has three links, two
turning pairs and two sliding pairs variously connected. Taking
the primary form in Fig. 448,
1. Fixing A 0 gives Donkey pump mechanism.
.2. Fixing A B and A c
at right angles, and
removing turning
pair to c
3. Fixing A B and A c
at right angles ; put—
,, Elliptic trammels.
ting one turnmg p_a1r ” Rapson,s Slide
at C ; two sliding . . . d 1
and one turning pair (Grvmgan increase everage as the
at B tlller IS moved hard over).
Quadric or Lever-Crank Chaim—Fig. 449 has four
links and four turning pairs.
. . - Beam engine: force closure b ﬂ *-
1. Fixing A B g1ves( Wheel => Y }
-2. Fixing A B, and l , .
making AC = B D ,, Watts parallel motlon.
-3' A: 03‘; Wheel coupling gear for locomotive :
links égqualpp ” closure by double chain.
.4. Ditto, but altering Special motion in wire rope-making :
lengths ” preserving verticality of drums.
Roberval’s balance :
:2 allowing weight to be placed anywhere on
the chain as shown
pan.
"5. Ditto, but doubling }
Most lower-paired chains can be reduced to these three
‘cases, which shows the advantage of discussing mechanism
‘.kinematically.
Higher Pairing.


44o.
PRIMARY FORM
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Classiﬁcation of Higher Pairing—All examples of line:
or point contact are included, as follows :—
Rron) LINKS. FLEXIBLE LrNxs.
Spur gearing. (Acting also as pairs at point of;
Bevel gearing (conical chain). Contact‘)
Friction gearing- Pulleys of all kinds, with.
cams- rope, chain, or strap-
Escapements. connexion.

and these are usually combined with lower pairs.
Augmentation of Chains. 489
Flexible links are called tension elements; and ﬂuid con-
nexions, as between boiler and engine, or accumulator and
machine, are termed pressure elements, but the latter are always
connected to lower pairs. A pump is kinematically the same as a
ratchet, the valves being equivalent to pawls (see Fig. 450).



@450. Ewen/tied‘
Augmentation of Chains is the multiplication of parts,
for convenience or the reduction of friction. Trains of gearing,
and anti-friction rollers (Fig. 451), are examples.
Summing up, mechanism may be divided into simple chains,
formed of rigid or ﬂexible links, which are again united by higher
or lower pairs, and all chains must be closed, either by the chain
or by external force.*
LIST OF KINEMATIC CHAINS.
Lower I. Crank chains: Sliding and turning and screw
pairing. I 2. Screw chains : I pairs.
High 3. Pulley chains : Tension and pressure elements.
and 4. Wheel chains: Uniform motion.
low 5. Cam chains : Variable motion.
Pairing 6. Ratchet chains: Intermittent motion.
A driving and working end are recognised in each of these,
corresponding to P and W respectively, and the
Velocity Ratio of P and W in Kinematics will now be
investigated graphically. Considering the instantaneous motion
* Friction closure is one form of force closure.
490 Curves of Velocity.
of the two ends P and W of a link, each point may be supposed,
for the instant, to be travelling in a sepai'atecircle, whose radius
will be at right angles to the aforesaid direction, and the two
radii will, unless the directions of motion are parallel, meet on one
side or other of the line PW. The meeting point is known as
‘the instantaneous or virtual centre, and the ratio of the
velocities of P and W will be the same as that of the radii from
the virtual centre. Of course these may change at every instant,
and the centre will move along a path known as the centrode.
Crank and Connecting Rod (Fig. 452).—In the position
given, W is travelling tangentially, and WD is its virtual radius,
while P is moving towards A, and has a radius P D. D then is the
virtual centre, and at the instant considered, the movements being
along the dotted arcs, p, wl,
vel. P _Bl>
vel.W _ DW
Taking various other positions, we may obtain a series of
virtual centres, and through them draw the centrode E D F,‘Wh61‘€
E and M are the positions of P when W crosses the line K E. The
curve passes out to inﬁnity at F and o, reappearing at L and Q, the
direction being given by the line J P when W is at G and P at H.
This means that P and W have then equal velocities. The
relative velocities being found for any position, their inversion will
give the relation of the forces P and W.
Curve of Velocities—It is often required to construct a
curve of velocities for one of the points, when the other moves
uniformly. Taking the second diagram in Fig. 452, the triangles
W o A and W P D are similar, so that
vel. P DP A_q
véh—W =‘Wv _ AW
Assuming W to move uniformly, being provided with a ﬂy-
wheel, A W will represent cranh velocity, while the projection of
PW upon the vertical at c or c will give AC or Ac the piston
velocity. In Fig. 453 the value AC is found and transferred to
the line A W at A E, and this being done for all positions, the ovals
or polar curves may be traced, whose radius vector always shows
Time and Distance Bases. 491
PS velocity for the given position of crank, while the crank arm
itself gives W’s velocity. Taking various positions of P on H J,
and setting up the corresponding polar radii, the curve of P’s
_ velocity is obtained as H K J, while the ordinates A w, set up on a
base N o of half crank circle circumference, shows crank velocity.
0


.0 Q Cca/n/c anal Gonneclzng [2001.
Assuming P’s pressure as uniform, the ordinates lm will give
a curve of pressure 3 and the A E ordinates, being transferred from
the polar curve to the base NO, will give a curve of tangential
pressures on crank. Notice points Q R and s T, where P and W
have equal velocities, and also points F and W, where P has its
highest velocity, and W its greatest pressure.
Time and Distance Bases—The proﬁle of velocity
curve depends on the terms in which we state the base-line
divisions. The curves in Fig. 434 are drawn with a time base
line (equal times), but the oblique lines at c and D would be
parabolas if a distance'base (equal distances) were used. In
Fig. 453, H j is a distance base, but supposing NO to represent
b
492 Acceleration Curves.
piston travel, Nho would be P’s velocity on a time base. The
ordinates at corresponding times are always the same, but the
abscissae vary, and the two cases must be thoroughly grasped by’
the student. :
Acceleration Curves show the rate at which the velocity
is changing. Let a point move from A to B, Fig. 454, with
changing velocity, as shown by the curve AC B, AB being a distance
hase (here a necessity). Draw any tangent DEF and a normal
EG, drop the perpendicular E H, and turn H 9 round to line HE,
giving a point in the acceleration curve. Continuing the con-
struction for various points, K LM is obtained, whose ordinates
show acceleration from A to L, and retardation from L to B.
N.B.—If velocity and distance scales are the same, the ac-
celeration may be measured to the same scale; but, if otherwise,
and
v = ft. per sec. of velocity to one inch,
d = ft. distance to one inch,
a new velocity scale must be made, being the velocity scale,
. . a’
stretched or compressed in the ratio ;.
The Oscillating Lever is examined in Fig. 455. The
virtual radii are drawn: WB a normal to the circumference, and
P B perpendicular to w _I. Then :
vel. P B P A D
vel. W=1;v or as AVV
For AD being to JB, the triangles WDA WJB are similar.
Turning A D round to A c, we obtain one point in the polar curve,
found as at Fig. 456, where ADW is right angle. W’s velocity
being uniform, the polar radii show P’s velocity. The centrode
curve passes to inﬁnity at K, N, G, and P, the direction of the
dotted lines being at right angles to WP, when the latter is tan-
gential to the crank circle, namely when P and W have uniform
velocities.
Whitworth’s Quick-return Motion (Fig. 457).-—B B
being the driver, revolving uniformly, the‘ velocities of W are to
be found. Imagine the links moved by a very small amount v:





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494 Linhwor/e Velocities.
let AP = r2 and B P = r1, while the angular velocities are respectively
102 and 611. Stated in circular measure (arc upon radius) :
'2) 7) w 7’ , 7w
w1=-—— and w2:.-'-—- __1=._2 and (02: 1 1
Conversely, linear velocity = w x rad.
or, veloc. W = 102 x A w and vel. P = w, r1

_;_—-—-
V6]. P w 7’ ' ' 7’ A P
1 1 and (substituting) 2
A W A W
' vel. W_tt>2><AW 1C0M2
Let the circle H JP1 be the curve of velocity for P. Produce
B P to B, drawing W E H A B. Then E is a point in the polar curve
for W, and B E shows W’s velocity for that position of arm.
Obtain several points, as E1, by joining AP1 and drawing W1 E1 A B. For proof draw W D P B. Then, by similar triangles :
vel. P AP PB
and from formula, ——- __ = -
vel. W AW E B
At J and H the velocities are equal. Plate XI. shows the practical
application of the motion.
The Pendulum Pump is treated by virtual centres at
Fig. 458, where the centrode is drawn, and
PS vel. __ 0 P _ ,
m - B—V-v for any position.
The Donkey Pump (Fig. 459).-Taking the lower diagram,
we may imagine W moved a small amount, tangentially, as Ww.
join W A, and drop c B perpendicular. Then, velocity being pro-
portional to distance travelled,
§>
ve1.P _jbw __ AB
vel.W_wW —Ti_c
B
W
;>
for the triangles p W w and B A c are similar. A series of points,
such as B, will deﬁne the polar curve, which is a circle, because
cBA is a right angle (Euclid, iii. 31), and while AW shows W’s





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496 ' - Stanhope Levers.
velocity, the radius vector shows P’s velocity. The motion of P
is known as pure harmonic, and occurs often in natural science.
Transferring P’s velocities to a distance base gives a semicircular
curve, but on a time base forms the curve of sines.
The Beam Engine linkage is shown in Fig. 460, with
centrodes and polar curves. The lines AP, BW, being at right
angles to the direction of motion of P and W respectively, will, if
produced, give the virtual centre M. Then if BK be to AP,
the triangles M PW and B K w are similar, and
vel. P P BK
-—____,__ _-
vel. W _ MW B w
the polar curves being completed as before. The centrode curve ‘
only reaches inﬁnity on the side J, when AH, Bw are parallel;
the ends OE meeting at a very great but ﬁnite distance. The
polar curves are similar to those of the crank and connecting rod,
P having greater velocity than W at times. When in the form 3,
Fig. 449, the quadric-chain has its virtual centres always atinﬁnity,
and therefore P and W have like velocities.
Point paths are often of more importance than forces, but
can always be obtained by drawing the links in successive
positions 3 and the mechanical advantage of a complex system is the '
product of the advantages of its parts. Taking now the power
transmitters in order,
(1.) Linkwork is suitable only for short distances, as in
the case of locomotive coupling rods, and is rather a modiﬁer
than a transmitter. We shall take a few further examples.
The Stanhope Levers, Fig. 461, were applied by Lord
Stanhope to his printing press. Two plan views are given: at
ﬁrst P and W have nearly equal velocities, but when they have
moved to the positions P,L and W1, the latter has no velocity, while
the former has yet the original motion.
P’s vel. 1 W inﬁnity
. - -- and __ =
W’s vel. 0 P 1

This means that a very great pressure is exerted at W when the
paperv and type are in contact. A polar curve for W’s velocity
has been drawn in the right band diagram, considering P’s velocity




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498 Toggle joint.
constant. D is the virtual centre, and D P, D W the radii; and the
triangle P E B being similar, P B may represent P’s constant
velocity, while P E shows that of W. The latter being transferred
to B P, gives points in the curve shown; reaches inﬁnity in the
direction B19, and nothing in the direction B A. W is then respec-
tively in the positions w and wl.
The Toggle Joint has many useful applications, the stone-
breaker and wagon-brake (Fig. 463) being examples. In Fig. 462
the joint is seen to consist of a simple slider-crank chain. 0 is
the virtual centre, and o P, o W the radii. Producing W P to c,
V61.P_E’_B_P_
vel.W_ BC_ BF

and several points, such as F, will form the polar curve B FD,
showing W’s velocity, where P’s velocity is uniform and repre-
sented by B P. The curve is a semicircle, having A as centre.
Cooke’s Mine Ventilator in Fig. 464 is a case of the
quadric chain. Crank and shutter shafts are connected by link
CD, and AB is a ﬁxed though virtual link. Two positions are
shown, the shaded air being drawn in, while the dotted air is‘
pushed out.
Quick-Return Motion.-See Fig. 457.
Valve Motion for engines needs examination only for
point paths, and will be treated in Chapter X.
Parallel Motions should strictly be termed straight-line
motions, but are now best known by the ﬁrst title. Watt’s,
(Fig. 465) is the simplest. A D and B 0 being equal, the upward
movement of P will be vertically straight, because D curves to the
left by the same amount as c deviates to the right. This is
extremely near the truth when a is below 20°, but not absolutely
so. Thus :—
60
a;(1—cos a) (1)
l
sin)8=sina+;;(1—cost9) (2)
D . t. {Pf r
evlielriirzgl mm} = 5 (COS a —- COS (3)
assuming (3 D to be vertical at central position.
Parallel Motions. - 499
To use the formula, ﬁrst ﬁnd 6, then the angle for sin ,8, and
ﬁnally the deviation, which is really due to a slight inequality
between a and ,8. If l = 12" and r = 24", then when a = 20°,
,6 = 20° 2' and the deviation is '00576", but is uncalculable at
much below ‘20°.
Peaucellz'e/s moz‘z'on, Fig. 466, consists of seven links, and is
ingenious but unpractical. It may, however, be adopted for
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'G'RHSSHOPPER
Paced/£66 Mail/‘0725.
extreme travels, being absolutely correct. P describes the vertical
straight line P R, which may be proved geometrically, ﬁrst pres
mising that D P, P E, E c, and c D are equal, while A B = B c.
c2=_y2+(z+x)2=_y2+z2+2xz+x2
Subtracting, :2 —62 i 22 + 2x2 = z (z + 2 x) = 2a
This being strictly general, we have, at position 19,
ail—[)2 = 21a, andza = 21 a1
500 Feathering Paddle- Wheel.
'01 z : 21 : : a1 : a, and the triangles are similar, so that angle a =
angle ,8. But a is a right angle, being in a semicircle.
Angle 5 is alwars a right angle, and
pr is a straight line.

Scott-Russell’s motion _ 5, Fig. 447, merely copies. at AD the
truth of the slide 0, DAC being always a right angle. A more
convenient form is the
Grasshopper motion, Fig. 467, where the slide is replaced by
a long link. The gear may be formed (1) with A B = B c = BD-
as in Fig. 447, or (2) A B : Bc : : B C : B D, the second being used
in grasshopper engines and the ﬁrst in a steam crane built by
Messrs. R. & W. Hawthorn, where a piston connects directly with
D to lift the load. The relation of the links in case (1) may be
found graphically : produce points D, B, c, to the respective
positions 1, 2, 3, on the base line 1, 3,: with centre 2 strike arcs-
1, 4, and 3, 5 : join 4, 5, and draw 5, 6, at right angles to 5, 4.
Then 6 produced gives point A 5 and length of A B, for 5, 2, is a
mean proportional between 6, 2 and 2, 4.
The Feathering Paddle-Wheel is shown in Fig. 468.
If the vessel move to the right with a velocity v, while the wheel
rim has a linear velocity of 'Uf; the ﬂoats should enter and leave
the water in the directions v, if they are to meet the water with-
out shock, for v, is the relative velocity of ﬂoat to water, found
by completing the parallelogram. The controlling mechanism
is obtained by quadric chain H G K E where H G is the ﬁxed link.
Stress in Linkwork Members may be found from the
principles in Fig. 423 et seq, the structure being balanced by
known external forces. 5
The Work Done at any point of a machine is obtained as
at Fig. 325. Taking the case of harmonic motion for donkey
pump, let total piston pressure P be uniform during stroke d’:
then Pd’ = work done at P and is shown by diagram in Fig. 469.
Setting out the pressure~curve for W, on a base 11' R, as explained
in Fig. 453, the mean of the ordinates will be ‘636 P, and as
work put in = work taken out
P x 2R= '636PX71'R
Arrangement of Shop Shafting. 501
which are equal, or no work is either lost or gained in trans-
mission, if friction be neglected.



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(2.) Shafting is used extensively for power distribution in
‘workshops, being combined with belting and toothed gearing.
Fig. 470 is the plan of a small shop as usually arranged. The
502 Shaft Couplings.
engine being ﬁxed at E H does not drive the main shaft M directly,
but through the medium of a main countershaft M c, so that M
may be stopped by moving the second strap on to the loose-
pullies, and the engine’s rotations be unaffected. The shafting
is supported by special bearings termed hangers, and by plummer
blocks in the wall thickness ; the hangers are bolted to the
roof principals, about 10 ft. apart. The machines are next.
arranged conveniently: in the diagram L L are lathes, D D drilling
machines, F L a face, B L a break lathe, P a planing machine,
HB a horizontal boring machine, SH a shaping and SL slotting
machines, M L milling machines, G a grindstone, E an emery wheel,
and T a drill grinder, while s is a surface plate. Next, short
countershafts are placed at cc, one to each machine; and the
power taken ﬁrst to these and thence to the machine, enabling:
the latter to be stopped and started by moving the horizontal
belt, without taking the vertical from off the cone pullies. The-
pullies should be placed as near bearings as possible, and be well
balanced to avoid vibration. Where one speed only is desired,
0 is not necessary; G, E, and T are cases in point, and D D have
the countershaft contained in the machine. The shaft might.
decrease in diameter, when further from the line M c, M ; but con--
venience in changing pulley position requires it to be uniform, and
if averaged-sized machines (about it H.P. each) are to be driven,
the pulley is simply gripped tightly on the shaft, both being made-
to Whitworth gauge: the main pullies must, however, be keyed.
Naturally, considerable power is required merely to turn the-
shaft without further transmission : this may be about 25 per cent.
of the total power required when fully loaded.
B B are ﬁtters’ benches, and B o is the boiler house.
Couplings connect the separate lengths of shafting, the most
usual form being the ﬂange coupling, Fig. 471, consisting of two
discs, one keyed to each shaft, and both bolted together, the bolt--
heads being sunk for safety : for strength, see Fig. 373. Couplings-
should be placed near bearings, and sometimes serve as pullies.
Marine shafts have the discs forged on to reduce weight, and thus.
form solid couplings (M, Fig. 126a, p. 132).
Clutches unite shafts, or pullies and shafts, so as to admit-
of disengagement when required. Fig. 472 shows the common


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504 Keys and Bearings.
‘claw ’ clutch. c is ﬁxed by key to the right-hand shaft, and B
slides on a pair of feather keys D in the left-hand shaft, so that
‘the claws at A may be locked or unlocked. The clutch strap E
encircles the clutch B, and is further grasped by the fork lever:
this gives a sufﬁciency of wearing surface between the rotating
clutch and stationary lever. The difﬁculty of entering the jaws is
met by the .adoption of friction clutches.
Shafts slightly out of line but perfectly parallel may be united
by the Oldham coupling, Fig. 474. A .middle plate 0, having
cross strips, unites with grooves in the ﬂanges A and B, and the
velocity is transmitted unimpaired. If the shafts are mutually
inclined, the Hoohe’s or Universal joint, A, Fig. 475, must be
employed, and if considerably out of line though parallel, B must
be used. A transmits the velocity unevenly, but the double
arrangement B rights this difﬁculty. Fig. 476 was adopted for
many years at a northern establishment: E is the engine, and
U I are universal joints, while the three shafts represent three
separate shops.
Keys were examined in Figs. 374-5. The sunk key is best,
but the ﬂat key is more often used in shop shafting. Cone Keys
(Fig. 473) are made from a hollow cone, turned and afterwards
divided : they give a very perfect grip.
Keys should have a taper in depth from front to rear, and a
gib-head adopted as in Fig. 477, if there are no means of otherwise
releasing the key. Although some workmen ﬁt keys at top and
bottom only, they should no doubt ﬁt accurately both at top and
sides. Shrinking boss on shaft gives very great security. Keys
are sometimes forged on the shaft. »
. Feather or sliding keys can be fastened either to boss or shaft
as most convenient. See A and B, Fig. 478.
Bearings are strictly gun-metal supports termed bushes, but‘
the supporting brackets take various forms. Fig. 479 is a
common hanger, Fig. 480 a wall box, and Fig. 482 a wall bracket-
The last two have bearing and bracket separate to allow of adjust-
ment. Fig. 481 shows a special hanger, having a long cast-iron
bearing lying in a spherical seat which adjusts itself automatically
to the shaft deviation. Permanent vertical adjustment is obtained
by screw and nut.
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506 Bushes and journals.
Footstep Bearings, Fig. 487, are required for vertical shafts.
Gun-metal bush A prevents side motion, and plate B, of hard steel,
supports the shaft. Even then there is considerable Wear, the
end being of comparatively small area, so the cotter is sometimes
introduced to adjust the bearing. There must be both inlet and
outlet for oil to secure good lubrication.
Thrust Bearings serve either as footsteps for heavy shafts or
to resist considerable end pressure in other directions. Fig. 488
shows the former. The bushes are in halves, being inserted with
the shaft, and the key A prevents their rotation. In the example
there are ﬁve annular surfaces resisting wear: one only is used in
a collar bearing.
Bushes are of gun-metal or brass, and in halves as at Fig. 484.
Being planed on the meeting edges, they may then be soldered
together, turned. and afterwards split. If made square, as in Fig.
485, they are planed throughout. Their position in the bearing
depends on direction of pull, Fig. 486 giving examples, where A
is an axle box, and B, c, and D horizontal engine bearings. If
one brass only can be used, the oiling is more perfect (see Fig.
580). Fig. 48 3 shows grooves ﬁlled with white metal, as adopted
with large shafts having variable moments, or where oiling is
difﬁcult; the particles of soft metal cover the surface, and form a
lubricant to prevent seizing.
Journals on shafting are often required to prevent end move-
ment : they are formed either by turning down, as at A, or forging
collars as at B (Fig. 489). The allowable journal load per sq. in.
. A I
.faunnals 489.





is reckoned on the projected area l>< d, and varies very much
with the speed of the journal surface, being low enough to avoid
squeezing out the oil. High-speed shafts have their journals
made as small as strength will permit, while the surface is obtained
by increased length, and the work lost in friction thereby reduced;
Horse-power transmitted by Ska/‘ling. 507
but in slow-speed shafts the frictional loss depends very little on
the speed, and the journal diameters are therefore large. The
following very useful table is taken from ‘ Unwin’s Machine
Design’ :—
ALLOWABLE PRESSURE ON PROJECTED AREA OF JOURNALS.

Pressure in lbs.
PuTPOSe- - _ per sq. in.
Very slow speed journals .. 3000
Cross-head journals 1200 '
Crank pins for slow engines 800 to 900 j
Marine crank pins < 400 to 500
Marine crank bearings 400 to 600
Railway journals 300
Crank pins for small engines I 50 to zoo
Marine slide blocks IOO
Stationary-engine slide-block 30 to 60
Propeller thrust bearings... 50 to 70
Main shafting in cast-iron bushes (Seller) 15



The ratio of l to a? must next be- decided by the following
empirical formula:
l
g= oo3N + T
which agrees well with practice. For the journal in Fig. 481, at
100 revs. per m., the ratio is 4: 1.
Pz'wz‘s supporting the ends of vertical shafts should not be
loaded beyond 2 50 lbs. per sq. in. for perfect lubrication.
Horse-power Transmitted by Shafting.-Taking a
round shaft, let to be applied to the end of a 12” arm.

lbs d3 lbs' 3
I6 12 x I6
ZUXIZ=
508 Square Shafts.
w being exerted through 21:- feet at every revolution :
w X 211'N flbs'n'd3 271-N flbsd3N
H.P.= = X =
33000 12 X 16 33000 320810

8
_ 3
_ 3 --—- H.P._ _ H.151

3 _—
H. P.
d O‘ x/f MN
Example 47.—-A shaft transmits 20 H.P. at 100 revs. Find (1)
how many H.P. it will transmit at 2 5o revs., and (2) dia. to transmit
40 H. P. at 2 5o revs. with f at 2 tons per sq. in. for stiffness.
(1) H. P. 0< d3 N
20 o: 100 _and H. P. req. 0< 250
100 :20 ::250 :H.P. and H.P. = 50
3
'7 = ' ——-———-————4O : ' I’
(7‘) Li- 6844‘V 2x224o><25o 225
Example 48.——Compare the weight of shafting in a twin with that
in a single screw ship, neglecting couplings : the H. P. in each being
the same and the speed of each twin being 25 °/o above that of the
single screw. (Hons. Mach'. Constr. Ex., 1886.)


3
d o: N/ o: 1 for ‘single shaft 0c '73 for each twin shaft.

Weights o: d2 o: 1 for single shaft 0= { Iggzicozr £21130 screws.
Square Shafts are often adopted in travelling cranes. In
Fig. 490, B is the longitudinal and A the cross girder of a crane,
the power being given from shaft D through mitre gear to F, and
by spur gear to G. As the carriage moves along B, the tumbler
bearings are turned through a right angle, and are only off the
shaft during the passage of the mitre wheels, the bracket at B
being shaped to serve as a tappet. -
S pur Gearing. 509
Long screws sometimes serve as shafts, as in large planing
machineswith travelling tool, and a linear advance of the screw
may produce rotation if sufﬁciently large in pitch, as in Fig. 491.




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(3.) Spur Gearing transmits power between parallel shafts
only. Spur wheels are the equivalent of friction discs, having
teeth provided to avoid slipping with heavy loads. The teeth
are formed partly above and partly below the disc outline, the
latter becoming virtual only, and then termed the pitch line.
Thus, a
5 I O C ycloidal Curves.
Pitch Circle, Line, or Surface of a spur wheel or rack
represents the contour of the ideal disc or straight-edge which will
transmit the same motion;
To transmit perfectly uniform motion the teeth must be
specially formed, and all teeth in gear at once must contribute
to the perfection of the motion. To fulﬁl these conditions the
normals to all points of contact must pass through the meeting
point of the pitch lines (Fig. 492), and this is obtained when one
tooth b c, on A, is the envelope of the relative positions of the other
tooth on B (Fig. 493) when the discs are rolled together. The
teeth are actually drawn, however, in a somewhat different
manner. .
Cycloidal Curves.-—A iycloid may be traced by a point
on the rim of a disc which rolls along a straight edge, and an
eqoi-cycloid when the disc rolls upon a circular arc (Fig. 494).
A hypo-cycloid is similarly traced within an annular disc as
at Fig. 495, noting that when the rolling disc is half the
diameter of the annulus a straight line is traced, as shown
dotted; a fact which has produced White’s parallel motion
(Fie- 496)-
Rolling Circle.—The above curves will serve for wheel
teeth, if the same rolling circle be adopted for parts that come
in contact, the tooth point being formed by epi-cycloids and
the root by hypo-cycloids. Taking the wheels A and B, Fig. 497,
a rolling circle is ﬁrst to be chosen as governed by the root
curves: thus, if the circle be half the pitch diameter, radial teeth
are formed, as at c 3 if larger, the root will be undercut as at D;
and E is drawn with a circle of i-pitch diameter. The latter
is reasonable, as giving strength, while yet avoiding oblique
pressure on bearings. Adopting then the rolling circles shown,
F may roll the root of B and the point of A, because these are to
engage, but G will serve for root of A and point of B. When all
the wheels of a train are at work together interchangeably, the
same rolling circle must be used throughout. If the tooth
pressure is always in one direction, as in Fig. 499, a large rolling
circle may be adopted for the acting surfaces and a small one for
the back surfaces, thus giving great root strength without oblique
action.
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512 Arc of Contact.
Rolling a Tooth.--Referring to Fig. 498, let AB be the
pitch line, and c the rolling circle. As the latter rolls from D
to E it takes up the various dotted positions, and the tracing
point D rises to I, II, III, and d successively, the positions being
found by making 1 I= 1 D, 2 II: 2 D, 3 III=3D, and Ed=ED,.
in every case measured round the curves by stepping off with
dividers. The tooth point being then sketched through, the
root curve may be treated in like manner, and the dotted tooth
formed by proportions found at a later page.
For a rack the same rolling circle is used for points and roots,
the curves being, of course, cycloids.
Rules for Small Pinions.——The ratio of wheel to pinion
diameter should not exceed about 8 to 1, or the obliquity of'
action is great; and the number of the teeth in the pinion
should not, if possible, be less than 20, though 15 and even '12
have been used in extreme cases. If the pinion be double
shrouded as at A, Fig. 500, the strength is doubled; and wear,
which is very great on the pinion teeth, well provided against.
Single shrouding as at B is of little advantage.
Arc of Contact.—In Fig. 501 a is the driver, t the
follower, and c the rolling circle, having tracing points E D
upon its circumference. Rolling 0 within a, the hypo-cycloids
G H are described, and the epi-cycloids K J formed round I).
But while 0 touches F, E D are equally ready to describe the one
or other set of curves, which means that D and E are the only
points of contact for curves G and J or H and K respectively ; and
all cycloidal curves drawn by 0 must have their contact points
along the arc cE F L. Supposing a to be moved round in the
direction of the arrow, the teeth will ﬁrst touch at L where h’s
point crosses circle 6; before this there would be backlash. If
(21 be struck below F, M shows the last touching point where a’s
point crosses circle c1. The path or arc of contact will be LFM,
LF being termed the arc of approach and F M the arc of recess.
FM is rather shorter than FL, so B is slightly greater than 6,
representing the greatest angles of ohliquity at recess and approach
respectively. If these be less than the friction angle,* there will
* The angle whose tan. is the coefficient of friction [.L. For rough cast iron
)1. :‘2, and friction angle : 111,9.







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514 Proportions of Teeth.
be no pressure on the bearings, the latter depending on the differ-
ence of ,6 and the friction angle. Drawing the teeth in position
at ﬁrst and last contact, their paths on their respective pitch lines
deﬁne the arc of action, which should be long enough to engage
two pairs of teeth at once, and avoid jerks.
Internal or annular wheels are examined in the same manner.
The obliquity is somewhat greater on the inside, as at f, Fig. 501,
and the curves are reversed for the wheel, an epi-cycloid forming
the root and a hypo-cycloid the point. Tooth point is sometimes
called addendum, and ﬂanh used instead of ‘ root.’
Proportions of Wheel-teeth, as at present adopted, are
given in Fig. 502. It is now proposed that they should be some-
what decreased in height, but the objection then is that fewer
than two pairs of teeth may only be in contact. The pitch Io”
should always be measured along the curve of the pitch line.
The difference ('52 — '48)]ﬁ" is termed backlash, and ('4— 3);)” is
called clearance. The former is sometimes eliminated entirely, as
in sighting gear for turret guns.
Example 49.—Determine the arc of action, and the greatest
obliquity of the line of action, in a pair of Cycloidal teeth. State also
how many teeth are in gear at once when p" = 2" ; T = 30 and 50 ;
dia. of rolling circle = 8%" ; height of points or addenda =3".
(Hons. Mach. Constr., Ex, 1892.)
Fig. 503 is drawn to scale. The arc of contact is from a to b, and
the
arcs of action are shown by radial bounding lines.
Greatest obliquity = 13?.
There are three pairs of teeth in gear at once.
The latter is found by stepping the pitch into the arc of action. Then
number of teeth in gear = no. of integral pitches + 1. -
Strength of Teeth.-The ﬁrst datum required is the
pressure on the teeth.
Example 5o.--A crab is required to raise 31; a ton by the strength
of one man ; 30 lbs. on a 15" handle. Sketch the gearing and'chain
barrel, pinion having 12 teeth of 1i- ins. pitch, and chain barrel being
74;” dia. Find also pressure on wheel teeth. (Hons. Mach. Constr.
Ex.,,1882.)
Pressure 012 T eez‘le. 5x5
Let x = No. of teeth in wheel.



By loads \g——= 5-2?)
BY gearing‘; “1:73,? 1" = HZZOXXIZOX 7.5 = 112 teeth.
Dia. of toothed wheel = NO' of teifh X pitch
'. = 4'7” dia. of pinion.
and Ill—2225i = 44'5" dia. of wheel
Then by moments, 3022? = 191 lbs. pressure on teeth
and the drawing is given in Fig. 504.
5,0 H£IGHT
PIT_C_H L/NE____

PROPO‘;
. Pﬁzstnr 1121;!”


. Assuming a possible pitch, the tooth is reckoned as a cantilever
wlth concentrated load, as at Fig. 505. Breadth b varies some~
516 Strength of Teeth.
what in different cases, but 2&1)" is a good working value, and h
is measured at the pitch line. If one tooth bears the whole
pressure and l = ‘716"; h = 48?": h = 2%Zp";f° = 2% tons for
cast iron. Then:

Safe load- 2 . . . .
on cast iron) = jig; = 2 5 x 2 562:.4819 X 48]) = ‘3222 tons
teeth. l 71” _—
Load may also be estimated in terms of the H.P. transmitted.
Thus :



M = HP, andw = M tons
33000 R N
But R — WT ' Load on tooth —- 1 ' ' ' tons
"" 27F ‘ ' '— 4 ‘
Example 51.—A C. I. toothed wheel 18" dia. makes 15o revs. per
m., transmitting 3o H.P. Find pressure on teeth, and pitch when
width is 2". (Eng. Ex., 1892.)


Pressure on teeth = w = ‘624 ton
'75 x 150 --———-
. _fo >< 2" >< (‘48th2 _.
Safe load - 6 x 7? _ 256p tons
'. '256p = ‘624 and pitch = 2'43”
Example 52.—A spur wheel 2" pitch and 4" face transmits 3o H.P.
with pitch line velocity of IO ft. per sec. Find H.P. transmitted by a
wheel of 4" pitch and 8” face, the velocity being 3 ft. per sec. (Hons.
Mach. Constr. Ex., 1881.)
0d/t2 0d ' 8 2 ,
w =f61 =f6 = 1955/36?’
H.P. = w X 60'” : '055ﬁ5ﬁ >< 60v
33000 33000
‘H.P. 0: W7,
(1) 30 o: 4><2><ro = 80
(2) H.P. o: 8X4x3 = 96
80:30: :96 :H.P. and H.P. = 36
= ‘00005 fo hﬁ'v
Involute T eel/z. 517
Summing up, spur gearing is designed as follows :—
(r.) Fix diameters to give advantage desired, keeping ratio of
each pair of wheels below 8 : I.
(2.) Calculate'pressure on teeth.
(3.) Decide on pitch, which should give at least 15 teeth in
pinion, and let tooth strength meet (2 ).
(4.) Roll the teeth, choosing the circle to avoid weak root or
great obliquity.
[Quite the easiest way of rolling is to draw the circle c (Fig.
498) upon tracing paper, and, placing it to touch at D, put a pin
at r 3 then turning the circle on centre 1, prick through at II.
Moving the pin to 2, c may be further rolled and 11 pricked
through, and so on till a’ be reached]
(5.) Mark off teeth proportions according to Fig. 502.
if
.9
’ ___ r‘ \ __ ;_.'\ _ 7 ..._},Z
429295 F’ 2K1’ /

Involute Teeth possess the advantage that their wheel
centres may be placed slightly nearer or further apart without
disturbing the accuracy of contact. The obliquity is, however,
greater than for cycloidal teeth. Fig. 506 shows the method of
drawing the curves. Draw two circles c and D whose radii are
518 M ortice and Helical Teeth.
each '968 of their respective pitch circles: their tangent CD is:
the path of contact, the obliquity being 1 51,; throughout con»
tact, and (i=0. Strike point circles cutting tangent at b the-
commencement, and at a the end of contact. If now a string:
be fastened at K, say, and a pencil attached to its other end c,.
the unwinding of K c will cause the pencil to describe the curve-
cd and ca K = d K. The curve is best found by drawing a line
on tracing-paper and ‘ rolling ’ it round ca K without slipping.
Internal teeth are similarly drawn, but the rack, Fig. 507,
has a base circle of inﬁnite radius R, so the teeth curves are-
straight lines.
Safe Velocity of Toothed Gearing, at pitch line, varies.
from 1800 to 3000 or 4000 ft. per m., the former for rough cast
iron, and the latter for machine-cut wheels.
Mortice Teeth, Fig. 508, are now little employed. They'
were introduced to decrease noise and jar, the teeth being of‘
Wood in one wheel, while the fellow wheel has iron teeth roughly
ﬁled up.








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8
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1729'. 508 _ 50
£49 ’- 9
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HELICAL Mei
R nee/cm
Q . 5H


Helical Teeth, &c.—The smoothest action being observed
to occur when a very small pitch was used, Dr. Hooke invented
his stepped gearing as in Fig. 509, to obtain strength and smoqth
action at once. These were changed later to the form at 510, for facility in casting and cutting, and recently the double-
helical teeth in Fig. 511 have been adopted to avoid endlong
pressure on the bearings caused by single-helical teeth. They
Bevel Gearing. 5 19
are machine-moulded by two half-patterns, and work smoothly if
well formed; being said to be stronger than ordinary teeth,
which is doubtful.
(4.) Bevel Gearing connects shafts whose directions meet
at any angle. Their ideal form is that of the frustra of cones,
as A and B, Fig. 512, having a common vertex, as c. The pitch
diameters are measured at d1, d2.
’
‘I’-
"-
‘—
'-
,'
w’
..
.’


I
/
¢







5,611.81» ‘Gearing; \
Two shafts A and B, Fig. 513, are to be connected so that
their revolutions shall be as 2 : I. Assume any convenient
diameter c D and draw c K and D M I] to A L. Taking E F = 2 c D,
draw E H and F G to B L. Through G draw GH at right angles
to B L, and G K at right angles to AL : then join H, o, and K to L.
520 PVorm Gearing.
Upon these cones the teeth are formed, their top and ‘sides
radiating from L.
Equal bevel wheels with shafts at right angles are termed
mitre wheels.
Bevel-wheel Teeth are set out as in Fig. 514. KGH
being the cones, draw Q P at right angles to G L, and with centres
P and Q strike arcs, upon which the teeth are to be designed as
though they were spur wheels. But although the teeth are struck
at G their strength must be reckoned at R, for there the teeth are
weaker in proportion to load than at G. Refer also to pp. 62
and 255.
(5.) Worm Gearing gives large mechanical advantage with
few parts. Friction, however, causes considerable loss unless the
gear be exceedingly well made. ' The methods of practical con-
struction are given at pp. 58 and 274, the latter being of course
preferable. In common with other gear giving high velocity ratio
with few parts, e.g., Weston block, &c., worm gear possesses the
property of non-reversibility; the wheel will not drive the worm
unless the pitch be excessive. The reason is that the direction of
pressure is within the friction angle and W is placed at a dis-
advantage.
M 6 Ch’ Adv. Vi’ : No. of threads in worm wheel
P N o. of threads in worm

Usually the denominator is unity. Plate VII. and Fig. 219 give
good examples. For the latter:
Total Mech. Adv.
. . . } = Adv. of worm >< Adv. of screw
neglecting fr1ct1on

__ 16 x 2x22><14 __1126.4
_ I 7 x 1'25 — 1
Man’s pull on handle W IO X 2240
when 10 tons are - = . = . = 20 lbs. nearly.
onjack 11264 11264 _'_—"_'_
Fig. 515 shows the forms of teeth, B being the best, though
A serves well enough for light pressures.
Screw Gear is used to connect shafts that do not intersect,
when moderate ratios are required. It is really exaggerated worm
Screw G earz'ng. 52 I
gear, with so many threads to the worm that it becomes a wheel.
Fig. 516 shows its application in a Multiple Drill where AA are
the drivers, and B B follow on the drill spindles D D. The wheels
are here equal, and the teeth inclined at 45° to the axis.


r‘\\
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'1 §
, -


Jhzzcw GWM
516.‘
Epicyclic Wheel Trains, like worm gear, produce a high
ratio with few parts. Kinematically they are ordinary trains
where one wheel is the ﬁxed link.
Case [.-—Fig. 517. A and L are in gear, with AL ﬁxed. If
A make a minus rev. with relation to A L, L will have made
A A . . .
1 plus revs., because 1 is the ratio of the tram. Next ﬁx A and
put L out of gear. If now arm AL make one plus rotation two
things have happened: A has made one minus rev. relatively to
A L, and L has made one plus rev. relatively to A. Finally, put
A and L in gear, and give A L one plus rotation. L receives two
I O O C A
motions : one plus rev. due to its connection with A L, and 5 plus

revs. due to the relative minus turn of A both relatively to
A, and
L’s revs. = I + i
522 Epicyclic Trains.
Case TT.—Fig. 518. The only alteration is the direction of Us
motion due to A’s minus turn, which is now reversed, so that
, ‘ A
Ls revs. - 1 — i
A special case is when A = L, and Us revs. = 0, the upright
arrow shown preserving its vertical position.

In Fig. 519 Ferguson’s paradox illustrates Case 11., giving
three different motions on one axis. Here L2 has equal teeth
with A, L1 has one tooth more, and L3 one less. Therefore

A
Ll’s revs. = 1 — A+ I and are plus.
A -
L2’s revs. = 1 — A and are nothing.
- and are minus.
A - 1
Case [TT.—Fig. 520. Let A and L be equal. Then, by
formula:
L3’s rev's. = 1 —

L’s revs. = 1 +
v-AIH
=2
Reverted Traz'tzs. 52 3
relatively to A. We may vary the experiment by carrying A
round L, but so that A does not revolve; then the relative posi-
tions will still be the same, as shown by a comparison of the
ﬁgures, and L will again make two revolutions while A is carried
once round it.
Watt’s sun and planet gear, Fig. 521, is a practical example.
A slight deviation from the rigid vertical occurs at e and a’, but
the total result remains; s makes two rev. for one rev. of the
crank. '
Case [V.—-A Reverted Data is where A and L have the same
axis. In Fig. 522, A is ﬁxed and L reverted, while aael shows
the train in direct order.

. . . ax!)
The tram ratio 1s and
e>< l
a ><t
l’s revs. = 1 - —-
exl
If A and L are nearly equal, we may obtain a very slow
relative rotation, as in Fowler’s ﬁrst coiling gear, Fig. 523. Stud
D supports the drum and gear, A is the ﬁxed wheel, and a dif-
ference of about one tooth in 40 between A and L causes the
latter to turn very slowly, rotating the cam E, and raising or
lowering the coiling lever and guide pullies as required.
Fig. 524 has an annular wheel, but is otherwise like Case II.
Opening out the train, it is found that while l’s revs. are minus,
those of L are plus, so A
' 7
Ls revs. - I + L
Its application is shown to a ship’s capstan ; and
I lever arm
‘VI - - =
l ech Adv Las revs_ X barrel rad.

D being inserted for steadiment.
Moore’s Pulley Blot/e, Fig. 525, is a reverted train with annular
wheels. Referring to the lower diagrams, the train ratio is
a x a’ . . . . . -
Z—X—l, and a minus rotation 1s induced in l or L by the relative
motion of a or A. A x D
'. Lsrevs. = I -—


.- _
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Moo/2934- Dlﬂenential/ Pulley Blow
526 M oore’s Pulley Bloch.
If A and L are nearly equal, we have a high velocity ratio.
In the block, the eccentric G, corresponding to crank e j: is rotated
by hand chain round H, so that A and L are turned oppositely,
each by half their relative motion, and W’s rise is due to this.
Then
P’s distance = 211R '
2 11' r X US revs.
W’s distance == 2
P’s dist. 2 R
and Mech' Adv‘ : W’s dist. : r x L’s revs.
In the example BC has 14, L 15, and A 16 teeth. If R = r
Mech. Adv. = ——f6—;;; = 32 :1
14X15
Another reverted train is obtained by bevel wheels, as in
Fig. 526, being applied as driving gear to traction engines and
tricycles. B is the arm, and AL the ﬁrst and last wheels respec-
tively. When the front road wheel is steered ahead, A, B, and L
are practically locked, and the two hind road wheels move with
equal velocities 3 but if the front wheel be steered, say, to the left,
A becomes ﬁxed and L revolves at double speed, thus steering
the engine in a much smaller curve. Fig. 527 shows a detailed
section through hind axle.
Fig. 528 is a disguised form of sun and planet motion, where
L is annular and the slider-crank chain is employed. Considering
A ﬁxed, as above,
, A
Ls revs. _ 1 -I
If A and L are nearly equal, a slow movement of L is obtained,
as in Fowler’s second coiling gear, Fig. 529. Eccentric B serves
as crank, and D as connecting rod; A and L have the same
meaning as in Fig. 528, and the cam and lever are as previously
described.
(6.) Belt Gearing has the disadvantage of slip, but is
_practically noiseless, and will transmit power a considerable
distance (say 30 ft.) without intermediate support.
Belt Gearing. 527
Tension of Belts.—In the ﬁrst place there must of
necessity be a fig/it and a slae/e side, whose relative tensions we
will investigate.

Q W
avenge/rye. ~\\\\\\\\\\
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x ‘V
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. R

FDA/Lars Gear
' 6515c o/vp)

. . l .
In Fig. 530 the belt embraces an angle 6, WhlCh 1s 7: 1n
circular measure. Considering a small angle 0', the greatest
tension without slipping being TH and the lesser tension t1, these
forces are balanced by reaction R, inclined to radius by the
friction angle (p. Drawing a l) perpendicular to R forms the
force diagram A a a, where A a = tension T,,, A l = tension t2,
and a a = reaction R, and if the construction be followed through
angles 0'1 0'2 0'3 0'4 and 05 the ﬁnal tension in is found for the slack
side of belt. Curve a a’ g is a logarithmic spiral, whose tangents
528 Tension of Belts.
make a constant angle with the radii, and if the angles 0' are taken
small, the construction is fairly correct. But greater accuracy is
secured by using the equation to the curve,
T—n = eye where s = 2'718, the base of Napieran logarithms.
n
More usefully the formula becomes
Tn l
Log-<7) = ‘4343 I“;




Then, the log. being known, the corresponding number is
found from a table, and the formula used for any value of
_2, even heyond 360°.
7’
COEFFICIENT oF FRICTION (a) 1N TENSION ELEMENTS.

Leather belting on iron pulleys ....... .. '3 to '4 '15 if oily.
Wire rope on iron pulleys ............. .. ‘I5 . not accounting‘
Wire rope on leather-bottomed pulleys '25 for wedge
Hemp rope on iron pulleys .......... .. '28 to '18 action


Driving Pull 0f Belts. 529
T
TABLE LOGARITHMS OF
72
'55 Log 3%: Log 2? Log
Il ‘09691 3% ‘54407 5% ‘75966
Ii» ‘17609 3% ‘57403 6 ‘77815
1% ‘24303 4 ‘60206 6% ‘79588
2 ‘30103 4% ‘62840 63; ‘81291
2% ‘35218 4% ‘65321 6% ‘82930
z-l ‘39794 4% ‘67670 7 ‘84509
22- '43933 5 ‘69897 10 1'00000
3 ‘47712 _ 5;} ‘ ‘72016 100 200000
3} ‘51188 5% ‘74036 300 2'47712



Driving Pull and H. P.—If two weights are slung over a
pulley, as in Fig. 5 31, the pull on the rim of the latter will be due


to their difference, 201-20, and as this is the same case as a
dI'iVing belt, Driving : Tn _ in
. ' n _ in V
and H. P. transmitted = U
33000
' ‘a H'P.=(Tn_ 11> 27TRN

33000
Strength of Belting, allowing for the joint, may be taken,
so that flbs (safe) = 320 lbs. per sq. in.
and the thickness varies from Iii," to %" in single-ply belts. The
width must be made sufficient to meet T n.
M M
5 30 Centrifugal Tension in Belts.
Example 53.—A leather belt is to transmit 2 H.P. from a pulley
12" diameter on a shaft making 160 revs. per 111. Find (1) the
tensions, when the belt embraces half the pulley rim, and ,a = '3 : (2)
the belt width when the leather is %” thick.

Tn ' 0 0 a Tn l
(I) Los- -;n-= 4343 X 3 X -;= 40905 ‘K = 31-2
HP, = <Tn- 11> "RN andTn_,n._. _2><_33_____ 00W: ,3, 1b,,
33000 2x22 x '5>< 160
There are two values of T,,, viz., (tn + I 31) and (2'5 tn).
2'5 tn = tn + 131; t1, = 87'3 lbs. and T,1 = 2183 lbs.
(2) w" x '25 x 320: TI, = 2183 w” = 2%"
Tension in Belt due to Centrifugal Force may be
examined similarly to the ﬂy wheel at Fig 3 5 3. The weight of a
cubic inch of leather (w) is '03 58 lbs., and the stress per square
inch becomes 2
12 wv lbs

0‘
<5
. _ . . u 2
Total tension on tight side -_- '1‘n + 43 ‘wt . 71
0’
<5
which is the total force the belt must resist at high speeds.
Creep, Slip, and Speed.-—As the belt tension changes
from TI, to tn, a small retrograde movement or creep occurs
due to release of tension, causing the follower to revolve at a
slightly decreased rate. The result is known as slip, and repre-
sents a loss of about 2 per cent. The speed of belting should not
exceed 3000 to 4000 feet per m.
Length of Belt (Figs. 5 32 and 533).—The length between
centres c should not be less than 6 times D if much power is
transmitted, though much less is used with light pressures. It
may be as much as 30 feet. Horizontal belts give better
results than vertical ones, and some inclination should always be
given if possible. Taking the open belt, Fig. 5 32,
ll: 6'2 : [2 = 22 z 2 2 2
and Total length of belt = 2l1 + 12 + l3


1\









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53.5.. Letitia;



5 32 Length of Belts.
In the crossed helt, Fig. 53 3, draw a f, be at right angles to Z1,
and f; H a h, The various angles 6 are equal, and

D a’
__+__
sine = 2 £2: 1);‘! from whichﬂmay be found.
Thenl1=c'cos.6 : 12:75!)— : 43:72’ l4=—6—X71D
2 2 360
6
[fr-:—
0 360x111!
and Total length of belt = 211 + 12 + Z3 + 2!, + 215

If D +d be constant throughout the pairs of cones, a crossed
belt will ﬁt equally well on any pair. Thus in Fig. 5 3 3, when the
belt is changed to the dotted pulleys, l1 has a constant value,
and as circumferences vary as radii, the sum of the embraced arcs
will also be constant. This is not exactly true for an open belt,
but may be safely reckoned on in practice. The diameters should
always be measured to centre of belt thickness.
Belt Fastenings.—The common methods of connecting
the ends of leather belts is by lacing (A) or copper riveting (B),
Fig. 534. There are, however, many convenient metal fasten~
ings, as Harris’s, at 0, being a spiked plate having the points
burred over after connection 3 and Lagrelle’s, at D, where the
belt is ﬁrst bent over. The belt being laid on the pullies and
tightly stretched, has the length marked, and the joint made while
lying round the shafts: the belt is then'placed upon one pulley,
and gradually drawn on to the other by tying it to the rim and
slowly rotating the latter. Large belts must be stretched by
means of clamps. Tullis’s chain belting, Fig. 535, has 2 5°/o more
grip by using the edge of the leather, but the method is expensive.
Advancing and Retreating Sides.—Let A, Fig. 536, be
a pulley whose belt enters at B and leaves at c: it will remain on
the pullies while exactly at right angles to the shaft, as at D.
If, however, the advancing side be deviated as at E, the belt will
slip off to the left, but the retreating side may be deﬂected, as at
F, without any harm. In a curved pulley, Fig. 537, the belt will
ride on the large diameter with safety, for if placed at A, the pull
causes a deviation which moves the belt to the right, if at c the


















TABLE
5 34 C ountershafting and Pullies.
movement is leftward, and the ﬁnal position is that at B. The
radius of curvature should be three to ﬁve times the pulley
width.
Countershafting and Speed Cones—Fig. 5 39 shows
how a shop machine M may be driven so as to be started and
stopped without affecting the main shaft revolutions or removing
the speed cone belt 0 c. B is the main shaft and A the counter-
shaft, the latter having fast and loose pulleys L and F. The fork f
on the striking bar 5 then grasps the advancing side of the belt,
and is moved to right or left by pulling the handles D, which act
on the belt crank L.
Quick return is obtained by the belting at Fig. 538. An open
strap turns the advancing, and a crossed strap the returning pulley,
and in each case there is a narrow fast pulley and a broad loose
pulley. The fork is shifted automatically at either end of stroke,
and the machine stopped or started by placing both belts in
position shown, from the handle H. The total width of pullies
may be reduced to four times belt width by the arrangement
shown below, where two striking bars are employed with which
the black tappets only engage at certain times. Many belt
examples will be found in Part I.
Problems in Belt Driving—The more difficult cases
are shown in Fig. 540, and will be understood if it be remembered
that the advancing side of the belt must lie at right angles to the
shaft, while the retreating side may make any deviation.
Pullies for Belt Driving are usually split, for convenience
in ﬁxing. Fig. 541 shows the construction of a cast iron, and
Fig. 542 of a wrought iron pulley. The former should have
curved arms if more than 12” diameter (see p. 67), and the latter
is adopted for lightness with high speeds or large pullies. Fig. 543
shows a section through a pair of fast and loose countershaft
pullies, which need not be split.
(7.) Cotton-Rope Gearing is much in favour for spinning
and weaving mills, and has been successfully applied to travelling
cranes and dynamo driving. For mills, the ﬂywheel rim has the
section shown in Fig. 544, and the ropes lie in wedge grooves.
With a ﬂat pulley the resistance to slip would be Pp, but in
the grooved pulley shown the resistance is 2 R71, there being two
Cotton-R ope Gearing. 5 35
friction surfaces. The grip is greater in the second than the ﬁrst
. . R . R
case in the ratio 31-)- : I. From the force dlagram, 217 == cosec.
22%° = 2'6131, and ‘a? = '28 X 2'613r = ‘732, which should
be substituted for [.1 in the tension formula already given.

___¢_._
Ltvlmou
l
Messrs. Jno. Musgrave and Sons, of Bolton, have ﬁtted up a
large number of mills with cotton-rope driving, and the following
remarks and tables are the result of their experience as given in
536 Cotton-Rope Pullies.
their treatise. Hemp and Manilla ropes do not wear so well as
cotton, or transmit as much force. If the pullies be large and the
rope as small as possible, to prevent disintegration of ﬁbre by
.\\\\\\\\\\\\\\\.
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_§\§\_\,\\\\\\\\~ zfilgll'lum





ll ‘1:. '-' l‘:-






l P
5.0. 544. PM yo} Concert R0__.
bending, the life of a cotton rope may be twelve years in good
hands, and has even reached seventeen years while still in good
order. Taking the area of circumscribing circle, the breaking stress .
is 4 tons per sq. in., but a factor of 30 being adopted, 300 lbs.
per sq. in. is the safe load; or about the same as leather belting.


Examples. 5 37
DATA FOR COTTON ROPES, WHEN V = 4700 FT. PER M.
(Messrs. MUSGRAVE.)
Ask Centri- 0 A
Dia. Area Weight *5 a ho fugal 8 ‘E. H. P. Centres Dia. of
of of per ‘a N stress 8'2‘: l trans- pulley smallest
rope. circle. foot. t "*+ I2 202/2 5 3p? mitted. grooves. pulley.
6’
ins. sq. ins. lbs. lbs. lbs. lbs. ins. ins.
% ‘I963 ‘081 47 16 all 443 %- ' 15
g1 '3067 ‘125 72 24 48 6'84 I I8
% ‘4417 ‘184 106 35 71 1007 Isl 22
% ‘6013 '25 I44 48 96 I367 1T5? 26
I ‘7854 '33 190 63 127 1805 1.12 30
1;}- 1'2272 '51 294 98 196 279 1%?- 37
1% 1'7671 '74 426 I42 284 4048 23}— 45
Ii 2'4053 1'00 576 I92 384 547 2% 52
2 3'1416 1'30 750 250 500 71'10 2% 60


The centrifugal stress is wezlg/zt per foot x 212 —:— g, and the
fourth and sixth columns assume that 1,, = '2 Tn which gives Tn :

tn : : 5 : I. From the tension formula,
Log- 5 or 69897 = 4343 X (P X 2613) xiii-Q?’
: 4'893 : 48
27463
1%” is the usual diameter for main rope.
Fig. 545 shows a spinning-mill driven by cotton ropes, the
power being given to ﬁve ﬂoors by separate sets of ropes, a good
arrangement in case of breakdown. The slack side being upper-
most gives a large arc of contact. Fig. 546 shows a travelling
crane. The rope is endless, passing round the pulleys D, H, A, G,
F, and E in succession, and kept taut by the weight at H. Worm
gear is used in taking off the power, at E for travelling, at B for
lifting and lowering, and at c for cross-traversing; and either rope
is put in gear by the press pullies a, [2, actuated by hand levers P, Q.
E is reversed by friction gear worked from handle L.


‘
4
5..
i









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5
. I S ;
[Jill/ml- Wm”,

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9.


W ire-Rope Gearing. 539
It should be noted that horse-power, depending upon pressure
x speed, may be obtained either by a large value of the one or
other quantity. Thus cotton-rope driving depends upon a low
pressure and high speed, but high-pressure driving will now be
considered.
(8.) Wire-Rope Gearing, introduced by Him in 1851, and
called by him ‘ telo-dynamic transmission,’has since been used in
many long-distance cases, for example :
. From turbines to distant mills.
. For vsteam ploughing.
In collieries : both for hauling and raising.
For travelling cranes.
F unicular railways and cable tramways.
Boat towing on canals.
gene-gash‘
The rope is of steel wire, with hemp or steel core, and six
strands of from 7 to 12 wires each. The wear is more uniform
if the strands twist in the same direction as the rope, as in Lang’s
patent. The following table refers to the latter ropes :


~ . Breaking Stress. Dia. of Construction.
Clrcumf. Dia. of ‘ smallest _ '
of rope. clrcle. Hemp Steel sheave. NO. of VVrres in
Core. Core. strands. sfragilhd.
ins. ins. tons. tons. ins.
4 I i- 34 5 I 2 4 6 I 2
3% 1-8!‘ 2 7 4O 2 I 6 I 2
3 I 9 2 8 I 8 6 I 2
2 I 4 2 I I 2 6 I 2
2 41— 2- I o I 5 1 o 6 I 2
2 g- ' 8 I 2 I o 6 I 2
I {'- -1-%- 6 9 8 6 I o
It i 4% 6-i- 6 6 8


The wire core does not affect the safety of the rope in bending
round pullies.
540 Pullies for Wire Rope.
Pullies.-—The section is shown in Fig. 547, having a groove
ﬁlled with leather on edge which is afterwards turned : ‘u then is
'25. Fowler’s clip pulley, Fig. 548, has its rim divided into a
series of toggles, the mere pull of the rope causing great grip, as
shown at A. E is a huge screw on the pulley rim which permits
adjustment, after which the bolts are re-inserted. The clip
pulley has enabled wire rope to be applied in many cases hitherto
unsolved. Fig. 549 shows a guide pulley.
At Fig. 5 50 a turbine (or horizontal water wheel) Tb drives a
distant workshop. A B is termed a relay, which should not
exceed 500 feet, and c c are guide pullies. Fig. 551 shows two
methods of steam ploughing: (I) is the ‘direct’ system, engaging
two engines which‘ wind up the rope alternately, and advance
along the headland between bouts; (11) is the ‘roundabout’
system, where a portable engine A drives a Windlass B in either
direction as required. c, D, are self-acting anchors, which resist
the pull of the rope; and as the slack-rope anchor automatically
winds itself in the direction of the claw anchor F, the tight-rope
anchor is meanwhile ﬁxed. G is a rope porter. Fig. 5 51 serves
to explain underground haulage. An endless rope is used at 1,
being crossed at J to obtain a greater grip on the clip pulley H,
and tightened at E with a heavy weight. (11) employs a pair of
winding drums c, as in the case of steam ploughing. The haulier
attaches his wagon by scissors grip at A. The up and down rails
are omitted for clearness.
Fig. 553 represents the lifting gear at a pit-head. The cages
move in opposite directions, and while one drum is winding
the other pays out, a brake being attached to each. When the
mine is very deep, the conical drum, Fig. 553a, is advisably
employed. It is on the fusee principle. When the cage is near
the bottom the load is greatest, due to rope weight, and the
drum radius is decreased, so that an approximately even turning
moment is required throughout the lift. Overwinding has con-
stituted a serious danger, and may be avoided either by
automatic reversing gear on the engine, or the detaching hook
_in Fig. 556 (Walker’s). The mouth of the hook is usually
closed by the ring A, but if the engine be over-run the hook
attempts to pass through the ring B, in the beam 0 above the
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542 Stresses in Wire Rope.
pit-head ; and A is thereby caught, being slipped relatively down-
ward. The jaws then open or catch on B, as at D.
Fig. 554 shows Fowler’s travelling crane driven by wire rope
round clip pullies. A is the rope arrangement, and the power is
distributed for travelling at c 0, cross traversing at D, and lifting at
E F. The last is accomplished by the rotation of screw F, which
shortens the lifting chain attached to nut E. The arrangement is
suitable for very heavy cranes. _
Cable tramways are useful for bad inclines. An endless rope
travels in a conduit A, Fig. 555, and the car carries the gripping
lever B, which, when moved to the vertical, raises the rollers cc,
and brings the jaws D D together. Some jerk is, of course,
unavoidable.
Fig. 557 is a towing arrangement adopted on some German
canals. A rope is anchored on the canal bottom, and the
tug winds itself along by the engine-driven clip pulley. The
rope serves as a rail, and with the pulley forms a kinematic
pair.
In wire-rope transmission the tension ratio is usually 2 : 1 and
the speed 3000 to 6000 feet per 111. The stresses in the rope are
due to :
( 1) Weight of rope and the form of hanging curve.
(2) Bending of rope round pulley.
(3) Centrifugal force.
(1) In Fig. 5 58 the catenaries may be considered as parabolas
for all practical purposes. Then the tangent T A being drawn, by
bisecting CD at A, the force diagram will give the value of T, in
terms of W the weight of rope between the pullies, and B the
pressure on the bearing. The weight of wire rope per foot =
(1'34 x d2) lbs. (2) Taking the general bending formulae,
Bm=—E;-I-=fJ—I,-=fZ andI=Zy
where p = radius of pulley, and y that of the rope:
iii—Z)! =fZ orflbs= El’ =30,000,000 J—l.
P "-" P - p







O-
_ (‘L 1P PuL‘fY










544 S hachles.
(3) has been already treated for belt and cotton rope. The
safe strength of the rope must meet the combined stress (1) +
(2) + (3), but the driving tensions TI, and tn caused by T will
both be decreased by the stresses (2) and ( 3).




xY/Lcco/cl/es ‘for Wake
Two shackles are shown at Fig. 559. At A the wires are bent
back and soldered, giving a joint equal to the rope strength; but
B is wrapped round a wrought-iron eye and then spliced, the joint
having but 50 or 60 °/o of the rope strength.
(9.) Pitch-chain Gearing serves the purpose of belting
where positive driving is required or considerable pressures
are to be transmitted. If high speeds are employed, the gear
should be exceptionally well made. Much power is lost in
friction, and the journals must be adjustable to take up stretch
or wear.
Fig. 560 shows three forms of chain. At A the teeth bear on
solid inner links, but at B and 0 they engage with the pins, and
the. smaller pitch obtained gives more regular driving. There are
Piz‘e/i- Chain Gearing. 5 4 5
two sets of friction surfaces ; the teeth on the pin and the pin on
the inner links. B decreases the friction of the former surfaces by
the introduction of rollers, and at c the latter surfaces are enlarged
by riveting a ferrule to the inner links. ' The pins should be
shouldered, so that the links may work clear at the sides ; and
the teeth are involute curves having the arc of pin centres as base
circle.
___-'.
i



D is a road roller supplied with pitch chain, and Fig. 569 an
electric car driven by chain from a dynamo. Cycle driving is a
well~known application.
(IL) Compressed Air under certain conditions is of great
advantage as a long-distance transmitter. In mines the exhaust
serves to ventilate the Workings, and has a similar use in tunnel
boring. Very often the compressing plant is on a large scale, as
in Fig. 561, where B B are the steam cylinders and A A the com-
pressing cylinders, from which the air passes to a receiver 0 for
distribution to the motor. D is a section of the air cylinder, where
N N
546 Compressed A ir.
E E are the suction and F i" the delivery valves, and as considerable
heat is generated during compression, water must be either
injected as spray or circulated through a jacket. The former
method, though most effective, is objected to on account of its
deteriorating action on the cylinder.











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ﬂu" O/Iri/futetsnwm ,5 /;,______b,________,,

Cooling the air either as above, or during its passage along the
connecting pipe, causes considerable loss of power, and the
exhaust from the motor has such a low temperature that snow is
formed by the cooling of the surrounding vapour. When work
is done on a gas, the temperature is raised by reason of the con-
Losses in Cooling. 547
version of that work into heat, and the loss in cooling might be
practically measured thus :
(No. of lbs. of water heated x rise in temp. F ° x 772) ft. lbs.
Again, when a gas does work its temperature is lowered, for similar
reasons. The changes may be understood from Fig. 562. Draw
the co-ordinates or for pressures and o J for volumes; then let
the piston commence with a cylinder volume I, opposite A, and
atmospheric pressure 15 lbs. at I A, the temperature being 60° F.
AC is a hyperbola or isothermal* of 60°, while EB and DK are
parallel hyperbolas at 320° and —201° respectively. In com-
pressing the air without subtracting heat, its temperature rises to
320°, and the pressure curve is the adiabatici" from A to B, the
volume being now reduced to '5 with pressure 45 lbs. Suppose
the temperature now lowers to 60° during transit to motor, the
pressure remaining constant, which is practically true, the volume
will decrease from B to c, viz., to '32. Now let the air expand
behind the motor piston’ without adding heat, and its pressure
will fall to I 5 lbs., while its volume becomes '74, and the expan-
sion curve will be the adiabatic c D, the ﬁnal temperature of which
is - ‘201°. The area A B F G shows the work given to the gas, and
CD G F that restored in the motor ; while the loss due to cooling
is shown by the area A B c D.- These assumptions are, of course,
strictly theoretical; in practice, the curves would be more correctly
the thick dotted lines, thus somewhat decreasing the loss.
Several attempts have recently been made towards improvement,
and with considerable success. Re-heating the air near the motor
gives some advantage, for the increased work obtained in the
latter much more than balances the heat supplied, and the
exhaust air is thereby raised to 60° temperature. Thus the loss
without re-heating is put at 70 ‘X, of the power originally given,
but re-heating decreases this to 50°/°. In Figs. 563-4, B is an
electrical re-heater formed of resistance coils in the circuit of the
dynamo A, and G is a stove re-heater through which the air-pipe
passes.
Still another saving is obtained by air injection. As heat is
* Meaning ‘equal temperature.’
1‘ Meaning ‘ not letting heat pass through.’
548 A ir and l/Vater Transi-nission compared.
nothing but a form of work, it may be made to do work as soon
as generated instead of being allowed to dissipate. In Fig. 564
this is obtained by allowing the hot air to pass from the receiver
D through the injector nozzle F, and thus an additional quantity
of air is drawn into the cold receiver E to ﬁll up the loss caused
by shrinkage during cooling. The air being ﬁrst compressed to
100 lbs. at a temperature of 484°, is reduced tO 50 lbs. in E
with a temperature of 201°; but the gain is certain, for the heat
has been made to do work. It is said that the ﬁnal loss when
injecting and re-heating may be reduced to 20 °/°, but we should
be inclined to put it nearer 4o °/°, which is then a considerable
advance on the former 7o °/o loss. For much of the above, the
writer is indebted to Mr. Saunder’s paper before the Franklin
Institute.
Three miles used to be the limit of pipe length, but compressed
air may now be taken with advantage from 1000 feet to several
miles, if leakage be prevented and large pipes employed. The
following is due tO Prof. Unwin :
COMPARISON OF COMPRESSED AIR AND HYDRAULICS.
WATER.
High pressure and small velocity
for economy, on account Of friction
and inertia : size of mains limited
and consequently power.
Taking : _
Press. : 700 lbs. vel. =3’ per sec,
Main : 6'67" dia. '
Logipfi’ifclggg }~ =91bs. (negligible)
Assumed efﬁciency :
Accumulator pump : ,1.
Motor : g
Total efﬁciency : i x % : 6o°/o
[F or 250 H.P. main : 10'54” dia.]

AIR.
‘Efﬁciency much lower than for
water. A large power transmitted
with low initial pressure.
250 H.P. motor (no re-heating or
injection) :
Press. : 588 lbs.
Main : 11'33" dia.
Loss per mile by friction : 5°/°.
Efﬁciency :
Pump, main and motor: 391 °/°.

Or if main = 8'95 dia.
Loss per mile by friction : 25 °/°..
Efﬁciency :
Pump, main and motor =32'2 °/°.
Practical considerations would ﬁnally determine choice.
History of the Dynamo. 549 _.
RICE/VII?
' |
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6’
i8 Aﬁi M
A 0Y”"M° DOWN MIA/f TOP or MINE
~_——_-_






B
HOTR£¢£Iv£ﬂ l HAUL/nu; MOTOR <04‘
m ‘re-Wm
INJEC‘NR DOWN MINE
E

I COLD RL'Cf/VER
C'Qﬂlﬂ/Bee'spd 6Z1!‘ Tljarw/n (Lie/Lon.
Refer to Chapters VII.

(12.) Hydraulic Transmission.
and XI.
(13.) Electric Transmission can only be brieﬂy described.
Faraday, in 1831, discovered magnetic induction, by which a
current is generated in a closed circuit wound on a bobbin, when
the latter is moved before the poles of a permanent magnet
(A, Fig. 565.) Pixii, Clarke, and others thereupon, in 1832,
devised the magneto electric battery B, where the bobbins are
rotated, and introduced the commutator to reverse the alternate
currents formed at c and thus ‘ straighten out’ the total current.
Nollet, Van Malderen, and De Meritens improved this machine
up to the year 187 r, dispensing with commutator, and thus pro-
ducing alternating currents (D). Dr. Siemens devised the H
armature E in 1857, working with compound magnet, and in
1866 Wilde employed a small Siemens machine F with commuta-
tor to excite the electro-magnets G of a much larger machine, and
thus avoid the necessity for large permanent magnets. The pro-
gress now was very rapid, and in 1867 Siemens, Wheatstone, and
Varley separately discovered the ‘dynamo-electric principle,’
by which the machine was made wholly self-exciting, the mere
residual magnetism in the soft iron core, whether new or after
use, being sufﬁcient to commence the current, which then
gradually increased up to its maximum. K is a Siemens dynamo
with H armature and commutator, the currents being thereby
550 Electric Transmission.
continuous. In 1871 Gramme developed the Pacinotti ring
armature as at J, to obtain a steady continuous-current dynamo,
and this is the end of our story, for all modern dynamos are
developments of either K or J. It is most important to notice,







) I‘ l J
however, that all dynamos are reversible, that is, may be used
either as generators or motors.
Fig. 566 shows a generator-dynamo at A and a motor-dynamo
at B. Power given to A will be transmitted electrically to B, and the
latter will rotate, thus returning the mechanical energy deposited
at A; but the rotation of B will be in the reverse direction of AB
rotation. This is called direct transmission.
Electric energy may, however, be stored. In 1800 it was
found that when the electric circuit was completed by dilute acid
between platinum poles, oxygen was given off from the positive
and hydrogen from the negative wire (A, Fig. 567). Ritter, 1803, showed that the platinum poles and liquid constituted a
battery, which would return the current. In 1879 Planté made
this fact of use by building the storage battery B, which consisted

Direct or from Storage. 55 I
of two sheets of lead a and o, rolled into a spiral, with insulating
strips between, and placed in a vessel containing dilute sulphuric
acid. Charging till the positive surfaces were coated with lead
dioxide and the negative with metallic lead, the plates were in
such a chemical condition as to constitute a return battery.
Faure shortened the time of charging by coating the plates with
red lead (the lower oxide), and covering this with parchment tied
with strips. The only difference in action was that spongy lead
w k


all-Uri JULPHURIC ACID
(1/


LEAD
IIll
SA'rrERY
45y J/t'ofaqi/l Fig. .567
Eleni?“ Tr/azwmwsaon.

was formed at the negative plate, thus giving a large surface.
Present storage or secondary batteries (otherwise accumulators)
are on Faure’s principle, and do not really store electricity, but
change electrical energy into that of chemical separation. They
are useful where the demand for power is intermittent, and
are fairly effective, the leakage during a few days being but
small.
Efﬁciency.—The work lost during transformation in a
‘dynamo may be as low as 8 ‘Z, though it more often reaches I 5%
or 20 A greater loss usually occurs, however, between generator
5 5 2 Electric Form nice.
and motor, the resistance of the circuit causing dissipation of
energy as heat. If
C = current in amperes, Q
electromotive force in volts, W
quantity in Coulombs,
work in foot pds.,
F1
ll
ll
R : resistance in Ohms,
Then:
CZR EC E2
H.P = -_ - _- -
746 746 746R
W = ‘737 EQ
__ E _ /746H.P.__746H.P.
c - R - a ' R 1 T
746 H. P. ______.__ w
E = CR = -—-—- =./H.P. 46R=————-
C 7 737 Q
E 746 H. P. E2
R :22 _ = w : --—-———--~—-———~
c c2 746 H. P.
W
Q _ 737E
If l he the length of a circuit in feet, both lead and return,
and a = sectional area of wire in Sq. in.,
8'4

_.
Rat60°F==5><
a
1,000,000
when copper wire is used. Also if the E. M. F. drops from E to‘
C and the current from C to c in ﬂowing ‘from generator to
motor, and if W is the work put in by generator and w that
received by motor, '
Efﬁciency of circuit = —— = - =

Example 54.-—A dynamo driven by turbine can generate 50'
amperes at 300 volts. The current is carried by two N o. 6 W. G.
copper wires to drive a workshop motor i mile away. Assuming the
commercial efﬁciency of the generator as 86°10, and that of the motor
as 84°[°, ﬁnd the mechanical efficiency of the whole system.
Numerical Examples. 5 5 3

. E C 300 x 50
H. P. lven out b generator = ———— = ---— —— = 20
g y ‘’ 746 746
H. P. Turbine must give to dynamo = g?) = 23'2 5
R of circuit, taking lead and return 2640 X 8.4
(dia. of wire = ‘192, area = '03, = ,———————- = '74 ohms
Z: 2640 03 X 1,000,000
2 .
H.P. lost in wire = 9—5 = 5w - 2'48
746 746
H. P. delivered to motor
is that generated less = 20— 2'48 = 17‘ 52
that lost in wire.
H. P. available at shop shafting = 1752 x '84 = 1471
But H. P. given by turbine was 2325
H. P. taken out _ 1471
H. P. put in _ 2325
H. P. delivered to motor
H. P. generated
Gross efﬁciency = = ‘6327 01' 632i 0/0


and efficiency of circuit only =
_ I7'52 __ . . . o
— 20 - 876 01 876 [0
there being 124 °/, of the generated H. P. lost in the wire.
Two actual cases may be quoted. (1) 4% H. P. was trans-
mitted 8 miles through g5?" telegraph wire, with a total efﬁciency
of 30 (2) The dynamos having a resistance of 470 ohms, and
the circuit 950 ohms, the line being 34 miles long, a total efﬁ-
ciency of 32 70 was obtained by decreasing revolutions from 2100
at generator to 1400 at motor, the potentials dropping 2400 to
1600 volts, a method of working ﬁrst advised by Siemens.
Storage cells are objectionable for tramcar and locomotive
driving on account of their great weight, 2 tons of cells being
about the weight required for a 1-ton car. The following results
are from an actual experiment with F aure accumulators :
35 cells of 95 lbs. each = 1% tons.
H. P. absorbed in charging = 1'5 58.
Time of charging = 22 hrs. 45 mins.
Lost work in charging = 34 ‘X,
Chemically stored energy = 66 70
Recovered electric energy = 60 ‘Z of 66 ‘Z, = 396
554 Practical Examples.
Figs. 568 and 569 are examples of electric transmission. In
the former a turbine A drives vertical shaft D, and, through bevel
gear, the generator-dynamo E. A motor F then gives the power
to a line shaft G through counter-shafting H. In Fig. 569 a car is
driven by motor and pitch chain, the current being taken from


.5.


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line wire by a trolley A, through the ‘ﬁshing rod’ B, and the return
taking place by earth. 0 is the conduit system adopted by Mr. Brain
where the wire is underground, and the slit covered by a strong
steel band. The latter is lifted by the little trolley, as it passes,
to allow of the connection between circuit and motor. Electric
travelling cranes are a recent development, the motor being placed
on the travelling girders.
Solid Friction. 5 5 5
Laws of Frictionw—“Solid’ friction is here meant, in
contradistinction to ﬂuid friction. There are three laws, as
follows:
The tractive force required to overcome friction :—
(I) Depends directly on the pressure between the surfaces in contact.
(2) Is independent of the extent of the pair of surfaces in contact, but (2a)
° increases in proportion to the number of pairs of surfaces.
(3) Is independent (at low velocities) of the relative velocity of the surfaces.
Further, the force depends on the Co-efﬁcient of friction (,u)
for the particular materials, thus,
Tractive force Fn = ,uP where P = total pressure.
COEFFICIENTS (,i) OF STATIC FRICTION. (MoRIN.)

Method of Lubrication.
MATERIALS. P 1, h d
Dry. 'Water. e Lard. Tallow sag. Oalride
greasy.
Wood on Wood... '5 '68 '21 '19 '36 '35
Metal on Metal... '18 '12 ‘I_ ‘II '15
Wood on Metal... '6 '65 ‘I '12 '12 'I
Hemp onWood. .. '63 '87
Leatheronlron... '54 ..
Leather on Wood '47 '28
Stone on Stone '7 I
Stone on W.I. '45
Wood on Stone... '6


As )1 is the trigonometrical tangent of the friction angle gb,
the latter may be found as in Fig. 570, by dividing a base-line
into tenths and setting up n on a perpendicular from the
mark I, to the same scale. Thus, for dry metal, ¢ = 10°.
when. ,u = '18.
5 56 Laws and Exceptions.
Morin’s experiments are not reliable for heavy loads or high
velocities. For the ﬁrst, Ball gives
F,n = '9 + '266P
for wood on wood, and the relation is Set out in Fig. 571, the
dotted line Showing the result of the ordinary formula with
M = ‘336-
‘W
119. .520



' .57!



As regards velocity, at the Brighton brake trials, 1878, the
following results were obtained when the static coefficient was '2 42.

Vel. ft. per sec. 1“ bgrtlgexfrﬁeigfke a begggegiilirheel
80 ‘106 ,H
50 "53 ‘065
40 'I7I ‘o7
20 Qls .072
1° ‘242 ‘088
nearrem: -242 -242


Solid and Fluid Friction. 557
As there was probably considerable abrasion in these results,
it is doubtful whether they should be accepted, further than
generally, for pure friction. Evidently the wheels should not be
allowed to skid when stopping the train.
If surfaces are thoroughly lubricated the frictional resistance
is of a ‘ mixed’ kind, being neither solid nor ﬂuid. The following
comparison is useful:
COMPARISON OF THE LAws OF SoL1D AND FLUID FRICTION.
Solid friction is :-— Fluid friction (gas or liquid) is :—
I. Directly as pressure. 1. Independent of pressure.
2. Independent of surface. 2. Directly as wetted surface.
3. Independent of velocity 3. Directlyasvat creepingvelocities.
(at low velocities). as 712 at moderate velocities.
as 713 at high velocities.
Friction of Journal Bearing was investigated by Beau-
champ Tower for the Institute of Mechanical Engineers. The
load was carried on one brass only, a top one, and the journal
ran in an oil bath. The coefﬁcient varied with the lubricant.
With oil-bath lubrication Fn was independent of pressure, and
1 .
71 0c —. In terms of velocity,




11 = 6*
P
where e varies with the lubricant. Thus, when 6 = 4 and p = 300.
Lubricant. 6 i [1, Lubricant. e 71
Olive oil .... .. ‘289 ‘00192 Sperm oil . ‘194 ‘00129
Lard oil .... .. ‘281 ' ‘00187 Rape oil... ‘212 ‘00141
Mineral grease ‘431 ‘00287 Mineral oil '276 ‘00184


With syphon lubrication ‘u. =2 when e, = 2'02 for rape oil,
and with pad lubrication 7a = ‘01 for rape oil. The bearing seized
when p rose above 600 lbs.
5 58 Friction of Turning Pairs.
Friction of a Collar Bearing.—- This was examined
under the same auspices. Here the friction was nearer the
‘ solid’ condition, the lubrication being less perfect. The
pressure p varied from 15 to 90 lbs., and v from 5 to 15 ft. per
sec. The coefﬁcient was '036 for ordinary loads, the usual
formula being applicable.
Work Lost in Journal and Collar Friction.--Rp
being outside or mean radius respectively,
Work lost in foot pounds perm. = Fn xV = )uP x 2 WRN
itP x 21rRN
33000
and H. P. lost ==

Work Lost in Pivot Friction—Following the method


lP "‘
a .9
2 P
5425.5 J14"
i ’ -—-
_ l 0 6 l
‘g; ‘5,24’ s a ,, Fég, .5 72
t 0

Work lost? in PlveAf/ridiQLr/L
of Fig. 371, let r be the pivot radius in Fig. 572. ' The pressure
being equally distributed,

O p P Q C i I
7, = pressure per sq. m., and ~77,- = force of friction per sq. in.
71 “ 77'
Total friction on any ring = unit friction >< area of ring
. . . P , 2 P
Total friction on outer ring = 'u—E >< 211r x t’ = —‘u— x t”
717’ r
. . i . 7'2 ZFP ,,
and Total friction on ring r2 = — >< —- x t
r r
Examples. 5 59
the resistance increasing gradually from o to B C. But the force
must be muitiplied by the arm to give the moment. The lamina
A B CD represents the moment for the outer ring, being
force ( >< arm (r)
r
Similarly a o ed is the moment at ring 1'2, and the pyramid volume
5 will give the total moment, thus:

. . 2 P
Moment of frICtIon = ‘u x r x? = g ‘u Pr
r

If P and r are in lbs. and inches, the moment is in pound inches,
and the distribution of pressure may be such as to reduce it to 5—
p. Pr. Concentrating the total force at the outer ring, it will be
t H P r.
—-— and 2
7 Work lost perm. =§nP>< ZvrRN
And may decrease to § ,1 P x 2 12' R N
Example 55.—Find H.P. lost in a footstep, whose dia. is 4", total
load 3000 lbs., revs. 100 per m., when p = '06. (Hons. Mach. Constr.
Ex., 1887.) i
H. P. lost =

2><'06><3000><2><22><2><100__ 8
3x33000><7><12 -3——'
Example 56.——Mean dia. of thrust bearing = I4", screw thrust
40,000 lbs., and pitch I 5 ft. ,u = ‘003, and 1000 miles are travelled in
3% days. Find H. P. lost in friction. (Eng. Ex., I888.)
1000x5280
W60 ft. per m.
Speed of vessel =
and as vessel travels 15 ft. per rev.
1000x5280
3'5x24x60x15

Revs. per m. =
“P 21rRN _ '003x40000x2x22x7x IOOOX 5280 __.93
H.P. lost =
-————- 33000 33000><7><12x3'5><24x60><15 ——

The form of pivot surface may be ﬂat, conical, spherical, or
specially formed. If Conical, 5%! must be substituted for P,
where a = angle at cone apex.
560 S chzele's Pivot.
Schiele’s Pivot, Fig. 573, is generated by a tractrz'x revolving
on its own axis. The curve is drawn as follows: Step off equal



divisions 1 to 10 3 with radius OB and centre 1 set Off 1a and
join: with same radius and centre 2 set Off 1h on 1a and join:
Similarly 3c, 4d, &c., and then sketch the curve from B to K. This
pivot wears equally on all rings, but wastes more energy in friction:
Moment of friction = juPr
or 50%D in excess of a ﬂat ‘pivot.




lw
Limiting Angle of Resistance.—-If a weight rest on a
perfectly smooth surfaceas at A, Fig. 574, the reaction is normal
Angle of Friction. 56 I
to the surface, but if the surface be rough, the reaction is inclined
“to the normal by the friction angle, in a a’z'reelion away from the
pull P, and the latter must now be increased by F,, in order to
move the body. If not on the point of sliding, the obliquity of Rt
may be anything less, down to zero. Two cases are shown for the
inclined plane, P being directed up or down the plane, but its
value may always be found by force diagram. In moving up the
_ plane, total pull must balance gravity+Fm but in moving down
the plane must balance Fn — gravity.
Example 57.—A road engine weighs 12 tons. Find (1) tractive
force of engine to pull 48 tons behind it on a level road, and (2) the
load drawn up a I in 10 incline. Coefﬁcient of traction = 150 lbs.
per ton.
(1) Tractive force = (12+48) 150 = 9000 lbs.
(2) P x length = W X height and P = W x J-
10
. . 22 o
Tractive force to balance gravity = T: = 224 lbs. per ton.
Tractive force to overcome friction = I 50 ,, ,,
Total tractive force = 374 ,, ,,
But the engine only exerts 9000 lbs.
. . . . . 9000
Total load on incline including engine = m = 24 tons.
and Load drawn exclusive of engine = 24— 12 = 12 tons.

Diminishing Friction by Lubrication.—Spongy metals
like cast iron, brass, and white metal decrease frictional resistance
considerably, but the best results are only obtained by the appli-
cation of unguents.
Lulrieanz‘s may be solid, as blacklead; semi-solid, as greases
and fats; and liquid, as oils. ‘Body’ for support, and fluidity
to avoid resistance, are both essential requisites, and a careful
choice must be made between extremes. The following are the
unguents used for various purposes :—
o o
562 Lubricants.
1. At low temperatures: Light petroleums.
2. For intense pressures : Graphite or soapstone.
3. Heavy pressures, slow speeds: Tallows.
4. Heavy pressures, high speeds : Sperm or heavy petroleums.
5. Light pressures, high speeds : Sperm or reﬁned petro-
leums.
6. Ordinary machinery: Lard oil or tallow oil.
7. Steam cylinders : Talloworheavy petroleums.
8. Metal on wood bearings: Water.
‘ Gumming’ or quick oxidation is to be avoided.
Lubricants are tested in about six ways :——(1) By chemical
analysis; (2') for speciﬁc gravity; (3) for relative viscosity when
new; (4) for gumming action; ( 5) for ﬂashing and burning points;
(6) generally, by testing machine.
Beaumé’s hydrometer is shown at Fig. 575, being a glass bulb
A weighted by mercury at c, which ﬂoats in the liquid B to be
tested, and the depth to which the stem sinks will show the
relative density of B. Thus for
Spec. Grav. Spec. Grav.
Sperm oil '881 Castor oil '966
Olive oil '915 Petroleum oil :866
Lard oil '917
Viscosity may be observed by dropping the oil from a ﬁne
tube, and gumming by the apparatus in Fig. 576. The various
oils are dropped through the holes A A, from the tube B, and as
they travel slowly down a glass plate their positions on the scale
are daily noted. Fig. 577 is a graphic rendering of some results,
the slowing points being shown by circles and the stopping points
by crosses. Flashing points are observed by heating the oil in a
closed vessel, then lighting the gas when collected ; burning points
are where the whole oil takes ﬁre. A low ﬂashing point shows a
dangerous oil.
Flashes. Fires. Burns.
Sperm oil 400° 485° 500°
Lard oil 475o 525° 525°


l


seﬁiwwn é




DISTANCE TRAVELLEO 9r DROP
l







r\ GALLIPOLI 0"-
P f '
564 Lubrication.
The most effective test is Obtained by machine, of which‘
Professor Thurston’s (Fig. 578) is probably the best. A is a
pendulum hanging on the test journal B, whose brasses can be
adjusted for any pressure by turning the screw D E against the
spring 0, while P shows the value, both totally and per square
inch. The thermometer G indicates the temperature. The
journal being rotated towards the right, the pendulum moves to
the left, together with pointer F, and the scale K at once indicates
the friction per sq. in. of journal, so that
= F ’S graduation.
F P's graduation.
Every ﬁve minutes during a test the revolutions, temperature, and
graduations are noted, values of a afterwards found, and the results
plotted as curves wherever possible. In his ‘railroad ’ machine,
Prof. Thurston uses a full-Sized locomotive journal.
Lubrication—The oil-bath gives the best result, but is
rarely found in practice. The self-lubricating bearing, Fig. 579, is
perhaps the next best, where the oil is lifted by the shaft collar
and distributed by a wiper. The next in order is the oil pad, as
contained in the locomotive axle-box, Fig. 580, the bush merely
embracing the top half of the journal. Usually lubricators have
to be ﬁtted, and are then designed for the conditions. B, Fig.
270, p. 266, is a common Syphon lubricator. The oil level being
below the Syphon-pipe, a piece of wick is placed in the latter and
hangs Over in the Oil. The ﬂuid then rises by capillarity v3 and the
wick is to be removed when the machinery is stopped, Otherwise
there is unnecessary loss of oil. Leuvain’s needle lubricator, A,
Fig. 581, is a glass vessel, ﬁlled with oil, closed by a wooden plug
and inverted. Within the stopper a ‘needle’ ﬁts freely, and the
oil trickles down the latter only when vibrated by the shaft. If
the dropping of the oil is to be Observed and its regulation
obtained, such a lubricator as the Crosby sight-feed at B, Fig. 581,
may be adopted. When handle a is vertical, the valve h is
raised, and adjustment given by the nut d ; but when a is horizontal,
t is closed, and the supply stopped.
A loose pulley may be fed with tallow by means of Stauffer’s
screw-down lubricator c. Oil would only ﬂy away by centrifugal




.19.; 2





a I \ \\ _ “
1 1 _
. 7.V§\\\\\\\\\\\m





566 Diminishing Friction by
action, and is therefore inadmissible. A closed sight-feed
lubricator (Crosby’s) as used for steam cylinders, has been already
described at p. 264 and Fig. 270. Fig. 582 shows a method of‘
oiling an engine crank-pin by centrifugal action. The oil being‘
fed from B down the inclined tube, is caught by the cup A and.
whirled round, when it passes through the pipe 0 to the crank pin._
Nothing but uniform oiling will ensure against seizing.
Grooves must be cut in the bushes from the lubricator pipe to the-
furthest ends of the brass, and more than one lubricator used in
long bearings. In some cases small oil pumps have been adopted,..
but the oil tends to gum by exposure.
Contrivances for Diminishing Friction.-'1‘he cart-
wheel A, Fig. 583, is the simplest example. Comparing with at
sledge, the friction is reduced in proportion to the distance--
travelled by the sliding surfaces in each case, or as %: 1. In
small physical apparatus the anti-friction discs at B may be
employed, the journal a resting on the wheel circumferences,
and the sliding at dd being thus still further reduced. 0 is a
coned bearing much used in clocks and watches, the work
lost being here decreased by the adoption of a small diameter of '
rubbing surface; lathe centres form another example. A great
reduction in friction is obtained when statical is substituted for‘
sliding contact. Examples are given in Figs. 584-86. Fig. 584
shows the ‘live’ rollers used to support the turret of an ironclad.
They are tapered towards the centre A, being really bevel cones,
and two light rings prevent them changing their prescribed
position regarding their fellow-rollers. Referring to Fig. 585, the-
weight Q compresses the rollers, in the manner shown exaggeratedly
at the dotted arcs. The rollers will tend to turn round the fulcra
marked, and the equation of moments will be
N(<S+<S,)+W<S,=T><2r
But P=2TandQ=2N .-. P=Q(5+61)+2VV51
27’
If more rollers are used, let n = number of rollers : then
P=nTandT=€ Q=nNandN=%
72
Live Rollers, Go. 567
The equation becomes:
g(5+81)+W51 = Ex 2r
n n
...P=Q(5+¢S,)+nW8,





Q9. 5 84'.
6 is found by experiment, and
8 = '36" for rollers of wood 3' to 4' long.
5 = '72" for rollers of wood I’ long.
5 = '016" to '018" for rollers of iron 5" or 6" long.
568 Ball Bearings.
Prof. Osborne Reynolds shows that the action is not so Simple
as we have supposed, and Prof. Cotterill gives the formula
P=Qi
7‘
where 5 = '02" for hard wood or metal.
5 = '09" for softer materials.
5 = '5" for wheels on macadamised roads.
Statical or rolling friction is not sensibly diminished by lubrication.
Ball and roller bearings are shown at A and B respectively,
Fig. 586. The former is an excellent arrangement, but the latter






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emah
MAcﬂt'Slum
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an.
s










cannot be adjusted after wear. Knife edges, Fig. 332, form an
example of Statical contact. Fig. 586 Shows also a case where
ﬂuid friction has been substituted by Eiffel with advantage. The
observatory dome at Nice was ﬂoated in an annular tank, whose
section is given, the liquid having a speciﬁc gravity of 1%. The
moving load was 95 tons, but could be turned by one man in four
minutes. The live rollers were not a support but only a steadi—
ment against wind.
Uses of F rictiOn.—-Very often friction is a positive advan-
tage: such cases we will now discuss. Fig. 587 is one of many
loch nuts, the grip being obtained by the compression of the split
nut. Friction clutches provide disengagement for shafts or pulleys
Uses of Friction. 569
while the machinery is in motion. There are many examples in
the market, all possessing one advantage or another. That in Fig.
588 combines Musgrave’s grip with Hathorn and Stuart’s adjust-
ment. A is a loose pulley on shaft B, and the bell E is keyed to A.
D is keyed to ,the shaft, and carries the right and left-handed
screws FF. Levers K K being ﬁxed upon F F, are connected by
-links H H to the sliding clutch boss G, worked by lever; so it
follows that when G is moved to the right and the screws rotated,
the gripping shoes are pressed against the bell E, thus connecting
the pulley with the shaft. K K are small worm spindles for adjust-
ing the levers to suit wear of shoes. A clutch like the above
should be symmetrical in design, so as to be in perfect balance:
the shoes should not rest upon the bell-drum when out of gear;
and there should be good adjustment.
Weston’s clutch, Fig. 589, is designed on the principle of
multiple gripping surfaces (see law 2a). It is now adopted only as
a safety appliance, allowing wheels to slip when a shock comes
upon them, and thus avoiding breakage. The example shown is
the elevating gear for a large gun, the pinion on the right gearing
with a rack on the gun, and the connection from A to B made by
means of the clutch. Steel discs of a’ ﬁt on the hexagon c, but are
free regarding the worm wheel ; and gun metal discs ff are keyed
to the wheel but free on the shaft. When nut o is tightened, the
discs are gripped, and A connected to B ; but when G is released,
the wheel is free. H are spring washers. ‘
Brake straps are a means of absorbing power by friction,
dissipating it as heat. Fig. 590 represents a traction engine
having abrake-drum B securely keyed to its hind axle A. The
iron strap B (sometimes lined with wood or leather) encircles the
drum, and is tightened whenever the lever D is raised by the
screw. Brake blocks, with toggle gear, are shown at Fig. 46 3.
Friction plays an important part in causing a grip between a
locomotive driving wheel and the rails, and the weight of the
engine should be sufﬁcient to prevent slipping when starting the
load. The resistance of a train to direct pull is from 4 to 25
and even 30 lbs. per ton, which gives the tractive force
required. The resistance to slipping is found from the following
table :—

The Glpejt/wr .Lpa‘c-md'
I 1119. .58?


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MW




JZr'ez/i .BZt'a/ce
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. g I—
at’ 7A
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Friction Gearing. 5 7 I
ADHESION OF LoCoMoT1vEs.
(PER ToN OF LoAD ON DRIVING WHEELs.*)
Rails very dry 600 lbs. per ton.
Rails very wet 550 ,, ,,
Average weather 450 ,, ,,
Greasy rails 300 ,, ,.
Frosty weather 200 ,, ,,
(10.) Friction Gearing tramsmits power without jar, and
will slip under shock. The forces transmitted are, however,
limited. Referring to Fig. 591,
Fn=pPandP=53
)u
Taking ,u. = '2 5 for leather on iron, pressure on bearings =
= 4 times power transmitted (see A) and in right-angled bevel
gear = U4; times power transmitted (see B).
To avoid bearing pressure, Prof. jenkin invented his ‘nest
gearing,’ which is shown in Fig. 592, transmitting power between
engine shaft A and dynamo B. To obtain adjustment for the
intermediate wheels D1 D2 D3 the shafts A a are out of line, and
the intermediate studs ﬁxed to a plate with curved slots. The
disadvantage of the gear lies in its having six compressed surfaces
instead of two.
In Fig. 593, A shows examples of Robertson’s wedge gearing,
and B, a more recent design of friction gearing, has plates of leather
on edge forming the driving surface, the follower being smooth
cast-iron. [n all cases grip must be obtained by pressure on the
bearings, either by spring as at Fig. 591, or by weight overhanging
eccentric bush as at C, Fig. 593.
Efficiencies of Machines—The frictional loss in a
machine could be investigated for every sliding pair, but in a
large machine this would be cumbersome, and considering the
variations in the value ,4, very probably inaccurate. The engineer
prefers then to make experiments upon existing machines and
* Every coupled wheel is a driving wheel.
572 Eﬁiciency of Machines.
keep a list of results. By comparing the theoretical and practical
ratios of P to W, we may ﬁnd the ratio of work got out to work
put in, which is the efﬁciency of the machine. Any machine
could be taken as a case in point if we knew where P and W
f5.






ﬁ
g
‘a g
%/
\ -_.
/
\i I


hi
////////r.
L-_;_-- __‘


I!‘
were to be applied; we will, however, consider the crane in
Fis- 5 94-
Commencing by measuring the motions of W and P, we ﬁnd
that while W moves one inch P moves 224 ms, so the ratio of W
to P is 224:1. Calculate then the theoretical values of P for
A n Experiment. 57 3
various loads at W from 1i ton to 5 tons. Next hang constantly
increasing loads at W, and balance each with the heaviest weight




FE . 5.94
i
3
0
£
100 L35‘. .
Morm~=224 w l- 560'“
possible at P without moving; note the results, and collate as
follows :—
CRANE EXPERIMENT.

Load W in tons. jiisiiglsgrlzoirrrllgtiz'aé? Theoretical P.
5 100‘1 5o
4% 92‘4 45
4 84'7 40
3% - 77 ‘O 35
3 69's‘ 30
2% 61‘6 25
2 5 3 ‘9 20
1% 46‘2 I5
I 385 10
i 30‘8 . 5
unloaded 2 3'1 0


5 74 Distribution of M achzne Friction.
Next plot these ﬁgures as in Fig. 595, the horizontal scale
showing W, and the vertical ordinates the corresponding values of
P, o D being the theoretical, and A B the practical proﬁles, which
400'!
F'mo
92-4 B -
F90





~ it
01
q, FORCE P m! kPm/Aw$\\‘3
| l l -
.l
O

LOADS W av TONS
are both straight lines. Draw AC H to o D. Then at any ordinate
except 0 A the total P consists of:
1. Force to overcome load, neglecting friction.
2. Force to overcome friction of unloaded machine.
3. Force to overcome friction due to load.
( 2) being a constant quantity as shown between lines A C, o D.
Then, if w be the equivalent weight of the unloaded machine
causing friction,
(I) (2) (3)
P = 221W + P w + PW
Fit
From (3) we ﬁnd ,u. = W = 5—554—0 = '00687.
Supposing )1 a constant throughout the machine,
W
P = —- + ‘00687 w + ‘00687 W
224
and as oA = 23'1 = 3362 x '00687 : w = 3362 lbs.
A 6sorption Dj/726t77’107726l67’. 57 5
power utilised X 100 _ u x 100

Efficiency per cent. =


power put in _ U
When W = 5 tons, efﬁciency = iii—35232 = 50% nearly
and when W = I ton, efﬁciency = {£32200 = 26% nearly
which shows the advisability of working a machine near its full
load.
Dynamometers are best used when the power given to
or by a continuously-moving machine is to be ascertained.
The method just described might well be employed to measure
starting loads; but working loads are very much less,
and the above treatment is not admissible. Dynamometers show
the load supported with any speed of revolution, and the latter is
measured by a counter. Absorption dynamometers abstract the
work while measuring it, and dissipate it as heat, while transmis-
sion dynamometers pass it on unimpaired, absorbing only an
inappreciable amount in frictional loss.
An Aosorption Dynanzonzeter, or ‘brake,’ is shown in Fig.
596. The engine whose power is to be measured has its crank
Coupled to A, and revolves in the direction of the arrow. Belt
driving should be avoided on account of the loss in slip. The
drum B Carries a brake strap C lined with wood, which is tightened
at H. Sufﬁcient resisting weight is hung at W, whose rise is pre-
vented by the stop J, after H has been screwed up to just support
the average load: the self-acting lever D E preventing any important
rise or fall of the points G H, which must be level with drum
centre. As Ewould travel further than F, a right-handed slip of
the strap will slacken the latter, and a left-handed slip tighten it,
thus preserving the original position. The spring balance 5 con-
veniently measures small deviations of load, and the weight
supported will be (W—S), the radii R, R, being equal. Then
work absorbed per rev. = weight x distance travelled =
(W-S) lbs. x 2 1rR feet, and
(W—S)><21rRN
33000
H. P. =


5 76 Transmission Dynamometer.
Friction is only the medium for absorption, and does not enter
into the calculation. The arrangement at K permits adjustment
for various motors.




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e\\\\\\\mI// ar- 0
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White’s Transmission Dynamometer is represented
in Fig. 597. A is the motor shaft, and B that of the driven
machine. AS A turns left-handed, the arm F E is held back by the
weight E, and thus B is turned to the right. Supposing the arm
were carried round, no wor/e would be given to B, which would be
stationary, but E’s rotations would be half those of A (see Fig. 526).
The load supported on A would therefore be half that on E (at
equal radii). But although the power be taken off at B, A and E
have yet the same relation, so that
List of Eﬁiciencies. 57 7
work transmitted = load on A x distance travelled on A
and load on A = half that on E,
work per min. = i2 x 21rRN
EvrRN
33000
and H. P. =

F counterbalances the lever weight.
List of Efficiencies.—Efﬁciencies in various cases, as
found by the methods previously described, are as follows:
Cranes worked by spur gearing... 30°/(, to 6o°/o
Weston pulley block, well greased 4o°/o
Screw jack . 15°/o to 3o°/°
Cornish engine expansion U Bral-éé H-
0 0
and condensation i Indic_ H_ p_ X 100 35 /o to 60 /°
Undershot water wheels... .
250/O 300/0
Overshot ,, ,, 7o°/o to 75°/°
Breast wheels (Poncelet’s construction) 6o"/o to 6 5°/o
Pelton water wheel motors 80°/o
Turbines (full sluice) 60°](, to 80°]o
Worm gearing (indifferently constructed) 3o"/o
,, ,, (very carefully constructed) 90°/°
Hydraulic press (neglecting pump) 98°/° to 99"]o
Frictional loss in engines does not vary appreciably with the
load, and is therefore often arrived at by taking an indicator
diagram with the engine ‘running light 5’ then comparing with the
working diagram.
We will close this chapter with a few comparisons :
COMPARISONS OF THE ADvANTAc-Es AND DISADVANTAGES OF
TRANSMlTTING PoWER BY VARIOUS METHoDs.
A a’vantages. ‘ Disadvantages.
‘ 1. LINKWORK.
Useful in modifying power and Dead points often occur, to be over-
obtaining special motions, as with come by force or chain closure.
valve gear, parallel motions, &c. Will only transmit over very short
Coupling rods a case of pure trans- spaces.
mission.
Frictional loss slight.
578
A dvantages.
S hafting and T oothed Gearing.
Disadvantages.
2. SHAFTING.
Useful in connection with belt and
spur gearing as a distributor from
central motor to machines.
Practically noiseless.
Will transmit across moderate dis-
tances only, unless used in relays.

Frictional loss about 25°]o to 5o°/o
in a large shop system: might be
smaller with well-lubricated bearings.
Loss proportionately large with light
loads.
Inconvenient for turning corners,
though Hooke’s joint may be em-
ployed for small deviations.
3. SPUR GEARING.
For positive transmission.
A good modiﬁer of power.
Practically no pressure on bearings
when teeth are well formed, excepting
that due to weight of wheels. The
latter is, however, considerable.

Frictional loss in a train, from
5o°/o to 60°/,,. Less if teeth are
machine cut. '
Not suitable for long distances,
except in conjunction with line
shafting and bevel gearing.
Noisy, especially if much reversed.
Teeth break under shock for want
of slip, unless a slipping clutch be
introduced. Breakage due to exces-
sive backlash rather than heavy load.
4. BEVBL GEARING.
Assists shafting in turning corners,
and modiﬁes at the same time, if
required.
Is therefore useful in connecting
parallel shafts considerably separated.
Should not be used if belting or spur
gearing will serve (see Fig. 476).

Frictional loss quite as great as
with spur gearing, for teeth are difﬁ-
cult to cut by machine, and are rarely
well formed.
Noisy for similar reasons.
Oblique pressure on bearings.
5. WoRM GEARING.
Gives a high velocity ratio with
few parts.
Non-reversible if the ratio be
greater than 8 : I, and therefore serves
as a safety gear in cranes and such
appliances.
Practically noiseless.

Frictional loss io°/o to 70°/,,. The
former result has only once been
reached, with exceptionally well out
teeth, and the worm in an oil bath.
5o°/o is a good average.
Hob-cut teeth (p. 274) should be
used wherever possible.
5a. SCREW GBARING.
Comes under the last head.
Tension Elements.
Advantages.
579
Disadvantages.
6. BELT GEARING.
Useful in connection with shafting
as a distributor and modiﬁer with
comparatively few parts.
Easily started and stopped.
Practically noiseless.
Very convenient for bridging rea-
sonable distances.
Large pull on bearings, but in well-
lubricated bearings friction does not
depend on pressure.
Slip an advantage in case of shock.

Frictional loss principally in the
line shafting: about 25°]o to 50°]o in
a shop system. .
Large belts with heavy pressures
are expensive to maintain.
Slip a disadvantage where exact
velocity ratio is required.
7. COTTON-ROPE GEARING.
For fairly long-distance driving in
mills, and for travelling cranes.
Better grip than belts, due to wedge
pulleys.
Quite noiseless.
Separate driving to the various
ﬂoors of a mill occasions less loss of
time in breakdowns.
Small liability to break down also.

Frictional and other losses probably
somewhat larger than with belt gear-
ing, due to heavy pullies and ﬂy-
wheels.
'Working speeds being high, rope
tension is increased 50°]o by centri-
fugal force : but bearing pressures are
not thereby affected.
8. WIRE-ROPE GEARING.
Suitable for very long distances, say
for several miles, when relays are
adopted. Cases quoted in text.
Moderate speeds being employed,
little increased tension from centri-
fugal force.
Frictional and other losses 22°]°
per mile, not including motor and
machines : lesser and greater distances
in proportion.
9. PITCH-CHAIN GEARING.
As useful as belt driving in de-
creasing the number of parts while
modifying the power: but gives at
the same time positive transmission,
and may be used with heavy loads.
Adapted for high as well as low
speeds if well made, but the former
should go with light pressures.

Large frictional loss, probably about
60°]o in a single pair of wheels: there
being two sets of friction surfaces, not
including the journals.
Increase of pitch after wear causes
excessive friction and bad working.
A dvantages.
Other Transmitters.
Disadvantages.
Io. FRIcTIoN GEARING.
Almost noiseless and non-vibrating.
Advantage of slip when shocks are
received.
Useful for high speeds.
Frictional loss about the Same as
for belt driving to shafting, being
comparatively small with one pair of
wheels. Unequal wear.
Large pressure on bearings; de-
creased in nest gearing.
II. COMPRESSED-AIR TRANSMISSION.
Of great value for long-distance
transmission in close workings.
Better than hydraulics when high
Speeds are required in piston motors.
LOSS by cooling varies from 70°/-(,
under common conditions to 4o°/o with
re-heating and air injection.
LOSS per mile by friction about 5°/,,.
12. HYDRAULIC (WATER POWER) TRANSMISSION.
Suitable for long distances. More
especially useful for intermittent de-
mand in power distribution, and the
concentration of immense power by
continual Storage.
Leakage slight.
Inertia an advantage sometimes, as
in riveting machines.
Losses Slight if low velocities are
taken, Say 15°/,, in usual machines;
5°/o per mile due to friction in pipe.

Unsuitable for continuous work.
Uneconomical with high velocities
and reversible motion, on account of
Shock due. to inertia. (Damage ob-
viated by relief valves.)
Velocity should be kept down to 4
or 6 ft. per second usually, and slow
moving rams adopted, necessitating
multiplying gearing.
Piston engines run at 60 or 80 ft.
per 111. but are usually wasteful.
I3. ELECTRICAL TRANSMISSION.
Especially Suitable for long dis-
tances.
Wires may be conducted in any
direction.
No moving parts in line of trans-
mission.
Easy subdivision of power.
May be Stored by Faure cells.

Loss in line varies as the Square of
the current used (C2 R): hence high
voltage is adopted for long lines,
giving an economic loss of from 5°/o
to 4o°/o in the line.
LOSS in dynamos from 5°]o to 20°/o
each, of the energy intrusted to them.
Storage cells, being heavy, have
not as yet proved really suitable for
transportation purposes. Loss in
charging, &c., about 35°]o
CHAPTER X.
ON HEAT AND HEAT ENGINES.
IT is customary, in dealing with any branch of Natural
Science, to collect known facts fromtime to time, in order to
devise a general Theory of explanation, which would serve as a
basis for further investigation. Two such theories we shall now
describe.
The Molecular Theory states that matter is discontinuous,
its limit of mechanical divisibility being the minute particle
termed a molecule. Chemists show that some molecules are
compound, being further divisible by chemical means into atoms.
The Dynamical Theory of Heat‘ teaches that heat is
not a substance, but a condition of matter: being a ‘pendulum’
motion of the molecules, never entirely absent, even during
extreme cold, but increasing with the intensity of heat, the latter
being, in fact, due to the motion. In solids, the molecules are
very close together and their excursions small, being limitedby
mutual attraction or cohesion; in liquids, they glide about and
change positions by but slight external force 3 while in gases, the
heat energy overcomes the cohesive or molecular forces, and the
particles ﬂy out to any distance when allowed to do so.
Black taught the caloric or material theory of heat in 1798,
but Rumford and Davy, in 1802, produced heat inexhaustively by
solid friction, and thus proved it identical with motion. A
little thought will suggest many cases where work and heat
are interchangeable. , , ‘
Transfer of Heat—When a hot and cold body are placed
in juxtaposition, heat passes from the former to the latter till
582 Radiation and Conduction.
both have equal temperatures. Such transference may occur by
radiation, conduction, or convection.
Radiation is the passage of heat between substances not in
contact, without at the same time raising the temperature of the
intervening medium. Thus a ﬁre may heat surrounding solids,
and the air receive its heat from the solids in turn. To explain
radiant heat, a ﬂuid of inﬁnite tenuity is imagined, called the
Ether, ﬁlling space and the interstices of matter, and transmitting
radiant heat, by wave motion, without increasing molecular
motion. If, however, the undulations be arrested, the energy
is absorbed as molecular motion, and becomes apparent in the
arresting body as heat. Radiation is an aid to heat dispersion,
as in heating apparatus, but a disadvantage with boilers and
steam cylinders, there causing loss. Good radiators must
therefore be adopted in the former, and bad ones for the
latter cases. Good radiators are good absorbers, to an equal
degree, and reﬂecting power is the exact inverse of radiating
power.
RELATIVE VALUE OF RADiAroRs,

' Relative
Substance’ Radiating Value.
Lampblack or soot _ 100
Cast iron, polished .. 26
Wrought iron, polished 23
Steel, polished 18
Brass, polished 7
Copper, polished... 5
Silver, polished . 3


Conduction is the transfer of heat by contact, molecular
motion being then directly caused. Heat is thus transmitted
through the thickness of a furnace tube. There are good and
bad conductors, the former being chosen for ﬁreboxes, ‘other
things being suitable.
Convection. 583
RELATIVE VALUE OF GOOD CONDUCTORS.

Substance‘ CondliiziilrilgvValue.
Silver 100
Copper 73'6
Brass 23'1
Iron II'9
Steel 116
Platinum 8'4
Bismuth 1'8
Water ‘147


Bad conductors are of value for clothing boilers, steam
cylinders and pipes, &c.
RELATIVE VALUE OF BAD CoNDUCToRs (OBsTRUcToRs).

\ V
Substance' Obstrgcetlilrilg Value.
Silicate cotton or‘ slag wool 100
Hair felt 85'4
Cotton wool 82
Sheep’s wool 73-5
Infusorial earth 7 3'5
Charcoal 71'4
Sawdust 6I'3
Gasworks breeze 43-4
Wood, and air space 35-7


Convection is a means of transmitting heat to liquids and
gases. A ﬂask of water being placed over some heat source,
the lower or heated portion of the water becomes lighter and
rises to the surface, up the vertical centre-line, only to become
_ Cool again and ﬂow down the sides to the bottom. Thus are
continuous ‘convection’ Currents formed, which soon distribute
heat throughout the liquid. Similarly also is the air of a room
584 Expansion and Tgmpemz‘ure.
heated: the ﬁre, near the ﬂoor, rareﬁes the immediately sur-
rounding air, which rises to the ceiling and falls again when
cooled against the walls. Water, being a bad conductor, cannot
well be heated by any but the convection method, hence the
. adoption of a low position, in a boiler, for the ﬁre-grate.
Expansion is the result of the application of heat to all
bodies, whether solid, liquid, or gaseous; the ﬁrst being least
and the last most expansible. Many examples may be suggested
of the application of this law, some useful and some detrimental.
Shrinking of gun coils is of the former type, while the endlong
clearance between rail lengths of the permanent way avoids the
injurious effects of the summer heat. Fig. 327 shows how work
might be done by the expansion of solids. Water, between
32° and 391° F., is an exception to the law of expansion; during
that period it contracts as the temperature'increases. Cast iron
also expands when cooling in the mould, and bismuth and
antimony follow the same rule 5 gold, silver, and copper contract.
Measurement of Heat.—-—We proceed to measure intensity
and quantity of heat, bearing in mind, however, that heat is not a
substance but a form of energy.
Temperature is a measure of the z'nz‘ensz'z‘y of heat, being
registered on a thermometer or pyrometer. Thermometers are
based on the expansion of liquids or gases in a glass bulb, which
then rise in a capillary stem from which air has been exhausted.
Mercury or alcohol are the usual liquids, the former for ordinary
and comparatively high temperatures, and the latter for very low
temperatures : the boiling point of mercury being very high, and
the freezing point of alcohol unknown. The freezing and boiling
points of water, under atmospheric pressure, being unchangeable,
are ﬁrst marked on all thermometers, after which the graduations
are spaced according to one of the following methods:


Divisions -
Thermometer. between Freezing Flgzeiiltng Boiling Point.
and Boiling. '
Fahrenheit 180 _ 32° ' 312°
Centigrade IOO 0° 100°
Réaumur 80 0° 80°


' Quantity of Heat. 585
Réaumur divisions are adopted in Russia ; those of the Centi-
grade by scientists and the Continental public 3 while Fahrenheit
divisions, being used by English engineers and the English-
speaking public generally, will therefore be adopted in this work,
and the Fahrenheit degree he looked upon as the unit of intensity.
Centigrade readings can be translated into Fahrenheit and vice
versci, by the following simple formulae:
F° = (C°’>< —2-) + 32 and C° = (F°—32)%.
Pyrometers are required to measure excessive temperatures,
such as those of furnaces; they will be discussed on a later
page.
Air thermometers are of advantage in experiments of great
delicacy, because small increase of heat will cause large expansion
of air. The instrument is usually laid horizontally, and has a
small index of coloured sulphuric acid, as at c, Fig. 601, which is
moved along the tube by the expanding air, the end B being
open to the atmosphere. The reading is considerably affected
by change of atmospheric pressure, so the barometer reading
must always be taken, and a correction made to standard
pressure. The expansion of gases is more perfect than that of
liquids.
Quantity of Heat.—More or less heat motion may exist
in a body, depending on mass, heat capacity, and temperature.
The British Thermal Unit (B.T. U.) is the amount of lzeat required
to raise the temperature of a pound of water t/zroug/i one Fa/zren/zeit
degree, the water being near its greatest density 391° F. This
unit represents an amount of energy equal to 772 foot pounds.
Speciﬁc Heat.--But some bodies have greater capacity for
heat than others, that is, weight for weight, will absorb more heat
for a deﬁnite rise of temperature. Taking capacity for water as
1, the relative capacity of another substance, called its Speciﬁc
Heat, is therefore the amount of lzeat in t/zernzal units required
to raise the temperature of a pound of the substance t/zroug/z one
degree F.‘ Bunsen’s ice calorimeter has been used to determine
various speciﬁc heats, but we shall describe the met/rod o n-zixture,
which is precisely the same in principle. The body, being regu-
larly heated in a bath of steam, is removed, and put in a vessel
containing a measured weight of water at a certain temperature.
586 ﬂdethod of M iocture.
When the body and the water are in thermal equilibrium, the
ﬁnal temperature of the mixture is taken. Then, if
w = weight of the body in lbs.
w1 = weight of water in lbs.
s = speciﬁc heat of the material.
s1 = speciﬁc heat of water = 1.
temperature of body after steaming.
t1° temperature of water at ﬁrst.
T° _ ﬁnal temperature of the mixture.
N
II
II
Heat lost by body == Heat gained by water.
weight >< spec. ht. x fall of temp. =weight >< spec. ht. >< rise of temp.
ws (t° — T°) = w1 s, (T° — t1°),
shown graphically at A, Fig. 598. Inserting known values, that of



I; Cemiuof stewn
212° l ' area;
" l‘rwlLtcm ii .i'. -
I f ”' - _;: _-- Manta/12.3;
It meme s3 5””
41 '
J 5 I 596’.
Q NON CONOUC TOR
o


s may be found, the following table being obtained by this and
other methods.
SPEciFic HEATS oF VARioUs SUBSTANCES.

Water at 39'1° 1'00 Wrought iron '113
Water at 212° 1'013 Steel ‘116
Ice at 32° '504 Copper '095
Steam at 212° '48 Coal '24
Mercury '033 Air '238
Cast iron '13 Hydrogen 3'404


l/Vater Pyrometer. 5 87.
Example 57.—Find the speciﬁc heat of copper from the following
data :-—Half a pound of copper is heated to 212°, and being plunged
into a pint (20 oz.) of water at 60°, raises the temperature of the
latter to 655°.
__ w1s1(T°—- t1°) __ 20 X I (655 — 60)
_ w(t°— T°) _ 16 x '5 (212 —- 655)

= ‘0938
Pyrometers, for measuring very high temperatures—Wedge-
wood’s and Daniell’s, based on expansion of solids, are now
obsolete. Siemens’ electric pyrometer measures the resistance
of a circuit, which varies directly as the temperature of the wire.
Wilson’s and Siemens’ water pyrometers depend on the method
of mixtures. A cylindrical vessel of sheet Copper, clothed with
felt to retain heat, is provided with a cover and thermometer (see
B, Fig. 598). A small solid cylinder of copper, of known weight,
being placed in the furnace whose temperature is required, is
shortly removed, plunged into the water of the pyrometer, when
the latter is closed. The ﬁnal temperature of the pyrometer
water being observed, that of the furnace can be deduced.
Example 58.—— Find a furnace temperature by water pyrometer
from the following data :-—Quantity of water = I pint, its ﬁrst tem-
perature 65°; weight of copper cylinder = 4;},— 02.; ﬁnal temperature of
water = 77'5°
wst°— wsT°= 'w1(T°—t1°)

o o o 39 - 4'_2_5 . .
o=w1(T -'t1)+'Z@/ST =16X 125+4I25X x775=696.60
ws _— o
16 X 095
‘.1
Expansion of Gases.—Two laws govern the varying
volume of a gas, according to whether temperature or pressure
be kept constant.
Tlze ﬁrst law of gas expansion, discovered by Boyle in 1662,
and veriﬁed by Marriotte in 1676, states that the volume of a
portion of gas varies inversely as its pressure, if the temperature be
constant. Shown by symbols:
V or P, and PV = a constant.
The relation of P and V is shown by diagram in Fig. 599,
the ordinates PP1 of the curve representing pressures, and the
588 Boyle’: Law.
abscissae V V1 corresponding volumes, a temperature z‘° being
maintained. Only one curve, the rectangular hyperbola, has
ordinate >< abscissa constant throughout, and that is the form
of the curve AB. Although always approaching the co-ordinates
00, or), it only meets them at inﬁnity. '

















‘~23
“s
k
g .
‘t
E,
L . . -——
aﬁ. mamas’
Laws.
FIRST SECOND
P081 r/0N P081 1'/ ON A
Isothermals. By reason of equality of temperature, AB is

also known as the isothermal of a pezy‘ea‘ gas, that is, of a gas
following Boyle’s law perfectly. Marriotte’s tubes, Fig. 600,
prove fairly Well the accuracy of this ‘law. A and B are strong
Charles’ Law. ‘ 5 89
glass tubes, A being sealed at top, level with mark 10, and c is
a stout though ﬂexible rubber tube. Taking the ﬁrst position,
mercury is poured into the funnel D until about level with o, and
a ﬁnal adjustment made by moving B up or down. The portion
of air imprisoned in the leg A, supports a pressure of one
atmosphere, D being open, and has a volume of 10 ins.
Raise B until the mercury reaches 35", and the ﬂuid in A will
have risen to 5". The difference of mercury levels is now 30 ins,
representing an additional pressure of one atmosphere : so the air
now supports two atmospheres, and has a volume of 5 ins., or P x V
is constant. Intermediate experiments can easily be obtained,
and the law more generally proved. The so-called permanent
gases are practically perfect, and others fairly so, if measured at a
much higher temperature than that of liquefaction.
The second law of gas expansion was discovered by Charles in
1787, published by Dalton in 1801, and by Gay-Lussac in 1802,
all independently. The last-named completely veriﬁed the law,
which states that the increase in volume of a portion of gas varies
directly as the temperature, 2}‘ the pressure he constant; or, if V be
the original volume, V1 the increase, V2 the total volume after
increase, and t° the rise in temperature,
V1 0: t°, and V1 = V x at°
a being the coeﬁicient of cuhical expansion. V and a are constants,
and t° the only variable;
V2 = V+V1 = V+Val° = V (1+at°).
The coefﬁcients of linear expansion for solids, p. 369, vary
with the substance, as do also their cubical coefficients (being
three times the linear ones); but all gases not only expand
regularly, but each to the same amount, increase of temperature
being equal, one coefﬁcient serving for all. Between 32° and

212° the total expansion is ‘3665 V or ‘31225 = ‘00204 for each
degree ; ﬁgures found by Gay-Lussac, expanding the air in an air
thermometer, the bulb dipping in heated water, whose tempera-
ture was taken by mercury thermometer.
Absolute Zero of Temperature. Let AB, Fig. 601, be
an air thermometer with an air-tight piston c, and let the volume

590 Combination of Boyle’s and Charles’ Laws.
Ac be called 1, the temperature being 32°. Set off ordinate CD
for volume at 32°, and FE for that at 212°. The latter will be
1366 5, and the gradual volumetric increase be shown by the
straight line DE. Supposing the law true for extreme limits, line
DA (a production of DE) will mark out the volume as we decrease
the temperature, ultimately meeting AB in A. Then, at A, the
volume will have decreased to nothing, and all the heat will have
been taken out of the air. Though these possibilities are absurd,
their supposition enables us to ﬁx a zero point having important
advantages in thermo-volumetric calculations.
To ﬁnd A, the absolute zero of temperature, we proceed by
similar triangles :
Ac_DG __DG><CD 18o><1
CD _- (BE and Ac - GE = .3665 = 492 about,

'. A’s reading = 492 - 32 = 460° below zero F.

Any ordinary temperature F. may, then, be made absolute by
adding 460, and while t° indicates Fahrenheit readings, 1' will
show absolute readings.
Note that Fig. 601 is a graphic statement of Charles’ law, AE
being an isojbiestic or line of constant pressure, as AB, Fig. 509, is
a line of constant temperature.
Combination of Boyle’s and Charles’ Laws.-—PV is
invariable for any particular position on the thermometric scale;
but if t° be raised, the value of PV will be raised also. In
Fig. 601, if P be kept constant V will vary as r; so if V increases
at the same rate as 7', any series of multiples of V will similarly
increase ; and as P would be such a multiplier in Fig. 601,
PVocr and PV= or,
which is strictly general, c being a coefﬁcient depending on
the gas.
Taking one pound of air at a temperature of 32°, and at atmo-
spheric pressure, reckoning in lbs. per sq. ft. and in cubic feet,
Regnault found by experiment that

62
PV= 26,214 = or, c— 2 ’ I4
_ 32 + 460 = 53.28.
For superheated steam c = 8 5' 5 (proven later).
Latent Heat of Water. 591
The above formula gives P or V at any temperature, when c
is known.
Three States of Matter.—These, the solid, liquid, and
gaseous, are well understood, and it is also now admitted that all
bodies are capable of existence in each state successively, though
not necessarily at the normal pressure and temperature. Taking
one pound of any substance and applying the speciﬁc heat due to
its state, its temperature rises one degree, and as the speciﬁc heat
is approximately regular for each state, practically the whole heat
is registered on the thermometer. But in all substances two
critical points occur called the points of fusion and evaporation,
and known respectively in the case of water as the ‘freezing and
boiling points;’ at ‘these points additional heat is absorbed merely
to do the work of re-arranging the molecules, of fusing or melting
on the one hand, and of evaporating on the other hand. Such
‘latent’ heat is not observable on the thermometer, and must,
therefore, be otherwise detected.
Latent Heat is the quantity of lzeat units aosoroed or given
out in changing one pound of a suostance from one state to another
wit/tout altering its temperature. This phenomenon, ﬁrst observed
by Black about 1757, will now be demonstrated in the case of
water, and the units measured.
Latent Heat of Water is that required to melt one pound
of ice. Provide a vessel with felt-covered sides, similar to that at
Fig. 598. Fill it with water of known weight (zv) and tempera-
ture (t°). Take a piece of ice which has begun to melt, wipe dry,
weigh (zvl), place in the water, and close the apparatus. When
the ice is quite melted, gently stir, and measure the ﬁnal tempera-
ture (T°), which may be a few degrees above 32°. Let L1, = the
latent heat of water; then
Heat lost by water = Heat gained by ice
weight >< fall of temp. = weight >< (latent ht. + rise of temp.)
to (t° -T°) = zvl {L}, + (T° — 32°)}.
Supposing 20 oz. of water at commencement, at 60°, and 2 oz.
“\of ice at, of course, 32° ; the ﬁnal temperature being 45°, then
20 (60 - 45) = 2 (L11 + 45 — 32),
and Lh = isle—2:32 = 137 units.
592 Laz‘em‘ Heat of Steam.
Supposing, further, that one degree in the ﬁnal temperature
has been gained by radiation from the room, 44 will be the
temperature due to mixture,
H
20 (6o — 44) 2 (Lh + 44 — 32)
320 — 24
l h = ———-——— = 148 units.
2 __—
T he correct result should be 144 units, only obtained with
careful preliminary radiation experiments.
Latent Heat of Steam.——In Fig. 602 water is boiled in
ﬂask A, and steam then passed by tube B to ﬂask c, where B dips
into water. The screen D is to prevent radiation from A to c,


.S'CRESN



and the experiment is continued till the water nearly boils in c.
By weighing c both before (all) and after the experiment, we have
the amount of steam condensed (20). Then,
Heat lost by steam = Heat gained by water,
20 {(212 + Lh) —T°} = w1(T° — z‘1°).
Suppose the’ weight of water is 20 oz. at temperature 70°, the
weight of steam condensed 1%- oz., and the ﬁnal temperature 146°,
a loss of 1° occurring by radiation.
1'5 (212 + Lh — 147) = 2o ([47 - 7o),
,’ Lh : I540 _ 1'5
The exact value is 966 units.
= 96 | ‘6 units.
It should be well grasped that latent heat is a kind of speciﬁc
heat given to the body during the change from solid to liquid and
Saturation and Boiling Points. 593
from liquid to gaseous. In the reverse order an equal quantity
of heat is given out. Thus, 1 lb. of ice below 32° will give
out or absorb ‘5 unit for every degree, and 144 units when
melting. Water between 32° and 212° will require 1 unit per 1b.,
approximately, for every degree, but when evaporating absorbs
966 units per lb. Finally, if the steam be superheated beyond
212°, ‘48 unit will raise each lb. by one degree at a time.
Fig. 603 shows the changes indicated, A B 0 being the curve
of volumes, with D E F as base, and the dotted line a curve of
corresponding temperatures. The base-line lengths indicate units
of heat required to change both volume and temperature under
atmospheric pressure. The volume at F is too great to be shown
on the diagrams, but is given to a smaller scale at G.
Saturation and Boiling Points.-—If a boiler be open,
the steam is formed under atmospheric pressure, or 147 lbs. per
sq. in., which it exactly balances; and its temperature will be
212° F. By covering the oriﬁce with a weighted valve, steam is
formed at a higher temperature, because under greater pressure.
If the water be boiled in a partial vacuum, the temperature will
be below 212°, because the pressure is relieved. When ebullition
ﬁrst commences, and steam is emitted (see E, Fig. 603), the
boiling point is reached ; and the temperature has a deﬁnite value
in accordance with the pressure. The steam now forming is in
contact with the water, and, being more or less full of watery
particles, is called Wet Saturated Steam. The latent heat is
gradually absorbed ; and, when fully taken up—namely, when all
the water has just boiled away—the saturation point is reached,
and we have Dry Saturated Steam (see F, Fig. 603). Applying
heat still further without further supply of water, expansion takes
place (approximately) according to Gay-Lussac’s formula, and the
steam is said to be superheated. The boiling and saturation
points then, although having the same temperature, by no means
represent the same condition. In practice, dry saturated steam
is only approximated to by providing domes to boilers, to take
the steam as far from the water as possible.
Besides having speciﬁc temperature and pressure, dry satu-
rated steam has a speciﬁc volume. In Fig. 603, the volume of
steam to that of water is 16 50 : 1, called its relative volume, while
Q Q
594 Saturated and Superheated Steam.
the volume of I lb. weight is' 2636 cubic ft., termed the speciﬁc
volume.
Deg‘. I.—The Saturation Point is attained when all the
latent heat required for the steam has heen tahen up.
Def 2.——The Boiling Point occurs when the tension in the
water overcomes the surrounding pressure.
Def 3.——Dry Saturated Steam is that which has a speciﬁc
volume, pressure, and temperature, corresponding to its
complete formation.
De)‘. 4.—-Wet Saturated Steam is in process of formation,
and is in contact with the water.
Def 5.-—Superheated Steam is that which has its tem-
perature raised ahoue formation point.
Dej‘. 6.—Speciﬁc Volume is the numher of cuhic ft. to the
lh. wezght, and SPECIFIC DENSITY is the number of lhs.
in a cuhic
weight of dry steam
weight of water particles
given volume is called the dryness fraction. Taking I lb. of
wet steam with w = weight of dry steam in it 3 then (I -w) =
weight of water particles and
Dryness Fraction.—The ratio in a

dryness fraction = (a whole number.)

Curves of Saturation Points.—The comparison of
temperature and pressure of dry saturated steam has been
proved by experiment. From — 22° to 32°, Gay-Lussac used the
apparatus in Fig. 604. Both barometer tubes have vacua above
the mercury, but B has a little water on the surface of the mercury,
whose vapour pressure reduces the height of the'column. As
I in. of mercury represents about @- lb. per sq. in., the pressure is
therefore known. Various freezing mixtures successively surround
the blind end of tube B, their temperature being shown by
thermometer.
Fig. 605 was Regnault’s apparatus for temperatures from 32°
to 122°. As before, barometer A has a perfect vacuum, while
B’s vacuum is impaired by vapour rising from water lying‘ on the

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596 Regnaalt’s Experiments.
surface of the mercury. Both tubes are surrounded by heated
water, whose temperature is shown by thermometer.
Regnault further found, as in Fig. 606, the temperatures and
pressures of saturated steam between 122' and 219°, the experi-


r'VACUUM


60?.


ment having since been carried to 432°. A is a boiler where
steam is formed, and B a copper sphere containing an artiﬁcial
atmosphere, produced by the condensing syringe c. As fast as
steam is formed, it is condensed by water passing from D to E
round the steam pipe ; but this is a practical detail. Essentially,
the pressures in B and A balance, being measured by the open
Total Heat. 597
syphon tube F, of great height for the highest pressure (twenty-four
atmospheres). Four thermometers at A measure the temperature
of the steam.
The relation between temperature and volume may be found
by Dumas’ method, Fig. 607. The ﬂask A, having stopcock E,
is (1) exhausted of air and weighed, and (2) its weight is found
full of water. A little water being retained, the ﬂask is lowered
into B, a bath of fusible metal, whose temperature is found by
thermometer c, and when all the water evaporates and A is full of
steam only, the cock is turned off (3) and the weight of the ﬂask
obtained. Deducting (1) from (2) and (3) gives weight of equal
volumes of water and steam respectively, from which the volume
of 1 lb. of steam may be deduced.
Fig. 608 shows the results of the above-described experiments.
Ahsolute pressures)‘ are measured up the vertical centre line; to
the right are the corresponding speciﬁc volumes, and to the left
the temperatures Fahr. The latter forms also a curve of expansion
for dry saturated steam—that is, steam kept always at saturation
, point.
Total Heat of Evaporation is the quantity required to
raise one lh. of water from 32° to a given temperature, and then
evaporate it. The investigation of total heats at various tempera-
tures was successfully pursued by Regnault. Referring to
Fig. 609, steam was passed through a coiled pipe (A) surrounded
by water, to which the latent heat was given up; an artiﬁcial
atmosphere being introduced at B, while thermometers showed
temperature of both boiler and tank. From his results, Regnault
devised the empirical formula:
Total Heat T.H. = 1092 + '3(t°-32°).
From- which, deducting the sensible heat t° - 32° :
L1, = 1092 — ‘7(t° — 32) = 966 — ‘7(t° — 212°)

—formulae serviceable both above and below 212° if the steam
be saturated.
* Pressures from the ‘vacuum line’; that is, from a condition of perfect
vacuum.
598 Steam and Water Mixture.
P/wsuna; Wenz/wraaere d’; Volcano
9f Dag Saar/med imam.

TEMPERATURE PAH.
VOL. or ILB W1’. CUB. FT
Mixtures of Steam and Water.-We can now calculate
the quantity of condensing water required with a given tem-
perature of steam. For convenience, we shall measure from
o° Fahr., and omit the Lh of ice.
Example 59.—The temperature of condensing water being 60°,
and that of the exhaust steam 193°; while the condenser remains at
a temperature of 120°. Find the weight of condensing water per lb.
of exhaust steam. (Hons. Steam Ex.) '
Mec/ianical Equivalent of Heat. 599
Heat lost by steam = heat gained by water.
Izv (S;1 + Lh — T) = u/1(T — t).
I [193 + {966 — '7 (19s — m>l - 120]
= 193 + 9793- 120
1 120-60
201 (120 - 60).

= 1753 lbs.
Mechanical Equivalent of Heat.—We shall now brieﬂy
describe how Joule compared a quantity of heat with its mechanical
or work equivalent. Rumford and Davy had made their friction-
heat experiments on solids ; but Mayer, in 1842, heated water by
'ii_
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mere agitation. Adopting the latter method among many others,
Joule at the same time measured the work required to raise the
temperature. A cylindrical copper vessel (A, Fig. 610) containing
water, had diaphragms as at B, through slits in which paddles
revolved on the vertical axis C. From roller D passed light cords
to the large pulleys EE, upon whose axes were smaller pulleys FF.
600 First Law of Thermodynamics.
From the circumferences of FF'weights GG were hung, which,
being allowed to fall, rotated the paddles and raised the tem-
perature of the water. By repetition, the temperature of the
water was raised to a measurable quantity, the work of the falling
Weights being simultaneously noted, until the average of many
experiments gave the ‘mechanical equivalent’ as 772 foot lbs. to
one B. T. U. We may now state the
First Law of Thermodynamics.—Heat ana7 rnee/zaniral
energy are mutually tonuertille, and foule’s equivalent (f) is the
rate 0f exchange.










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Internal and External Work during Evaporation.
—In heating water and evaporating it:
r.-—The temperature of the water has been raised.
12.—The water has been changed into steam at the same
temperature.
3.—The volume of the water and steam has been increased
against external resistance.
]nternal and External Worh. ' 601
For one other change, the separation of the molecules during
steam formation, Joule showed experimentally that no heat was
required, so we need not further consider it.
Take the vertical cylinder, Fig. 611, of 1 sq. ft. base,
and let 1 lb. of water at 60° lie within it, covered with a
piston. Upon this piston there is a pressure of 1 atmosphere, or
(14‘7 x 144) lbs. = 21168 lbs.
1 cubic ft. of water weighs 62' 5 lbs.
‘. 1 lb. of water will stand at = ‘016 ft. high.
Speciﬁc volume of 1 lb. of steam at 212° = 2636 cubic ft?‘
Heating from 60° to 212° does not materially change the water
volume (see Fig. 603) ; but when all the water has become steam,
the piston would assume the dotted position in Fig. 611, having
risen 2636 ft. against a pressure of 2116‘8 lbs., thus absorbing
55,799 ft. lbs. of work. During formation, we know that 966
thermal units, or 966 x 772 = 745,752 foot lbs., have been
required, so that 745,752 - 55,799 = 689,953, foot lbs. have been
used as internal work merely to change the state, and 55,799
foot lbs. have done external work against the atmosphere during
that change. In addition, there have been required, to raise the
temperature of the water, 212 — 60 = 152 thermal units, or
152 x 772 = 117,344 foot lbs. Collecting these results, we have:
S%1::;le{ 1. 1 17,344 foot lbs. to raise water’s temperature.
2. 689,95 3 foot lbs. to change from water to steam, as
Latent ‘ in a vacuum (internal work).
Heat. 3. 5 5,799 foot lbs. to raise piston against atmosphere
(external work).
Total, 863,096 == {966 + 180 - (60—32)} 772.

And the three values have the proportions 2'1 : 12‘36 : 1.
* Speciﬁc volume of saturated steam at any other pressure is found from
the formulae of Rankine or Fairbairn respectively:
iv“ = 475 (e + ~35) (v- ‘41) = 389-
602 7 Eﬁiciency of Steam.
Commencing at 0, Fig. 61 I, draw the co-ordinates oY, ox, for
pressure and distance respectively. Measure 2636 ft. at 0A, and
21168 lbs. at o B; the rectangle A B then shows external work.
Make 0 D and D E 12'36 and 2'1 times 0 B respectively; the area
0 F is the internal work during evaporation, and D G shows the
work required to raise the water’s temperature from 60° to 212°.
Rectangle AB representsthe only useful effect, the rest being
expended on internal resistances, and the
external Work _ 55,799 _ .0646
Efficiency of the steam = W _ 863,096. _

Let us next examine the case of steam at I60 lbs. pressure
(above atmosphere), as in triple-expansion engines.
I lb. of steam at 1747 lbs. per sq. in. absolute has a speciﬁc
volume of . . 2' 5 cub. ft.
Load on piston = 1747 x 144 . . . . . = 25,156 lbs.
(1) External work = 25,156 x 2'5 = 62,890 ft. lbs.
Temperature of steam . . = 370° F.
Latent heat = {966 — "7(370 - 212)} x 772
(2) Internal work = (660,369 -— 62,890)
(3) Heat to raise water’s temperature
= (mo—@772
And total work = (I) + + (3)
660,369 ft. lbs.
597,479 ft- lbs-
239,320 ft. lbs.
899,689 ft. lbs.
external work _ 62,890
Efﬁciency of steam = total Work - W

Which proves that high pressure steam, weight for weight and
without expansion, is not more economical than low pressure
steam.
Speciﬁc Heats of a Gas.--As with other substances,
these are the number of T. U. required to raise the temperature
of I lb. weight through one degree F. But there are two methods
of raising the temperature, the speciﬁc heat being a different
quantity for each case. Assuming the gas enclosed in a cylinder
and covered with a loose piston, we may, While supplying heat,
(I) allow the piston to rise freely, or (2) ﬁx it immovably. In
(I) we are heating at constant pressure, and ‘in (2) at constant
two speciﬁc heats,
Speciﬁc Heats of a Gas. 603
volume: the former requiring a larger heat supply than the latter,
because external work is there performed in addition. Regnault
found the speciﬁc lzeat at constant pressure (C1,) of any ‘ permanent
gas,’ like air, to be '2 37 5 thermal unit.
Using the piston and cylinder illustration, with 1 lb. of air at
bottom, as in Fig. 611. Then :
1 Cubic foot of air at 32° weighs '0807 lb.
1 lb. of air will stand at = = 12'4 feet
_I___
‘0807
under atmospheric pressure and temperature of 32°. Heat to
212°. Then, from Fig. 601,
Increase of volume = '3665 x 12'4 = 4'54 feet,
which is also the rise of piston against 21 168 lbs.
External work = 21168 x 4'54 . . . . . = 951027 ft. lbs.
Total work = rise in temp. >< spec. ht. = 180 x "2375 = 42-75 T.U.
= 3'3003 ft. lbs.
Internal work = 33,003 — 9510'27 = 23,492'73 foot pounds,
or 304; T.U.
But the last ﬁgure is the heat required to raise the temperature
at constant volume through 180°.
. 0'
Speciﬁc heat at constant volume = 3-15 = ‘1672 T. U.
or, more correctly, may be taken at ‘1686; and the ratio of the
= QB : "2375 =
Y Cv '1686

1'408
a number we shall require later.
We may also represent the speciﬁc heats of a gas in foot lbs.,
using symbol K instead of C. Then,
Kp = ‘2375 x 772 18335 foot pounds.
Kv = ‘1686 x 772 = 13016 foot pounds.


Regnault’s LaW.—T/ze speciﬁc heat of a gas at constant
pressure is the same at all temperatures. If volume V1 of a gas
604 - Speciﬁc Heats of Steam.
be increased to V2 under constant pressure P, the temperature
rising from 1'1 to 1'2 absolute : ‘
External work = P (V2 -Vl) = 6(1'2 -— 7'1)
Total heat expended = spec." ht. >< rise in temp.
=ma-o
and Internal work = Total - External
: KP (7'2 _ 7'1) " 5 (7'2 " 7'1)-
But, when a gas is heated at constant volume, only internal
work is done.
Kv (T2 _ T1) : KP (T2 "' 7'1) _ 6 (la-7'1)
and Kp — KV = e.
Speciﬁc Heats of Superheated Steam.—By experiment
Kp = 370'56 foot lbs., and as steam a few degrees above satura-
tion point is a practically perfect gas, Kp will be a regular quantity.
Further, we are heating at constant pressure and
For steam PVs = esr For air PV,1 = ear
. . v
Now the who of speciﬁc volumes 3 = ‘622.
. is = _ _ i2- _ 523 =
' ea 6 2 an is 622 ' 22 é-S—s—
Then Kp - K.v = 855 and Kv = 37056 - 85'5 = 285-06 foot pds.‘
- _ 51: _ §7°_'56 _ .
Finally 'y - Kv - 28506 - r 3.
Expansion Curves and their Areas.—The hyperbola,
co-ordinating Boyle’s law, has been shown at Fig. 599, and one
other expansion curve, as these are called, has the formula pv"=e,~--
the exponent n changing with the substance. Now the shaded \\
area, Fig. 612, shows the work done during expansion, and could
Isothermals and Adiaoatics. 605
be actually measured (see Fig. 325); but as these curves have
deﬁnite formulae, it is easier to use algebraic methods. Then,
Area of curve having formula PV = C is PV x loge $2—
1
v . .
and as PV = er, and ‘72 = the who of expansion r.
1
Area = cr loge r.

The logarithms are hyperbolic. '
is P1 V1 — P2 V‘2
Area of curve having formula PV" = C n _ I
Isothermals and Adiabatics.——If a gas expand, and
advance a piston against a resistance, it does work requiring
expenditure of heat. Such heat being abstracted from the gas,
the temperature of the latter falls; but if heat be supplied just
as fast as it is abstracted, the temperature will remain constant,
the expansion be according to Boyle (PV = C), and the curve is
called an isothermal.
If no heat be supplied, the pressure-volume curve will fall
below the hyperbola, as in Fig. 613, according to the formula
PV" = C, and be then termed an adiahatic. Similarly, in com-
pressing, the adiabatic will rise above the isothermal, because
the gas becomes heated by work done upon it (Fig. 614).
Adiabatic Exponent—The value of n will now be found
for the adiabatic.
P1V1 — 132V2 __ c
n - 1 _ n — 1

Area of curve = (1'1 — 1'2) = External work.
Total work - Internal + External
c

=Kv(7'2"7'1>+ﬂ_1<7'1“"2>
K._K,)*
__(7'2—T1)<Kv+ "-1—
= (T. - T.) (Kv (7’ 7311K" _ K") = (‘2 - ‘1> )
* Notice change of sign in two places in order to balance.



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Expansion Curves. 607
But in the adiabatic no heat is communicated from outside,
and none taken away.
0
nKv—Kp) _
n—I _
Total heat supplied (1'2 - 1'1) (
that is, one of the bracketed quantities is nothing. But (1'2 - 7'1)
is tangible,
.0 n—I
K
andn=-—K—='y
V
'. PVY is the general equation for the adiabatic.

In adiabatic expansion, external work is done at the expense
of internal heat, and is therefore negative.
Comparison of Temperatures in Adiabatic Ex-
pansion.
—1 -1
P2V2Y = PIVIy and P2V2 (V2), ) : P1V1(V17 )
' y—I 1—1
P,v2 = P1V1 or a, = a,
2
. 1' = T -— I‘ 'r = T - '
2 1 7, 2 1 7, for aIr.
Various Expansion Curves, as represented by their
formulae, may now be collected:
For isot/zernzal expansion of a perfect gas,
PV = C (a true rectangular hyperbola).
For adiaoatic expansion of a perfect gas,
PVY = C (y = 1'408 for air).
For expansion of dry saturated steam, without becoming wet or
superheated ; being the ‘curve of saturation points,’ Fig. 608,
pVii = C = 475 (Rankine’s curve)‘.-
(,4 + '35) (V — '41) = C = 389 (Fairbairn’s curve).
Both founded on Regnault’s experiments.
608 [sot/zermals of Saturated Steam.
For adiaoatie expansion‘ of saturatea7 steam,
,oVI'BS: C (Zeuner’s curve).
pv‘s" = C (Rankine’s curve).
For aa’iaoatie expansion of superheated steam,
Pv"3 = C
Rankine’s adiabatic represents the expansion of steam in a
cylinder under good conditions. All starting from the same
point, A, Fig. 615, the hyperbolic curve lies highest, then the
saturation curve, adiabatics for saturated and superheated steam
respectively, and lastly the adiabatic for air.
Isothermals of Saturated Steam or other Vapours.
—In Fig. 616, A B is the saturation curve, and P a point showing
a’ry saturatea7 steam at pressure P, volume v, and corresponding
temperature. If v be decreased by compression, temperature
being constant, some steam liqueﬁes, P is kept constant, and the
compression curve is P Q, the steam becoming met. If, again, v
be increased at constant temperature, the steam becomes super-
heated, and expands along P R, rising above the saturation curve
P B, which is a curve of lowering temperature. Q P R is sometimes
called the expansion curve of dry saturated steam—an incorrect
description, for the steam is only dry at one point P. The adia-
batic g r has the formula PVX50 = C.
Cycle of Operations.—-If a working gas be passed through
a series of heat changes, and ultimately returned to its original
condition, the changes constitute a eye/e, and external work has
been done equal to the neat expended, because the gas, reverting
to its original state, will have returned the internal ze/or/e ﬁrst
absorbed. The indicator card represents a particular cycle.
Carnot’s Reversible Cycle or Perfect Heat Engine
is the most perfect example of an engine cycle. It should be
understood that the object of making changes upon a gas is to
obtain external Work from heat; and though Carnot’s engine is
unattainable, yet its perfection should be approached as closely
as possible by practical engines. All engines, Carnot’s included,
receive heat energy from some lzot loa’y; during. expansion of the
working substance, give external work to moving mechanism;
Conditions of a Perfect Heat Engine. 609
and, ﬁnally, reject a smaller quantity of heat-into some cold body.
In the steam engine these ‘bodies’ are the boiler and condenser
respectively. We shall see that the efﬁciency of the engine does
' not depend on the working substance (if the perfect cycle be
imitated), but only on the difference of temperatures between
which the substance is utilised. A perfect heat engine should
have the following qualiﬁcations :—
1. The heat must be received at the temperature of the
hot body.
2. The heat must be rejected at the temperature of the
cold body.
3. The cycle must be reversible.
For perfect working, it is clear that all heat represented by
drop of temperature between the hot and cold bodies should
be delivered to the engine as work. But if there be a fall of
temperature between hot body and engine, or between engine
and cold body, some heat will be lost on the way which does
not reach the engine. Hence the reason for (1) and (2). We
may explain (3) similarly, ﬁrst premising that by direct action we
mean the transformation of heat into work by abstraction of heat
from hot body; reversed action being obtained by turning the
engine backward, giving all the work back to the hot body. In
a perfect engine, the work given by the gas during one direct
cycle must equal the heat returned during one reversed cycle,
which is to say, that all the ‘ available ’ heat must be transformed
into work.
Carnot’s cycle fulﬁls these three conditions, and none other
can have a higher efﬁciency, as we shall prove. Fig. 617 is the
ideal engine, having a non-conducting cylinder A, and piston B,
the latter connected to suitable working mechanism. 0 is the
hot body, E the cold body, and D a non-conducting cylinder-
cover; and the underlying diagram indicates the changes we
are now to follow. First operation: Commencing with a portion
of gas behind the piston, at temperature 1'1 (that of the hot body),
pressure P1, and volume V1, we allow this to expand at constant
temperature while doing work. Placing the left end of the
cylinder on the hot body, the expansion curve is the isothermal
R R
610 Carnot’s Perfect Engine.
1 2. Second operation: The expansion continues, without supply
of heat, by placing upon the non-conducting cover ; and the
adiabatic curve 2 3 is traced, the temperature falling from 1'1 to 1'2,
on account of work done by the gas. Third operation-LCom-
pressing the gas at constant temperature 1'2, we place the cylinder
"07' 800)’ c
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NON- CONDUCT.
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on the cold body, to receive such heat as must be rejected 3 and
the curve is the isothermal 3 4. Fourth operation .' Finally, place
the cylinder on the non-conducting plate and compress along the
adiabatic 4 I 3 the substance is then returned to its original con—
dition and temperature T1.
During these operations the work done hy the gas is shown
by diagram F, and that on the gas by diagram G, their difference
\
Efficiency of Carnot’s Engine. 61 I
H being the effective work given to the engine. Reckoning the
heat used, we have :
From I to 2 (r1). Heat expended, being work area I,
= P1 V1 loge r1 = crl loge r1.
From 2 to 3 (r2). 1V0 heat expended, external work, J, being
done by abstraction of heat from the gas.
From 3 to 4 Heat rejected, as at K,
= P3V3 loge r3 = e72 loge r3.
From 4 to 1 (r,,). M heat rejected, external work, at L, pro-
ducing internal work on the gas.
We have previously found (p. 607) the comparison of tempera-
ture in terms of r, during adiabatic expansion or compression :
<I)y—I
1' =1- —
2 l 7,
from which may be deduced:
7'2
Referring to Fig. 617, expansion from 2 to 3 and compression
from 4 to 1 are between the same temperatures, so the ratio of
adzahatic expansion equals that of adiahatic compression .- r2 = r,
v v v v.
And as, i‘ = i Vlv3 = vzv4 and -2 = -2
v v v v
2 1 1 4
Or the ratio of isothermal expansion equals that of isothermal
compression .- r1 = r3 = r, say.
Resuming ; when the cycle is complete no internal work has
. been done—all is external work:
External work = Heat expended - Heat rejected
= c1-1 loge r - cr2 loge r3 = (r1 — 1'2) c loge r.
Work done
Eﬂicrency of Ené.’me = W
_ (1'1 — 7'2) (6‘ log, 7’) : T1 — 1'2
T1 (6‘ log, 7') T]
It will be easily seen that for the highest efﬁciency, 1'2 must be
nothing, or the condenser must have a temperature of ‘absolute
612 Reversed Action and Second Law.
zero,’ a condition practically unattainable, and all the heat in the
working suostance can never a utilised. The energy obtainable is
only that between the availaole temperatures, and difference of
T1 and r2 must be as large'as is practically possible.
Reversed Action occurs, as previously suggested, when
expansion takes place along 1 4, 4 3, and compression along 3 2,
2 1, the operations being entirely the reverse of those just con—
sidered. External work is done on instead of l] the gas, and
heat is taken from the cold oody and rejected into the not lady. No
better practical example of a reversed cycle can be given than
that of an air-compressing cylinder as at Fig. 562, p. 546,
Let it be possible to have an engine (No. 2) of equal power
but higher efﬁciency than Carnot’s (No. 1) ; and let No. 2 drive
No. 1 in reverse order. Then‘ No. 2, taking its heat from the hot
body and rejecting into the cold body, and giving all its external
work towards driving No. 1, the latter thus takes heat from the
cold body, which, together with the work received, it delivers
into the hot body. No external work being left over, the con-
trivance is self-acting.
Let H2 be the heat taken from the hot body by No. 2, and n,
that rejected into the cold body; H1 the heat rejected into the
hot body by N o. 1, and n, that taken from the cold body. Power
being equal,
(Reversed) Hl—lz1 = Hz—lz2 (Direct) . . . (a)
Hl - l21

- . H --/2
Efﬁclency of NO- I = Efﬁciency of No. 2 = 2 2
H1 H2
— l2 . _ it
But 132-3 15 to be greater than L
H2 H1
And, by (a), the numerators are equal,
H2 must be less than H1.
The heat taken from is less than that given to the hot body,
and by a self-actingprocess heat is being taken from the cold and
delivered to the hot body, which is impossible by the
Second Law of Thermodynamics—[feat cannot pass
from a cold to a not oody wit/rout external aid. This is the
.result of experience, the tendency being always to equalisation
Losses in Steam Engines. 613
of temperature by heat passage from the hot to the cold hody; so
we conclude that no engine can have a higher efﬁciency than
7‘ Carnot’s.
In practice it is difﬁcult to ﬁnd a sufﬁciently perfect substance.
Thus, steam is condensed by the cold body, and cannot be raised
to 1'1 by compressing, an essential in the perfect engine. Though
air can be thus treated, it is an indifferent heat conductor, and as
the changes can only be taken up with sufficient rapidity when
large surfaces are presented, the apparatus becomes unwieldy
for high powers. Small engines have been fairly successful;
the substance being usually raised to T1 by a combination
of compression and re-heating. The efﬁciency is thus less than
that of the Carnot cycle, the diagram being shown in Fig. 617
at M.
Steam engines have also much lower efﬁciency than the
perfect engine, and some causes of loss will now be considered
including friction.
Losses in Steam Engines :—
1. Steam is not supplied at the temperature of the hot body
(furnace).
2. Steam is not rejected at the condenser temperature and
pressure, but falls as regards both when leaving the
cylinder.
. The feed water has its temperature raised in the boiler
in stead of being originally at the temperature of the
steam.
4. The expansion should be adiabatic, as in a non-con-
ducting cylinder, but it varies considerably from this
(Fig. 618).
5. The steam should be compressed from condenser tem-
perature to boiler temperature. It is, however,
only compressed through a portion of this rise,
the rest being obtained by heat supply from the
boiler. _ '
. Clearance in cylinder being unavoidable, must be ﬁlled
by steam at each stroke, which does no work during
‘ full-pressure ’ period.
0»)
O\
614 Initial Condensation.
7. The boiler ‘primes’ more or less, that is, sends water
particles to the cylinder along with the steam, which
pass to the condenser without doing work, ‘or, still
worse, abstract heat from the cylinder steam in their
endeavour to vapourise.
8. The limits of working temperature are small in com-
parison with the temperatures themselves: ‘r1 being
ﬁxed to prevent burning of cylinder oils and packing,
and 7'2 by the cold well temperature.
9. Work is lost in (a) the ‘solid’ friction of the engine
parts, (b) the ﬂuid friction of the passing steam.
Initial Condensation and Re-evaporation.—-When
hot saturated steam enters a cylinder cooled to exhaust tempera-
ture, a sudden ‘initial condensation’ occurs, causing gradual fall
in temperature and pressure, through about half expansion period.
But the liquefying steam attempts to return to the remainder
that latent heat liberated during liquefaction. After about half
expansion curve the re-heating causes a certain re—evaporation, the
effect on the expansion curve being shown in Fig. 618, where the
full line is the saturation curve and the dotted line the usual
practical result. From A to B the pressure falls below the satura-
tion curve, and B to c shows a rise due to re-evaporation. The
work curves are probably equal in area, but the rise B 0 occurs at
a bad portion of the stroke, or near a ‘ dead-point.’
To avoid initial condensation, clothing should be applied in
quick running engines, but the steam jacket is best for engines
of a slower type, where time is allowed for the jacket heat to be
taken up. It might be thought that the steam used in the jacket
would balance the advantage, but actual experiment has shown a
return in favour of the cylinder. One important point is, that
the liquefaction occurs in the jacket and can be removed, whereas
in the cylinder it is detrimental. Live steam should always be
supplied, and the jackets kept well drained.
Theory of Compounding.-—Another way of decreasing
liquefaction is to divide the work among 2, 3, or 4 cylinders; and,
if great differences of temperature be employed, no other course
a is possible. Thus we arrive at the Compound, Triple, or Quad-
Theory of Compounding. 615
ruple expansion engine.ale The advantage of compounding was
long doubted, the true theory of its application being misunder-
stood. ‘ In Fig. 619, area A shows work done in the high-pressure,
B that in the intermediate, and C that in the low-pressure cylinder,
the object being to divide the work equally, while equalising the
fall of temperature as nearly as possible. The actual diagrams
will be discussed later, as also a further advantage of the system,
resulting in more even turning moment on the Crank shaft.




\


ﬁrm A B 0
l
| a I ’
5 §- \\ ///
v: ’ .
j / .\ 6'20
: é ____ __ -__;=- K
| 5 C
‘I’ / / / // /
J‘ Ok.-._ _._ volurnes or stroke, ‘F
I | 4 l
re-1——--+————e———————-—+:
Expansion in the Cylinder.—-Assuming steam to follow
Boyle’s law, Fig. 620 is a crude diagram of work done. The
' steam being admitted during, say, a quarter stroke, and the supply
cut off, the rest of the stroke is completed by :expansion. From
A to B there would be full steam, and from -A to C the pressure
would approximately fall along the isothermal and hyperbola B C.
Then area 0 A B G shows work done by the full steam, and G B C F
the additional work during expansion.
Construction of Hyperbola.-To draw this curve: join
0 D, produce the crossing point E horizontally to- C, which is a
point in the curve. Other points being found similarly, between
B and D, by projecting from the ends of radial lines, the curve is
traced through the crossing points.
* More correctly, 2, 3, or 4 stage compounds.
616 Steam Engine Indicator.
ClearancaﬁSupposing a certain clearance in the cylinder,
to be ﬁlled before the piston moves. Representing this by 0 J in
terms of the stroke 0 F, the steam now expands from J G to J F,
and the hyperbola must be drawn from the new origin J, thus
raising the curve to B K as dotted; and the rate of expansion
will have changed from
o F J F r + c
7,
—— to ~— or from—to ——
0G JG I I+c
The Steam Engine Indicator is a well-known apparatus
‘(ﬁrst invented by Watt, and much improved by McNaught and
Richards) for the purpose of automatically describing the pressure-
stroke diagram just considered. Fig. 621 represents a ‘Tabor’
indicator, one of the most recent varieties of the instrument.
A is a small cylinder containing a liner, in which a piston, B,
slides freely. Steam being admitted under B, pencil F is raised
by the connection (3, D being a rocking fulcrum. F would describe
an arc but for the slot E, which compensates the curvature and
compels the pencil to move in a vertical straight line, its displace-
ment indicating rise or fall of steam pressure. The drum G, pro-
vided with paper for the diagram, being rotated on stud L—by the
cord H (attached to the moving engine) in one direction, and by
the clock spring M in the other direction—represents the stroke
of the engine piston. Both actions occurring at once, a diagram
like Fig. 620 is obtained. Certain deviations, however, occur,
which we shall afterwards discuss.
Figure N represents the indicator gear usually adopted. It is
there applied to a horizontal engine, but may be modiﬁed to suit
other forms. Lever s vibrates with the crosshead, and carries on
its axis the ‘brumbo’ pulley T for decreasing the stroke of the
cord to suit that of the indicator drum. The indicator is con-
nected to each end of the cylinder by a pipe provided with stop-
cocks at P and Q, and an indicator cock at R. The latter is seen
in section at U and v, having a three-way passage to admit the
steam ( 1) to the indicator and out to the air for blowing through,
(2) to the indicator only, or (3) the cock may be closed. To
avoid clearance in pipe P Q it is better to use two indicators, ﬁxed
at P and Q. Notice also the spring w, of which several different
T/w (‘Tabor ”
AY/l'ecurv- E


Indicator?

ESFFNE

./
a

6 I 8 Indicator Diagram: Topography.
strengths are provided, so as to indicate pressure to any con-
venient scale: two wires are coiled in the same direction, but
start from opposite sides of the base.
To use the indicator, ﬁrst let the engine rotate uniformly, then
connect the cord. Open cock P and turn R to blow through.
Open indicator to atmosphere and let pencil describe atmospheric
line 5 then connecting indicator to steam, bring the pencil gently
round and describe the diagram. In like manner also with the
cock Q, after which the paper may be removed. The ‘pencil’ is
usually brass wire, and the paper that known as ‘ metallic.’
Topography of Indicator Diagram.—Taking a con-
densing engine, i.e., one which exhausts into a vacuum, and has
additional pressure due to the atmosphere on the forward side of
the piston, as in Fig. 622. o A is the vacuum or zero line, and
B c the atmospheric line of I 5 lbs. absolute ; D A is the stroke,
and o D the clearance (valve passages and clearance proper) in
terms of DA.
The clearance space ﬁrst ﬁlls, and the pressure rises to F.
Then the piston moves to G, where steam is cut off, expansion
takes place between G and H, release to exhaust at H, pressure
falling only to J, while the piston returns because we cannot
entirely eliminate vapour pressure in the condenser (back pressure)
shown by A J. Exhaust being fully open between 1 and K, a hori-
zontal line is drawn up to compression point K, and the remaining
steam compressed to L, where it is met by incoming fresh steam,
due to the opening (lead) of the valve before commencement of
stroke, and the pressure once more rises to F.
Deviations from the Normal Diagram are shown in
Fig. 623. Wire drawingr at cut-of is indicated at K, the full
steam line falling on account of narrow ports or throttling by the
slide valve. B shows late admission, the piston travelling some
distance before full pressure is felt, due to want of lead on the
valve, which should open hefore the end of stroke. Late release
and excessive clearance are seen at L, and a leaky piston would
cause diagram F, the pressures on each side of piston tending to
equalise. A leahy slide value, as at G, would raise the expansion
curve at ‘the expense of fresh steam, and initial condensation, H,
may be detected, by drawing the hyperbola. Too much or too
gag,
Diagram Examples. - 61 9
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Didi/cotter Dxiocgmam/ 6'23.
little compression would give diagrams C or D respectively, and a
shaky diagram, like E, would be produced by an IndICator w1th
too light a spring or too heavy a piston. DIagram A shows
l
620 Indicated Horse Power.
serious initial condensation. The upper and lower diagrams at J
are from the top and bottom of the piston respectively in a
Cornish single-acting pumping engine: and M shows the varying
diagrams obtained from a locomotive, (1) when starting, next (2),
and lastly (3), as the valve gear is linked up from the reversing
lever.
From the Indicator diagram we may therefore deduce:
. The points of admission, cut off, release, compression, &c.
Comparison of cylinder with boiler pressure.
. The wire drawing in steam and exhaust passages.
The back pressure.
The condensation, re-evaporation, and relative dryness.
The indicated horse power from the diagram area.
9‘9‘-P°°$°H
Calculation of Indicated Horse Power, or that shown
upon the indicator diagram, and representing the work given to
the piston by the steam or gas.* Three pairs of diagrams, in
Fig. 624, are taken from the respective cylinders of a triple-
expansion engine; and are copied from the Hons. Engineering
Exam. 1887. The mean eyfective pressureper square inc/z (It) will
ﬁrst be found, so the diagrams are divided into 10 parts by
equidistant vertical lines. Knowing the scale of the indicator
spring, the pressure may be measured at the middle of each
division, within the enclosed curve ; these ﬁgures representing the
@fective pressures. Notice that at A and F, Fig. 623, the loop
encloses minus effective pressure; every measurement must there
be treated as minus, and only added to the other plus measure-
ments algebraically. Adding the 10 measured parts, and dividing
by 10 gives mean effective pressure for each diagram; the mean
of the pair being then found by adding them and dividing
by 2.
Multiplying (p) by piston area (a) gives total mean pressure,
and this again by stroke in feet (L) gives work in foot pounds per
stroke. Further multiplying by number of strokes per minute (N)
gives work per minute, and the whole divided by 33,000, or one
* Brake horse power is found by dynamometer, as at p. 575, and
B. H. P.
me ' I l :
chamcal eﬁiclency 0f engme 1 H P.
Advantages of Compounding. 621
horse power per minute, will represent the indicated horse power
of the engine, the formula becoming
pLaN
33,000
Taking the high pressure cylinder in Fig. 624, the addition of
the pressures on the left diagram, 73, 103, &c. = 6795, and the
mean pressure = 67‘9 5. The right diagram similarly has a mean
pressure of 595, the ﬁnal mean pressure becoming 6795 + 59‘5
—I— 2 = 6372. Area of cylinder is 10 x 10 x 22 —:- 7 = 31416
stroke is 3 feet, and number per minute 63 x 2 = 126. We
have then:
Indicated horse power (per min.) =
6372 x 3 x 314‘16 x 126 _
33.000 _
In the intermediate cylinder, mean pressure on the left is 2 3'9
and that on the right 22, the ﬁnal mean being 2295. Area of
piston .= 8 5 5‘3 ; stroke and revolutions as before.

I. H. P. in H. P. cylinder = 2293.
22'95 x 3 x 855‘3 x 126
33,000
Mean pressures on left and right respectively in low pressure
cylinder are 9'5 and 765, and the mean of these is 857. Then,
I. H.P. in L. P. cylinder = 8 57 X 3 X 2290 22 X I26 = 224‘41
33,000 —————-
Advantages of Single, Double, and Triple Stage
Expansion.—The advantage of expanding steam in a single
cylinder, instead of using full pressure to the end of the stroke,
was demonstrated by Watt in 1782, and can be understood from
Fig. 625. E o is the stroke, and F N that portion during which full
steam is used, the rest of the stroke, N 0, being completed by the
pressure of the expanding steam. From what we know of the
work diagram, sBcU will show work performed by the ‘full’
steam, without condensation, UcKT that by expansion without
condensation, and HST J that produced by the use of a condenser.
Not only then do we obtain additional work by condensing, but
we are also enabled with the assistance of high pressure to
introduce an earlier cut off and higher rate of expansion: thus

I. H. P. in I. P. cylinder = = 22444.

using a less weight of live steam.
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Combination of indicator Diagrams. 623
Though very high rates of expansion are theoretically possible
in a single cylinder, the practical economical limits are soon
__ reached, for very high ratio means very high initial pressure, and
a great difference of temperature between live and exhaust steam.
The former entering a relatively cold cylinder, considerable initial
condensation results, which largely neutralises the advantage of
increased expansion ratio. This loss is best avoided by allowing
the steam to successively expand through one, two, three, or even
four cylinders, thus introducing the so-called Compound, Triple,
and Quadruple forms of engines. Referring now to Fig. 624, the
fall of temperature in the high-pressure cylinder is from 366° to
287° or 79°, that in the intermediate cylinder 71°, and that in the
low pressure cylinder 88°; a fairly equal division of the total fall,
which, if the work were performed in one cylinder, would be no
less than 226°. The total ratio of expansion is nearly 14 z 1, an
amount impossible in one or even two cylinders, because of the
serious loss from initial condensation occurring along the expansion
curve; and it is in this, the diminishing of the effects of initial
condensation with high grades of expansion, that the advantage
of compounding is most apparent.
One other advantage of dividing the work is that two or three
cranks are then employed, set mutually at angles of 90° or 120°
respectively; causing a more equable turning effort, as will be
more fully demonstrated later, avoiding dead-centres. Even
before the practical introduction of compounding, doublecylinder
engines were found necessary where frequent reversal was re-
quired, as in locomotive and marine engines. Each piston
should, however, give to its crank, as nearly as possible, the
same amount of work as any one of its fellows, a requirement
of greater importance than equal distribution of temperature fall.
Both points have been well met in Fig. 624, for the total work is
divided as 229, 224, 224, while the corresponding temperature
drops are 79°, 71°, and 88°.
Combination of Indicator Diagrams in Compound
and Triple Engines—Diagrams W, x, and Y, in Fig. 624,
are just as received from the indicator, where for practical con-
venience different pound scales are employed: the lengths of the
diagrams are also made to suit convenience of taking. Now
624 Combination of Diagrams.
primarily the base line should be volumetric, so in representing.
"these diagrams to the same scale, the bases must be altered to
suit the volume of each cylinder respectively, and one pressure
scale be used throughout; we shall then see at a glance the
comparative work performed in each cylinder, and shall further
be able to judge how nearly the total diagram corresponds with
what should take place were the whole expansion to occur in one
cylinder under theoretically good conditions.
Strokes being equal, the area, or diameter squared, will
represent cylinder volume. The squares of the diameters are as
4 : 10'89 : 29'2. Taking clearance at a cylinder volume for the
H. P., T16 for the I. P., and 1% for the L. P., they are represented
by '5, 1'1, and 265. In the large diagram, set up at MA a scale
of absolute pressures per sq. in., and measure volumes along OK
to any convenient scale. Thus the dotted rectangles CE, ZH,
and QU are obtained, in which the indicator diagrams are to be
inserted. Divide DE, GH, and JK, each into 10 parts, and erect
vertical lines, upon which pressures are to be placed, as taken from
corresponding lines on the diagrams W, x, and Y, being careful to
set them up to absolute scale ; and the shaded curves are obtained.
Next mark point of cut-off B, from which to draw‘ the satura-
tion curve. The latter being always shown in terms of speciﬁc
volume (see Fig. 608), divide AB into 2'7 parts, or the volume of
one pound weight of steam at 165 lbs. absolute pressure. The
method of division is shown at ML: an inclined line is drawn and
2'7 divisions to any scale placed upon it ; then parallel lines to ML
will divide the latter proportionately. The volume '41 cub. ft.
has thus been found,’ which being crossed by '35 lbs. sq. in.
minus, gives the new origin for the curve, BSR, to be drawn as a
hyperbola in the usual graphic manner (Fig. 620). A second
curve CTU may be traced by dividing AC into 2'7 parts and
proceeding as before, the origin being then much nearer o.
By stepping the cut-off ML into the whole volume MK, the
number of total expansions 1384 is found, the pound weight of
steam occupying at the end of the low-pressure stroke a volume
of 1384 x 2'7 or 374 cub. ft. The shaded areas, then, further
represent the work done by one lb. weight of steam, if the base
lines be speciﬁc volumes, and the pressures taken from the
f. H. P. from [deal Diagram. 625
pressure scale, but multiplied by 144 to obtain pounds per sq. ft.
The gaps between areas and saturation curves show work lost, but‘
' while there is a loss on the side 5, there is a gain on side T. If the
clearances were such as to cause the compression curves to follow T,
the expansion curves would no doubt follow 5 more closely, but
this would necessitate large clearance in the L. P. cylinder. Of
'course it must be understood that the saturation curves cannot be
exactly followed except where good steam jackets are adopted;
the curve would probably otherwise be nearer Rankine’s adiabatic
PV150 = C, which falls slightly below the saturation curve.
Calculation of Work and Horse Power from
Theoretical Indicator Diagram.—It is sometimes con-
venient to make rough preliminary calculations from a simple


AF"


IN/ TIA L PRESS.


LENGTH
EFFE i.‘ r/ YE
mzssuﬂq
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LENGTH OF




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N
hyperbolic diagram as in Fig. 62 5, where various losses at the
corners, caused by release, wire-drawing, cut off, &c., are neglected.
Then Area of BN = pi 1'
I L+c
Area of cKNG =191V10gJ =1“! +6) (loge 11+)
Mean effective pressure p. = (areas BN + CKNG + L) -- 19b
_Zii I I ( .. Eif _
- L{l+(l+c) logez,+ﬁ)} 19b
peLaN
33,000
Then
’ Horse Power =
SS
626 Diameter of Cylinder for given H. P.
The logarithms are hyperbolic, of which a table follows :
HYPERBoLIc 0R NAPIERAN LoGARITHMs.

N 0. Log. No. Log. N 0. Log. N 0. Log.
I 0 3'5 1'252 6 1791 8'5 2‘140
1'25 ‘223 3'75 1'321 6'25 1832 8'75 2'169
1'5 ‘405 4 17,86 6'5 1871' 9 2'197
1'75 ‘559 4'25 1'446 6'75 1'909 9'25 2'224
2 ‘693 4'5 I‘504 7 1'945 9'5 2‘251
2'25 '810 4'75 I'558 7'25 1"981 9'75 2"177
2'5 ‘916 5 1609 7'5 2'014 10 2'302
2'75 1011 5'25 1658 775 2047 12 2484
3 1098 5'5 1704, 8 2079 15 2'708
3'25 1'178 5'75 1749 8'25 2'110 18 2890‘



Diameter of Cylinder for given Ind. Horse Power
may be deduced from the formula already given for the latter.
Thus:

d2
LL
2) 4 1i = H. P.
33,000
d: P. X 33,000 = 205 P.
p x I x L 16L
4 .
Horse Power in terms of Steam used.-—Piston area
being measured in square feet, (l' + c) A = volume of steam up to
cut-off, and (l’ + c) AN = cubic ft. of steam used per minute.
But if area be in square feet, steam pressure must be measured
per square foot in the horse-power formula: also

;—I~:=7’ andL=r_(l'+¢)_;
ELP, =£I:_A_1ll ___ 14425{1'(l' + c) - c} AN
33,000 33,000
_ I441>{r(l'+ c)AN - cAN}
33,000
_ 14415 (r x steam per m. — cAN)
_ 33,000

Horse Power for Steam used. 627
Such a method of reckoning horse power is convenient when
“ deciding boiler capacity and heating surface. Then :
Steam used per minute ) _ (I. H. P.) 33,000 + 144pcAN
in cubic ft. ) 144 pr
' I. H. P. cAN
77 t a
B.H. P. cAN
r711 + Y

22916
= 22916

where )7 is the mechanical eﬁiciency of the engine. Some
allowance must be made for water used as well as steam, whether
passed through cylinder to condenser or liqueﬁed in jacket, but
the formulae will serve many practical purposes.
In the above formulae p is mean effective pressure per square
in. At p. 625, this quantity is estimated in terms of initial
pressure. If then itv be required to know the volume of steam
used, in terms of the initial pressure, it is only necessary to
substitute the value at p. 625 for p.
General idea of the various forms of Steam Engine.
—-The steam engine is a prime mover designed for converting
heat into work by allowing steam to expand behind a working
piston. Sometimes the work need only be of a reciprocating
nature; while in other cases, and this by far the greater number,
rotative motion is required, and the crank and connecting rod, or
some similar appliance is then employed, as fully set out at
pp. .486 to 496. Sometimes also a rotative shaft is introduced,
with a fly-wheel to assist in maintaining regular reciprocating
motion, where that only is needed, or perhaps to work the valves.
The Beam Engine, though almost obsolete, has served and is
serving much useful purpose, and a few of its applications will
therefore be described. In Fig. 626, A is a Cornish pumping
engine, a being the cylinder, e the working beam,‘ and f the
pump-rod passing down the pit-shaft. Steam is that known as-
‘low pressure,’ having only a few pounds’ pressure above the
atmosphere; and there are three drop valves, [2, c, d, for its
distribution, called respectively the steam, equilibrium, and
exhaust valves. The last passes the steam into the condenser g,
628 Various S low-speed Engines.
where a vacuum is formed and maintained by the action of the
air pump /2. Fig. 608 shows that water under low pressure (as
in a condenser) will boil and form vapour at a low temperature ;
and the air pump has to remove this vapour as far as possible,
as well as the condensation water. Even then there is always a
back pressure of 3 or 4 lbs. per sq. in. When the piston
descends, valves o and d are open and c'closed, there then being
boiler steam at top and a vacuum below; during the upstroke,
o and d are closed and c is open, which places the piston in
equilibrium, when the pump rods raise it by their weight. The
parallel motion (Watt’s) is explained at p. 499 ; but in A, Fig. 626,
one radius link is formed by the portion ek of the beam, and a
parallelogram then connected to the middle link fat, so that the
valve and piston rods move on parallel lines.
A rotative beam engine is shown at B. It differs from A in
having the crank and connecting rod instead of pump rod, and
four drop valves instead of three, the reason being that each end
of the cylinder must now be connectable with boiler or condenser
at will, and must therefore have a steam and exhaust valve. The
method of distribution is given in Fig. 629, where the left pipe
admits live steam to either end of cylinder, and the right pipe .
similarly removes the exhaust steam, whenever the proper valves
are lifted. _
A direct-acting pumping engine like that at c may have a
beam solely for actuating the valves and air pump, though it also
serves to guide the piston-rod. The straight line motion is
Scott-Russell’s (see p. 486), sometimes called ‘ grasshopper’
gear. A beam blowing engine is shown at D, a being the steam
cylinder and o the blowing cylinder, the latter having inlet valves
do’, and outlet valves ee, for both ends, so that the issuing air
may pass continuously to the blast furnace or other place of use.
The ﬂy-wheel is introduced to steady the motion.
E is a compound beam engine. The high-pressure cylinder a
is placed nearest the beam trunnion, and the low-pressure cylinder
further outward. The valves are not shown, but are so arranged
that, when the steam has done its work in the H.P. cylinder, it is
allowed to expand into the LP. cylinder before passing to the
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6 30 Various Medium-speed Engines.
The side lever marine engine F, the ﬁrst form considerably
adopted on steamboats, was but a beam engine doubled upon
itself so as to save room. a is the paddle-shaft, h the steam
cylinder, c the beam or ‘side lever,’ and d the air pump.
The Direct—acting Engine is shown in various forms in
diagrams G to R, Fig. 626. G is a horizontal factory engine, with
condenser a behind a cylinder b, so that the air pump may be
worked in a simple manner by projecting the piston-rod back-
ward. By dispensing with the beam very considerable friction at
the trunnion bearing is avoided, caused as such friction was by
both load and resistance, or double the piston load. In the
horizontal engine there is, however, some additional frictional
loss, due to weight of parts and thrust of connecting-rod, while in
the vertical engine, although the former is eliminated, the latter
still remains.
The diagonal paddle engine at H, like other marine engines,
is designed to save room. Whenever paddle propulsion is em-
ployed, these engines are now chosen for the purpose. The
condenser and air pump are placed within the ‘triangle.’ J is a
form of factory engine seldom employed, but given as an example
of a vertical engine with cylinder at bottom and crank overhead 3
the slide valve replaces the four drop valves of Fig. 629, being
worked by eccentric from the crank shaft.
Two other paddle engines are shown at Q and M. Q is the
oscillating engine, exceedingly simple so far as the main mechanism
is concerned, dispensing with a connecting rod 3 but the valve gear
is more complicated than with ﬁxed cylinders. The steeple
engine (M) was introduced to save head room in shallow boats.
Two piston rods are employed, and the paddle shaft is placed
between crosshead and cylinder 3 the connecting rod is said to
be ‘returned.’ The principal objections to this design are the
difﬁculty of staying the slide bars, and of keeping two parallel
glands steam tight.
The Penn trunk engine (N) and Maudslay return-connecting
rod engine (P) are examples of early screw engines. Being both
placed athwart the ship, they must be shortened in length as
much as possible. Penn got rid of piston rod length by using a
trunk piston and driving the air pump by a rod connected directly
Various Medium-speed Engines. 63 I
to the latter. The practical objections were the difﬁculty of
packing the necessarily large glands, and of getting at the trunk
pin; but a more serious objection was the increased cooling
surface. . Maudslay’s engine was essentially the steeple engine
laid horizontally, the air pump being worked from a projection
on one of the piston rods. The packing of the parallel glands
was the only difﬁculty.
The modern marine engine is always either compound, triple,
or quadruple in design, the two-cylinder compound being shown
at L, which will also serve to explain the triple or quadruple.
The type is known as the ‘ vertical inverted,’ or ‘steam hammer,’
and is merely a direct-acting vertical engine with cylinder above
and crank below, to give Sufﬁcient propeller immersion with direct
driving. The slide valves are driven by eccentrics as at J, and
the air pump by a rocking lever. The surface condenser is cast
with the standards, on one side, and the exhaust steam sometimes
passes through one of the standards; but the method is not
advised by some engineers, because of irregular alignment caused.
by expansion. When the triple engine is adopted, the valves are
either placed between the cylinders, or as at R, on one side. In
the latter case the valve gear must be somewhat altered. a, b,
and c are the cylinders seen in plan, and d, e, f the respective
valves: in this example of piston form. The passage of the
steam will be understood from the sketch, entering ﬁrst through
d to a, then through e to b, through f to c, and ﬁnally out to the
condenser. .
High-speed Engines are a class of engine, usually of
small proportions, making 500 revolutions per minute or more.
A few principal examples are given at Fig. 627. A and B are
types of the rotary engine, much in favour with inventors some
twenty or thirty years ago, but now practically discarded. A may
be called the ‘annular’ and B the ‘eccentric’ type, a sliding
‘abutment’ a being required in each case to receive the re-
actionary pressure. There were difﬁculties in these engines
regarding packing and expansive working. Willans’ side-by-side
three-cylinder engine C, and Brotherhood’s three-cylinder engine D,
dispense with valve gear. At C the piston rods a, b, c, act as
valves, each admitting or cutting off steam to the next high-
6 32 Various H zg/c-speed Engines.
pressure cylinder in order. The high-pressure pistons further
act as valves for similarly distributing steam to the low-pressure
cylinders. Engine D has a special valve of annular form, through
which the steam passes both to and from the cylinders, as shown
by arrows. c and D are single-acting engines, so far as each






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cylinder is concerned, the steam pressure being felt only on one
‘side of the piston; but, taking the three cylinders together, there
15 an impulse every third of a revolution, instead of every half
revolution, as in ordinary single-cylinder double-acting engines.
In both engines it is only necessary to turn on steam to start in
any position, while if reversal is required, an extra four-way plug-
cock, called a reversing valve, is interposed, whose duty is to
Various ffigh—speed Engines. 6 3 3
change the order of the passages, making the steam the exhaust
passages and vice versa.
The Tower spherical engine, E, and the Fielding engine, F, are
kinematically based on Hooke’s joint (Fig. 475, A). In the former
two revolving bodies, a and o, are hinged on opposite sides of a
central disc or ‘wobbling’ piston c, the hinges being at right
angles to each other. Within the hollow sphere are four divisions,
1, 2, 3, and 4, the last shown closed. ‘As the bodies a and l
rotate, and the disc c wobbles, the divisions will in turn open and
close; and it follows, conversely, that when steam is admitted to
these chambers consecutively, the said movements of the disc
and bodies will be imitated, and the shaft d rotated. To effect
this, steam is admitted on one side of the supporting web e,
passed through proper ports to the four divisions in correct order,
and exhausted on the opposite side of e. The Fielding engine
works similarly, the practical difference being that four curved
cylinders are employed, instead of quadri-spherical chambers, corre-
sponding pistons being formed on the central disc. A larger obtuse
angle between the inclined axes probably reduces the frictional loss.
The Westinghouse engine, 0, is a type of many modern high-
speed engines, two simple~acting pistons forming the equivalent
of one double-acting engine. A piston valve distributes the
steam, and the alignment of piston and crank should be noticed.
The down-stroke only being of importance, the cylinder centre-
line splits the crank radius instead of the crank circle; the con-
necting-rod’s angular vibration on down-stroke is therefore halved,
and a much shorter rod may be ‘employed, securing compactness.
During the up-stroke the rod is at a bad angle, but that is of no
consequence. The Newall engine, shown in section at H, is
exceedingly interesting, through dispensing with so many working
parts; in fact, greater simplicity with efﬁciency could scarcely be
conceived. There are two sets of rings on the trunk piston,
between which are slotted holes for the passage of steam. The
distribution is effected by enlarging the trunk pin or connecting-
rod end into a hollow valve, with a partition; and ports are so
arranged that steam is admitted to, or exhausted from, the back
of the trunk, at correct times, merely by the vibration of the
connecting rod.
6 34 Valve Gear for Cornish Engines.
Distribution of Steam in Cornish Engines.—As no
rotative shaft is employed, the valves must be lifted by means of
some exterior device, the apparatus usually adopted being.
known as the cataract (Fig. 628). G is the steam, H the equili-
brium, and J the exhaust valve. L is the cataract for opening the
steam and exhaust valves, and M that for the equilibrium valve,
while A and K are the respective ‘plug’ rods, worked from the
beam. Supposing A to move downwards, the roller P catches the
cataract lever B, and raises the pump plunger D, drawing in a large
volume of water through the suction valve E. Meantime the
valve lever R is held by the stop-piece N on the plug rod, and
further secured by the catch lever s, holding the quadrant3 so
that valve G remains closed.
_ The plug rod now returns upward, and the weight 0 acting on
lever B endeavours to push the water out of the pump into the
tank3 as it cannot pass by the suction valve, it must leave by the
cock F, which admits of regulation, and thus the speed of fall of
D, or rise of V, may be accurately adjusted. The lifting rod v,
travelling upward, will strike and raise the catch levers s and s, at-
any appointed time, and the plug rod then being at the top of its
stroke, the valve lever R is free to rise by a left-handed turn, as
soon as released, the actual movement being caused by the fall of
weight Q, and thus the steam valve G and exhaust valve J are
lifted by the cataract L. In like manner cataract M governs the
opening of the equilibrium valve J, which, it will be remembered,
is to be open during an opposite phase of stroke. ‘
Double-acting Engines with Drop Valves.—It has
been already mentioned that two steam and two exhaust valves
are required for these engines. Fig. 629 is a vertical and Fig. 630
a horizontal arrangement, the pipes being connected to a ‘ nozzle
box’ at each end of the cylinder, in each of which a steam and
exhaust valve may be lifted at the required time by automatic
valve gear. An eccentric usually actuates the exhaust valve, but
the steam valve is worked by cam or some form of trip gear.
The former arrangement is shown in Fig. 631, the shape of cam
being such as to open the valve through a small portion and close
it during a large portion of the stroke. Sliding the cam on its
shaft"(in plan) will vary the cut-off.


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636 T/ze S/cort-D Slide Valve.
The form of drop valve, known as the Cornish double-beat
valve, is given in Fig. 632, and is there shown raised, so as to
clearly distinguish the valve from the seats. The steam is taken
as entering from below, and while the lower seat is a ring A, the
upper one consists of a plate B supported from A by the wings c,
and bolted to the bridge piece D. As B exactly covers the
opening, though at a higher level, the valve when closed is
entirely shielded from the steam pressure below, so far as that
pressure tends to lift or depress the valve, and the latter is there-
fore only the recipient of horizontal pressure. Consequently the
valve is wholly ‘balanced,’ that is, the rod E has merely to lift
the dead weight. On account of distortion caused by unequal
expansion, the valve should be ﬁnally ground on its seat while
hot. '
Distribution of Steam by Slide Valve—Murdoch
(Watt’s manager) substituted a single slide valve for the four drop
valves in the double-acting engine, the early form being the
‘long D,’ so-called because it took the shape of a pipe of D
section, the flat towards the cylinder. This was soon altered to
the ‘short D’ valve so well known nowadays, and illustrated in
Fig. 6 3 3. Its position in the cylinder is shown in Fig. 634, where
A is the piston sliding in the cylinder B, c the piston rod, D the
crosshead, and E the connecting rod, FG the crank, M. the valve
spindle, and N the slide valve, P the steam chest, and Q the steam
pipe, R and s the steam ports, and T the exhaust port. The valve
is just opening to steam by the port R, to move the piston to the
right, while the exhaust passes by port s, through the valve
chamber and T, to the exhaust pipe. When A has completed
its stroke, N will have been automatically moved to the left, thus
admitting steam on the right side of the piston, and exhausting
on the left side, causing the return stroke. The slot Y in the
valve allows the latter to adjust itself to port face after wear.
Lap of Slide Valve.——The ‘ normal’ valve, Fig. 63 3, being
that shown hatched only, just covers the steam ports when at mid-
stroke. Such a valve admits full steam during a whole forward
stroke, and exhausts during the whole of the return stroke. An
early cutoff is obtained by the addition of lap, the black patches
U and v being known as OUTSIDE oR STEAM LAP, and those at w
Relation of Cran/e and Eccentric. 6 3 7
and X as INSIDE OR EXHAUST LAP, forming an additional width
to the valve face, in line with valve spindle, on the steam or exhaust
edges of the valve respectively, for the purpose of giving early cut-off
to steam or exhaust. By adding steam lap the width of opening
is decreased, which is, however, compensated by giving increased
travel to the valve. Inside lap is rarely necessary, the alterations
in valve position caused by introducing steam lap usually giving a
sufﬁciently early cut-off to exhaust (compression point). Various
interesting points are raised by altering the proportions of the
slide valve, which will be fully investigated later. -
Relation of Crank and Eccentric.——The commonest
valve gear is the eccentric and rod. The eccentric is merely a
convenient form of crank whose pin is so enlarged as to envelop
the shaft: it follows that the eccentricity or length of eccentric
cran/e must be measured from centre of eccentric sheave to
centre of shaft. This amount we shall sometimes call the throw.
While, then, the piston moves the crank, the latter in turn moves
the eccentric, and so automatically, by the slide valve, adjusts the
supply of steam.
(l/Vithout lap.) A normal valve must of necessity be at half
strohe when the piston is at the end of its stroke—that is, when
the crank is at a dead centre; for then the valve should be just
opening to steam. The eccentric crank must therefore be placed
at 90° to the engine crank. Further, the direction of rotation
will be determined by the position, right or left of it, of the
eccentric. The eccentric will always lead the cranh or travel
before it; for, if we endeavour to turn oppositely, we shall only
‘close the steam port at the very time it should be opening, and so
block the supply. Therefore, in a-normal valve, the eccentric must
lead the crank hy 90°.
(I/Vith lap.) Let us next consider a valve having lap. Re-
ferring, again, to Fig. 634, the thin outline shows a valve with
lap, placed at mid-stroke. It then covers the steam port plus the
lap. The crank being on dead-centre F, it follows that, in order
to admit steam by port R, valve must be moved bodily to the
right, and the eccentric lead the crank hy 90° + lap, as at H1. A
little consideration will show that strictly similar conditions obtain
with the crank on the dead-centre z.
638 Reversing hy Loose Eccentric.
(I/Vith lead.) To assist the compression steam in preventing
a knock on the crank at the end of the stroke, it is advisable that
the valve be slightly open when the crank reaches the dead-centre.
This is called lead, and is the amount of opening of steam port at‘
the commencement of the strohe. When a valve, then, is provided
both with lap and lead, the eccentric must lead the cranh hy
90° + lap and lead, the lap only being apparent on the valve,
while both are apparent in eccentric position.*
Reversing Gear.—Factory engines always rotate in one
direction, and thus only require a ﬁxed eccentric. Again,
changing eccentric from H to J, Fig. 6 34, ‘will change the direction
of motion, then shown by the dotted arrow instead of by the full
arrow. Fig. 635 gives a means of moving the eccentric to the
opposite position, when the engine is at rest. Sheave B being
ﬁrmly bolted to a ﬁxed plate A, can, on unloosing c, be slid from
h to j and rebolted, or, still further, can be made to take any
intermediate position between h and j, giving a variation of travel
with the same lap. Such decrease of travel means earlier cut-off,
as we shall see later.
Reversing by Loose Eccentric.—-But it is not always
convenient to stop the engine for any considerable period, and
Fig. 6 36 shows one of many methods by which a single eccentric
may be quickly changed from one position to the other. c is the
crank, having a stop D ﬁxed symmetrically, and A the eccentric
sheave, which, being loose‘ on the shaft, is provided with a balance
weight E to prevent spontaneous movement. At present the
sheave has its centre at j, and while the eccentric leads the crank,
the crank drives the eccentric ,- so, although j causes the crank to‘
turn round left-handed, it is at the same time pushed before the
crank by the stop D. But the sheave may be swung round to
j or h, when starting the engine, in a manner to be described.
Lifting the gab F from the valve spindle pin disconnects eccentric
from slide valve x, when the latter may be moved, by the hand
lever H. On starting, then, the left hand lifts the handle G, while
H is moved by the right hand, and thus steam may be admitted
at will to either side of the piston, according to the direction in
* The student must carefully distinguish between the two applications of
the term ‘lead,’ which need not, however, create confusion.



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64o Reversing 6} Link Motion.
which the engine is to be turned. The slide valve K once opened,
G may be dropped, crank c catches up the sheave A by the stop D,
F ﬁnd its way to the valve rod pin, and the gear is once more
automatic. The engine may be stopped by lifting the gab.
Reversing by Link Motion.-If two ﬁxed eccentrics be
placed on the shafts, one for forward and one for backward move-
ment, it can be arranged to put either eccentric in gear as
required, the other remaining inactive. The gear for this purpose
is known as link motion, and, though more complicated than
loose-eccentric gear, is more easily manipulated, and is absolutely
certain in action whatever the position of the crank. In Stepken-
son’s Link Motion, Fig. 6 3 7, the eccentric rods A B are connected
to either end of a link 0, curved to a radius from D. The valve
spindle F supports a die E capable of vertical movement relatively
to link 0, such movement being controlled by the lifting link G.
At present the radius link is in ‘mid gear,’ and any ‘plus’ move-
ment of one eccentric rod would be met by a ‘minus ’ movement
of the other rod. If these movements were equal, the valve
would not travel at all; but, as the sheaves are not placed directly
opposite on the shaft, the plus and minus displacements do not
balance, and the valve opens to lead.’‘‘ If the reversing rod H be
moved to the right, the rocking link G will lift the radius link
until rod B is nearly level with the valve spindle, and the valve
then receives almost all the horizontal movement of the B, while
A’s motion is all but inoperative on the valve.’ The eccentric B
is then in ‘ full’ gear. If H be moved to the left, the A rod is put
in gear and B is practically inoperative. J is termed the weigh-bar
shaft, and 11 is coupled to a hand lever on‘the driver’s platform]L
In Gooc/z’s Link Motion, Fig. 638, the eccentric rods A and B
always vibrate at the same height, and radius link 0 rocks from a
ﬁxed point G. But the valve rod is in two parts, one of which, ‘K,
the intermediate valve rod, being lifted or lowered, changes also
the position of the die E. In the ﬁgure, it is shown in direct
connection with the rod A, while B’s vibration has no effect on the
valve. When K is at its lowest position, ‘rod B is in gear and’ A is
inoperative; link (3 has it curves struck from D. It should also
* Larger lead than that in full gear.
Jr In large marine engines it is usual to reverse by steam power.







ﬂawa} Lzinlc Motion, .|
642 Reversing by Radial Gear.
be noticed that when the radius link allows the valve spindle and
eccentric rod centre lines to be continuous, as in Fig. 638, valve
travel and diameter of eccentric circle are equal; but if not con-
tinuous, as in Figs. 6 37 and 6 39, the eccentric circle must be larger
than the valve travel. Either method may be adopted. When the
link is lifted, as in Stephenson’s gear, its concave side lies towards
the crank, while if the valve rod be lifted, the concavity is towards
the valve. Consequently, were the link to be lifted simultaneously
with a lowering of the valve rod, or vice versa, it would curve
neither to one side or the other—that is, would be straight. This
is obtained in Allan’s Linh Motion, Fig. 6 39, the movement being
analogous to Watt’s parallel motion. A double-armed lever is
ﬁxed to the weigh-shaft J, which, being turned by rod H, moves
the rocking links D and G in opposite directions, so as to bring A
or B opposite x, as required. -
Reversing by Radial Valve Gear.-Many inventors
have‘endeavoured to obtain a simpler reversing gear than those
described, by taking motion from the connecting rod. The most
successful is foy’s Valve Gear, Fig. 640. A point A on the
connecting rod describes a horizontal ellipse, as at A1 a, and a link
A F, being attached to the vibrating link F K, causes point B
within AF' to describe the curious oval B1 5. A third link BE
connected to A F at B, and to the die D, being compelled to travel
at its lower end in the oval B112, moves the die D up and down
the curved slot CG, point E tracing the true vertical ellipse cg.
The proportions of the links are such that the width h j of the
ellipse exactly equals twice (lap + lead). Now, the curved slot
C G, whose centre of curvature is J, is carried on a weigh-bar shaft
having its axis coincident with the point D. So long, then, as
C G is vertical, a vertical ellipse cg is formed by point E, and the
valve cannot open more than to lead at each end. This is the
‘ mid-gear’ position. Should the weigh-shaft be slightly turned,
and the slot therefore inclined, an inclined ellipse hl or mn is
formed when H is moved to right or left respectively. The total
valve travel would now be represented by the horizontal projection
of the ellipses 3 thus the opening of the steam port would be
(lel — h j) + 2, measured horizontally, in addition to the lead.
When point D crosses the weigh-shaft centre, the link takes always
Reversing by Radial Gear. 643
the same angular position; the ellipses must therefore intersect
at the same points, h j, whatever the angle of C G. B might have
been coupled directly to A, but that an unsymmetrical motion
would then have been given to point D. To avoid this error, the
compensating links K F and F A are introduced.
We have still to show that the slewing of CG from right to
left, or vice versd, will reverse the crank motion. Let the crank
be moved as shown by arrows ; E will then be in position h, and,
CG being ﬁxed by a left-handed turn, the ellipse hl will be
described, E moving from h to h, and opening the valve to steam
at the side of piston required. If, on the contrary, ellipse m n had
been adopted, the movement h to m would have closed the valve,
or the crank could not have moved in the required direction. It
can also be shown that when E is constrained to move in the path
m n, the crank will turn oppositely to that described.
Hachworth’s valve gear, Fig. 642, is another form of radial
motion, inasmuch as the valve travel is derived from similar
vertical ellipses to those of Joy’s. The ﬁxed eccentric A is
directly opposite the crank web B, and the other end of the rod
carries a die c, sliding in a vertical guide DE. A point F will
then describe ellipses such as m n, hl, Fig. 640, and the motion
of the valve be as previously described. H is the reversing rod
for changing the angularity of DE.
A modiﬁcation of the previous arrangement known as
Marshall’s valve gear is shown in Fig. 643. Pin F is on the
opposite side of fulcrum c; eccentric A is therefore coincident
with the crank web B, and a much smaller sheave results. The
pressure on the fulcrum C is, however, very great, and a vibrating
link DC, with fulcrum at D, is substituted for the vertical slide.
The usual ellipses are described by point F, and the necessary
angularity is produced by change of position of the fulcrum D —
moving the bracket-lever E c to K C or to J C by the reversing rod H.
Walschaert’s valve gear, Fig. 641, does not describe the
ellipses which are a sign of radial gear, but having some other
points in common, is here introduced. The eccentric is ﬁxed
at right angles to the crank, as though the valve had no lap
or lead; and if connected directly to the valve spindle, would
of course only allow the crank to turn in one particular direction.
644 Oscillating-Engine Valve Gear.
An intermediate valve rod F, may, however, be changed from
D to B, or vice versa, by‘ the reversing lever E, so that F may move
' either in the same or the reverse direction of J. When F is at B,
the eccentric must lead the crank, as in Fig. 634; but when F is
at D, the eccentric must follow the crank. The intermediate ‘rod
F, again, is only connected to the valve rod G through the lever
LM, the pin K forming a fulcrum upon which LM is rocked by the
crosshead N. The travel, LP, thus obtained, represents twice
(lap + lead), as at 12], Fig. 640, and takes effect at the dead Centre
positions. When F, therefore, is in mid gear at c, the valve opens
only to lead, but when moved to D or B, the opening is eccentric
tkrow minus lap, as in Fig. 6 34.
Valve Gear for Oscillating Engines.—-The method by
which a satisfactory motion of the valve is obtained will now be,
made clear by reference to Fig. 644. T and U are the valve boxes,
of which there are two, in order to keep the cylinder balanced.
v is the cylinder and vw the trunnions, being steam and exhaust
pipes respectively, supplied with stufﬁng boxes. M m and N n
are the valve levers, rocking on fulcra R and s; and P Q the valve
spindles, guided at their upper end. All the parts mentioned
share in the rocking motion of the cylinder, the remainder are
either ﬁxed to the ship or take motion only from the crank.
z z are ﬁxed guides for sliding link L, whose slot is curved to a
radius from trunnion centre. To L is again connected, by centre-
pin F, the usual radius link G H, which is moved by eccentrics cd
through rods D E. X is the trunnion bearing.
It will be seen that the rocking of the cylinder can in no wise
affect the vertical movement of the valve levers ; but any motion
given by the eccentrics to the link 'L is faithfully transmitted to
the valve spindles through their levers, the discs J it always lying
in the link L. On account of the introduction of the rocking
levers M and N, the eccentric motion will be reversed. The
eccentrics are therefore set to follow the crank by 90° minus lap
and lead, and the rods are said to be crossed.
Steam enters at v, and passes into the valve chests by the
belts ee, entering through port a. After giving work to the
pistons through either steam port 6 o, it exhausts through the
mid port c, and passes out through the belt f to the exhaust


Va (we Gear
.15; ' 640.
~—
646 Oscillating-Engine Valve Gear.

Via/1,0,0 &ear for‘ OsczLLLol/Llhg Eng/inc.
644.

pipe w. Sketch g is a front view of the ports. A loose eccentric
or single ﬁxed eccentric may replace the link motion, but the
link L is always required.
The Simple Governor. 647
The Simple or ‘ Watt’ Governor was invented by Watt
for automatically regulating the supply of steam to his engines,
The form adopted by him, (a) Fig. 645, consisted of two radius
arms EE mounted on a vertical revolving spindle H, and each
carrying a ball or weight P. The centrifugal force’ in the balls,
when spindle H was rotated by the crank shaft, tended to‘ lift the
sheave G by the lifting arms QQ, and thus through bell-crank
lever F, cause the valve lever L to turn and endeavour to close
the throttle valve M lying in the steam pipe N. The valve, being
of elliptical form, ﬁts the pipe when inclined at about 30° to a
cross sectional plane, and is, further, ‘balanced ’—-—that is, the
steam pressure on one half tends to close it, that on the other
half having an opening tendency.
The function of the governor is to keep the engine speed
within reasonably constant limits, whatever the load. The ﬂy-
wheel obtains approximate uniformity of crank pressure and
speed during each revolution, but cannot govern the speed over
several revolutions: that is left for the governor, which similarly
is unable to control the sudden changes during a revolution.
When the speed increases, the balls ﬂy outward and tend to close
the valve, throttling the steam supply, which reduces the crank
pressure and causes a return to the normal speed. Should the
velocity of the balls decrease, the exact converse will happen.
Three forces keep each ball in a raised position, and their
proportionate amounts may be determined by force diagram, as
. 2
at (e). Then 3%, T, w, are respectively proportional to R, L, H :


wv2 GR?
H:R::w:—--— andH=92
s'R 2’
. 2 RN
.But v = 21rR7t = W
60
/ gR‘~’X12 gR2><60><60><12 35,200i Che
'. t = , = , = n s.
7,2 4 7,.2R2N2 N2
8 '6 . .
And N = “35%) = 1—27— revolutions per minute
Z

1 I
orh 0c ——, andN 0c —-—__.
N2 W,
648 T be Loaded Governor.
The Weighted or ‘ Porter ’ Governor.—-The Watt
governor is not sufﬁciently ‘sensitive,’ that is, the desired action
on the valve will not take place without a large increase or
decrease in engine speed. Increasing the weight of the ﬂying
balls will add to the ‘power’ of the governor, or the capability
of its performing the work it has to do, but as the centrifugal
force varies directly as the weight, the sensitiveness is not thereby
increased: the height, in short, is independent of w. Placing,
however, a heavy weight on the centre spindle, as in the Porter
governor (at 5, Fig. 645), it can be shown that the required
increase in revolutions for a given height of lift can be con-
siderably diminished, and greater sensitiveness thereby obtained,
without, of course, adding to the centrifugal force.
It is customary, in the weighted governor, to make the four
arms equal, and the angle a approximately equal to the angle [3,
the rise of W1 being consequently twice that of W. Now half W1
pulling at each ball, by the principle of work its effect at point B
will be equal to W,.* We have, then, a total downward pull at B
of W + W1, the centrifugal force remaining as before. Reasoning
from force diagram, as at (e), we have:


9
wv~
H : R :: w+w1:
0R
c5
9
w+w1 gR~ X 12 w+w1 35,200.
k = 2 = —--- — 9 inches.
w v w N~
Or, for a given speed, k is greater than in the Watt governor in
'ZU-l-"U ' ‘ ' ' '
w‘ 1 : 1, and for a given var1at1on in height,
the variation in speed is less than in the common governor in the

the proportion of

TU
- 1. For, from the above formula,
w+w1 '
N = N/ w 876
proportion of N/

w + w1 x/Z
Assuming then, a speed variation from N to N1, the height
varying from It to ill : the difference of revolutions in the common
governor would be
* :1; W1 >< dist. 2 : W1 x dist. I.
S ensitiveness. 649
I I
N--N1 = 1876 (--_--—:)
an an,
while in the weighted governor it would be







If the four arms are not equal, B may be supposed to rise
one inch, and the rise of D noted. Then the effect of w1 at B
will be w1 x rise of D+ 2, and H may be found as before.
W1 varies in practice from 60 to 300 pounds, W from 2 to
4 pounds, and such a governor is run at high velocity to get
sufﬁcient lifting power. Fig. 261, p. 254, is a good example,
where to avoid one fault of increased sensitiveness, the taking up
of small changes of load, the vertical vibrations are damped by
6 50 The C rossed-arm Governor.
the dashpot F, containing air capable only of passing in or out at
a very slow rate.
The ‘ Head’ or ‘ Farcot’ Governor.—Sensitiveness to
change of load may be otherwise obtained. At (c), Fig. 645, is a
vertical glass vessel A, containing a liquid, and mounted on a
pulley D. A second larger pulley B, provided with a handle, is
connected by a cord to D, and constitutes with it a ‘whirling
table.’ A high speed of revolution being impressed upon A, the
liquid will rise up the sides so that its surface forms a paraboloid
of revolution, the height H, or suhnormal of which is constant
wherever measured. We may very well look upon these particles
of water as very-small governor balls, endeavouring to ride over
each other in the easiest possible manner 3 so, allowing our ﬂying
balls to move in a similar parabolic path, we may expect them to
rise with the least difﬁculty, and as a practical fact, such a
governor, called parabolic, is extremely sensitive, so that the balls
will rise or fall to the full extent with a very small alteration in
speed. In some governors, the weights are rollers riding up
parabolic paths; but the usual form is the Crossed-arm governor
(d), Fig. 645, where the ball paths are very nearly parabolic. A
spring is placed on the spindle to resist the rise of the sleeve
under small changes of load.
Variable Expansion-Gear.--Whenever the engine-load
falls below the normal, the steam supply must be reduced to
avoid ‘racing,’ and two means suggest themselves: (1) wire-
drawing or throttling, by narrowing the steam passage, either at
' V'ﬂ/m'xz/bhe aqwgmsion
venous biz/‘,0 __ZZLgl " 64500




= ask
the supply valve or at a throttle valve worked from the governor;
(2) the slide valve may be so regulated as to cut off steam at
an earlier point of the stroke, the method known as variable
expansion. To compare the two processes, consider an engine,
Reversing-motion Expansion- Gear. 6 51
Fig. 645a, cutting off steam at half stroke, and giving the diagram
BAENH; and let the work be reduced to the equivalent of a
quarter cut-off. With true expansion and sharp cut-off, the
diagram would be BACMH, but if throttling be adopted, cut-of
still taking place at half strohe, diagram BA J KH would be the
result, both producing the same mean pressure. Now the steam
used when expanding is shown by the area B A CD, but that when
throttling by area BA JF, proving at once the economy in favour
of the former.
Linking-up is a means of obtaining variable cut-off. It may
be shown by Zeuner’s valve diagram, to be explained later, that
a decreased travel to a D slide valve will cause an earlier cut-off to
steam, but will also compel an earlier cut-off to exhaust, or com-
pression point, on the back stroke. Referring to Figs. 637 to
639, the mid-gear positions will produce very little motion on the
valve; but, when the links are in full gear, the valve will travel its
greatest. Any intermediate travel may be procured, and therefore,
within limits, any desired cut—off. When, therefore, a locomotive
is started, the reversing lever is pulled right over ; but when full
speed has been obtained, the work becoming less (being that
required only to overcome frictional resistances), the driver links
up to such a position as to supply just enough steam to do the
work. The diagrams obtained are shown at M, Fig. 603 : I being
that at starting, 3 with full speed and least resistance, and 2, an
intermediate condition. Herein lies one advantage of link motion
over the loose eccentric: the former is an economic expansion
gear, while variable work must be met in the latter by throttling.
The radial gear, Figs. 640, 642, and 643, may also be linked up
by turning the curved guides in Figs. 640 and 642, or the lever E C
in Fig. 643, through a smaller angle, when the projected width of
hl will be smaller, and the valve travel be thereby decreased.
One advantage of this gear has already been referred to: the
distance hj is absolutely constant, whatever the position of the
curved guides ; or the amount of lead never changes, whether in
full, half, or mid gear. This is not so with link motion; with
‘ open’ eccentric rods, as in Figs. 637 to 639, the lead is much
greater in mid gear than in full gear, and proportionate at other
places. With crossed rods (Figs. 644) the lead decreases towards
6 5 2 ' l/l/[eyer Expansion- Gear.
the central position (see Fig. 656). Walschaert’s gear, though
adjusted like link motion, has a constant lead in all positions.
It is practically impossible to obtain very early cut-off with a
D slide valve without considerable wire-drawing, and in any case
a large lap is required, making it possible, even in a double-
cylinder engine, to have both valves so placed that the engine will
not start in the right direction—a matter of some importance with
locomotives. Further, it is 'not always advisable, especially in a
factory engine, to alter compression and cut-off at the same time.
A Back-cut-of valve or expansion valve is then applied, as in
Fig. 646, for controlling cut-of only, all the other points on the
diagram being governed by the main valve. When the two blocks
constituting the expansion valve are rigidly connected, and the
variable cut-off is obtained by altered travel, the title ‘back-cut-off’
is applied, as in Fig. 648*; but if right and left-hand threads are
formed on the expansion valve spindle, Fig 646, and variable cut-
off be obtained by turning the latter round, thus altering the lap,
the arrangement is known as a Meyer expansion valve. In
Fig. 64 6, A B is the main valve, being a common D valve, supplied
with walls A and B to form ports 0 and D. The blocks E and F
can be separated by turning the hand-wheel G, which has a square
hole in its boss, through which the valve spindle reciprocates.
Encircling the boss is a screw carrying a pointer H, whose move-
ment represents the altered expansion to the eye. When E and F
are close together, they are out of gear, and cut-off is given by
main valve; but when separated, they cut off steam at the outer
edges of the ports 0 and D. The expansion eccentric leads the
crank by 180° in a reversing engine, and rather more in others:
and the two valves move in opposite directions at cut-off, thus
decreasing wire-drawing.
When the separate expansion valve was ﬁrst introduced, a
separate steam chest was provided; so that after passing through
the expansion valve, .the steam had‘ to ﬁll the main valve chest
before proceeding to the cylinder, thus forming additional clear-
ance steam, which would do no work except a small amount
during expansion, and, being delivered into the condenser, would
tend to increase back pressure. We are not surprised, then, to
* See also Fig. 263, p. 258.






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6 54 A utomatic Expansion- Gear.
learn that very little economy was thus secured. A ‘gridiron’
valve was adopted for the expansion valve, the ports being split
into eight or nine portions, for reasons to be explained in the
next paragraph. Clearance is decreased as much as possible in
the back-cut-off valve, especially in Fig. 648, though it must
always be greater than in a single valve.
A Double-ported Valve, as in Fig. 647, is usually adopted for
low-pressure cylinders of marine engines. As frictional loss
depends directly on distance travelled (total pressure being
equal), it is advisable to decrease the travel as much as possible.
This may be done by dividing the steam ports into two parts,*
as at AB 3 only half travel is then required. Of course the valve
must be made somewhat larger, which increases the total pressure,
and consequently the force of friction 3 so a portion of the back
is often shielded or ‘relieved’ from pressure by the ring CD,
which lies in the annular groove E F, being kept steam tight'with
the back of the valve by the springs GH, and with the groove by
the ring J.
At Fig. 648 is shown a back-cut-off valve with double ports, the
main valve being designed to shorten the steam ports and decrease
clearance. Fig. 649 shows double ports, both for Meyer and main
valve, the arrows indicating the paths of live steam and exhaust.
Automatic Expansion-Gear.-Instead of connecting the
governor sleeve with the throttle valve, as at (a) Fig. 645, it may
be allowed to alter the travel of a back-cut-off valve, with in-
creased economy and direct action. The most common arrange-
ment is shown generally at Figs. 271 and 272, pp. 270 and 271,
and in detail at Fig. 261. The expansion eccentric is coupled to
the central pin of the radius link, the latter rocking on a pin at
the upper end. When the governor sleeve M, Fig. 261, rises, it
lifts, by lever H and link K, an intermediate valve rod. Thus the
height of the governor decides the height of die in radius link,
and therefore the amount of travel on the expansion valve.
Eccentric travel remaining constant, when the engine speed
"increases and the governor sleeve lifts the die nearer the link
fulcrum, the travel of- the valve is decreased, cut-off is earlier,
and less work done. This brings back the speed to the normal.
* Or more, as in gridiron valve.
Marine Governors. 6 5 5
If, on the contrary, a heavy load is put on the engine, the
governor revolving at a low height gives the valve the utmost
travel, securing a late cut-off.
The Shaft governor provides automatic cut-off by a very
simple and compact arrangement, especially adaptable to small
high-speed engines. The gear of the Westinghouse engine is
shown at (b) Fig. 652, the object being to directly vary the
eccentric throw. AA is a disc ﬁxed to the crank shaft, having
pins B B for carrying centrifugal weights E E, and pin H for
supporting the eccentric H J. The latter may ‘rock to the right or
left on pin H by a limited amount, to be determined by the
position of weights E E, their deviation causing an alteration in the
eccentric throw. The weights are connected by the link CD, so
that their movements shall be simultaneous, and are attached to
the eccentric by link FG. If the engines then revolve at a high
speed, the weights E E ﬂy outward and pull the eccentric sheave
to the left, decreasing throw and producing early cut-off; if the
speed decreases, the strong springs K K bring the weights towards
the centre and increase the throw.
Marine Governors have always been difﬁcult to devise,
and, although no perfect governor exists, the arrangement at (a)
Fig. 652 is probably the best, acting as it does on a direct
principle. The ﬂuctuations in speed of a marine engine are
caused by the propeller either partly or entirely leaving the water
rather suddenly, thus decreasing the lead. The consequent
increase of speed or racing cannot be entirely obviated, but may
be considerably modiﬁed by the use of Dunlop’s governor. C is
a large pipe communicating with the water near the propeller, and
D an air chamber which can be shut off from C by the screw-down
valve A, worked by hand-wheel B. F is a pipe containing only
air, the entrance of water being prevented by the baffle-plate E.
H is a diaphragm in communication with F, and L K a rod which
partakes of the movement of H, transmitting it to the piston slide
valve M, for admitting to or exhausting from cylinder P. The
cock L admits steam to M, and the piston rod Q R is connected to
the lever Rs, which has its fulcrum at W. Finally, ST is a rod for
actuating a throttle valve in the high-pressure steam ‘pipe of the
engIne.

NTRE_ 0F CYL-i/VDER _


EX PADS?
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PLAN or war. v6‘




6 Bram/$7 e f

Cvvizlss Vmdue 0w 65 0'
Corliss Gear. 6 5 7
If the propeller sinks below the normal, water rises in D, and,
compressing the air in F, presses on diaphragm H, lifting K L and
moving K 2 round fulcrum 2. Valve M being opened to steam at
the bottom end, piston P is raised, thus depressing the rod s T and
partly closing the engine throttle valve. But, as s moves'down,
the lever K z is turned round K as a fulcrum, and valve M is once
more placed in mid position. Suppose the propeller rises, the air
in F becomes more rare, and spring 1 moves L K downward,
opening M at the top, bringing QR down, and raising ST, thus
opening the throttle valve.



THE W65‘ rnvc; not/5!
DUN/.0193’ MHRIN£ GOVERNOR .S‘Imrr GOWERNO/P

Corliss Valve Gear.—Of all the ‘trip’ gears,* this is
probably‘ best known. In Fig. 650 the upper diagram shows the
‘valve gear, the lower being a section through the cylinder and
valve chambers. There are several advantages possessed by this
valve arrangement and gear, some being common to other trip
gears: (1) a sharp cut-off is obtained, when the ‘trip’ takes place,
preventing wire-drawing; (2) an easier-working form of valve, g,
is adopted; (3) steam and exhaust parts being separate, there is
less loss by initial condensation; (4) clearance is very small;
(5) the variable cut-off is automatic. -
The valves aa admit steam, and ee pass the exhaust, being
represented in plan at g. They are hollow cylinders having a
* Term given to rapid cut-OH gears, worked by the trip of a valve lever.
U U
65'8 Trio Gears.
large portion cut away, and are rotated by spindles to which they
are connected loosely. The steam pipe is shown at h, and ff are
the exhaust pipes, forming the cylinder supports. Taking the
valve gear, A is the eccentric rod, which by a to-and-fro motion
rotates the disc or wrist-plate B3 to the latter are connected the
four valve rods, two of them at CC actuating the exhaust valves,
the other two at D D working the steam valves. The exhaust rod
CE is directly connected to the valve lever EF, and moves it
through rather less than 90°. The steam-valve rod DG is more
complicated, consisting of two parts: one, DoRP, attached to the
wrist plate; the other, QNG, connected to the valve lever GJ.
These tend to separate, by reason of the force in the compressed
spring T, but are prevented by the spring catches PP. If, how-
ever, the latter are prised apart, spring T is released, and, pulling
J rapidly to the left, closes the steam valve. The prising action
is obtained by the toe lever MN, which, pinned to QNG at N, rocks
on fulcrum M. As the pin D moves from z to D, the rod DG takes-
a more crosswise position relatively to the toe N, and at some
intermediate position the catches PP liberate the parts D and G,
permitting the valve to be closed. When D moves back to z, P P‘
regain their normal condition and D and G are connected. The
position of fulcrum M determines where, between z and D, the toe
shall release part G, and this is decided by the height of governor
sleeve, the latter being connected to rod m. When the governors.
rise, m is pulled to the left, moving M an equal amount to the
right, levers WK and wL being geared together at x. This causes-
the toe to separate PP at an earlier part of the stroke 2 to D, and
the converse will happen when the governors fall. Lastly, the-
dashpot 5 being full of air only capable of passing out at U,
reduces the shock caused by the sudden release of the spring T,
the set screws serving to regulate the air passage, and the back
chamber v is usually connected to the condenser to ensure decision.
The Proell Valve Gear is another good trip gear. The-
lever D E, rocking on fulcrum E, may for the present be looked
upon as rigidly connected to the arm F F, and toes FG. At point
E is attached the eccentric rod, and a movement of D to the right .
will cause the left-hand toe G, trailing along H J, to ﬁnally slip,
when spring L closes the steam valve B. Meantime, the right-
Proell Gear. 659
hand the, which tripped on the last stroke, must be replaced
on JK, and this is attained by making the L-lever xFG free to
turn on the pin F, until G ‘is high enough to slip into place. The
dash-pots are similar to those already described, set screws M M

‘Fined/.3" Kai/we Gaza/r
adjusting the compression of the springs L L. A rigid bracket 5 8
supports the governor gear; within it the hollow spindle TT re-
volves, and the balls, ﬂying outward, pivot RT on T, raising the
Central weight P, while lifting pins vv and the spindle W to a
higher position. This rise affects the positions of the toes GG,
660 Z euner Valve Diagram.
bringing them nearer together; the reverse happening when the
governors fall, and thus is obtained automatically an early or late
cut-off respectively. A dash-pot within P damps small vibrations
on the governor, entrance or exit of air being adjusted by screw Q.
The steam valves BB, being double-beat, are balanced, besides
requiring only half the lift of a single valve.
Zeuner’s Valve Diagram is a graphic and ready means
of ﬁnding the various positions of the engine crank, where
admission, cut-0H‘, release, compression, &c., take place with a D
‘slide valve, when the valve dimensions are known ; or, conversely,
of ﬁnding valve dimensions when certain crank positions are
given.
Imagine a valve without lap, and let CD be the eccentric
throw or radius at (1) Fig. 652. When the eccentric is at D, the
valve is closed, and, when moved to H, the opening tov steam on
the left is c G. Turn G round to L ; then c L is steam opening for
eccentric position H. A series of points such as L may be found
and the curve 0 L B drawn, whose radii vector show gradual
opening and closing of the left-hand steam port. The left diagram
being obtained similarly, join A x. Then triangles cA K, c J F are
similar and equal, and A K c is a right angle ; the two polar curves
are circles, and while circle CB shows steam opening, circle cA
represents the opening to exkaust, together being known as curves
of position for a valve without lap.
Taking a valve having lap, both to steam and exhaust, its
position curves are those at (2) Fig. 6 5 3. For the opening, either
to steam or exhaust, will be that at (1) less the respective lap.
At centre 6, strike arc M N with radius = lap, while 0 P = exhaust
lap. Then 4 B is full opening to steam at left-hand port, eccentric
being at B; Q is admission position, and R that of cut-off. Simi-
larly AS is full opening to exhaust at right-hand port, eccentric
being at A; T the release, and s the compression position.
We must now translate eccentric position into crank position.
Still assuming a right-handed rotation, we must turn back in a
left-handed direction all the eccentric positions, through the angle
by which the eccentric leads the crank, to effect the above purpose.
This angle is 90° plus the angle of advanced‘ The change has _
* Angle of advance = the angle whose sine = (lap + lead) —2- throw.

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INDICATOR DIAGRAM
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Zeuner Problems. 66 3
been made in diagram, (3) Fig. 65 3; from T to U through 90°,
and from U to B through the angle of advance, WX being
lap + lead, as formerly stated. The Zeuner diagram, now com-
plete, shows positions of engine crank for various points on the
indicator curve. It should be further noted that points k, l,]', and
n may be found by the tangents k l and jn, and that the perpen-
dicular distance from s to kl is equal to lead. Rarely, too, is it
practically possible to have full opening to exhaust, as given by
diagram; so the width of steam port must always be marked off
by arc gh.
To ﬁnd corresponding piston positions, the simplest method
is to drop perpendiculars, as shown by dotted lines : and dividing
stroke ST into 10 parts, ﬁgure in decimals of forward or backward
stroke, as required. But as this is only approximately true for a
very long connecting rod, or a slotted rod, the method in (4) Fig.
6 54, is more advisable. Horizontal lines AB and CD being drawn,
for forward and backward stroke respectively, set compasses to RF
the length of connecting rod, and strike an arc from every point,
as F f As radius EF must not be altered, centre E will be
changed for every arc; the dead-centres will be at A, B, c, and D,
and the points obtained represent the correct positions of the
piston regarding these.
The Zeuner diagram further enables us to ﬁnd very closely
the form of indicator diagram before the engine is built. The
method is shown in Fig. 653, and may be corrected further by
(4) Fig. 654, due regard being also paid to the various losses.
Zeuner Problems—A few problems will now be discussed,
where, certain data being given, it is required to draw the whole
diagram as in Fig. 653:
(1) Given valve travel, both laps, and angle of advance. This
is too simple to need explanation.
(2) Given greatest opening to steam or exhaust, both laps,
lead, and position of cut-oﬁ“. Strike travel circle with radius =
lap + opening, and arc of lead at s ; ﬁnd l, and join kl. Bisect
angle kw l, and complete.
(3) Given angle of lead, travel, and positions of cut-off and.
release. BA is found as in last case; then, n being known, nj
may be drawn at right angles to BA and the rest is clear.
664 Z euner Diagram for Meyer Valve.
(4) Given travel, or opening to steam or exhaust; also both
laps, and lead. Strike travel circle and mark points w, v, and x ;
diameter Bw being known, the steam circle is struck and BA
found; and the rest easily completed.
(5) Given steam opening for any particular position of crank,
position of crank at cut-off, amount of lead, and exhaust lap.
This is answered at (1) Fig. 654. Draw opening 1, 2: lead 1:
position of crank for that opening, 3: and position of crank at
cut-off, 4. Drop perpendiculars 5 and 6. Draw 7 at 90° to 4,
and 8 at 90° to 3. Bisect angle 5, 7, by line 9; and angle 8, 6,
by line 10. Their meeting point is the centre of the diagram,
the dark line showing the primary circle.
(6) Given the lead, and the positions of crank at cut-off,
release, and compression. See Fig. 654, diagram Let 1 be
the lead, while 2, 3, 4 are the positions of crank at cut-off, release
and compression respectively. Drop perpendicular 5 and draw
6 at 90° to 2. Bisect 5, 6, by 7, and 4, 3, by 8; their meeting
point being the centre of the diagram. _
(7) Given lead, maximum opening of steam port, and position
of crank at cut-off ; also inside lap. For solution see ( 3) Fig. 654.
Let 1 be the lead, 1 2 the greatest steam opening, and 3 the
angle of crank at cut-off. Drop the perpendicular 4, and erect 5.
Draw 6 at right angles to 3, cutting 4 in A. Bisect 4, 6, by 7,
and produce at 8 to G: join 9. Draw 10 horizontally, and with
centre A strike 11; join AB by 12. Draw 13 parallel to 12,
cutting 7 in E, which is the centre of the diagram.
Zeuner Diagram for Meyer Valve.—-Concerning cut—
off point only, the real opening to steam will be due to the
relation between main and expansion valves at any moment. In
Fig. 655, let AB be the stroke of the main valve, CG its steam
circle, and 6 the angle of advance. Also let 0, be the angle of
advance of the expansion eccentric (nearly opposite the engine
crank), and cH its throw. Taking position E, CF would be the
movement of main valve from central position, and CD that of the
expansion valve, the difference or relative motion being DF.
Measuring this difference at c J for several positions such as E,
cJK is found, which may be proved to be a circle. To ﬁnd cK
directly, join HG and complete the parallelogram HK by parallels
Z euner Diagrams for Linh Motion. 66 5
GK, CK. Then, with certain limitations, the radii vector of cK
will show opening to steam at the Meyer valve for all positions of
engine crank.
» Let the back valve be adjusted to any desired width, and R be
measured when at mid position ; with radius R describe the circle
L M N o. Strike the steam lap at P R o ; the vectors within PT 5 U
then show opening to steam for the respective crank positions.
Admission is given at P by main valve, in the usual manner;
after T the opening is also controlled by the R circle, and when
the difference vector equals R, as at cs, cut-off takes place. We
see from this diagram how decrease of R secures an early cut-off
and vice versa, and rapidity of cut-off can be judged by decrease
towards s of the vectors of the shaded area. The exhaust circle
is governed by the main valve only.
Zeuner Diagrams for Link Motion.--We have stated
that decreased travel when linking-up causes earlier cut-off. We
have now- to examine, by Zeuner diagram, Fig. 656, the exact
result obtained. Taking the upper diagram ﬁrst, the case of
Open rods. With throw as radius, strike travel circle FE, and
draw valve circle D E for full gear. Draw the link A B, represented
by full travel of die, with DA, D B as the distance between die and
sheave centres. Through point G, where D A and valve circle
intersect, draw E GH to meet the centre line D c in H. Then D H
is the diameter of the valve circle in mid gear, and any other
circle, as D e, will have its diameter bounded by E H; position e,
between E and H, corresponding to proportionate position between
A and c. The centres KL J will form a parabola, lying concave
to D and with vertex at J. Draw the lap circle a6, and erect
perpendicular a’ Y. YE will be the lead in full gear, and the
amount of lead will increase as the travel decreases, shown
by the shaded ﬁgure, being dH in mid position, or equal to
the lap.
Crossed rods. In the lower diagram, the full-gear circle 0 P is
set out as before, also the link M N. The crossing point R, made
by the further rod M0, is joined to P, when SP bounds the
diameters of valve circles. The centres of the circles now make
a parabola convex to o, and with vertex at T. Strike the lap
circle f g, and draw the perpendicular g X. x P is the lead in full
666 [deal Diagrams.
gear, and the shaded portion indicates the change in lead value.
Decreasing towards the centre, it vanishes entirely at W, where the
opening is h w. At 0 v the throw is equal to the lap, and there-
fore the valve does not open at all at positions on the link
corresponding to between points v and s.
Space prevents us giving proof of the above, which, while
being only approximate, is quite near enough for practical
purposes.
Ideal Indicator Diagrams for Compound Engines.
——We examined in Fig. 622 the form of diagram We should
expect to obtain from a single cylinder, and in Fig. 624 some
actual diagrams from a three-cylinder compound. The forms in
the latter case were sufﬁciently clear to show considerable
difference of character over those taken from a single-cylinder
engine. We shall investigate the ideal diagrams for two-stage
compounds, believing that a careful examination will enable the
student to carry the method to three or four-stage compounds.
To simplify matters, we shall work with numbers instead of letters.
Naturally, in building up such diagrams, the only question we ask
from time to time is, ‘What is the change of pressure with a
particular change of volume?’ Two formulae are needed to meet
all cases.
(1) When the volume increases or decreases regularly within
the same vessel : P V
7)
(2) When two or more vessels, having each a particular volume,
and each containing gas at a particular pressure, are
suddenly placed in communication :
PV+Pv+j>v
Pﬁna]: V + V + 2)

Also, for simplicity, the hyperbola is taken to represent the
relation of pressure and volume. See Fig. 620.
I. Tandem Engine, with one cylinder behind the other, and
both pistons on one rod. Sketching the cylinders at A, Fig. 657,
we adopt the artiﬁce of applying a movable paper strip B to
'41
.ritii‘llwg
‘
/\*'
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Quit)‘
-W/k6
668 Tandem Diagrams.
represent the position of the pistons at any moment, and aid the
memory. The data are as follows :
High P. = 1 Clearance H.P.
Volumes { Low P. = 35 Clearance L. P.
Receiver -_ g
I
II II
930°?‘
Cut-off : H. P. = ‘4. L. P. = '6.
Initial steam pressure, 120.
Sometimes a large receiver is an advantage, as in Fig. 659;
but, in any case, the receiver must be present, even though
only represented by the pipes between the H. P. and L. P.
cylinders.
Set .up the scale of pressures culminating at 120, lay off
volumes 4% and '3 per clearance, and 1 and 3% for the cylinders.
Mark off '4 to Po, the cut-off in H. P. Draw a hyperbola through
P0 to the end of the whole diagram, and measure P1 at end of
H. P. = 56. Here there is a sudden opening to R and LC, and,
though we know the volumes of these vessels, we do not know
their residual pressures from last stroke. Such pressures can be
found directly, but only by troublesome formulae; so we recom-
mend that pressures be assumed, and one complete cycle followed
in the ﬁrst place. The residual pressures then found may be
used, a second tour of the cycle made, and so on, till the
pressures assumed are equal to those reached at the end of the
cycle. The method seems complicated, but in practice is really
not so; for it is never necessary to go round more than three
times, and often only twice. On the ﬁrst stroke assume—-
Receiver pressure PR = 15
L. P. clearance pressure P, = 18
The latter being ﬁxed by taking a back pressure of 5 lbs., and a’
compression up to 18 lbs. On the second stroke we measure
P,,, and ﬁnd it has risen to 37, P1 remaining, of course, at 18. On
the third‘ stroke, by combining P1, Pm and P,,, we have by
formula (2) :
56x1%-+37><%+18x'3
P, = =
1%- + 35 + '3

45
S ide-hy-side .‘ Late Cut-of. 669
And now expansion takes place simultaneously in H. P., L. P.,
and R, up to cut off in L. P. Using formula (1):
d+i+s
‘4+§+%+'3+2‘1
which brings P3 up to the general hyperbola in the L. P. cylinder.
It should be noted, however, that only certain proportions between
the three vessels will do this, and the curve may be either above
or below the general hyperbola, as in Fig. 659. The rest of the
low pressure diagram, Fig. 657, is easily understood, the com-
pression curve being a hyperbola through PL. Intermediate points
between P2 and P3 can, of course, be found by calculation.
Following the H. P. diagram, the steam will now be only in
communication with the receiver, and must therefore be com-
pressed in H. P. , He, and R, from P3 to P,,, by formula (1) :
4+i+i
P4 = 25'3 W = 41'5

%=45X =ws
Being cut off to exhaust before reaching P4 we assume a con-
venient point P,,, and measuring, ﬁnd P,, = 37, or the residual
pressure we started with.
II. Compound Engine with cranks at right angles: cut of in
L. I’. after half stroke. This is worked out in Fig. 658, the data
being as follows :
H- P- = I Hc : %
Volumes{L. P. = 3% Lc = -3
R. = ‘45
Cut off a. H1 P. at ‘45, L. P. at '6.
After ﬁrst cycle it is found that
P,R = 17'7, and P, is assumed at 18 as before.
Arriving at P1 =. 62, the H. P. piston will be at the end of its
stroke, but the L. P. piston will be at mid stroke. We therefore
make a sudden communication with R, LC, and half L. P., all
which will have the same residual pressure as R, and
= 62 x 1% + 17'7 (‘45 + '3 + 1%)
. = 1'4
1§+'45+15,‘-+‘3 3
P2
670 S ide-lzy-side : Late C ut-oﬁ‘.
Next the L. P. piston moves to cut-off at P3, but the cor-
responding movement of the H. P. piston is so small that it may
be neglected. Expanding regularly in all the vessels, we have:
I%+'45+1i’-+'3. .
= 28 6
1% + '45 + 102+ '3 + ('1 X as)
The rest of the low-pressure diagram up to P, will be understood.
Following the H. P. diagram, P3 is compressed regularly to P4, so
1%- + '45
t+t+45

P3 = 31'4 x
P4 = 286 x = 417
And now there is a sudden communication with the clearance
LC, having a residual pressure of 18 3 therefore,
_41'7 X (-t>~+%-+'45>+'3 X 18
P.-
d 5+§+'45+'3

= 36's
Then there is a gradual change of pressure, all three vessels
being in communication, but the curve is not a hyperbola, because
not only are the cylinders of different area, but the piston speed
varies considerably. At centre B strike the larger semi-circle, and
at centre A strike the smaller semi-circle, to represent respectively
the L. P. and H. P. cranks. Assume the H. P. compression
point 6 and join 6 A, then draw B 6 at right angles to 6 A3 also
divide the portions between 5 and 6 on each crank circle into
equal parts, and letter as shown. Now the total volume at any
point between 5 and 6 can be found, it always being (Hc+ Lc + R)
+vol. in H. P. +vol. in L. P. Thus at P5, volume=(Jg+ '3 + '45)
+'5+0=1'375. For any other position, w for example, the
volumes in H. P. and L. P. may be found by taking off both the
distances * >l< with dividers and measuring these by the scale F G.
We have not space to consider every point, but at P6 vol. will
clearly be ‘875 + '08 + ‘7875 = 1742. Then,
I'375 _ 28,8
P6 = 36'5 x 1742 _

Intermediate points between P5 and P6 on H. P. diagram
being obtained, an arched curve is found as drawn. The H. P.
diagram is next completed by drawing a hyperbola through P6.
The L. P. curve from P5 to P6 must next be drawn. Now ‘the
RECEIVER _
VOL._é R





cl
RECEIVfR
voz . ~45

672 S ide-by-side .' Early Cut-of.
pressures have already been obtained for these points, and it only
remains to deﬁne their volumetric position. To do this take all
the points from 5 to 6 on the larger semi-circle, and transfer them
to the left side of the circle; thus B 6 is changed to B J. Pro-
jecting these downwards we only have to set up the heights
previously found, to complete the L. P. curve from P5 to P6.
The further expansion from P6 to PR is only in L. P. cylinder and
receiver. Therefore,
P1R = 28.8 x '45 + '3 + ‘7375 =
'45 "i" '3 + I'75
or we have arrived at the residual pressure assumed at ﬁrst.

I7'7
III. Compound Engine wit/z cranks at rzg/zt angles; cat-of in
L. P. bey‘ore lzalf stroke. Referring to Fig. 659, and taking the
following data:
H. P. = 1 HC = '1
Volumes{L. P. = 3 Lc = '3
R. = 1'5
Cut-off H. P. at '3, L. P. at '4.
PR will be found to be 30'2, while P, is 18 as before. P1=44
by measurement. Then the drop to P2 is much less than that in
Fig. 658 because the receiver only is opened to H. P. cylinder,

and P _ 44 x 1'1 + 305 x 1'5
2 1.1 + 1.5 = 36'2
Compressing in H. P. and R,
_ - __I_'E_i_I_'5_. _ .
P3-362x I_I+I_5__é--448
A sudden expansion occurs by opening to LC, and
__44'8x {%+'I+I%}+18><‘3
— 5 + '1 + 1% + '3

P4 = 41'4
Then, while L. P. crank moves from 4 to 5 on the large circle,
the H. P. crank moves through a similar arc on the smaller circle,
at right angles to it, as before. Taking volumes at P4 and P5 we
have’ _ 41'4 x {'5 + 'I + 1'5 + '3}
5_ '1+'1+1'5+'3+'61

Correction for Inertia. 67 3
Finally, expanding from P5 to PR in L. P. cylinder and re-
ceiver,

. . .6
><15+ 3+ 1
PJR = 38
1-5 + ‘3 + 1-2
= 30'5
the residual pressure.
While a small receiver should be adopted in Case 11., a very
large one is advisable’ in Case III. in order to equalise the work
in the H. P. and L. P. diagrams. Of course, Case II. compels
a large gap in the combined diagram, on account of drop in
receiver and low-pressure cylinder, and the arrangement is not,
therefore, counselled. The student should compare actual
diagrams with ideal ones, and endeavour to distinguish between
Cases I. and III.
Correction of Indicator Diagram for Inertia.—-The
indicator diagram, as obtained from the cylinder, does no more
than transcribe the changing pressure and volume on one or other
side of the piston. The actual pressures tending to move the
piston are not correctly shown, at least not without a small
correction; but those transmitted to the crank, which are what
we most require to know, are considerably different, on account
of the deductions and additions required to respectively start
and stop the reciprocating parts at the beginning and end
of each stroke. We shall now examine the modiﬁcations to be
made in the indicator diagram in order to arrive at the tangential
pressure on the crank pin; and, to make the investigation as
useful as possible, shall take an actual case of a vertical engine,
where there is not only the inertia force to contend with, but
the dead weight of the moving mass. In a horizontal engine
there is no such dead weight, while in a diagonal engine the
pressure along the incline caused by the weight is the effective
resistance.
Let the crank circle, J KLM, Fig. 660, have a radius of 1'9”,
as measured by its own scale. Divide the circumference into,
say, 20 equal parts, and, with a connecting rod 7' 6” long, mark
corresponding positions of piston stroke from A to B. Draw the
polar curves, KU and UM, by the method given at p. 491, and
transfer the ordinates to the base AB, so as to form the velocity
x x
674 Correction for Inertia.
curve AXB. Supposing the crank to revolve uniformly at eighty-
ﬁve revolutions per minute, the velocity-of crank pin,
v = 161 ft. per sec.
that is, XY should measure 16'1. Dividing this ordinate into
161 parts will give the scale of piston velocity. 5' _
Next ﬁnd the acceleration curve, QTR, adopting the method
already explained at p. 492, and illustrated in Fig. 454. QT will
show, from base AB, the rate .of increase of velocity, and TR the
rate of decrease, for the top diagram, viz., when the crank moves I
through JKL3 but on the return stroke, from B to A, lower
diagram, RT will be acceleration and TQ retardation. The
acceleration scale will not be the same as the velocity scale,
but must be compressed in the ratio 5, as explained on p. 492.
In other words :
Reading on acceleration scale
. . v
= reading on velocity scale x 2,
Produce x horizontally to Q. Then
16'1 x 161
1'9
By dividing AQ into 148 parts, an acceleration scale is there—
fore formed.
Now the force required to produce a given acceleration in Ta
given mass (p. 473) is 1i’ f : that is, the inertia force is propor-
tional to the acceleration. The weight of moving parts in this
engine is 80 30 lbs., and the inertia force at any moment, ‘
__ w f __ 8030
0‘
<5
Reading AQ =

= 148
x acceleration reading.
The acceleration curve may then be transformed into a curve
of inertia pressure (total) by multiplying by the above fraction or
by 8030 + 32'2 = 2494, that is, the distance AQ must be divided 3
into 148 x 2494 = 36,911 parts. This has been done along BP.
From the total pressure scale take 8030 lbs., with dividers,
and move the curve QR down by that amount, to NP, thus repre—
senting the dead weight of the reciprocating parts.
Correction for inertia. 67 5
It is convenient to make one more scale, to show pressure per
square inch of piston. The piston area being 491 square ins,
divide the total pressure reading by 491 to obtain reading per
sq. in. ; stepped off at st.
The indicator card for the top of the piston is set out by the
unit pressure scale at st, and appears as E-QXHB, the bottom of
diagram touching the base AB. Similarly FPGA isthe card from
the bottom of the piston. Now, while QXHB is being drawn by
the indicator on top side of piston, AFR would be formed by
that connected with the bottom side, and the effective pressure
will be the difference of these curve ordinates. Deduct those
at F from those at H, and the result is the curve WR. So also
VN is the curve of effective pressure on the bottom side of the
piston.
Now the actual total pressure to be carried forward to the
crank pin will be, during the ﬁrst half of the stroke, less than that
on the indicator diagram by the amount required to set in motion
the reciprocating masses, viz., their inertia; and during the second
half of stroke the indicated pressure will be increased by the
backward pull needed to absorb inertia. Brieﬂy, then, the ‘top’
card loses by the area ANs, and gains by sBP, the resulting
pressure area being NxwP; and similarly the resulting area for
the ‘bottom’ card will be PtvN. Setting up the resulting
ordinates on the straight base AB, we have the curve Abd B for
the top and Be fA for the bottom of piston, the total pressures
being written on each ordinate; and in order to equalise the
areas the cut-off in top diagram has been placed at '3 and in
bottom at '6 of stroke, the dead weights having to be supported
in the latter case.
We must next distinguish between reciprocating and rotating
parts, for only the former cause inertia force. The piston, piston
rod, crosshead, and smaller end of connecting rod are recipro-
cating weights, but the larger end of connecting rod is a rotating
weight. As regards the connecting rod itself, about two-thirds
may be called reciprocating and the remaining third reckoned as
a rotative weight. The reciprocating weights directly affect the
indicator diagram, and the latter must be altered, by increased
compression or later cut-off, until a fairly even pressure is
676 Curves of Crank Eﬁort.
obtained. The revolving parts must be balanced by opposing
weights on the crank shaft.
Curves of Crank Effort—If the crank be on either dead
centre, there is no tangential or turning effect produced by the
steam pressure on the piston, all such pressure being received
upon the bearings. When the crank is midway between dead
points the whole piston pressure is transmitted tangentially, and
there is no pressure on the bearings except that due to dead
weight. Between the two conditions part of the pressure is
transmitted tangentially and part normally. But (p. 491) the
polar curve proportionally represents tangential crank pressures,
other things being equal. Divide then Jo, Fig. 660, into tenths
and measure the radii vector of the curve UK in terms of these
divisions: the numbers obtained will represent the virtual crank
arms in relation to pressures transmitted along ABO. Taking the
total pressures from A to B, multiply each pressure ordinate by its
virtual crank arm, and the result will be the tangential crank
pressure for that position. Setting out these results radially, with
the crank circle JKLM as a base line, we obtain the two curves of
crank effort J gkjL and Lklm J for the top and bottom of piston
respectively. These again are better understood on a straight
base, so the base JK is stepped out at co, KL at 0D, and the
radial ordinates transferred as vertical ordinates on the new base
CD. Curves cup and D _to are thus arrived at.
Combination of Crank Effort Diagrams.—Though
the ﬂy wheel may equalise very tolerably the crank effort, there is
still the difﬁculty of starting when the crank is at either dead
centre. This is not a material difﬁculty for a factory engine
which has only to be started twice a day; but in locomotive and
marine practice it would be a very serious obstacle. In loco-
motives two cranks at right angles are employed, as at 1a, Fig.
447, p. 486, while in marine practice it is usual to place three
cranks at 120° mutually. The latter give the best conditions, but
the advantage of both will be made clear in Fig. 661.
At (a) two cranks set at 90° are each supposed to have effort
curves, as in Fig. 660. Plot these with relation to the respective
cranks, AA being the top curves, and BB the bottom ones.v Then
the curve of total effort may be found by super-position, that is, at



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Weight of Fly Wheel. 679
every radius the ordinates of both curves are added to form
the resulting curve CC. An average circle is struck, and shown
dotted; and a clear conception of the more even turning move-
ment is then obtained. .
Three cranks are set out at (b), Fig. 661, and the like process
followed. The same letters are adopted throughout, and a more
regular turning movement results. The differences between the
c C curve and the dotted circle may seem little better than before,
but they form a much smaller percentage of the effort ordinate.
Calculation of Fly-wheel Weight required.-—-The
crank radius, Fig. 660, being 15,3 feet, the circumference of the
crank circle is exactly 11 feet. In Fig. 662, let ad be 22 feet,
and let it be divided so that a e and h d are each 2%’; feet, and e j‘,
fg, and gh, are each feet. On ef and gh set up ordinates
of crank eliort on the up stroke, and on fg of that on the down
stroke, those on ae and ha’ each representing half the down
stroke effort. Now take the mean of the ordinates on e f .-
dividing the base into 10 parts, measuring at centre of each part,
adding the ordinates and dividing by 10 : the result is 29,500 lbs,
The mean of the ordinates on fg is found similarly to be 25,000
lbs. Adding and dividing by 2, gives 27,250, the mean effort
for the continuous diagram ad. Draw jk at this pressure
above a d.
Now the areas, A, C, 810, show surplus work, while the crank
travels from l to m, and from n to p respectively, while the areas
B, D, 810, show a work deﬁcit between m n and pq. The ﬂy
wheel must absorb the work A or C, and give it out again at B or D,
and thus tend to equalise the crank effort. The mean pressures
and distances traversed have been measured at A, B, C, and D, and
are shown by work rectangles. The total surplus and total
deﬁcit of work per revolution is found to be 88,700 foot pounds,
and the mean of the four work areas, A, B, C, and D, is therefore
88,700 + 2 = 44,350 foot pounds. This is the excess of energy
which the ﬂy wheel must be able to absorb, such absorption
increasing its velocity, while the delivery of energy will in like
manner reduce it. But the heavier the ﬂy wheel, the less will be
the ﬂuctuation of velocity ; and the problem is to ﬁnd the weight
of wheel which will absorb the surplus energy and re-deliver it,
680 Wager of Fly Wkeel.
keeping the ﬂuctuation of velocity within a certain percentage of
the mean. Let v = mean velocity, and let
Fluctuation of velocity}
1
. . = — of v
on either, side of mean
k
then the value of k depends on the regularity required, and
may vary from 100 for very steady driving, to 20 where constant
speed is of little value. With feet and seconds units, let v1 be
maximum velocity and v2 minimum velocity of the ﬂy wheel at its
mean radius, consequent on absorbing and delivering the given
energy, and let E represent the energy area, or the 44,350 foot
pounds of Fig. 662, while the velocity falls from v1 to v_.,.
. w v 2 — "l 2
Energy delivered = LIZ—gill
<5
where w is the weight of the ﬂy wheel. But this energy is equal
to the area E,
a 2
= w (o,2 — v2 )

'. E
2s
1
Now v1—v2=v x z v,+v2 = 2v
21:- RN
and v=
60
R being radius of gyration of ﬂy wheel.
Putting also the ﬂy-wheel weight in tons,

W = E x 2g : 2 Egk
-— (v1+v2) (v1—v2) 2240 2v2 x 2240
__E32'2k60X6o Ek

4 71'2 R2 N2 2240 _ 5.24 R2 N2
If the ﬂywheel diameter be great, and the rim heavy in com-
parison with the arms, its radius may be taken to the centre of
rim section. If the weight of arms and boss are considerable, the
following method may be pursued, with strictly correct result:
Assume a section of ﬂy-wheel, replacing the arms by a thin disc
of equal weight; treat the wkole cross section of the wheel, through
shaft centre, as a beam section, and, referring to pp. 430 and 431,
Steam Port A rea. 68 1
ﬁnd its modulus, or z ; multiplying z by y, the outer radius of the
ﬂy wheel will give I, the moment of inertia of area ; dividing I by
the actual and total area of the ﬂy-wheel cross section will give
R2, the square of the radius of gyration. If inches have been
adopted, R must be changed to feet when inserting in the ﬂy-
wheel formula. Also v must be measured at radius R. If W does
not now agree with the calculated weight, the section must be
altered, and a new calculation made.
Area of Steam Port—Practice has decided certain average
speeds of piston in particular cases, and the following list has
been thus deduced :—
MEAN PIsToN SPEED IN FEET PER MINUTE.
Locomotives ....................................... .. 1000
Marine engines ..................................... .. 700
Horizontal engines .................................. .. 400
Pumping engines .................................. .. 130
To attain this speed, we must not endeavour to pass the steam
through the steam port at a greater speed (according to Rankine)
than 100 feet per second.
cylinder area 100
Ratio of - . .
port area speed of piston in ft. per sec.

If the port be much contracted, a lower piston speed will be
attained than that intended. We shall close this chapter with
some practical examples, together with a few remaining points
of theory thereupon raised.
Horizontal Compound Pumping Engines.—Figs.
‘663-4—5 are views of a pair of compound engines designed and
built by the East Ferry Road Engineering Works Company,
Millwall, serving as examples of the Stationary or Land engine.
The engines are used at the Millwall Docks for pumping water to
hydraulic accumulators, under a pressure of 7 50 lbs. per sq. in.
‘The bed plate H is in two parts, and supports the high-pressure
cylinders BB, the low-pressure cylinders AA, the pump cylinders
22, and the crank shaft bearings mm. The H. P. cylinder is
supplied with a main valve D, and an expansion valve E, of Meyer
form, the valve spindles being lettered respectively G and F. The

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684 Compound Pumping Engines.
valve 0 for the L. P. cylinder is double-ported, but not relieved
from steam pressure at the back. The piston rod Y Y, being pro-
longed, forms the pump plunger, its sectional area being half that
of the pump piston, for reasons to be explained in the next
chapter. J J is the steam supply pipe to the H. P. cylinder, K its ’
exhaust, as well as supply for L. P. cylinder, and the L. P. cylinder.
exhausts directly into the condenser, as will be seen in Fig. 665

@6. 65-
The surface condenser N N consists of a rectangular casing, con-
taining a nest of tubes. Cold water being allowed to ﬂow in
through the pipe M, passes through these small tubes, ﬁrst through
the top half, returning through the lower half, then out by the
pipe L. The exhaust steam distributing itself outside the tubes,
becomes condensed, is taken away as water by the air pump Q,
and delivered to the hot well U; then by the feed pump v to the
boiler. The air pump bucket has four valves at T, ﬁxed foot
Three-cylinder Marine Engines. 68 5
valves 5, and delivery valves R to prevent the water returning.
The bucket is actuated by the bell-crank lever WW, connected by
links to the crosshead X. The connecting rod e has a long fork
to clear the pump barrel; it is also light in construction, its sole
duty being to transmit equalising energy to or from the ﬂy wheel,
in addition to the power required to work the valves. The pump
suction pipe is at dd, and the delivery pipe at bb, but full ex-
planation will be left to the next chapter. We must not omit
to mention the hydraulic governor g, the invention of Mr.
C. R. Parkes, M.I.C.E., which has given great satisfaction in
its working. The ﬂying balls are driven from the engine in
the usual manner, but the sleeve opens a small D valve to
hydraulic pressure or exhaust, according to whether it rises or falls.
Nothing takes place until the governor has attained a speed of
15 revolutions per minute, when high-pressure water is admitted
into the cylinder h, and the ram j is pushed downward, thus also
pulling down the strap k and raising the Weight l. The conse—
quence is that the pulley f, on the expansion valve spindle, is
rotated so as to increase the lap of the Meyer valve and secure an
earlier cut-off, and the action will continue until the speed of the
engine has returned to the normal, when the governor sleeve will
fall,open the D valve to exhaust, and allow the weight l to lift
ram j to its original position.
Triple Expansion Marine Engines.—Figs. 666 and
667, Plate XVII., are two views of the triple-expansion engines of
the Paciﬁc steamer Iberia, designed and constructed by Messrs.
David Rollo and Sons, of Liverpool. The bed plate y, in three
pieces, carries the left-hand standards; the right-hand standards K,
K1, and K11, being built upon the condenser v. Cylinders—The
H. P. cylinder A is 33 ins. diameter, B the intermediate is 54 ins.,
and c the L. P. cylinder is 88 ins. _; while G, H, and J are the
respective ,oistons, of conical form to combine lightness with
strength, and each having a stroke of 60 ins. To minimise the
number of spare parts, the cranks YY Y, connecting rods zzz, piston
rods DEF, eccentric s and rods STU, links r, gudgeons az, crossheads v,
and pump levers jk, are all made respectively interchangeable;
only a small alteration occurring with the rod D, which must have
the tail or upper part out off. Valves—A piston valve b is
686 Condensers.
adopted for the H. P. cylinder, packed with ﬂat rings, but dis-i
tributing steam like a D valve. To save space two piston valves c
are supplied to the I. P. cylinder, as seen by the valve rods 3 and
4, connected at t’heir lower ends by the strong crosshead 5 3 and
the L. P. valve d is double-ported, while being relieved on its
back by the hollow piston h. Piston g, with steam pressure
underneath, supports the weight of valve d, and the I. P. valves
are similarly supported by pistons within or and w. Relief valves
uu, on the cylinder covers, are wing valves weighted with springs,
serving as safety outlets for condensation water, which might'
otherwise break the covers when the pistons moved. The H. P.
and I. P. slide valves, being vertically above the crank shaft, are
worked with ‘open ’ rods, but the L. P. valve is moved by the
rocking lever QR, and ‘ crossed ’ rods arev therefore required,
Stephenson’s gear being applied in every case. The radius link
is formed of two plates, having the die between and the eccentric
rods outside, thus enabling the pin centres to be coincident when
in full gear. The steam reversing cylinder t has its rod u coupled
to the weigh bar lever s}, which, through the drag link gr, moves
the link r to fore or aft positions 3 expansive adjustment is given
by the screw 9, and 9 is the valve lever for cylinder t. The
exhaust steam passes to condenser v through standard K 3 and air
pump x and circulating pump W are worked from crosshead v by
levers jlh. 7 and 8 are oil pumps, and 6 an oil reservoir with
gauge. The cylinders are jacketed at sides, top, and bottom 3
and drains connect to tanks which show the water used.
Condensers.--The advantages of condensation having been
discussed theoretically, we will now describe the three principal
methods of realising those advantages practically. '
The jet Condenser, Fig. 668, applied to most land engines,
‘consists of the condenser A, where exhaust steam E is met by a
constant spray of cold water from injection cock G 3 the air pump
B, worked from the engine piston rod 3 and the hot well C, from
which the condensed steam and water is taken to feed the boiler.
In order to make B’s action continuous, there is a suction valve s
and a delivery valve D at each end of the cylinder.
The Surface Condenser, Fig. 669, avoids the mixing of cooling
water with the steam directly. If such water were dirty or briny,
PLATE xv“.
( To [ace
p 686.)
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688 Propeller, Thrust Bearing, and Stern T uhe.
a deposit from the feed water occurred on the boiler plates, and
the latter were injured through overheating.
A large number of small tubes AA being arranged in the
casing B, the exhaust steam C is condensed around them before
being removed by the air pump D to the hot well E. The
circulating pump, H, takes condensing water from the sea and
forces it in at F, through the top nest of tubes, into chamber J,
along the bottom nest, and out to the sea again at G. Con-l
siderable heat is thus thrown away; but the method is more
economical than that of intermittent blowing-off of hot water
from the boiler.
The Ejector Condenser, Fig. 670, is there arranged for a double-
cylinder engine. EE are the exhaust pipes, and C is connected
to a cold water tank having, preferably, a little head. Live steam
introduced at L starts the action, but is afterwards cut off, and the
condensing water adjusted by wheel A. Steam is then condensed
so rapidly as to cause a vacuum in chamber v. The boiler is fed
from the hot well F, as before.
Further Marine Details.—In addition to the engine
details already described, there are the various connections to
the propeller, and the propeller itself.
The Screw Propeller for the [heria is shown at Fig. 672. The
blades A A have a helical or screw surface (see Fig. 35), and are
bolted separately to the boss, to allow of adjustment and renewal.
The boss is cast steel, and the blades of manganese bronze.
E is a section, and C a development of the ﬂat surface.
Fig. 674 represents the position of the parts between engine
and propeller, the length of shafting depending on the engine
position, usually central for stability.
The Thrust Bearing (described at p. 506) is shown in Fig. 671
as applied to the Theria. To increase the surface resisting pro-
peller thrust, there are seven horseshoe bearings DD, and seven
corresponding collars CC on the shaft. The bearings being faced
with white metal, and supplied with oil boxes E E, are strung upon
screwed bolts FF, ﬁxed to the main casting A3 and the nuts so
adjust the bearings, that each takes its proper share of the thrust.
GG are ordinary supporting bearings with oil boxes HH. The
shaft is cooled by circulating water beneath it, and the hollow
Compound Locomotive. 689
horseshoe bearings have Water passing in and out at J J. K K are
lifting eyes.
The Stern Tube, Fig. 673. A is the tail shaft, tapered to ﬁt
’ the propeller, Where it is keyed and gripped by a nut and split
cotter. A renewable muntz-metal sheathing D is rolled on the
shaft, and gives a smooth, non-corrosive working surface. The
tube B, bolted to the water-tight bulkheads at H H, and supported
by the stern frame at C, has a bush E in which are placed staves
of hard wood (lignum vita), being the best bearing where water
is the lubricant. At the other end a stufﬁng~box, formed by the
neck ring F and gland G, prevents water entering the tube.
Compound Locomotive—The general arrangement of a
locomotive being well known, one good typical example will here
suffice. The example chosen serves to illustrate the ordinary
‘inside cylinder’ engine, having cylinders within the frame, the
only main difference being the arrangement of steam pipes. It
also shows one of the most successful adaptations of the com-
pound principle to locomotives. ’
Figs. 67 5—6—7, Plate XVIIL, are views of a Compound
Express Locomotive for the N orth-Eastern Railway, on the
‘W orsdell and Von Borrie’ principle. The main frame consists
of two plates LL, a cross stay L1, and buﬂer beams MM: the front
beam carrying the buﬁ'ers N N, draw hook b, and coupling screw c,
while the back beam faces that of the tender Q. Between M
and Q are placed buffers P, pivot 50, and safety links 88, the pull
being taken by the draw-bar 6. 35 is the foot-plate, 19 the cab,
to shield from the weather, 34 the platform, and y the splasher for
the driving wheel: ff are lamp brackets, and dd lifeguards. The
cylinders A and B are bolted between the frame plates, and slide
valves aa1 are placed above the cylinders to suit Joy gear, whose
various links 2, Y, X, and W are explained at Fig. 640. There are
four slide bars qq to each cylinder, and two motion blocks rr:
n and p are the piston rods, and mm the connecting rods. The
weigh-bar shaft s is moved by a hand-wheel and screw at 21,
coupled to lever t by the rod u. E E are the driving wheels, and
FF the trailing wheels, with J and K the respective axles: the
former is known as the crank axle, and in the N .E.R. example is
turned throughout. The wheel centres are of cast steel, but the
Y Y
690 C ompound Locomotive.
tyres are rolled weldless and ﬁt into annular grooves in the wheel
rim, to resist centrifugal force. The front end of the frame is
supported by a trolley or bogie, which permits certain side move-
ment when travelling round curves. H H is the bogie frame, with
stay rods TT, co the bogie wheels, and GG the axles. A block“ or
die 43, curved to a radius from 42, is held by the .pin D ; and
guides 44, similarly curved and forming part of the bogie frame,
ride upon the die. If 43 were rigid, the bogie would only swivel
round 42, and would only adjust itself to certain curves; but the
freedom of 43 on D permits a further angular movement, and
the virtual centre 42 is therefore variable. The buffers UU limit
the lateral deviation, and springs gg return the bogie frame to
central position.
Laminated springs, k and 13, and helical springs, 45, placed
between frames and wheels, lessen the shock due to inequality of
permanent way, and the necessary vertical sliding is met by
providing special bearings, S, x, and 14, termed axle boxes, for
the bogie, driving, and trailing axles respectively. R, w, and 15
are the guides in which the boxes rise, and z is a wedge to take up
wear in the main box.
A hand brake 11 is used in emergency, but the regular work
is performed by the Westingkouse compressed air brake. The
steam pump 51 ﬁlls the main air receiver 5, from which auxiliary
receivers—one to each carriage, and one, 46, for the engine—are
further supplied. From 46 pipes are led to the cylinders 4 4,
and the air pressure moving levers 2 2 put the blocks 3 3 on the
tyres. Upon exhausting, 3 3 are released by springs. When
ascending steep gradients, sand is driven between wheel E and
the rail by means of a steam jet from pipe l, the sand passing
’ from sandboxes jj, down the pipe k. Cylinder cocks 18 act as
relief valves, and are opened after the engine has stood some
time.
Boiler 20, and ﬁrebox 21. Very little description is needed
beyond that at p. 335. Girder stays 53 are of cast steel, and 52
are long stay bolts. A ﬁrebrick arch 23 deﬂects the current of
heated gases over the box, and the ask pan 2 has doors or
dampers, both before and behind, for regulating the draught.
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692 Compound ‘Locomotive.
hlast pipe 39, gradually contracted towards the oriﬁce to cause the ‘
necessary velocity 3 and the smoke hox 22 must be air tight, so its
door 3 3 is provided with two handles, one for turning the tongue
catch, and the other for tightening the screw. A jet of steam
from the hlower 40 causes draught when the engine is standing.
The steam regulator, 56, has two slide valves worked from handle
34, the main valve 27 being treble-ported, and the ‘ easing ’ valve
28 double-ported and small. A pin 55 connects both valves to '
the gear3 but the hole in 27 is slotted, so that when opening, 28
is ﬁrst moved (easily, being small) and a ﬁlm of steam admitted
between the main valve and its seat. Next, 27 is caught by the
pin, and, on account of the relief just given, can be moved
without difﬁculty. ‘
Under ordinary Conditions steam ﬁrst enters the H. P. cylinder
B by the pipe 27, exhausts thence to the L. P. cylinder through
30 and 2,8 (the whole pipe forming a receiver of a capacity equal
to B), and ﬁnally leaves by the blast pipe 39. But if H. P. crank
be on a dead centre at starting, steam must ﬁrst be admitted to
the L. P. cylinder A, and yet be prevented from entering B for
fear of blocking the piston. Outside the smoke box a valve box
61 is ﬁxed, having a starting valve 59 opened by a rod from the
foot plate when required, but at other times kept closed by a
strong spring. Pipe 41 takes steam from the'boiler to 61, and 57
Carries it away to the main pipe 28, entering at 293 and a piston
62, ﬁtting in the valve box 61, is connected to the rod 60 for the
purpose of lifting the ﬂap or intercepting valve 58, which is
normally open. When the driver wishes to start, he opens
regulator valve 27, and if the H. P. piston refuses to move, he
pulls the small lever which opens 59 3 and steam, wire-drawn to
half pressure, enters 61, moves 62 clear to the left and closes 58,
then passes by 57 and 29 to move the L. P. piston. Once the
engine moves, steam enters the H.P. cylinder by 27, the proper
path, exhausts by 30 and 29, and acting on the large area of the
ﬂap 58, opens it, and once more valve 59 is closed by its spring.
Instead of feed pumps, injectors are now favoured for feeding
locomotive boilers, and two of these, 12, 12, are supplied. They
draw from the tender through a strong rubber pipe, and deliver
through the clack box 2 5, in which is a non-return valve. A

‘...—-
PLATE XVIII.






INTER‘QEPTING - VALVE
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Tractive Force. 69 3
double spring-loaded safety valve, 31, is placed over the ﬁrebox.
The valves are inverted cones, ﬁtting easily, and either centre-
point can be lifted by the lever 32 to test the working. A safety
link placed within the spring holds the lever in case of breakage.
71 is the steam whistle ,- 70, a lamp bracket; and 72 the chimney,
of cast iron. 38 are lubricators for the steam chests. '
Tractive Force of a Locomotive is usually taken as
the mean pull exerted on the moving train, and may be estimated
from the principle of work. Thus :
Work given by Steam = Work done on Train.
Total mean pressure half wheel
}‘>< stroke = Tract. force x {
in both cylinders circumference
pads;
2 x -—4—-- x l = T x 11'?’
'. T : M
2 r
The tractive force for any particular starting position can
only be found by ﬁrst ascertaining the crank effort for that
position (E); then, by moments:
El
T=--
27’
Of course, the greatest value of T must not overcome the
adhesive force, or slipping will occur (see p. 571). The tractive
force required is given at p. 569.
Boiler Fittings.-—Boilers having been described at pp. 330
to 339, it remains to consider the principal mountings with which
they are ﬁtted.
Safety Valves.--Lever-loaded valves, p. 482, are not now
in favour, on account of the fear of explosion due to sticking.
Directly-loaded valves may be either spring or weight loaded.
The former has been shown at 31, Fig. 675, Plate XVIII. ; and a
dead-weight valve is given at Fig. 678, as applied to stationary
boilers. A casing A, containing the weights, is hung on a cup-
shaped valve resting on the conical end of the pipe B. The
ﬁgure shows also a low-water ﬂoat c and a high-water ﬂoat D,
which raise rod E whenever the water falls too low or rises too
high respectively. Marine valves are spring-loaded, and the
694 ' Boiler Details.
Board of Trade Rule gives half a sq. in. valve area for every
sq. ft. of grate surface.
Mudhole Coven—Manhole covers are merely ﬂat plates.
covering the raised mountings shown at Figs. 310 and 311 : mud-
hole covers, Fig. 680, are more perfect mechanically, the oval
plate A being kept closed by the steam pressure, and further
secured, by bolts, to bridge pieces B B. The oval shape permits
the plate to be entered narrow-ways, after which it is adjusted
into position.
Pressure and Vacuum Gauges—The Bourdon Gauge,
Fig. 681, is now generally adopted for both purposes. Within
the Casing A is a curved tube C, of ﬂattened section, as at D : it is
open to pressure at B, but blind at E. If the pressure increase
above the atmosphere, the tube distends, and point E moves out-
ward 3 but a decrease of pressure below atmosphere still further
ﬂattens the tube, and point E moves inward. ,Both movements
are transmitted to sector F, which turns, by a pinion, the pointer,
thus multiplying the motion 3 and a hairspring on the pointer axis
takes up backlash. The graduations are made by experimental
comparison with a mercury gauge.
Injectors—There are two ways of feeding a boiler with
water when under steam: (I) by a pump either driven from the
engine, or steam-driven and self-contained, then known as a
‘donkey-pump3’ (2) an injector may be used. Pumps will be
treated in the next chapter. The injector forces water into the
boiler without the intervention of moving mechanism, and the
only loss’ is that due to ﬂuid friction, while the delivery of hot
instead of cold water is a gain, not to speak of the diminished
strain on the boiler. In Fig. 682, A is a section of the instrument,
and B shows its application. The injector represented, being
non-lifting, must be placed at the tank bottom, but its parts are
essentially the same as those of other injectors. C is the water-
cock, D the steam cone, E the combining cone, F the overﬂow
pipe, and G the delivery pipe. H is the steam cock, and J a
non-return clack box. Cocks H and C being opened, water is
forced into the boiler by the steam; and it long remained a
surprise to engineers that steam could feed water against its own
pressure. The explanation is this : the velocity of efﬂux of steam‘


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696 ‘ Injectors.
is some 16 or 18 times that of water at the same pressure, and
the jet of steam escaping from D is so suddenly cooled by the
tank water through c, that it has not time to reduce its velocity
to that due to it as water, and therefore succeeds in piercing the
boiler water, carrying the tank water with it. An overﬂow takes
place at F when ﬁrst starting, which, however, ceases when cocks
c and H have been mutually adjusted.
A lifting injector must permit of regulation at the oriﬁce D
and ring oriﬁce E, for the conditions of vacuum-forming and
water-forcing are quite different, and the former must be ﬁrst
satisﬁed, after which the latter may be met without disruption
of the water column. An ingenious method of automatic lifting
injector is now in operation, where the throat E is split longitu-
dinally, and one half hinged near the annulus, the ‘ ﬂap nozzle’ thus
formed also causing a re-starting, should the ﬂuid tend to disunite.
Slightly altering the cone proportions, and giving the water a
few feet of head, produces an injector workable by exhaust steam ;
but, on account of the variation in pressure, the ﬂap nozzle must
be provided.
Otker Mountings for the boiler are: a blow-off cock near the
ﬁrebox bottom, gauge cocks about 3 ins. above and below the
water line, ﬁre bars and bearers, furnace doors, mud plugs, fusible
plug in furnace crown to melt in case of overheating, and thus
cause the ﬁre to be extinguished, clack box (J Fig. 682), damper
for regulating draught, a ﬁlling branch when no other hole is
convenient, and sometimes a scum cock.
Combustion.—Combustion or burning is rapid chemical
combination accompanied by heat 'and light. If considerable
noise be caused it is termed an explosion. During combination,
heat is produced equal to that required to separate the same
elements. The separation of carbon and hydrogen, and their
recombination with oxygen, is what the engineer needs to
understand, so we will consider the burning of a simple hydro-
carbon like marsh gas, shown by the formula :
Marsh gas + Oxygen = Carbon dioxide + Water (steam)
a case of complete combustion, for no single element remains.
Combustion. 697
Taking the atomic weights of C, H, and O, as 12, 1, and 16
respectively, we have:
Marsh gas + Oxygen = Carbon dioxide + Water
(12+4) +2(16><2)= {12+(16x2)} +2(2+16)
that is, 16 lbs. + 64 lbs. = 44 lbs. + 36 lbs.
or, 1 lb. + 4 lbs. gives 2'75 lbs. + 2'25 lbs.
Again, 1 lb. of carbon burnt to CO3 gives 14,500 thermal
units, and 1 lb. of hydrogen burnt to H20 gives 62,032 units.
In 1 lb. of marsh gas there is 3} lb. of carbon and i lb. of
. hydrogen.
Units.
ilb. Carbon + 0 gives 14,500 x a} 10,875
ilb. Hydrogen + O gives 62,032 x % 15,508

Total . . 26,383

Practically we obtain a total of 23,582 units, or 2801 units
has been required for decomposing the C and H.
Good dry bituminous coal contains on the average, by weight,
Carbon, 8 3'5 Hydrogen, 4'6 %. Oxygen, 3'15 °t.
the remaining 87 5 %, being Nitrogen and Sulphur, inactive
elements. Taking 100 lbs. of fuel the 3'15 lbs. of oxygen is
already united to 7% x 3'15 = ‘4 lb. of hydrogen as water, and the
hydrogen does not assist combustion; so we have left:
8 3'5 lbs. of Carbon 4'2 lbs. of Hydrogen
Now 12 lbs. of C unite with 32 lbs. of O, or as 1 : 2'66; and
2 lbs. of H require 16 lbs. of O, or as 1 : 8.
lbs. of O.
83‘5 lbs. C require 83‘5 x 2'66 = 222
and 4'2 lbs. H require 4'2 x 8 = 33'6
Total weight Oxygen for 100 lbs. coal = 2 5 5'6 lbs.
or 2'5 lbs. of Oxygen is needed to burn 1 lb. of coal. But air is
composed of 77 parts Nitrogen to 23 of Oxygen, by weight.
23 : 100 :: 2'5 = lOibS. of air per lb. offuel.
698 Forced Draught.
Again, we have per lb. of such fuel '8 3 5 lb. of C and ‘042 lb.
of H,
Heat units.
‘835 lb. Carbon + O gives 14,500 x '835 = 12,107
‘042 lb. Hydrogen + 0 gives 62,032 x '042 = 2,605

Total units . . . 14,712

By careful laboratory experiment a lb. of such coal is found
to have a caloriﬁc power of 14,701 thermal units, and evaporate
15 lbs. of water at 212°. Also 12 lbs. of air are required per lb.
of fuel.
In actual practice considerably less heat is developed, and the
evaporation is good at 10 lbs. of water, being commonly 6 or 8.
Also 24 lbs. or 312' cub. ft. of air are required, with natural
draught, to dilute the gases and allow the air to reach the fuel.
Forced Draught—The essential advantage of forced
draught lies in the fact that a smaller dilution of the gases can
be allowed, 18 lbs. of air per lb. of fuel, or only times what
the chemist requires. In consequence, a higher temperature is
obtained, the grate and heating surface being much more efﬁcient;
and thus a smaller boiler will serve the purpose, a great advantage
in torpedo boats.
The air must not be solely fed through the ﬁre bars, or a
tongue of ﬂame would meet the stoker whenever he opened the
ﬁre door. The closed stokehold, the earlier method'of solution,
places the stoker in a plenum of air at a moderate pressure, which
enters the furnace as usual. The latter method, the closed ash-
pit, requires a box-shaped ﬁre door, into which air is fed as
well as to the ashpit 3 but the air to the latter is at a much lower
pressure. The air from the box door passes to the coals through
holes in the bafﬂe-plate, and the supply is cut off automatically
whenever the door is opened. Both methods still have their
advocates. The pressure is caused by a fan.
Waste of Fuel is largely due to formation of smoke and
incomplete combustion, the carbon partly being burnt to CO.
Alternate or continuous ﬁring, by careful men or mechanical
stokers, and a sufﬁcient supply of air, are the only remedies.
The gases also pass up the chimney at a greater heat than 600°,


The Gas Engine. 699
the best temperature (that of molten lead), being also required
to cause draught: a quarter of the total heat is thus wasted, and
can only be partly obviated by forced or induced draught.
The Gas Engine.——It was early discovered that steam and
the steam boiler might be dispensed with if a mixture of gas and
air were ﬁred within the cylinder, the arrangement constituting a
true heat engine, both pressure and temperature rising at the,
moment of explosion.
Supposing marsh. gas to be mixed with just enough air for
complete combustion, a sharp explosion occurs when ﬁred, but
if either gas be diluted by too much of the other, combustion is
retarded and the explosion is weaker. Dugald Clerk in 1880
made experiments with coal gas and air, and found the sharp-
ness of explosion could be tempered as desired; also, that the
pressure was better sustained with slow combustion. This is our
experience with heavy ordnance. Treating the gun as a steam
cylinder, rapid explosion causes high pressure, followed by pretty
rapid fall, and but a small work area is enclosed. Slow—burning
powder gives a lower pressure curve, which rises somewhat slowly,
but is better sustained, and a much larger work area results.
Clerk showed that the best working proportions, using lighting
gas, was 1 of gas to about 11 or 12 of air.
The ﬁrst practical gas engine was produced by Lenoir in
1860. It was double-acting, charging with air and gas during
a half stroke, ﬁring during the remaining half, and expelling the
products during the return stroke. Passing over the Otto and
Langen engine of 1867, and the Bisschop of 1870, we reach the
ﬁrst commercially successful engine, the Otto-Crossley, introduced
in 1877 by Dr. Otto, who applied the cycle of operations, originally
proposed by Beau de' Rochas, the operations being as follows :
1st stroke : outward 222-» charge of gas and air.
2nd stroke : inward <—-es compression of the charge.
Dead centre ignition.
3rd stroke : outward re—> expansion of the gases.
4th stroke: inward <-ss expulsion of burnt gases.
An explosion only occurs, therefore, every fourth stroke, and
a heavy ﬂy-wheel becomes necessary.
700 Metkods of Ignition.
But one detail has caused some trouble to all inventors, the
question of igniting the explosive mixture without escape of gas.
Three methods have been used :—(1) Flame ignition, where a
portion of burning gas is carried through an aperture in the slide-
when the latter is just closing. This method has been used
extensively, but occasions frequent misﬁres when the small aper-
ture becomes carbon coated. (2) Tube ignition, Fig. 682 a.
Here the blind tube A is kept at a white heat by the bunsen
ﬂame c, supplied with gas from B, and whenever the timing valve
(l/v LENOIR ENGINE)
______



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E is opened by the spring G, the charge, which has been com-
pressed into the ignition chamber D, then ignites. F is the boss
of a lever which keeps valve E on its upper seat, and allows the ‘
contents of the tube to be cleared through hole T. Small engines
have no timing valve, ignition only occurring when the charge is
compressed into the tube. Tubes have to be replaced every
fortnight at the latest. (3) Electric ignition was adopted in the
Lenoir engine, but in a faulty manner. The current from battery
L was intensiﬁed by the coil K. It passed through insulators at
MM, and by platinum points through the cylinder N, the circuit
being closed by the crosshead J, causing sparks at MM. The
covering of the platinum points with carbon or watery vapour
The S implex Gas Engine. 701
was the cause of failure.* In the Simplex engine a constant
shower of sparks takes place in the chamber x, the current
passing through the insulator U and back by v. In the ﬁgure the
cylinder is being charged from 5, through Q, but when the slide
moves to the right, R connects W with x, and ignition occurs
with certainty.
We may now describe the SIMPLEX ENGINE (Systeme Delamare-
Deboutteville et Malandin), Figs. 683 to 688, as a type of a
well-designed gas engine. A is the cylinder, supported on the
bed plate H, and surrounded by a water jacket B, which also
protects the slide casing and exhaust outlet; N is the mixing
chamber, and c the piston or plunger. D is the connecting rod,
E the crank, F the balance weights, R the crank shaft, and GG the
ﬂy wheels, having a pulley P attached for driving purposes. Pipe 1
is always open to air, and the gaspipe K admits gas when cock L
is opened. But such gas is only allowed to enter the cylinder
at proper times, viz., when the charging valve M is opened by
projection h on the slide spindle g. As the cycle occupies two
revolutions, the shaft Q (which moves the slide d backward and
forward through the disc crank f) makes two rotations to one on
the main shaft, and the wheels at R and 5 together have a velocity
ratio of 2 : 1. The charging and ignition having been described,
the governing and exhaust arrangements remain. Taking the
former, shown in Figs. 687 and 688, the method adopted, as in
other gas engines, is to cut out one or more chargings when the
engine speed increases. Upon the spindle h is a small tapered
‘rocker’ j, and when this is allowed to catch the stem k of the
charging valve the latter is opened. The governor is a pendulum
n 1, whose lower end is lifted to the right by the rocker j, and,
being allowed to return freely, its time of fall is invariable.
Noting that the rocker j is constantly depressed, as in Fig. 688,
by a spring, suppose engine speed to be normal, and j to be
moved to the right, lifting the pendulum. Returning, the pen-
dulum bears slightly upon the rocker, catch m lifts j to the hori—
zontal, and the valve is opened. But if the slide travel too
quickly, m misses 7' when returning, and the result is a ‘misﬁre,’
* M. Delamare inclines to the former, Prof. Wm. Robinson to the latter
cause.
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Petroleum Engines. 705
as shown in Fig. 688. The pendulum may be adjusted to the
greatest nicety by raising or lowering ball n. The method of
opening the exhaust valve is seen in Fig. 686. A cam e on the
shaft Q lifts the lever T, pivoted at U, and, through rod V, the
‘crocodile jaw’ W ; thus raising the valve against the springs aa.
W has a shifting fulcrum at X, giving a larger leverage at ﬁrst, and
a quicker opening afterward.
Fig. 684 shows the indicator diagram obtained, which still
further illustrates the Otto cycle. One difference in the Simplex
working is noticeable; the mixture is over-compressed, that is,
a small return motion is made, after leaving the dead point,
before ignition occurs, and the force of the explosion only reaches
the crank when it is in a better position,_viz., at 15° from dead
centre.
For the best economy, gas engines should work with ‘poor
gas,’ as produced by the Dowson plant in England, and the
Buire-Lencauchez in France: the latter is used in conjunction
with the Simplex Engine. Rich lighting gas is expensive for
large engines.
Petroleum or Oil Engines, like gas engines, are of the
internal combustion type. Petroleum occurs naturally in Russia
and America, but is also obtained as parafﬁn by shale distillation.
It is highly complex, consisting of several liquid hydrocarbons
having different boiling points: thus, when heated, giving off
ﬁrst the lighter oils, then the burning and lubricating oils, and
lastly parafﬁn wax or Vaseline, leaving a residuum. The light
oils, including benzoline and naphtha, are dangerous, ﬂashing at
73° F. ; while the heavy or lighting oils, like kerosene, are
thoroughly safe, resisting the ﬂame of a match, or even the
electric spark. But the heavy oils are difﬁcult to prepare for
the motor, where they are to be intimately mixed with air to
form the charge: if vaporised at low temperature, a troublesome
residue is formed, while gaseﬁcation at high temperature produces
also tar.
In 1888 Messrs. Priestman Bros. acquired the'Eteve patents
(where spraying with air and evaporating in a hot chamber was
ﬁrst proposed), and after considerable experiment produced the
ﬁrst practically successful engine working with safe oil, doing for
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Priestman’s Petroleum Engine. 707
Oil what Otto had done for Gas. While some air was required
for spraying, a further quantity was introduced to complete the
explosive charge, and the mixture then ﬁred, the combustion
being chemically identical with that in the gas engine or boiler
ﬂue. To prevent gaseﬁcation, the hot chamber was kept at
saturation temperature, and the engine cycle was that of Beau de
Rochas, now adopted in all oil engines. .
Figs. 689 to 692 show the present form of Priestman’s engine,
Figs. 689 and 690 being side and end views respectively. A is
the cylinder; B a jacket, through which water is circulated,
entering at U and discharging at v; and X an escape cock,
removable for insertion of an indicator. C is the plunger piston,
D the connecting rod, E the crank, F the ﬂy wheel, and P the
the driving pulley. The main frame G has cast with it the
bearings HH and drip cups K K, the oil tank J, and the air
passage V, from air pump to oil surface. The air pump L,
supplying pressure air for urging forward and spraying the oil,
has an adjustable suction valve, and a lubricator Y. The pump
rod M travels at half the speed of the connecting rod (due to gear
at 14), its prolongation Q opening the exhaust valve s1. A gauge
4 shows air pressure, which is regulated by relief valve 9. The
igniter z is an Edison—Lalande battery, capable of working four
months without attention, the current being intensiﬁed by an
induction coil; and while one pair of primary wires is connected
to terminals 10, and pass through porcelain insulators to platinum
points within the cylinder, the other pair couple to a brass
spring 11, and the circuit closes when the knob N makes Contact
with 11, ﬁring the charge. N o diﬂiculty occurs, as in the Lenoir
engine, from carbon deposit or watery vapour. h is the spray—
maker, and a the vaporiser, the latter kept at constant temperature
by the exhaust gases, which escape by pipe T, and chamber b, to
the outlet t. Lamps 3 3 and hand-pump w are both for starting
purposes, while 8, 7, 6, and 2 are oil or air pipes. Gauge 2 shows
oil level in tank, and the governor it acts on the oil-admission
plug. .
Fig. 691 is a vertical section of the cylinder, showing R the
inlet valve, and s the exhaust valve; the former opened auto-
matically by piston suction, and the latter by lever s1, struck by
708 Spraying and V aporising the Oil.
rod Q. The charge is prepared in the vaporiser a, shown in
horizontal section at Fig. 692, and afterwards drawn by inlet
pipe a’ through valve R: the exhaust gases pass by e to the
chamber b. The spraying nozzle n, shown to larger scale at n,,
consists of an oil passage p, and a re-entrant cap 9, forming an air
passage. Air and oil being ejected at equal pressure, meet at
the mouthpiece, and are there converted into a vaporous spray
ﬁlling the chamber a. The oil pipe r is seen in elevation at 7,
and the spraying air enters by pipe 8. The auxiliary air for
completing the charge is induced by the suction through valve k
(being there ﬁltered through cotton wool) and along pipe h to
annular chamber j; whence it passes to the vaporiser ; and a
shutter l may be adjusted by hand, or closed when standing.
Regulation of oil and air is effected by the action on plug j of
the governor u, whose vertical spindle is connected to the lever m,
depressing the latter when the balls rise. The oil hole is seen,
at j,, to be pear-shaped, closing or opening towards the pointed
end, never being entirely shut, and full open when the engine is
at rest. The throttle valve g, on plug spindle, tends to close
simultaneously with the oil hole, and thus the air and oil pro-
portions are always correct.
The difﬁculty of starting is simply overcome. A little pressure
from pump w forces oil and air, by two pipes at 2, to the lamps
3, 3, the six-way cock x being turned leftward (see The
lamps are then lit, and the vaporiser made somewhat hotter than
usual. Moving x to shut, the ﬂy-wheel must be turned till the
circuit closes at N, and the crank takes the dotted position; and
the relief valve 9 being screwed down, a pressure of about 25 lbs.
is produced by the hand pump w, occupying about 10 minutes.
Cock x is next opened to spray-maker, and the sprayed oil enters
the vaporiser for 10 or 15 seconds. Lastly, cock 5 being turned
on, a quantity of compressed air passes through 6 to complete the
charge, which, now having a high pressure, opens the inlet valve
R and ignites, the crank rotating till the next impulse, produced
automatically.
Oil supply in J is sufﬁcient for some 12 hours’ run, but may
be easily replenished by pump w or by gravitation, the suction
pipe being coupled to 12, while an air pipe from 13 to the
Other O‘il Engines. ‘ 709
external oil-tank serves to equalise the pressures. Lubrication is
effected in the usual manner, at all parts of the engine except the
cylinder; the oil condensed within which is ample for the
purpose.
Several forms of oil engines are now made by other ﬁrms, but
none spray the oil. In some, liquid oil is evaporated in a hot
chamber, forming vapour and gas, which is mixed with air and
ﬁred as usual; and it is said no deposit occurs in ordinary
working. In others, perfect oil-gas is produced, and then ex-
ploded with air, but the engine must be often cleaned from tarry
matter.
CHAPTER XI.
HYDRAULICS AND HYDRAULIC MACHINES.
Fluids are deﬁned by their negative property of non-resist‘
ance to change of shape, and may be highly compressible, as
gases 3 or very slightly compressible, as liquids. Hydraulics
treats of the ﬂow of water in pipes and canals, and with that
liquid—assumed incompressible—we shall only here concern
ourselves.* .
Head, Pressure, and Velocity Energy. The atmo-
spheric pressure supporting 30 ins. of mercury, the water
barometer has a height of 34 ft. 3 thus a ‘head’ of 34ft. balances
a pressure of 147 lbs. per sq. in., and

H = 2'31).
A vertical gauge tube C, Fig. 693, being inserted in a pipe B,
water rises in c to a height proportioned to the pressure; then,
connecting head and pressure,
PA = GHA
P = CH and H =
QI’V
where P = supporting pressure in lbs. per sq. ft. 3 H = height of
column, and A its area 3 and G = weight of a cubic ft. of water.
The latter varies from 624 at 39° F. to 598 at 212° F. for fresh
water, but is usually taken at 62.}- lbs. 3 and 64 lbs. for sea
water. '
* For numbers regarding compressibility of water, see pp. 363-4.
Head, Pressure, and Velocity Energy. 711
To connect head and velocity .- a water particle of weight w,
while at A, Fig. 694, has a potential energy wH, and when fallen
2
to B a kinetic energy of 33-. Neglecting losses,
wv2
2.?
and v = A/2gH = 8 JE nearly.
wH=
When water ﬂows steadily between reservoirs kept at constant
level, any portion of water will, neglecting friction and viscosity,
be in possession of an unvarying amount of energy, which may
be due to head, pressure, velocity, or all three. In Fig. 695, a
pressure column A falls short of level C, a portion of the head
energy having become kinetic; and the total head 3B consists
P v2
of H due to unexpended fall, a due to pressure, and —— due to
2g _
velocity. Multiplying each by w gives respective energy, and the
energy in one lb. of water
2
1g = H + E + g—
G 2g
An interesting experiment, due to Froude, is given in Fig. 696.
Two tanks, A and B, have discharge pipes C and D, the former
throttled at E, and the latter expanded at F, causing the velocity
energy to become respectively greater or less than at the tank
mouth, as shown by pressure columns. Further, the horizontal
pressures at E and at F exactly balance, and there is no tendency
to move the pipe.
The Jet Pump.—With suﬂicient throttling, the pressure
may be reduced below that of the atmosphere, the principle
employed in Prof. Jas. Thomson’s jet pump, Fig. 697. Water,
under a good head, enters pipe D, and passing through the nozzle
at a high velocity, produces a partial vacuum around it. More \
water entering at A to ﬁll the gap, the combined streams dis-
charge at B, and thus a ﬁeld may be drained or other work
performed.
' Discharge of Water from Oriﬁces._-A tank being
emptied through an oriﬁce near its bottom, the volume of water
712 Discharge of Water from Orzﬁces .'
passing is the product of water velocity (v) and oriﬁce area (A).
Neglecting resistances,
Theoretical discharge in cub. ft. per sec. Q = Av = 8 A Jﬁ
But on account of resistances v is less than 8 .JH in practice,
so, introducing a coqﬁcient of velocity c (about '97),
v = aa./H ........ ........................ ..(1)
Or, suppose the reduced velocity has been caused by a loss of
head Hr, a coejicient of resistance p (about '0628) may be adopted,
measured in terms of the remaining head H1. _

LetHr=pH1. _
ThenH=H,+Hr=H,+pH,=(1+p)H1
And, v = 8J5, = s\/ H ................... .. (2)
Equating the two values, (1) and ( 2) :—
2t/'H=x/H
1+p
_. I I
= /\/ a.’ p =
I+p

The above losses all occur within the vessel and oriﬁce: a
further loss is caused on account of the diminution of jet area by
contraction, at a distance beyond the oriﬁce of half the jet
diameter. Taking the coeﬁicient of contraction x (about '64),
let real area = KAI then,
'Actual discharge in cub. ft. per sec. Q, = Ev x KA
82' ICA. N/I—T
Or, from (2) = 8\/ H ,CA .
1 + p
For simplicity one multiplier may be adopted, the coeﬁicient-of
discharge C, equal to Z x 1: (about '97 x '64 = '62), and then
Qa :
All the coefficients are determined experimentally, E by
measuring the parabolic form of the jet, it by set screws as at A


and Coeﬁicients for ditto. 7 I 3
(Fig. 698), and c by gauging actual discharge. Fig. 698 shows
at A a sharp-edged, at B a re-entrant, at c a cylindrical and
external, and at E a bell-mouthed oriﬁce. At B the contraction



-___
C 0N5 TR N T \\\‘
- 1th.“
-__-._-_.

. __ , 0
- ____ _- __ will 62:9 2A_
7.



l
COMB/NED .5‘ TRe'A Ms

Jet P/LLD’Z/i
is greatest by reason of the abrupt deviation of the stream lines;
at c there is contraction within the oriﬁce; and at E no free
construction, so that C = 5.
714 Gauge N otches.
TABLE oF CoEFFICIENTs (average value).




oriﬁce is its: air... militia
2 '97 I '8’ '99
_p ‘0628 0 '5 '02
1c '64 ‘53 I I
c '62 -53 '82 '99

Measurement of Stream Horse-Power by Gauge
Notches.—Let a stream be partly dammed, the water ﬂowing
through the rectangular notch, a h c d, Fig. 699. To ﬁnd the
discharge, divide H into very small portions h, and treat every
small-rectangle as a separate oriﬁce, whose area will, when h_is
inﬁnitely small, be shown by B. At any depth H1, v = 8 N/H1,
and discharge through small rectangle = 8 B Showing the
various discharges by horizontal lines on base e f; the ﬁgure is a
parabola (the lines or ,J H1), whose base is 8 B Then
whole notch, in _ parabola _
cub. ft. per sec.
. Theoretical f __
Discharge through } Q _ area 0 _ ggB J'ITX H : SEQiHB N/H
Actual discharge Q,L = 5%; C H B ,,/H
where C, the co-efﬁcient of discharge
= '57 + {breadth of notch —:- (10 x breadth of weir)}
Prof. James Thomson adopted the triangular notch A, where
B/H is constant throughout, suspecting that C would be thereby
regular; and he found that Q or Taking an apex angle
of 90°,
Qa per sec. = 2'54 C Jw
where C = ‘617. Finally, for any notch,
height of
fall in
feet.

Horse Power _ foot pounds per sec. x 60 _ Q G
of Stream } _ 33,000 — 550 X

available %
Fluid Friction. 7 1 5
The stream velocity is found by a current meter, and the
head H by a stake, placed in still water above the notch.



Fluid Friction. -The general laws, p. 557, state that
F,,0c v2, and is independent of pressure, but depends directly on
the wetted surface. Measuring area A in square feet,
Fn = IuAYJQ
at moderate speeds, where ‘u = '004 for clean varnished surfaces,
and '009 for a medium sand-paper texture (Froude).
Friction in Pipes is principally due to surface or skin
friction, viscous resistance being extremely slight. Assuming
G = 2g approximately,
2
Total Fn = ,. GA 3-
as’
Supposing, now, a piece of water of length L and diameter D
of the pipe, is being pushed through the latter at velocity v .-
2 2
Fnpersq. ft. of} : HG WPL ‘ f_’_ : G4JuL._z_/_
sectional area vrD"—Z- 4 2g 1) 2g
- .f.
AS H : Press per sq t
(I , we divide by G, and obtain
v2.
. L
Head lost in friction = 4 ‘u T).
28'

7 16 Virtual S lope.
Experiments on pipes give ‘u = .'007 5; and it is more correct,
when calculating, to take L a few feet at a time.
Virtual Slope.——Water being discharged from reservoir A,
Fig. 700, by pipe B c, with a constant velocity energy, the nett
head may be shown at any place -by pressure gauges, D, E, F, and
G; and in any particular gauge F there is evidence of a loss H
due to friction. This varying as L, a straight line J G bounds the
the water columns, and is called the line of virtual slope or
.hydraulic gradient. Suppose the pipe be laid along B K, pressure
head would be constant, which is as though the pipe were level,
but frictionless; but however B G be laid, J G is inalterable, only
deviating with change in pipe diameter. After crossing the line
at G, the pressure within the pipe is less than atmospheric, and
the water tends to separate, the tendency becoming a certainty
at C.





Loss by Eddies and Shock—Water poured into a basin,
as at A, Fig. 701, delivers all its energy as shock ; but wherever a
sudden change of velocity occurs, eddies are formed which absorb
energy. Pipe B, suddenly enlarging, decreases the water velocity,
Loss by Shock. 7 17
forming eddies at the corners, and the relative velocity being
v -v
1 2’ Loss in foot pounds I _ 10(1), - 112)2
per second j 2 g
where w = weight of water passing per second.
__ 2
Loss of head = (Bl—5:2)—
b
At 0 the water velocity is increased, but the loss is about as
before. There is a very small loss from contraction at d, but the
loss by changing the velocity from v3 to v2 must be reckoned.
Any sudden deviation as at D causes loss of energy, probably
by eddies. Adopting the formula,
Loss of head = CZ—Zr
6
experimental values of the coefﬁcient Z may be inserted :

O 0 O O O O O O O O
6= 20 40 60 8o 90 100 110 120 130 140


C = ‘046 ‘139 ‘364 ‘74 ‘984 1'26 1‘556 1‘861 2‘158 2'431

When possible, bends should continually deviate in the same
direction : thus case E is worse than at F, for in the former there
is full loss from both bends, while at F, though there is full loss .
from the ﬁrst, there is very little from the second bend. With
gradual curvature there is little loss besides skin friction. -
Principle of Momentum.—At p. 473 it was stated that
force causing momentum was equal to Z-f—f. In another form
<5
wv
Pl. __= _ O , Impulse _ Momentum for}, = I;
g r exerted _ generated
If t = one second, and w = weight of water passing per second,
wv
= change of momentum, and P = -a— = change of momentum,
2‘!
g 0
a formula we shall now apply to the pressure on Wheel vanes.
Case L—To ﬁnd the pressure due to water jet on a ﬁxed
plate A, Fig. 702. Measuring v in jet direction, it = 0 at the
plate. Then, 20,, (GAZM,
Pressure on plate = 7 = -———-
0‘
<5
7 18 Pressure on Plates and Cups.
Case ]].—-Let the plate move in direction of jet, as at B.
Weight of water per sec. = GA(v1 — v2). - '
‘Pressure on _ Momentum before } __ Momentum after
plane _ impact impact
1
__ GA(v1 —- v2)v1 __ CrA(v1 — v_.,)v2 _ GA<711 — v2)2
0‘
<5 <5 <5
P
Case [TT.—The reaction wheel C is only different from the
last case in that the plate pushes the water and the plate pressure
is caused by reaction. Ships driven by water reaction, like the
Waterwitch, are also similarly calculated, and the best conditions
occur when v2 = v1.
H T -
D
31+ i ->
'14
case .1’. case-m


B
Q’
34* 3%
CASE 1!‘. __ f


Case [K—A moving hemispherical cup. Relative velocity of
jet and ﬂoat when meeting is v1 — v2 (forward), and when leaving
is v1 — v2 (backward) 3 so absolute discharge velocity is wheel
velocity minus relative backward velocity = v2 —— (v1 — v2).
Absolute velocity of jet before impact = v,L
,, ,, ,, after ,, = v2 — (v1 - v2) = 2 v2 — v1
Weight of water per second = GA(v1 -— v2)
P = difference of momentum
= M _ GAta—n) <2 ir.—e.) _
0'
0 g

2 5; A(v1 —- v2)2.
b .
If v2 = ~}v1, absolute velocity of rejection is zero, and all the
jet energy is expended on the cups.
Best Form of Vane. 719
Case V.—-The wheel E has a large number of vanes such as B.
Then- a plane is constantly before the jet, and relative velocity
is v,.
Weight of water per sec.
= GAv1
Momentum before impact = ._(GA31)711
b
3; after 7, = g
'- P = difference = Egg—Irv?)
8
giving the general rule : pressure on radial ﬂoats of water
. W _ 7).
wheel = weight 0f ‘water per 355, X (La—Pl
Case VT. (F, Fig. 702), is a similar modiﬁcation of 'Case IV.
Relative velocity before impact = v1, and
Weight of water per sec.
= GAv1
. GAv 2
Momentum before Impact = i71-
b
GAv 2 v. — v
,, after ,, -_- _.__1_(_2_1)
g
_. P : GAv1(v1—2v2+v) ____ 2 GAv1(v1—v2)
0
<5 6
g.ving twice the advantage of a ﬂat plate.
Best form of Vane.-—A B, Fig. 703, is the ﬂoat of an
undershot water wheel, receiving the impact of a thin stream D.
W’
is
Q“
\


k 0 ‘ '
\ /
7
////An. 0
‘5s
‘_
Fig; .203
"‘
‘\
Drawing v,- the velocity of water jet, and vf that of the ﬂoat
tangentially, the completion of the parallelogram gives v,. the
relative velocity, in magnitude and direction, to which the ﬂoat
720 Water Wheels.
should be made tangential. This form of vane is due to
Poncelet, and the action is essentially as at F, Fig. 702.
Water Wheels—the earliest forms of water motor—consist
of (1) those rotated by water falling down the rim, known as
weight machines; (2) those actuated by water impact on their
lower ﬂoats, and called impulse machines. Overshot and breast
wheels belong to the former, and undershot wheels to the
latter class.
The Overshot Wheel, Fig. 704, is suitable for falls of 10 ft. to °
70 ft., with a discharge of 3_to 25 cub. ft. per sec. A is the
supply, B the tail race, and C the regulating sluice. Fairbairn -
improved this motor by driving, from teeth upon the rim, a
pinion D so placed as to receive nearly all the weight of the
driving water. Previously all the power had been transmitted
through the axle. The efﬁciency of the machine is about '7 5.
Taking Q as discharge per second,
GQH x 60
—'——'_‘''"—7
33,000
H. P. =
and the water velocity will be slightly greater than that of
wheel rim. »
The Breast Wheel, Fig. 705, is there shown in its greatly
improved state, as due to Fairbairn. The breast A B, lying within
5" of the wheel, keeps the water in the buckets through a greater
distance than in the overshot wheel, permitting its escape into
the tail race with but little velocity. The regulating sluice is'
adjusted by a governor, and the penstock c is provided with
guide blades to direct the motion of the entering water. The
buckets are ‘ventilated,’ that is, are partly open to the wheel
interior, thus permitting air to pass out or in whenever the water
enters or leaves respectively.
The Governor, Fig. 706, is of the Watt type, but the move—
ments of the sleeve A merely direct instead of actually causing
the movements of the sluice. Spindle B, hollow in its lower
portion, carries loosely the mitre wheels 0 and D, each gearing
with wheel E on the sluice shaft. When the balls rise, sleeve A
lifts by rod H the clutch F; and 0 being thus put in gear, the
, shaft G is rotated to 'close the sluice. If, conversely, speed
Water-wheel Governor. 72 I
decreases, the balls fall and put D in gear, thus turning G oppo-
sitely, and partly opening the sluice. The governor is driven
from the water-wheel by a belt.



(linens/710,6 W/weL.
Fig. 704.




Fig" . 706.



The Undershot Wheel is shown in Fig. 707. The form of
ﬂoat has been drawn at Fig. 703, and there only remains to add
that. with Poncelet’s improvements in ﬂoats and race, the water
O
2 A
722 The Pelton Wheel.
leaves the wheel with little absolute velocity, and the efﬁciency
is about '66, a great improvement over that of the old radial-ﬂoat
wheel, which was only '3. As the water never ﬁlls the vanes,
there is no pressure, but pure impulse only, and the efficiency is
therefore constant under varying sluices. Horse-power may be
reckoned from head or velocity (see pp. 719 and 720). The
circumferential velocity is about '55 of that due to head, and the
jet thickness is about 8 or 10 ins. The wheel is suitable for falls
up to 6 feet, and the diameter may be four times the fall.
/ -"
A477‘); /
\ ’ I
\3‘ I’ ‘ ' '
\' ‘



.S‘£cr/0/v or cup

P/elbon/ W/heaL.

The Pelton Wheel, Fig. 708, is an American machine, in which
a small jet issues from a nozzle A3 with great head, and impinges
on a series of cups BB, of the form of a split semicircle in end
elevation C, and simply cup-form in side elevation D. In this
way the jet, about 51" diameter, is split, and returned without
serious shock. In one example 320 H. P. was given off from a
fall of 523 ft., the nozzles being one inch diameter. The efﬁciency
is commonly '8.
The Fourneyron Turbine. 72 3
Turbines, formerly including only horizontal types, is the
term now applied to all water wheels in which a relative move-
ment of the water to the wheel causes reaction. The Reaction
wheel, Fig. 709, is the earliest form, being a turbine without
guide blades. The casing A, or wheel proper, has tangential
nozzles BBB, through which the water leaves, entering at C; its
reaction on A thereby producing motion. If the best velocity,
that due to head, be employed, an efﬁciency of '6 is attainable;
but otherwise there is considerable waste of energy. This fact
led to the introduction of guide blades and curved vanes, and the
invention of the true turbine.



ﬂan/(ens mu. , 0!? Score” rune/~11


fig 709
The Fourneyron Turbine, Fig. 710, is an outward~ﬂow and"I
also a pressure turbine, the wheel passages being kept full. A, the
wheel, is keyed to shaft B to transmit the power, and the water:
ﬂowing downward from C is so deviated by ﬁxed guide blades DD,.
that it enters the wheel nearly at a tangent. The wheel vanes are
so curved that the ﬂow is then changed to a radial direction, the:
724 fonval and Girard Turbines.
water leaving with little absolute tangential velocity, having given
some 70 or 80 X, of its energy to the wheel. Regulation by
throttling always reducing the efﬁciency considerably, the wheel
is divided by horizontal plates at G, so that in the drawing there
are three separate turbines which can be shut oﬁ’ in succession by
lowering the hollow cylinder F. Oil is supplied to the footstep
J through a pipe, but immersed footsteps are now superseded.
Horse-power may be found either by head or impulse formulae.
The fonval Turbine, like the Fourneyron, is a pressure turbine;
but while the latter works best above tail water, the Jonval is
always drowned or else connected to tail water by a ‘suction ’
tube not more than 30 ft. high, and therefore full of water. Thus
a certain head may be saved, which might be lost, through com—
pulsory position of the turbine. Fig. 711 is a vertical section,
where A is the wheel, B the guide blades, and o the shaft; and
the water ﬂowing parallel to the shaft gives the title ‘parallel
ﬂow’ to this class of turbine. Regulation, formerly effected by
throttling, is now preferably obtained by closing a number of guide
passages, preserving complete admission for the remainder. In
the ﬁgure the guide passages form concentric semicircles G G in
plan, and are so bent in elevation as to meet the wheel passages
AA, which form a complete circle in plan. This arrangement
provides retiring room for the sluices F F.
The Girard Turbine was introduced to provide against the
loss of efﬁciency which always occurs when pressure turbines
work with fractional supply. This fault being due to the
attempted driving with a pressure for which they were not
designed, Girard widened his wheel passages towards the outlet,
.and ventilated them so as never to entirely ﬁll them with water.
The energy is then purely clue to velocity, and the turbine is
an impulse machine; it has also a parallel ﬂow and complete
admission to whatever guide passages are open. In Fig. 712,
AA are the guide blades and B the wheel. The latter is keyed
to the hollow shaft P F, which, continued upward, joins the
solid shaft G and transmits the power. The whole is hung on a
pivot bearing J carried on the ﬁxed pillar H, and the-same
arrangement appears in Fig. 711. The guide passages may be
closed by vertical shutters K K, whose rods are coupled to rollers
/
A
| 'i"
|
“Hill II
| I’II
Pl” I!
.I‘.
l:
R

r ‘\
ll! 6
E3,
l i .
i
|||
iimii
illl|il
I
lllil
611105 81-4058
0
E


‘33
///.' i







N =
.7-1. r
I 'Tlltimnmunun J
— L
“‘ _-_
____._ 0
li ' T. J
j!
I'll
726 T homson’s T urhine.
L L lying in the groove M M 3 and as the ring Q is revolved, by
hand or governor, through gear N, the shutters are completely
raised or lowered, according to direction of rotation.
In Fig. 713 the actual path of the water is shown in a _Ionval
turbine at A, and in a Girard turbine at B, a h being free path and
velocity due to guide blades, and b c the wheel velocity; a c is the
relative velocity, and shows actual path in general direction.
Making cd = h c, a d will be the line of wheel vane causing
curved water path a c, the horizontal ordinates of curvature on a d
and a c being equal.





V
b —-><:
are.’


fig. 714.

Fig. 714 is a diagram showing comparative efﬁciencies under
varying openings. Although the Girard is usually less efﬁcient
than pressure turbines with full sluice, its efﬁciency is unimpaired
by fractional opening.
Thomson’s Turbine, Fig. 715.—-—Here the supply water A enters
the rim of the wheel B, and escapes axially into C the tail race, so
the machine is called an inward-ﬂow turbine. Its energy is
largely due to pressure, the outlet being either drowned or
connected with a suction pipe. Referring to the plan, the guide
blades D D are pivoted at E E, and can be moved in or out by the
levers and links F F. Then the vertical shafts at F F are all
connected, and rotated, through worm gear, by the hand wheel G3
thus more or less water may be admitted to the wheel. Although
the gear is complicated, its action is very perfect, the supply being
regulated without materially affecting angle of blades or other
conditions, and a nearly maximum efﬁciency of 7 5% obtained for
all openings. The wheel is shown in detail at H.

Classiﬁcation of Turbines.

Turbines may be ﬁnally classiﬁed as follows :—
PREssURE OR REACTION
TURBINEs.
Wheel passages ﬁlled.
Energy largely due to pressure.
Discharge usually below tail water,
or into suction pipe.
_ Parallel or axial ....... .. (Jonval).
a. Outward .......... .. (F ourneyron).
_9_ Inward ............. .. (Thomson).
‘11
Mixed, inward and parallel
(Schiele).
IMPULsE TURBINEs: 0R, TURBINES
OF FREE DEVIATION.
\Vheel passages never ﬁlled.
Energy entirely due to velocity.
Discharge above tail water.
No suction pipe.
Parallel or axial ............. .. (Girard).
728 The Centrifugal Pump.
As the water has no forward momentum on leaving the wheel,
each pound suffers a change of momentum 3;, where v is the
forward component of the entering velocity. b
Forward pressure on wheel due to } _ 2
each pound of water per sec. g
Multiplying by v1 the velocity of wheel rim: Useful work
per lb. of water = 221 foot pounds per second. Now the energy
given per pound of viiater is H foot pounds, of which 1; H is given
to the wheel ;
‘. 1) H = 2?}
<5
the fundamental equation for turbines. The object also of
curving the guide blades is to give a large forward velocity to the
water; and the wheel blades are so curved as to reduce that
velocity to zero, thus giving all possible energy to the. wheel.
The Centrifugal Pump is simply a reversed turbine, for,
while water enters the wheel eye without whirl, it receives con-
siderable tangential velocity by the time it reaches the wheel
rim. The pressure thus given to the water being found from
momentum, increase of head is obtained ; then, from the previous
paragraph, taking v = tangential component of water velocity
when leaving, and v, the peripheral velocity of wheel
new},
8
where q is about '7. Fig. 716 gives the sections of a pump to lift
16 ft., with a pipe velocity of 7 ft. per sec. The water path from
eye to circumference is that of a free vortex, the form being a
logarithmic spiral, and the direction of wheel rotation is shown by
the arrow. The casing B is a volute-shaped pipe of increasing
diameter towards outlet, to accommodate itself to quantity of
water passing, D D are hand holes, and cover E is removable so
that the wheel may be withdrawn when required. F is a small
‘ whirlpool chamber’ to let the change from velocity to pressure
energy be made with little shock. In starting, sluice c is closed
and air exhausted by a steam jet through ejector G, when water
The Impulse Ram. 729
rises; the sluice is then slowly opened while the shaft is being
rotated, and pumping becomes continuous.







The Hydraulic Impulse Ram, invented by Montgolﬁer,
enables a large ﬂow of water with small head to lift a smaller
quantity against greater head; and is commonly used to provide
7 3O Suction and Force Pumps.
water supply from a low stream to a house on a hill. In Fig. 717
valve A is slightly heavier than the static pressure of the stream
water, which enables the latter to pass through and acquire
velocity. This rush closes A and the impact is received on B,
which opens, allowing a portion of the liquid to pass. The
water at C again endeavouring to come to rest, A opens, and the
action is repeated. The air vessel D promotes steadiness of ﬂow.
Piston Pumps.—The Suction or Lifting Pump, Fig. 718,
is placed at not more than 30 ft. above supply water. Piston A
carries a delivery valve, and C is a suction or foot valve, both
opening upward. Then the machine is at ﬁrst an air pump

SUCTION
procuring a partial vacuum within E, which at once ﬁlls with
water from D. When high enough, water is simply lifted from
E to F, and ﬂows away. The resistance to upward motion‘is due
to a column of water of height H, and base equal to piston area.
The Force Pump, Fig. 719, is adopted for greater heads, only
a small portion of the work depending on vacuum formation.
When plunger A is raised, water enters through the suction valve
B, and on A’s descent this water is forced through the delivery
valve C, the lift depending on pressure exerted. Air in the vessel
D is compressed during delivery, and acts as a spring to continue
the ﬂow, while the plunger is occupied on the suction stroke.
Cock E is used to re-charge with air when the latter is absorbed
by the water. A douhle-acting force pump has one delivery and
The Worthington Pump. 7 3 I
one suction valve to each end of the cylinder,* and the plunger
becomes a piston.
All the preceding may be driven by steam power. The oldest
steam pump yet in use is the Cornish engine A, Fig. 726. Its
pumps are of the lift type, arranged in relays with less than 30 ft.
between each pair, and the water is lifted from tank to tank till it
reaches the surface. Two forms of ‘ donkey pump ’ are also
shown at 4, Fig. 447, and 1, Fig. 448, pp. 486 and 488, where the
engine valves are operated from a crank shaft. There is, how-
ever, another class of pump which dispenses with the crank, being
therefore called ‘ direct-acting,’ and probably the best of this class
‘are those that necessarily work in pairs, being termed ‘ duplex.’
The Worthington Pump is a duplex steam pump, its ordinary
form being shown in Figs. 720 and 720a. Two steam cylinders
side by side at A, have pistons connected directly to two pump
plungers at B. When a D valve is employed for an engine
working without expansion, the valve and piston strokes cross
mutually at half phase, and the piston cannot then directly
actuate the valve. In this pump, piston No. 1 works valve No. 2,
and piston No. 2 moves valve N o. I, by lever gear, the motion of
the two pistons being alternate ; thus, levers L and M rock valve-
levers l and m respectively. The valves and pistons are, however,
so interdependent, that immediately steam enters either cylinder,
the action of the engine commences as a whole, and will continue
unless special friction difﬁculties intervene. To enable each
piston stroke to be completed before the valve reopens to steam,
the exhaust ports (2 C are separate from the steam ports D D;
a quantity of steam is thus also imprisoned as a cushion. In the
pump, E E1 are the suction, and F F1 the respective delivery valves,
small and numerous, to give suﬂicient area while diminishing the
closing blow. The arrangement, also, enables the pump to both
draw and deliver at every stroke, and the contrivance is double-
acting; in addition, the air vessel J equalises the ﬂow, and the
water leaves at K.
The expansive use of steam has been provided for in the
Worthington high-duty engine, Fig. 721. The engines are a pair
of tandem-compounds, where A is the high-pressure, and B the
* Except in the case of the accumulator pump, Fig. 722.
7 32 Accumulator Pump.
low—pressure cylinder ; and each engine works its neighbour’s-
valves. Thus the lever c of the opposite engine moves the rods
D and T, from which a system of link work connects to Corlissv
valves, the fulcra above and below the cylinders being used re--
spectively for the exhaust valves F F, and steam valves E E. After
use in both cylinders, the steam exhausts into the condenser G,
from which the water and vapour is withdrawn by the air pump H,
and ‘delivered into the hot-well s. The pump itself needs no-
description, but special attention must be drawn to the means
by which the driving force is so equalised as to be nearly uniform
when delivered to .the plungers. Compensating cylinders L L, or
‘ pots,’ rocking on pipe trunnions, contain water under a steady
pressure of about 200 lbs. per sq. in., and have plungers pivoted to»
the pump rod. This pressure constitutes a resistance to the steam
pressure during the ﬁrst part, and an assistance during the second
part of the stroke, much in the same manner as the inertia of the
reciprocating parts, and the effect on the work diagram is shown
at M. a and b are the indicator cards ; c and a’ show the pressure
exerted by the pot plungers, c assisting, and d opposing the steam
pressure : e is the combined effective-pressure diagrams from both
cylinders; and f is the resultant pressure ‘on the pump-rod after
adding c and deducting d. The pot pressure is kept sensibly con-
stant by the intensiﬁer N, whose larger piston P is under an air
pressure of about 75 lbs. per sq. in. from the air vessel K, due to
the water column ; and the smaller area Q is exerted on the- water
in the pots. The arrangement constitutes a sort of governor, which
controls the pump stroke, shortening it if a pipe happens to burst.
To accurately adjust the pot pressure, some air is admitted under
P by cock R, causing a pressure of about 35 lbs. per sq. in. These
pumps are constructed by Messrs. jas. Simpson & Co.
The Accumulator Pump, Fig. 722, is a double-acting pump,
requiring but one suction and one delivery valve. On account of
the great pressure to be resisted (750 lbs. per sq. in.), an air
vessel is inadmissible. Referring to Fig. 663, in addition to Fig.
722, the piston A has twice the sectional area of rod B; so when
A moves rightward, displacing the whole cylinder volume through
delivery valve D, half returns into B, and half goes to delivery _pzjbe
b. A, returning leftward, draws a whole volume through suction





.daa... ., .,
mesa. wens 98R 0am . i. ill ,, -

swage: as a
// dZ/da/
. Rs \\\NRRRRSP
. I



E:
:5 M .

__L_
_n__




(E QU\Q~<\




7 34 Pump E ﬂiciencies.
valve C, none passing D, while the volume in B, or half, goes to
delivery pipe .~ thus there is constant delivery, though suction only
occurs on alternate strokes. An additional non-return valve E
permits each pump to be worked separately.




. l
r0 AccuMuLnroR FROM RESERVOIR



E X PFINS/ ON
VAL VE

Pump EfﬁcienCie5.—-At Fig. 723 is a diagrammatic state-
ment of the efficiencies of both centrifugal and piston pumps
under different heads, from which it will be seen that the former-
The Pulsometer. 7 3 5
are least efﬁcient under large head, and the latter under low head.
In consequence, centrifugal pumps are only employed for pumping
large volumes of water under small head, while positive pumps
are more suitable for pumping small volumes under great pressure.
The Pulsometer is a pump in which steam acts directly
on the water without the intervention of a piston. It is naturally
wasteful in working, but is simple and quickly applied on emer-
gency. Referring to Fig. 724, there are two side chambers AA
to receive the water alternately, and an intermediate vessel H,
whose purpose will be explained. EE are suction and GG delivery
valves, B a foot valve, N the delivery chamber, connected to A by
short pipes FF, and Q the rising main or delivery pipe. To start
the pump, the three vessels are ﬁlled through the hole C, the
water resting on foot valve B. The ball L being compelled to lie
on one or the other seat at J], Steam is admitted at K, and,
entering, say, the right-hand passage, displaces the water through
F, without agitation, until the level falls to the upper edge of the
oriﬁce. Steam then blows through into F with some violence,
and an instantaneous condensation occurs, causing a partial vacuum
in A. The ball being now drawn to the right-hand seat, water
rises into the right chamber ready for the next stroke, steam
enters the left chamber, and the action is continuously repeated.
The vessel H, though uncharged with air, serves the purpose of
an air-vessel, assisting the steady ﬂow into N by the small head
of water which it provides; and to prevent the sudden shock
caused by the rush of suction water, air-cocks DD are placed on
‘the three vessels, and’ kept open to a very small amount. The
‘ Grel ’ valve at P is often applied to economise the steam supply.
It is simply a short hollow piston, which rises and falls on account
of the difference of pressure within and without it, thus closing
the pipe K after a portion of the stroke has been completed.
The Hydraulic Press may be looked on as the seventh
simple machine (see p. 480), and is the basis of the transmissive
principle. Fig. 725 represents the press, with pump attached, as
used to compress cotton bales. The pump A draws water from
the tank B, and forces it, under pressure, to the ram cylinder C,
a rapid exhaust being obtained through the relief valve E when
required. Let D = diameter of ram, and d that of the pump,
736 Hydraulic Press.
while the pump leverage is L: 1; from the principle of equal
transmission, one pound per sq. inch on the pump plunger is one
pound per sq. inch on the 1am, and
Total Mechanical Advantage
= Mech. Adv. of press and pump x leverage
area of press L D2 L
________._—__.__ X — -:
area of pump 1 d2


Neglecting friction. Taking pump efﬁciency
= '8, and press efﬁciency = '9; both combined = '8 x '9 = '72
D2L __ '72D2L
'.\V=PX—2:z—ﬂ—- d2




A“?
B 1.4
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The ram cylinder should be approximately hemispherical (see
p. 68), and its strength is found at p. 399. The leather collar E is
a most efﬁcient packing,_being distended by the pressure water
and pressed against the ram surface. The hydraulic jack, p. 206,
is simply a miniature press, where G is the ram and D the plunger.
Its efﬁciency is, of course, much higher than that of other jacks.
The Hydraulic Accumulator is probably the most im-
portant adjunct in hydraulic transmission, constituting an arti-
ﬁcial head, where the water pressure is caused by other material
than water. In Fig. 726, a series of weights at c hang from the
Hydraulic Accumulators. 7 3 7
T-head E, and, through ram D, exert pressure on the water within
A B. The weights being raised to position F, are a store of
potential energy, which may be given out at will through the
pipe B. Water is pumped in at A to raise the ram, by an engine
such as that in Figs. 663-5, and the latter is automatically
stopped and started from the accumulator, as required, by the
levers at G and H, struck by the load. The pressure water





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drawn at B may now be applied to the driving of machines doing
intermittent work, such as
Cranes upon dock wharves, &c.
. Boiler-shop and shipyard tools.
Lifts for hotels, &c.
Swing and other movable bridges.
Manipulation of heavy guns.
“sense
In all these cases the pumping-engine will have sufﬁcient time
between shifts to catch .up on the machines, and thus a com-
3B
7 38 Balanced Hydraulic Left.
paratively small engine, working all the time, may serve for very,
heavy work occupying only a short period (see Case 4). It is in
the great storing capacity, and the little loss (skin friction being‘
independent of pressure, and water incompressible) that hydraulic;
transmission is of such immense advantage. The usual large
pressure, 750 lbs. per sq. in., is adopted because the friction is-
then much less in proportion to power transmitted, area of pipe.-
being small. Chapter VII. illustrates hydraulic transmission
applied to Case 2, and the student may now refer to pp. 292—3,.
301-2, 314, 317, 320, and to Plates XV. and XVI., also to-
Case 12, p. 580.
Fig. 727 shows Mr. Tweddell’s Dzf’erential Accumulator,
where great pressure is obtained by considerably decreasing the
ram area; B is the load, and the effective area of ram is A
minus a. Comparing with Fig. 726, it must be understood that,
weights being equal, we lose in time what we gain in pressure, and
thus this machine is specially suitable for small machines, such.
as portable rivetters. The work stored in any accumulator is
wH, wP —:- G, or 2'3 wjﬁ foot pounds.
A Hydraulic Lift, as devised by Mr. Ellington, and known.
as a ‘balanced’ lift, is shown in Fig. 728. A long ram A,.
working in a cylinder C, thereby lifts a cage B, and the load.
consists of (I) the cage, (2) the people or goods, and (3) the
ram weight, the last two being variable. In the older and
dangerous method the average load was balanced by a weight
hung from a cord carried over a pulley, and connected to the top-
of the cage; but here the cage and people are lifted by separate
water columns, while the varying ram weight is supported by a.
head which similarly varies. The variation in ram weight is due
to the ram’s varying immersion, the upward support from the
water (apart from artiﬁcial pressure) being equal to the weight of '
ﬂuid displaced. Referring to Fig. 728, the pressure from the
main is led 'to the cylinders D and E. Upon piston F is a constant
pressure, through L, supporting weight of cage + ram when down ,-
and on piston G, through K, pressure water is admitted when
required, supporting the people + friction, viz., the nett load.
Both these pressures are used to intensify the water in M, which





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PRESSURE
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Ellogql'onis Bxx/Larcceci Hydﬁcuclic 119'. 728.
740 I ntensiﬁers.
is directly connected to the ram, and on account of such intensi-
ﬁcation the ram diameter can be as small as we please, merely
strong enough to prevent its bending. The volume in M being
just sufﬁcient to ﬁll the ram cylinder during full stroke, the pistons
F and G fall to the ‘bottom of their cylinders, due not only to
pressure from main, but to a constantly increasing weight of water.
It is this weight, due to water, ﬁlling nearly the cylinders D and E,
which, bearing on pistons F and G, so intensiﬁes the pressure in M,
.as to support the whole unimmersed ram weight ; being clearly a
maximum when the cage is fully raised, and nothing when the
cage is lowered to the bottom. The varying ram weight is, there-
fore, correctly balanced in all positions, and the only load to be
averaged is that of the people. When lowering, water is exhausted
from N, and the descent caused by the weight of the people.
The cord P, passing round a pulley on the working valve Q,
will open the latter to pressure p, or exhaust e, in any position of
cage. If the water in M decrease through leakage, the cage is
lowered to the bottom, and water at N exhausted : then pressure
water being admitted at R, the pistons are forced upward, com-
pelling some water to pass from above to below piston F, through
its packing ; at other times R is empty.
Intensiﬁers, or intensifying accumulators, are a means of
transforming small pressure, as from a town main, into a really
useful hydraulic pressure. Recent descriptions will explain the
principle, and a good example will be found at Fig. 3 3 3, p. 37 5.
Hydraulic Cranes have many advantages over others.
Being worked intermittently, a small pumping engine will store
the power: the latter, again, being used with considerable rapidity
.and saving of time, a consideration when loading vessels at wharves.
The lifting, too, being done without vibration or noise, makes
these cranes of special use in raising foundry boxes and other
like work. The cranes are also very simple.
Fig. 729 shows a cylinder, ram, and pulleys, the essential
apparatus for each motion of a hydraulic crane. Cylinder A has
a common stufﬁng box 0, packed with hemp, and carries a number
of ‘ﬁxed’ pulleys, D1D2 D3, the ram P supporting an equal
number of ‘movable’ pulleys 121112133. To prevent the ram
turning on its axis, the head F slides on guides G G, and the
Hydraulic Cranes. 741
whole apparatus is ﬁxed to the crane by feet J J. A wire rope orv
chain being attached to the eyebolt K, and carried round the
pulleys E1D1E2 D2 E3, leaves D3, by W, to the load or slewing
wheel, as desired. Examining by the pulley principle Fig. 439,
p. 483, the mechanical advantage will be inversely as the number
of cords or chains at L L, Fig. 729, P being now the greater, and
W the lesser force. Neglecting friction,
W 1
Mech. Adv. = -i- = m
And allowing for resistances,
W = ——l)— x 17
no. of cords
where efﬁciency 17 varies with the number of pulleys, by the
following table:
VALUES OF 17 FOR HYDRAULIC CRANEs.

N0.0FPULLEYS. o 2 4 6 8 10 12 14 16

n= -87 -8 ~76 '72 '67 '63 59 ~54 '5


and the greater tension, at tail end, equals P -:- (no. of cords x n).
Thus, a heavy pressure with slow speed has lifted a smaller
load at greater speed, the distance between pulley centres having
been increased.
In order that the ram shall ﬁnish its stroke quietly, automatic
cut-off gear is supplied. Valve H being opened to pressure by
raising rod N fully, the ram, ascending, strikes a tappet by means.
of the projection Q, when the stroke is nearly complete, thus
causing lever M to be pulled over to position s, and closing the
valve. A further movement of M to position T opens H to)
exhaust, and the ram descends by the pull of the load.
Reference may now be made to Plates XV. and XVI.,,
showing various hydraulic cranes. That on the left in Plate XV.
is the best example of pulley gear. Thus, cylinder D is for
lifting, E for traversing, and c for slewing, all worked from valves
at s.
742 Worhing Valve.
Working Valve—When a D slide is used, Fig. 7 30 is the
usual form, where P, R, and E are the passages from pressure, to
ram, and to exhaust, respectively. At B the valve is open to
pressure, and at A to exhaust, while at C the ram passage is
entirely cut off, by hand or automatic gear.
Hydraulic-pressure Engines, though wasteful with small-
pressures and high speeds, may reasonably be used when supplied
with water at 750 lbs. pressure or more, the piston speed being
not more than 80 ft. per minute. The ﬁrst piston engine,
invented by Lord (then Mr.) Armstrong in 1838, was of the
rotary type. Subsequently he adopted side-by-side cylinders with
reciprocating pistons, and in the present engine, as applied to
heavy work, such as turning ships’ turrets or swing bridges, there
are three oscillating cylinders, whose pistons connect to the same
triple-throw crank shaft, and each valve is worked by a rocking
lever on the trunnion. Fig. 731 is a section through one valve
box. Valve A is reciprocated by the trunnion lever, while valve B,
used for reversing purposes, may for the present be considered
ﬁxed. C is the pressure supply, D the exhaust pipe, and E F the
connection to the cylinder. Taking present position of B, a right—
hand movement of A admits pressure to E, and a leftward move-
ment permits exhaust from E, through H and G, to D. Supposing,
now, B’s position be so changed that H is opposite D, and G
(opposite _F 3 the conditions are reversed, and a leftward movement
‘of A admits pressure to F, while a rightward movement exhausts
through the valve to D. Thus B is a reversing valve, and is moved
by the piston of an auxiliary cylinder.
The Relief Valve J is simply a small, spring-loaded safety
valve, which permits an escape of water whenever the pressure
exceeds the normal, by reason of water inertia. Such valves are
.placed wherever there is liability to shock.
The Brotherhood-Hastie hydraulic engine, Fig, 7 32, is a com-
'bination of the well-known Brotherhood engine, p. 632, with
Hastie’s automatic stroke adjustment. Pressure water entering
.at P, passes to the cylinder by pipe A, and the exhaust returns
"through the same pipe, but is diverted by valve D into the outlet E.
If P and E are connected to a reversing valve, the pressure water
may enter at E and leave at P, and the direction of engine rotation
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PRESSURE
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744 Hydraulic Pressure Engine .'
is then reversed. The principal feature in this engine is the
crank pin B, which is not ﬁxed, but capable of sliding to a limited
amount, within a diametral groove in the crank plate 0, being for
this purpose screwed into a shoe plate M. The power given to c
is transmitted by a hollow shaft Q, through the strong volute
spring H, to the driving pulley U. Now U is keyed to the inner
shaft K, and when the load comes on the pulley there is a further
coiling of spring H, which causes shaft K to turn relatively to G,


T'jze .Bno/Uter/hoode fLaasblLe
ﬂydrpuxlxlc Engine fig. 732.
through an angle depending on the turning moment. The result
of K5 turn is to rotate a cam F in such a way as to move the
crank pin further from the shaft centre, and thus increase the
throw; while on the other hand a decrease in load reverses the
cam movement and enables the piston pressure to shorten the
crank centres. Now there are two ways of accommodating fluid
pressure to work required : alteration of stroke or of pressure. In
the steam engine reduced work is met by reduced pressure ; but
water, being inexpansible, can only be adjusted in supply by a
with ‘Variable Stroke. 745
corresponding adjustment of stroke. The result is roughly the
same, for pressure >< stroke = work done.
The cam F is peculiar in shape; it is shown under full load,
having turned through three-quarters of a revolution, in a right-
hand direction. Its highest point is at+, and its lowest at as,
and when the load is removed, the cam turns leftward until the
projection at =11: stops itself ' against the projection G. Similarly
the cam shown dotted serves when the engine rotation is reversed,
the projection J being then acted upon. Both G and J are one
with the shoe-plate M, but lie in different planes, so that the two
cams, also in one piece, may rotate without interference.
INDEX.
PAGE
BSOLUTE zero of temperature 589
Absorption dynamometer . 575
Accelerated velocity . . . 473
Acceleration. . . . . 473
curves, and scale . . 492

Accumulator, hydraulic, see Hy-
draulic accumulator.

. , pump . . . . 732
..Actlon, arc of . . . . 513
of cutting tools. . . 140
..Adamson’s seam . . . . 332
Addendum of tooth . . . 514
Adhesion of locomotives . 571
Adiabatic expansion, comparison of
temperatures in . 607
exponent . . . . 605
.Adiabatics, isothermals and . 605, 607

.Adjustable hanger, automatically . 504
.Adjustment of stroke, automatic,
in hydraulic pressure engine . 742
-Admiralty test requirements . . 388
.Admission, late, effect on indicator
diagram of . 618
.Advance of eccentric, angular . 637
.Advantage, mechanical, see Mecha-
nical advantage.
--—————— of machine tools . 288
Advantages and disadvantages of
various methods of transmitting
power . . . . . 577
of remelting cast iron 2, 42
of single and multiple stage


expansion . . . . 621
Agents, comparison of horse power
of different . . 48o
Aircompression cylinder . 546
Air pump for jet condenser . . 686
—— for surface condenser . 688
.Air vessel, casting and moulding . 27
-— -——-, use of, on pump . . 730
Allan’s link motion . . 642
Allotropic forms of carbon . . 72
Allowance for machining 49, 215
Alternative fulcra on testing ma-
chine . 375

Angle bar cuttingimacliine . 290
of cutting tools 139, I41
—-— of friction . 561
—- of obliquity . . 512



PAGE
Angle of resistance, limiting . 560
of tooth of mill . . . 177
of torsion . . . . 424
Angles, re-entrant . . - 67
Angular advance of eccentric . 637
Annealing malleable castings . 36
Annular or internal wheels . . 514
Anti-friction or Schiele’s pivo . 56o
rollers . . . 489
Appearance of fracture. . . 77
Approach, arc of . 12
Approximate method ‘of ﬁnding
moment of resistance . . 433


Arc of action . . . 513
—— of approach, contact, and recess 512
Area of steam port . . . 681
, virtual stress . . . 43o
Areas of expansion curves . . 604
Arrangement of lathe driving . 1 5 3
of machine shop . . 501
of mould . . . . 46
Augmentation of chains . . 489
Autographic test diagrams . 384
Automatic cut-oﬂ’ in hydraulic
crane cylinders . . . . 741
cut-off, variable expansion
by . . . 654—6
expansion gear . . . 654
—~——- lifting injector . 696
stroke adjustment In hy-
draulic engine . . . .
Automatically adjustable hanger . 504


Available energy . . . . 476
Axle, wheel and . . . . 481
, -———--, compound . . 483
ACK gear of lathe. . . 142
Backed-off mills . . . 175
Backlash of teeth . . . . 514
Balance for lift, hydraulic . . 74o
Balanced cores . . . . 57
lift . . . . . 738
Ball bearings . . . . 568
Band sawing machine . . . 294
Bar, puddled, composition of . 76
———, steel, rolling of . . .
Bases, time and distance, forvelocity
curves . . . . . 491
Beader, tube . . . . 326
748
. PAGE
Beam blowing engine . . 628
, cast iron, momental strength




of _ . . . . 434
engine, compound . 628
—-— , Cornish pumping . 627
-—-~ ————-, rotative . . 628
--'— , velocity curve for . 496
, wrought iron rolled, mo-
mental strength of . . . 434
Beams, bending moment of, see
Bending moment.
, continuous, and pressure on
supports . . . . . 445



, deﬂection of . . . 450
—--, of, table of . . 451
-——, moment of resistance of . 428
——, neutral axis of . . . 427
of uniform strength . . 452
, resilience of v . . . 451
, theory of . . . . 427
Bearing, collar, friction of . . 558
, crank shaft, machining . 235


, journal, friction of . . 557
, thrust . 506, 688
Bearings . . . . . 504
, ball . . . . 568
, collar, footstep and thrust 506
, tumbler . . . . 509
Bedplate of engine, machinin . 264
Bell crank lever, forging a . . 118
Belt driving; problems in, and

pulleys for . 534
fastenings . . 532
gearing . 526, 579
Belting, chain . . . . 532

, quick return by . . 534
Belts; creep, slip, speed and length
of, centrifugal tension in . . 530
, details of . . . . 531
. , direction of advancing and
retreating sides of . . 532
, driving pull, horse power an
strength of . . 529
, tension of . . . . 527
Bender, hydraulic plate . . 298
Bending and compression, com-
bined action . . .
and tension, combined





action . . . . . 453
and torsion, combined
action . . 461
Coefﬁcient . . . 36
coefﬁcients, table of, for
rectangular sections . . . 436
moment and shearing force
diagram combined . . . 444

Index.
PAGE?
Bending moment and vertical shear 437
, equivalent . . 461
for beam ﬁxed one
end, supported at other, loaded
with own weight . . .
moment for beam, ﬁxed both
ends, loaded centrally . . 441
moment for beam, ﬁxed both




ends, load uniformly distributed 442.

moment for cantilever, con-
centrated load . . 4 38-
moment for cantilever, uni-
formly distributed load . 439>
moment for girder, concen- '
trated load at centre, supported
both ends . . . . 439~
moment for girder, load at



any point, supported both ends . 440‘

moment for girder, load
uniformly distributed, supported



both ends . . 44o)
rolls, plate . . . 294
stress action . 426'
theories . 437
Bent crank, forging a . . . 122
Bessemer steel plant . . . 79»
Bevel gearing . . . 519, 578-
pinion, making pattern of 60.-
—— wheel moulding . . . 34
teeth . . . 520
Black wash . . . . . 8~
Blackening, object and composition
of . . . . . '
Blast furnace . 2, 73
, smith’s . . . . 90-
Block and tackle . . 482
Blooms . 76*
Blower, Roots’ 90‘-
Board of Trade rule for furnace
tubes . . . . . 46o-
Boiler, drilling and riveting a loco-
motive . . . 3 5 3..
Boiler ﬁttings . . 693
ﬁne drilling machine . 307
-— maker, geometry required by 3391
-——— maker’s tools . 283-286
-—-— making and plate work . 279-



manhole and mudhole . . 332.
, setting out a locomotive . 3 52'.
———, setting out a marine . 342:
-——-, setting out and riveting a
Lancashire . . . 354.
smith’s tools . . . 284.
stay tubes . . 351
stays, girder . 335, 3481
, gusset and longitudinal 33o

Breast water wheel
Index.
PAGE
"Boiler stays, palm . - 335
—, screwed . 335, 350

Boilers, Adamson’s seam and Gallo-
way tubes for ﬂues of; corrugated _
ﬂues for . . . . 332
——, Cornish and Lancashire 330, 354
--—, headers for tubulous . 339
—--, locomotive . . 335
--—, marine . . . . 333
—-—, multitubular 33 5
. riveting of - 334, 348. 353
, setting out and riveting tubu-
lous and vertical . . . 3 56
, strength of ﬂat surfaces in . 451
, tubulous or Water-tube 337, 356



—-, vertical . 337, 356
Boiling point . . 593, 594
Bolt, forging a . . . 102
Bolts, diameter and area at thread-
bottom . . . . . 402
, pitch of cylinder cover . 402
——, strength of . 402, 403, 415, 422
Boring bar . . . . . 162
machine, horizontal . . 160
Bottle jack . . . . . 205
Bourdon pressure and vacuum
gauges . . . . . 694
Brace, ratchet . . . . 202
Braced or framed structures . . 463
Bracket for governor, machining . 249
Brackets, shaft, hanger, automati-
cally adjustable hanger, wall box,


and wall bracket . . . 505
Brake dynamometer and horse
power . . . . . 575
straps . . . . .. 569
trials . . . . . 556
, Wagon . . . . 498
Brands of plate iro . . . 282
Brass, composition of . . . 84
founding . . . . 37
Brass-work, ﬁnishing . . . 264
Brazing . . . . . 86
Break lathe with treble gear. 157, 159
Breaker, stone . . 498
Breaking stresses . . . 392
, average, of materials 394
, table of, of materials 393
. 720

Bridge, suspension, stresses in
chain of . . . 466
British thermal unit . 479, 585
Bronzes, phosphor and manganese 85
Brotherhood’s three-cylinder engine 63 1
..Brotherhood-Hastie hydraulic en-
gine . . . . . 742




749
PAGE
Brumbo pulley . . 616
Buckets, ventilated, for water
wheels . . . . . 720
Bushes . . . . . 506
Butt joints, double riveted . . 410
, with two
cover-plates . . . . 411
—- treble riveted . . 411
ABLE grip . 543
Calculation of centre of gravity 432
-——~ of weight of ﬂy-wheel . 679
of work and horse power
from theoretical indicator diagram 62 5
Caloric or material theory of heat . 581


Caloriﬁc power of coal. . . 697
Cam for automatic stroke adjust-
ment in hydraulic engine . . 745
Cantilever . . . . 427
Capstan, geared . . . . 523
head for lathe . . . 200
Carbon, allotropic forms of . . 72
Case-hardening . . . . 124
Cast iron, composition of . . 2
, crystallisation of . . 67
, pig. white. mottled, grey
and commercial varieties . . I
—-, properties of . . 73
, toughening . . . 3
Casting and moulding . ‘ . . I

air vessel, conden-
sers and cone pulley . . 27
cattle trough . 6
chain pulley . 8
cylinder cover, hand
wheel, worm wheel, and drilling
machine table . . . . Io
ﬂy-wheel and screw

l

__-_




propeller . . . . 25
gas pipe main . 14
—— large steam cylinder 2 1
— pipe bend . . 17
———— plummer block . 31
———-—- road wheel . . 12
——- stop valve . . 31
——-—-- design, pattern-making and 43
—-— of wrought iron. . . 87
On . . . . . 12
rule for steam cylinders . 400
, softening a . . . 36
Castings, chilled . . . . 34
, contraction of . . . 62
———-, ,‘ table of . . 63
, malleable, annealing . 36
, steel . . . . 4
, warping and shrinking of. 69
750
PAGE
Catenary curve . . . . 466
Cattle trough, casting and moulding 6
Caulking and riveting . . . 286
, pneumatic . 322

Cement testing machine . 37o
Cementation process and furnace . 78
Centre, instantaneous, and virtual 490
of gravity found mechanically


and graphically . . . 431-2
of gravity found by calculation 432
Centreing machines . . . I 52
square . . . . 150
work in lathe . . . I 51
Centres, dividing,for millingmachine 181
Centrifugal force, tensile stress
caused by . . . . 400
pump, and path of water in 728

tension in belts . 53o
Centrode . . . 490
Chain and force closure . 487

barrel, building pattern in loam 65
belting . . . . 532
, double slider crank, and
quadric crank . . . 487
gearing, pitch . 544, 579
pulley, casting and moulding 9
——, slider crank . . . 486
——, strength of . . . . 397
, stress on, for suspension bridge 466
Chains, augmentation of . . 489




, closed . . . 487
, kinematic . . . 486, 489
Change wheels of lathe. . I47, 484
Chaplets . . . . . 17
Charging 0f cupola . . . 2
Charles’ and Boyle’s laws, com-
bination of . . . . 590
Charles’ law . . . . 587
Chasers . . . . . 213
Chemical combination and mecha-
nical mixture . . . . 72
Chill, depth of, in chilled castings 34
moulding . . . . 35
Chilled castings . . . . 34
Chills . . . . . . 36
Chipping . . . . . 209
Chisels . . . . . 187
, tempering . . . . 126
Chuck, dog . . . . . 149
, drill, independent, lever,
and universal scroll. . . 153
, eccentric . . . . I 5 5
, Whiton’s . . . 152
Circle, pitch, and rolling . . 510
Circulating pump for surface con-
denser . . . . . 688

I ndex.
' PAGE
Classiﬁcation of stress action. . 394.
Claw clutch . . . . . 503.
Clearance, effect on indicator dia-


gram . . 618
in cylinder . 616
of teeth . . 514
Clip pulley, Fowler’s . . 540
Closure, chain and force . 487
Clutch, claw . . . . 503
, Musgrave’s, and Weston’s . 569-
Coal, constitution and caloriﬁc
power of . . 697
Cocks, cylinder . . . . 264
Coefﬁcient of friction in tension


elements . . . . 528
of static friction .
of velocity of water through
oriﬁces . . . . 712-13
Coefﬁcients, bending, table of . 436
- of contraction, discharge,
and resistance, of water through
oriﬁces . . 7 I 2- I 3.
of linear expansion . 369=
Cogging and ﬁnishing section bars 279

Coiling gear, Fowler’s . . 523.
Collar bearing . . 506
, friction of . 558
Colours for steel tempering . . 125
Columns, long, strength of . . 457
, short, strength of . 405
Combination, chemical and mecha-
nical mixture . . . . 72'
of Boyle’s and Charles’ laws 59



of crank effort diagrams . 676-
of indicator diagrams . 623
Combined bending and compres-
sive stress action . . . 45 5
bending and tensile stress
action . . . . . 453
bending and torsional stress
action . . . . . 461
bending moment and shear-
ing force diagrams . . .
torsional and compressive
stress action . . . . 463
Combustion and forced draught . 696
Commercial varieties of cast iron . 1
Comparative costs and speed of

hand and machine riveting . 321
Comparison of agents . . . 480-
——-—-—— of compressed air and
hydraulics . . . 548
of temperatures in adia-
batic expansion. . 607
Compasses . . . . . 185
Compensating cylinders or pots . 732
iGvakuz
PAGE
Compensating cylinders, indicator
diagram showing effect of . . 732
cylinders, intensiﬁer for 732
Complete pairs (kinematics) . . 485
Composition of blackening . . 6
of brass and gun metal . 84
of green, parting and dry
sand ; and loam . . . 4
of Muntz metal . . 85
—-——— of pig iron . . . 2
———— of puddled bar . . 76
of steel . . . . 77
-————- of steel castings . . 82
Compound ideal indicator diagrams 666
locomotive . . . 689
pumping engines, hori-
zontal . . . . . 681
Wheel and axle . 483
——-— beam engine . . 628
Compounding, theory of . 614
Compressed air and hydraulics,
comparison of . . . . 548
air, losses in cooling . 547
—-, transmission of power
by . . .. . . 545,580
————- steel, Whitworth’s . . 82
Compression and bending combined 45 5
and torsion combined . 463
, cylinder for air . 546
, eﬂ‘ect of, on indicator
diagram . . . 618
Compressive stress action . 404
stresses, nature of . . 366
Compressor, intensifying . 37 5
quiet . . . .‘ 374
Condensation and re-evaporation,
initial . . 614
and re-evaporation, ini-
tial, effect on indicator diagram. 618
water, quantity required 598
Condenser, casting and moulding a 27
, ejector. . 688
, jet . . . 686
, surface. . 684, 686
Conduction of heat . . 582
Conductors, relative value of good
and bad . . . . . 583
Cone keys ‘ . . 504


pulley, casting and. moulding a 27
_, speed . . . . . 534
Conical ﬂue, geometry of . . 340
Connecting rod, crank and, velocity
ratio . . . . . 490
rod end, machining the parts
. _ . . . . 243
rod, forging a . . . I35
ofa.

575I
I PAGE
Connecting rod, machining a . 24o
, return . . . 630
Conservation of energy . . 477
of momentum . . 474

Constant pressure, and constant
volume, speciﬁc heats of a gas at 603


Constants, Gordon’s, for pillars . 458
Construction of hyperbola . 615
—-———— of wire rope . . 539
Contact, arc of . . 512
Continuous beams and pressure on
supports . . . . . 445
Contour of head of rivet . . 409
Contraction of castings . . 62
—- , table of . . 63
of water through oriﬁces,
coefﬁcient of 712-13
Contrivances for diminishing friction 566
Convection . . . . . 583
Conversion of thermometer scales . 585
Cooke’s mine ventilator . 498
Cooling compressed air, losses by . 547
, heating and, stresses caused

by . . . . . . 368
Cope . . . . . . 40
Copper, roasting and smelting . 83
Copying principle in machine tools 139

Core boxes . 3o, 55
prints . . . . . 55
Cores . . . . . 4
, balanced . . . . 57
—, drying of, and supports for . 39
for wheel arms . . . 61


, hung . . . . . 29
Corliss valve . . . . 657
gear . . . . 656
Cornish and Lancashire boilers . 3 30
double-beat valve . . 636
pumping engine . . 627
, distribution
of steam in . . . . 634-
Correction for inertia, of indicator
diagram . . . . . 673
Corrugated ﬂues . . . . 332
Costs, comparative, of hand and
machine riveting . . . 321
Cotter, forging a pin and . . 106-

joint, strength of . . . 415
Cotton rope, data connected with 537


gearing . . . 534
—- ——, mill driven by . . 538
—— _, pullies for . . . 536-
— , travelling crane driven
by . ._ . . . . 538
Countershafting . . . . 534
Couple, a . . . . . 417
752


PAGE
Coupling bolts, strength of . . 422
Couplings, ﬂange, Oldham’s . 504
, shaft . . . . 502
Cover, cylinder, machining . . 260
Cramp, D . . . . . 205
Crane, efﬁciency of a . 573
, F airbairn’s . . 456
~— hooks, strength of . 453
, jib of, &c., stresses in . . 468
, travelling . 538, 543
Cranes, hydraulic, see Hydraulic
cranes.
Crank and connecting rod, velocity



ratio . . . . . 490
and eccentric, relation of . 637
chain, double slider . 487
-—— , slider . . 486
-—— effort curves . . . 676
-—-— diagrams, combination of 676
, forging a bent . . . 122
——, a double webbe . 118

, a single webbed . 117






-—— pin adjustment (automatic) in
hydraulic engine . . . 744
—-—— shaft, forging a double throw 129
—- , a small . . 1 18
-—— bearing, machining a . 235
, machining a . . 238
‘Creep of belts . . . . 530
Crosshead, machining a . . 245
Crystallization of cast iron . . 67
Cubical blocks . . . . 185
Culmann’s funicular polygon. . 445
theorem . . . 446
Cupola, charging. 2
, tapping a. . 40
Cut-off, automatic 654-6
valve, back . 652
Cutter, tube. . 326
Cutters, milling . . . 174
. , , machine for grind-
ing . . . . . 197
Cutting a screw in lathe . an
edge on twist drill, form of 197
speeds . . . . 142
tools, action of . . 140
, angles of. . . 141
Curve, Fairbairn’s expansion . 607
of dry saturated steam . . 607
of inertia pressure . 674
-—— of saturation points . 595
of sines . . 496
——~— of velocity . . . . 490
-——, Rankine’s expansion . 607, 608
, Zeuner’s expansion . 608
Curved ﬂoats, pressure of water on 719

Index.


PAGE
Curves, acceleration . 492
, crank effort . 676
, cycloidal . . . . 510
, expansion, and their areas . 604
606, 607
—, polar . . . . . 490
——, velocity, of various mecha- '
nisms . . . 492-8
Cycle, Carnot’s reversible . 608'
of operations . 608'
— —--— in gas engine . 699
Cycloidal curves, cycloid, epicy-
cloid, hypocycloid. . . 510
Cylinder, air-compression and plant 546
clearance . . . ‘ . 616
cocks . . . . 264'
, compensating . . . 732
cover-bolts, strength of . 404
cover, casting and moulding 10
, machining . . 260
, expansion in . 615
for hydraulic press . 736
', steam, machining a . . 257
, straining, for testing ma-
_
chine . . . . 376‘
Cylinders, strength of . . 397
Cylindrical gauges . . . 214
CRAMP . .
. . 205
D slide valve, long and short 636‘
Davits, ships’ . . . 456
Dead-weight safety valv . 693
Decision of working stress . 393
Deductions from indicator diagram 620
Deﬂection of beams . . . 450'
—-——— , table of allowable 451


of helical springs . . 426
Deforming a bar, work done in . 366
Depth of chill . . . . 34
Density, speciﬁc, deﬁnition of . 594
Detaching hook . . 542
Details of governor . . . 252
of horizontal engine . 215, 267
Development of the dynamo. . 550
Deviations from normal diagram . 618
Diagonal paddle engine . . 630
Diagram, indicator, see Indicator
diagram.
, Zeuner, see Zeuner diagram.
Diagrams, autographic test . . 384
, crank effort, combina-

tion of . . . 676
' , reciprocal stress . 464 r
, stress strain . . 362, 385

————, ,showing elas- -
tic line . . . . . 388
index.
PAGE
Diameter of cylinder for given horse
,_ ‘power . . . . . 626
Die for slotted link, machining . 226
Die, stamping . . . . 123
Dies, stocks and . . . . 192
Differential accumulator . . 738
pulley block (Moore’s) . 525
--—-———~ (Weston’s) . 203
Dimensioning drawings, method of 277
Diminishing friction by contrivances 566
by lubrication. 561
Direct acting engine- . . . 63o
elasticity, modulus of . . 363
electric transmission . . 5 5o
loaded safety valves . . 693
pattern hydraulic riveter . 316
Discharge of water through oriﬁces 711
.____.__ __ ___ __ _____,
coefﬁcient of . . .
of water through oriﬁces,
table of coefﬁcients of . . 714
Distance bases, time and (for vel.
curves) . . . . . 491
Distress of materia . . 288
Distribution of friction in machines 574



712

of shear stress . . 437
of steam by slide valve . 636
in Cornish pump-
ing engine . 634
Dividing centre for milling machine 181
‘ head for milling machine . 180
Dog chuck for lathe . . . 149
Dome plate, geometry of . . 34o
Donkey pump velocity curve . 494
Double-acting engine with drop



valves . . . . 634
Double and triple stage expansion, -
advantages of . . . . 621
beat valve, Cornis . . 636
eye, forging a . . . 106
geared drilling machine . 163
ported slide valve . . 654
riveted butt joint, strength of 410
lap joint, strength of . 408
shrouding . . . . 512
slider crank chain . . 487
throw crank shaft, forging a. 129
webbed crank, forging a . 118
.—'—-



Drag . . . . . 4o
Drawbacks . . . . . 48
Drifts, key and square . . . 205
Drill chuck . . . . . 153
, tempering a . . . 126
, twist, form of cutting edge,
and grinder . . . . 197
Drilling in position . . . 306

752;

- PAGE
Drilling machine, double geared . I63
, feed for . . . I63
—— --—-— for boiler ﬂues . . 307
—- —-——, multiple, and portable 310
—- , radial 166, 303
—-- ——-, single geared . . I64
—- , slot . . . . I68
-——— ——, special . . . 0
table, castingand mould-
ing . . . . . . IO
, use of . . . 303
Drills, ﬂat-pointed, pin, and twist. 166
Driving pull of belts . . . 529
work in lathe, method of . 152
Dry sand, composition and proper-
ties of . . . . 5
saturated steam . 593, 594
Drying of cores . . . . 39

Dryness fraction . . 594
Dunlop’s marine governor . 655
Duplex pumps . . . 731
Dynamical theory of heat . 581
Dynamo, development of the . 5 5o

, history of the . - 549
Dynamometer, absorption or brake 57 5

, transmission . 576
CCENTRIC, angular advance
of . . . 637
chuck . . . . 155
, loose, reversing by . . 638
, relation of crank and . 637
rods, crossed and open 651, 665
, main and expansion,


machining . . . . 226
sheaves, machining . . 228
, setting. . . 273
, shifting, reversing by . 638
, straps, machining . 228
, throw of. . 637
Economical sections . . 433
Eddies and shock, loss of energy by 716
Eﬁfective pressure per square inch
from indicator diagram . 620
Efﬁciencies of various machines . 577
Efficiency, mechanical, of engine . 620
of crane . 573
——-~—--—— of electric transmission . 551
-—-—-——— of F ourneyron turbine . 724
of Girard turbine . . 726
of hydraulic cranes . 741
of machines . . 571
of perfect heat engine . 611
————— of plate joints . 408, 413
-————— of pumps . 734
of steam . 602
3C
754
PAGE
Efficiency of turbines, relative . 726
of water wheels, seeWater
wheels.
Ejector condenser . 688
Elastic limit, primitive . . 363


, raising of. . . 385
line, diagrams showing the 388
Elasticities, table of . . . 364
Elasticity, and limit of. . 361
, moduli of direct, trans-
verse, and volumetric . . 363
—————, transverse (or rigidity) . 363
Electric formulae . . .


. . . . . - 552
Ignition in gas engine . 700
—— in oil engine . 707
pyrometer, Siemens’ . . 587
transmission . 549, 580
by storage or
direct 551

' , efﬁciency of 551
, examples of . 5 54


welding . . 327
Elements, tension and pressure . 489
Emery grinder . . . . 195
testing machine. . 376
Energies, numerical estimate of
various . . . . . 477
Energy . . . .. . 473
available . . . . 476
, conservation of . . 477
, ﬂuctuation of ﬂywheel . 478
forms; potential and kinetic 475
, head, pressure, and velocity 710
in one pound of water . 711
, natural stores of . 476
of revolution of a ﬂywheel. 478
, transformation of . 477
Engine, beam blowing, compound
and rotative beam, and direct-
acting pumping‘ . 628
, beam, generally . 627
, Brotherhood three-cylinder 631
, Cornish pumping . . 627
, diagonal paddle, direct act-
ing, oscillating, Penn’s trunk,
side lever marine, steeple . 630
, double acting, with drop



valves . . . 634
, erecting an . . . 267
-————, Fielding . . 633
, gas, see Gas engine.
—-——-, grasshopper . . 499

—, horizontal compound pump-
ing . . . . _ . .
--————, horizontal, machining de-
tails of . . 215
681
I ndex.


PAGE
Engine, hydraulic pressure . . 742
, inside cylinder. . . 689
, list of details of . . 267
, losses in a steam . . ' 613

-———, marine, triple expansion . 685
, Maudslay’s and modern
marine . . . . . 631
, mechanical efﬁciency of an 620
———-, Newall . . . . 633




, perfect heat . . . 608
--——, —————-, efﬁciency of . 611
, petroleum or oil . . 705
, rotary; annular, and ec-



centric types . . . . 631
--———, stationary, example of . 681
--——, Tower . . . . 633
-—--—-—, Westinghouse . . . 633
, Willans’ side by side . 631
Engines, high speed . . . 631
, outlines of various . . 629
, sections of high speed . 632
Epicyclic trains of wheels . . 521
Epicycloid . . . . . 510
Erecting . . . . . 183
an engine . . . . 267
Erector’s tools . . . . 202
Equivalent of heat, mechanical . 599
twisting and bending
moments . . . . 461
Estimate of various forms of energy,
numerical. . . . .
Euler’s formula for strength of long
columns . . 456
Evaporation, total heat of . 597
, work done during . 600
Examination of plates . . . 28o
Exceptions to laws of friction . 556
Excessive clearance, effect upon
indicator diagram of . 618
Exhaust ports of Worthington pump 731
Exhausting in Simplex gas engine,
method of . 705
Expander, tube . . . . 324
Expanding mandrel, Noble’s I 55
Expansible mill . . . . I75
Expansion, adiabatic, comparison
607

of temperatures in . . .
, advantages of single and
multiple stage . . . . 621
caused by heat . . 584
, coefﬁcients of linear. . 369
curves and their areas 604, 606
eccentric rod, machining . 226
gear, automatic . 654
in cylinder . 615
of dry saturated steam . 607
[12 dex,



PAGE
Expansion of gases . . . 587
---~-—-— , laws of. . 587, 589
valve, machining . 262
‘ , variable . . . . 650
, , by automatic cut-
off . . . . . . 656
, ——, by linking up . 651

; gear and valve,
652
Meyer’s
6 5o
, versus throttling .


Experiments of Joule . 599
of Regnault . 596
Exponent, adiabatic 605
Extension in test specimens, local. 385
Extensometer . . . . 381
External work during evaporation 600
Extractor, ferrule . . . 326

Eye bolt, forging an . 1 11
ACE lathe . . . 159
Face plate of lath . 149
Factors of safety . . . 391
F airbairn crane . . 456
expansion curve . 607
rule for furnace tube . 460
Fan, Sturtevant . . . . 90
Farcot governor, head 0 . 6 50
Fastenings for belts . 532
Feather keys . . 504
Feathering paddle . 500
Feed for drilling machine . 163
— planing machine . I70
_ , star, for lathe . 160
Feeding gate 38
F erguson’s paradox . 522
Ferrule extractor . . . . 326
Fielding high speed engine . . 633
Files . . . . . . 189
Filing . . 209
Finger piece. . . . 60
Finishing, allowance for . 215
brass work . . . 264
section bars, cogging and
279, 280
F irebars . 330
Fitter‘s tools . 186
Fitting . . 137, 183
Fittings for boiler. . . 693
Fixed hydraulic riveter, large . 313
Flame ignition in gas engine. . 700
Flange couplings . . 502
Flanging presses . 298

, Piedboeuf and Uni:
versal . . 300
Flank of tooth . 514 '
Flat keys . 504

l
755
PAGE
Flat pointed drills . . 166.
surfaces in boilers, strength of 451


Flexible links . . . . 488
Fluctuation of crank energy . . 679
-————- of energy of a ﬁy-wheel . 478
Fluid friction . . . . 715
, laws of . 5 57
Fluidity of molten iron . z
Fluids, deﬁnition of . 710'
Fluxes . . . . . . 73
F ly-wheel, calculation of weight of,
required . . . . 679
, casting and moulding . 25
, core boxes for arms of . 27
, energy of revolution of. 478
, machining a . 262
, strength of rim of 401
Foot pound . 366
Footstep bearing . . 506
Force and mass . . . . 473
, centrifugal, tensile stress
caused by . . . 400
closure, chain and . . 487
—- pump, single and double acting 7 30‘
, shearing, see Bending moment.


, tractive, of a locomotive . 693
Forced draught . . . 698
Forces, polyglon and triangle of . 464
, uniform and variable, work
done by . . . 366
Forge, the . . 129
Forging a bell-crank lever . 118
a bent crank . 122
a bolt . 102
—— a box key . 1 13
——-—— a connecting rod . 135
—-——— a double and a single eye . 106
-——— a double throw crank shaft 129
—-—- a double webbed crank . 118
——- a holdfast . . . 104
an eyebolt and hooks and
harrow frame . . . I I 1
a nut‘ . . . 104.
---—— a pair of tongs . . 113
-————- a pin and cotter . 106
——-——- a piston rod . 134
————- a shackle and a spanner . 108
-—-—- a single webbed crank . 117
a small crank shaft . 118
by stamping . . 122
-—-—- , examples of . 125
by steam hammer . 117
, heating for . roo
, smithing and . . . 88
solid versus welding . . 1 15
steel shafts . . . 133
7 5 6
PAGE
Form of water-wheel vane . . 719
Forms of load . . 361
Formula, for long columns, Euler’s 457
, Gordon’s . 458



Formulae, electric. . . . 552
Foundry brass . . . . 37
ﬂoors, venting . . . 39
pits . . . . . 25
Fourneyron turbine . . 723
, efﬁciency of . 724
, path of water in . 723
F owler’s clip pulley . . 54o
coiling gear . 523, 527
Fracture, appearance of
Framed structures, braced and . 463
of three dimensions 471





Friction, angle of . . . 561
—————, coefﬁcient of, in tension
elements . . . . . 528
, coefficients of static . . 555
diminished by contrivances 566
~— by lubrication . 561
, distribution in machine . 574
gearing . 571, 580
. head lost by . . 715
in pipes . . . . 715
, laws of, exceptions t . 556
—————, ﬂuid . 557, 715
———, solid . . 555
of collar bearing . . 5 58
of journal bearing . . 5 57
, uses of . . . . 569
, work lost in . . . 558
Froude’s experiments on water
energy . . . . . 711
Fulcra of testing machine, alterna-
tive . . . . . . 375
Fundamental Zeuner valve diagram 661
Funic‘ular polygon . . . 445
Furnace blast . . . . 73
--—— , action in . . 74
, cementation . . . 78
' for forge . . . . 129
puddling . . . . 75
-— regenerative . . . 81
tubes, Board of Trade rule

Index.


. ’ PAGE
Gas engine, Simplex . . . 701
—— engines, Lenoir and other . 699
—- pipe main, casting and moulding 14
—, speciﬁc heats of a . . . 602
— used in gas engines, kind of . 705
Gases, expansion of . . ‘ . 587
, —————— ——-, Gay Lussac’s
formula for . . ‘. . 589
, expansion of, laws of . 587, 589
Gates . . . . . . 6
, position of . . . .
, size of, skimming, feeding . 38
Gauge, pattern-maker’s . . v45
notches for measuring H. P.
ofa stream ' . . . . 714
of split pins . . . 277
Gauges, cylindrical . . 214
, pressure and vacuum, Bour-
don’s . . . . . 694
Gay-Lussac’s formula for expansion
of gases . . . . . 589
Gear, automatic expansion . . 654
, Corliss valve . . 657
-—, Fowler’s coiling . . 523, 527
, Hackworth’s, Marshall’s,
and Walschaert’s valve . . 643


, joy’s valve . . . . 642
, multiplying, for hydraulic
crane . . . . . 742
, pit head . . . . 542
—, Proell valve . . . 658
, radial valve, reversing by . 642
———, trip valve . . . 657, 658
‘ , valve, for oscillating engine . 644



Geared capstan . . 523
Gearing, belt . 526, 579
, bevel . 519, 578
, cotton rope . 534, 579
, friction . 571 , 580
-——', pitch chain . 544, 579
————— , screw . 520, 578
>.spur - - 509.578.
, stepped . . . . 518
, tooth, safe velocity of . 518.
, train of . . 481
7 Wlre rope - 539, 579
,' worm . . 520
Gears, reversing . . . .
Geometry of dome plate and conical
ﬂue .
638



for . . . . . . 46o
tubes, Fairbairn’s rule for. 460
-—-—— for boilers . . 347
——, strength of . . 460
"‘ ALLOWAY tubes . . 332
Gas engine, and cycle of
operations in 699
Gas engine, ﬂame, tube, and electric
ignition in . . . . 700
. . . . . 340
required by boiler maker . 339
Girard turbine, construction and
regulation . . . 724
, efﬁciency of. . 726
, path of water in . 726
Girder . ‘ . . ‘ . ' . . 427




‘Index.

757
PAGE
Hand hammer . . . . 187
riveting and caulking . . 286

wheel, casting and moulding a 8

Hanger, automatically adjustable . 504
bracket . . 504
Harmonic motion, pure . 496
Harrow frame, forging a . . 111
Head, dividing, for millingmachines 180
gear of pit . 542
lost in friction . 715
of rivet, contour of . 409
or F arcot governor . . 6 5o
pressure and velocity energy . 710
, turret, for lathe . . 200
Headers for tubulous boilers . 3 39
Headstock of lathe . 144
Hearths, Smith’s . 88
Heat and heat engines . 581

, caloric or material theory of 581
, conduction of . . 582



——, dynamical theory of . 581
engine, perfect . 608
——— , , efﬁciency of . 611
, expansion caused by . 584
——-, latent, of steam . . 592
———, , of water . 591
————, measurement of . . 584
———, mechanical equivalent of 599
———, quantity of . . 58 5
, speciﬁc 585.

, methdd of ﬁnding, and


table of . . 586-
, , of gases . . . 602
———, , of superheated steam . 604
, total, of evaporation . 597
, transfer of . . . 581
Heating and cooling, stress caused
by . . . 368-

.for forging . . . 100
Helical springs, deﬂection of . 426
teeth . . 518

Hemispherical cup, pressure of


' Girder, lattice, stresses in a .
PAGE
. 468
, plate, momental strength of 435
--——-, riveting a . . 356
, stays for boiler . 335, 348
, Warren, stresses in a . . 466
Gooch’s link motion . . . 64o
Gordon’s constants and formula for
long columns . . 458
Governor for Priestman oil engine 708
for Simplex gas engine,
pendulum . . . . . 701
——-— for Water wheel sluice . 720
, head or Farcot . 6 50
————-~——, hydraulic . 685
, marine, Dunlop’s . . 65 5
, parabolic . . 65o
, Porter, machining the
various parts of a . 249
, shaft . 655
, simple or Watt . 647
——-———, weighted or Porter . 648
Gradient, hydraulic . . 716
Graphic solution of centre of gravity 432
of moment of in-
ertia and resistance . . 43o
Grasshopper beam engine . . 499
Gravity, centre of, methods of ﬁnd-
ing . . . . . . 432
Greenhill’s formula for combined
torsion and compression . 463
Green sand, composition and pro-
perties of . . . . . 4
sand mouldin . 5
Grel valve for pulsometer . 735
Grey cast iron . 1
Gridiron valve . 654
Grinder, emery . . 195
, twist drill . . . 197
Grinding machine for milling cut-
ters . . . . . I97
Grindstone . . 195
Grooving mill . I75
Gudgeon, machining a. . . 238
Guide blades of turbines . 724, 726
Gun metal, composition of . . 84
Gusset stays . . 33o
ACK saw . . . . 209
Hackworth’s valve gear . 643
Hammer, hand . . 187
, lead . 209
, steam . . . 7, 129
-——'——, , force of blow of 98
, tilt . . . . . 78
Hand and machine riveting, com-
parison of . . 321
water jet on . 718
High speed engines . . 631.
, sections of. . 632
Higher pairing . . 488
History of the dynamo. . 549
Hobbing a worm wheel . 274.
Holders for lathe tools . 157'
Holdfast, forging a . 104
Hollow keys . 504.
Hollow round shaft, moment 0i
resistance of . 419
Hook, detaching . . 542
, forginga . . . 111
Hooke’s universal joint .‘ 504.



7 58
PAGE
Horizontal boring machine . . I60
compound pumping engine 681
engine, ﬁtting up . . 215
, details of . . 267
Horse power and work from theo-
retical indicator diagram . . 625
, brake . . . . 575
-—— -——-— from indicator diagram. 620
—-— in terms of steam used . 626
-———- of stream, measurement
of 14
. . . . . 7
transmitted by shafting. 507


Housing plane 45
Hung cores . . . . . 29
Hydraulic accumulator . . 736
, differential . . 738
, intensifying . . 74o
, use of . . . 738
, work stored in an 738
balance for Ellington’s lift 740
cranes, automatic cut-off in 741
, efﬁciency of . . 741
, examples of . . 741
, ﬁxed and moveable

Ill


l I








‘Index.
_ _ _ PACE
Hydraulic riveter, direct pattern . 316


, large ﬁxed . 313
—— , lever pattern . 317
——- , portable . 315

transmission of power 549, 580
Hydraulics and compressed air,

comparison of . . . . 548
and hydraulic machines . 710
Hydrometer. . . . . 562
Hyperbola, construction of . . 615
Hypocycloid . 510
CE water and steam, relative
volumes and temperatures of 595
Ideal compound indicator diagrams ;
tandem . . . . . 666
compound indicator diagrams ;
cranks at 90° . 669, 672
Ignition of charge in gas engine . 700
—— in oil engine . 707



Impact . . . . . 47 5
Impulse machines; water wheels . 720
; turbines. . 724
ram, hydraulic. . . 729
Impulsive load, stress caused by . 368
Inclination of mould . . . 14
Inclined plane . . . . 483
Incomplete pairs . . . . 485
Independent chuck . . . 153
Indicated horse power, diameter of
cylinder for given . 626
horse power from diagram 620
Indication of machining on drawings 21 5
Indicator diagram; correction for
inertia . . . . . 673
diagram, deductions from 620
—-———— 3 effect produced
by bad indicator, compression,
excessive clearance, late admis-
sion, late release, leaky piston,
leaky slide valve, initial conden-
sation, re-evaporation, and wire
drawing . . . . .
diagram for Simplex gas

618

pulleys of. . . . . 74o
, mechanical advan-
tage in . . . . . 741
, multiplying gear for. 741
-——— , use of . . . 740
---——~ , working valve of . 742
governor . . . . 685
— gradient . . . . 716
-———-— impulse ram . . . 729
-——- jack. . . . . 205
-— lift, Ellington’s balanced . 738
-— —, balance for. . . 739
————— plate bender . . . 298
press . . . .
, mechanical advantage
of . 736
, shape of cylinder for 736
pressure engine, automatic
stroke adjustment in . . .
pressure engine, Brother-
hood-Hastie . . . . 742
pressure engine, sliding
crank pin in . . . 744
pressure engine, stroke
adjusting cam for . 745
pressure engines . 742
pressure engines, relief
valve for . . . 742
pressure engines, reversing
valve for . . 743 l
punching and shearing
machine . . . . . 291
engine . . . . . 705
cliagram,horse powerfrom 62 5
, theoretical . 625
, topography of . 618
diagrams, combination of 622
, ideal compound,
see Ideal, &c.
-————— plugs . . . . 267
, steam engine . 616
————-—-, Tabor . . . . 617
Inertia, correction of indicator dia-
gram for . . . . . 67 3
Index.
PAGE
Inertia, moment of; for any section,

found graphically . 431
, pressure, curve of . 674
Initial condensation and re-evapor-
ation 614
condensation and re-evapor-
ation, effect on indicator diagram 618
Injection cock for jet condenser . 686

Injector, automatic lifting . . 696
Injectors . . . . 694
Inside cylinder engine . . . 689
Instantaneous centre . . . 490
grip vice . . 187

Intensiﬁerfor compensatingcylinder 733
Intensifying accumulator . 740
Intermediate valve rod, machining 226
Internal or annular wheels . 514
work during evaporation . 600


Involute teeth . . 517
Inward ﬂow turbine . . . 726
Iron, cast, mixtures of . . . 41
, , varieties of. , . . 1
, ﬂuidity of molten . . 2
or steel, test for . . . 83
ore, properties of. . . 73
, scrap, and uses . . . 41
-———, wrought, see Wrought iron.

ACKS, bottle, hydraulic, and
with worm gear . . . 205
et condenser . . . 686
— pump . . . . 711
-— of water, pressure of . 719
Jib of crane, stresses in . 468
Jigs . . . . . . 274
Joint, cotter, strength of . 415
, Hooke’s universal . 504
Joints, riveted, see Riveted joints.
-—-—--, eﬂiciency of plate . 408
, table of eﬂiciencies of various 413
Jonval turbine 724


; guide blades, regu-
lation, suction tube, and wheel
vanes . 724

- turbine, path of water in . 726
Joule’s experiments . 599
Journal bearing, friction of . . 557
, shaft . . 506

Journals, formula for pressure on . 507
, table of allowable pressures
on . . . . 507

Joy’s valve gear . . 642
ENNEDY’S testing machine 372
Key drift . . . . 205
Key, forging a box . . . 1 13

759
PAGE
Keys; cone, hollow, sunk, ﬂat,
feather . . . 504
, strength of . . . 423
Kinematic chains . . 486, 489
link . . 486
Kinematics of machines . 485
, velocity ratios in . . 489
Kinetic energy, forms of . 476
ANCASHIRE boilers . . 33o
Lancashire boilers, setting out 354
Landore-Siemens’ steel process . 82
Lap joints, see Riveted joints.
Lap of slide valve . . . 636



Large ﬁxed hydraulic riveter . 313
Late admission and late release,
effect on indicator diagram . 618
Latent heat of steam . . . 592
of water . . . 591
Lathe, arrangement of . . . 141
, back gear of . . . 142
-——-, break, with treble gear 157, I 59
——, capstan head . . . 200
-—-—, centreing work in . . 151
, change wheels of . . 147
, cutting screw in . . . 212
-—, driving work in . . . I 52
, face . . . . . 159
, face plate and dog chuck for 149
—— headstock . . . 144
, leading screw of . . . I47
—-—- mandrel . . . . 142
saddle . . . . . 147
, screw-cutting . . . 141
slide rest . . . . I47
, speeds of . . . . 143
, supporting work in . . 150
, surfacing by . . . 147
—- tool holders . . . . 157
tools . . . . . 156
, treble geared . . . 157
, turret head . . . . 200
, wood turners’ . . . 46
Lattice girder, stresses in a . .
Law, Boyle’s, Charles’, Marriott’s. 587


of thermodynamics, ﬁrst . 600
————— , second . 612
-——, Regnault’s . . . . 603
——, Wohler’s . . . . 390
Laws, combination of Boyle’s and
Charles’ . . . . . 590
—-—- of ﬂuid friction . . . 557
—— of friction, exceptions to . 556
of solid friction . . . 5 5 5
Lead hammer . . . . 209
Lead of valve . . . . 638

760
PAGE
Lead of eccentric . . 637
Leading screw of lathe . 147
Leaky piston or slide valve, effect

on indicator diagram. . . 618
Leg vice . . . . . 186
Lettering used in Part II. . . 358
Lever, the . . . . . 481
_ , bell crank, forging a . . 118
—— chuck . . . . 153
-loaded safety valve . . 481
. pattern hydraulic riveter . 317
Levers, Stanhope. . . . 496
Lift, hydraulic, see Hydraulic lift.
Lifting injector . . 696
Lifting or suction pump .' . 730
Limit of elasticity . . . 361
, primitive . . 363
, raising the . . 385
Limiting angle of resistance . . 560
——-———-_-

__—


stress, line of . 430
Line of limiting stress . . 430
Line, pitch . . . . . 510
Linear expansion, coefﬁcients of . 369
Lining out . . . . . 183
Link, kinematic . . . . 486
—- motion, Allan’s . . . 642
—— , reversing by . 640
—— , Stephenson’s and I
Gooch’s . . . . 64o
-—— , Zeuner diagram ap-
plied to ‘665
, radius. . . . . 247
, suspension, strength of a . 405
Linking up, variable expansion by 651
Links, rigid and ﬂexible . 488

Linkwork, relative velocities in . 494
7 use of - 496, 577
List of efﬁciencies . . 577
Load, forms of . 361
Loam boards . . . . 61
, composition of . . . 4
moulding . . . _, 1
Local extension in test specimens . 38 5


Lock nut, gripper. . 57o
Locomotive, adhesion of . 571
boiler . . 335
-— , compound, various
parts of . . . . 689
, setting out the boiler
of-a . . . . . . 352
~—-—-———, tractive force of . 693
Logarithms, table of . 529, 626
Long columns, ‘strength of . 4 57
‘Long-D slide valve . 636
Longitudinal stays . 330
Loose eccentric, reversing by . 639

I naex.
PAGE
Loose pieces . . . . 23
Loss of head by eddies and shock . 7.16
; coeﬂ‘icients for pipe


bends . . . . . 717
Losses in cooling compressed air . 547
in steam engines . . . 613
Lower pairing . . . . 485
Lubricant testing machine . . 563
Lubricants . . . . . 561
Lubrication . . . . . 564
--————, diminishing friction by 56.1
Lubricator, sight feed, ﬁxing . 264
Lubricators . , . . . . 565
ACHINE, angle-cutting ‘ . 290
Machine, band sawing . 294
, deﬁnition of a . . 480
—-, distribution of friction

in a . . . . . . 574
, drilling, see Drilling ma- '
chine. _
, ﬂanging . . . 300
, horizontal boring . . 160
, milling, see Milling ma-
chine. '
, plate-bending . . 294
, planing, see Planing ma-
chine.

, punching, see Punching
machine.
, riveting, see
machine.
riveting compared with
hand riveting . . 321
——_, shaping . . . 171
shop arrangement . . 501
, slotting . . . 173
, strength of the parts of a 361
, testing, see Testing ma-
Riveting
chine. '
————. tools . . . 137
, advantage of . 288
, reciprocating versus
continuous . I38
; uses and examples,

locomotive boiler shop . 318
— ; uses and examples,
marine ‘boiler shop 3 19
; uses and examples,
ship building . . . .. 320

vice, Taylor’s . . 182
Machines, centreing . . . 152
,- copying principle in . 139
—— , efﬁciency of . . . 571
, kinematics of . . 485
—————,_" simple . . . . 481
Index.






761
PAGE
Metals, melting point of . 87
Meyer valve, double ported . . 654
, expansion . 652
, Zeuner diagram ap-
plied to . . . . . 664
' variable expansion gear . 652
Mill driven by cotton rope gearing 538



Milling cutter grinding machine . 197
cutters . . . I74
——-— machine . . . . 174
-——— dividing centres . 181
head . 180
-— , proﬁling . I80
— , universal . 179
, vertical . 180
Mills . . . . . 174
, angle of tooth of. . 177
———, ‘ backed oil" . . 175
; expansible, grooving, spiral,
twin. . . . . . 176
for spur-wheel teeth . 178
, speed of . . 177
Mine ventilator, Cooke’s . 498
Mitre wheels . . 520
Mixtures of iron . . . 41
of steam and water . 598
Modern marine engine . . . 631
Moduli of elasticity; direct, trans-
verse, and volumetric . 363
Modulus of rupture . 436
— section . . 430
Molecular theory of matter . . 581
Molten iron, ﬂuidity of. . . 2
Moment, bending, see Bending
moment.
of inertia . 429

—- of any section
found graphically . 430
of inertia, table of . 429
of resistance, approximate
method of ﬁnding -. .
of resistance, graphic
tion of . . . . . 430
of resistance of beams . 428
of hollow round

solu-
shaft . . . . . 4I9
of resistance of rectangular
section shaft . . .
of resistance of solid round
shaft . . . . . 417
of resistance of square shaft 419
Momental strength of cast iron
beam . . . . . 434
strength of plate girder . 43 5
of steel rail and
- 434-

421

PAGE
Machines, theory of . 48o
Machining . . ' . I37, 183
, allowance for 49, 215
, indication of, on the
drawing . . . . 215
various parts of an en-
gine . . . . . . 215
Main slide valve, machining . . 262
Malleable castings, annealing 36
Mandrel, expanding . 15 5
of lathe . 142
Manganese bronze . 85
Manhole in boiler. . . 332
Marine boiler, setting out a . . 342
boiler . 332
engine, modern. . . 631
governor, Dunlop’s . . 65 5
Marking off . . 137, 183
tools . . 183
Marriotte’s law . 587
— tubes . 588
Marshall’s valve gear . 643
Mass, force and . 473
Material, distress of . 288
of plates . 279
of rivets. . . 281
theory of heat . . 581
Materials, metallurgy and proper-
ties of . . . . 72
, strength of . . 361
Matter, three states of . . . 591
, molecular theory of . . 581
Maudslay’s engine . . . 631
Mean effective pressure per sq. inch
from indicator diagram_ . 620
Measurement of heat . 584
of stream horse power 714
Measuring, strain . . . . 81
Mechanical advantage of hydraulic
crane . 741
of hydraulic
press. . . . 736
, principle of 481
--———- efﬁciency of engine . 620
— equivalent of heat . 599
mixture and chemical
combination . 72
——-————— powers . . . 480
Melting points of metals . . 87
Members, redundant, ot framed
structures. . . . 469
Metal, Muntz, composition of 85
patterns . . . 63
white, composition of 85
‘ Metallurgy and properties of ma-
terials . . . . 72
wrought iron rolled beam .

762 I ndex.
PAGE ' PAGE
Momentum, conservation of. 474 Ore, copper . . . . . 83
---———, principle of, applied , iron . . . . . 73
to wheel vanes . . . . 717 Originating surface plates . . 210
Moore’s pulley block . 523 Oscillating engine. . . . 630
Mortice teeth . 518 —-—-—-— , valve gear . . 644
Motion, link, see Link motion.
, parallel or straight line,
see Parallel motion.




— , pure harmonic. . . 496
Mottled cast iron . . 1
Mould, arrangement of. . . 46
, inclination of . . . 14
Moulders’ tools . . . . 4o
Moulding . . . . 3
——-—— a bevel wheel . . 34
box . . . . 4
___, casting and . . . 1
—-————, chill . . . . 35
in loam. . 5, 14
machine, Scott’s . . 31
, open sand . . . 5
—-—-—, plate . . . .. 63
—— wheels by machine . 31
Mudhole in boiler . . . 332
— — , cover for . . 694
Multiple drilling machine . . 310
— punching machine . . 291
Multiplying gear for hydraulic
cranes . . . . 743
Multitubular boilers . . 335
Muntz metal, composition of . 85
Musgrave’s friction clutch . 569
ATURAL sines and cosines,
table of . . . . 272

Natural stores of energy . 476
Neutral axis of beams . . 427
of long columns . 457
N ewall high-speed engine . 633
Noble’s expanding mandrel . . I 55
Normal indicator diagram, and
deviations from .' 618
slide valve . . 636
Numerical estimate of various forms
of energy . . . 477
Nut, forging a . . . . 104
OBLIQUITY, angle of . . 512
Oil cup, machining . . 264
Oil engines, petroleum or, see Petro-
leum engines.

Oils, viscosity of . . 562
Oldham’s coupling . 504
Open eccentric rods . 665
—-—— hearth steel process . . 80
sand moulding . . . 5


lever, velocity curve for . 492

Outlines of various engines . . 629
Outward ﬂow turbine . . . 723
Overshot water wheel . . . 720
P ADDLE engine ; diagonal and
oscillating . . . . 630
feathering. . . . 500
Pairing, higher . . . . 488
, lower . . . . 485
Pairs, high and low; sliding, turn-
ing, and screw; complete and
incomplete . . . _. 485
Palm stays . . .- . . 335
Parabolic governor . . . 650
Paradox, Ferguson’s . . . 522
Parallel ﬂow turbine . . . 724
— motion, straight line or . 498
, Peaucellier’s . 499

, Scott-Russell’s . 500
lllll


————-, Watt’s. . . 499
, White’s . . 510
rimer ' . . . 209
vices . . . . 187
Part II., synopsis of lettering used
in . . . . . . 358
Parting sand, composition and pro-
perties of .
Parts of a connecting rod end,
machining the . . . . 243
of a: machine, Proportioning
the . . . . . . 394
Path of water in centrifugal pump . 728
in turbines . . 726
Pattern maker’s tools . 45
making ; casting and design 43
, wood used for . 43


—— of a bevel pinion . . 60
'——— of a chain barrel in 10am . 65
~-———-—- of a pipe . . . . 51
--—---~-- ofa pipe bend . 53, 54
— of a pulley . . . 51
-———- of a spur wheel. . . 58
-—-——— of a worm wheel . . 58
—-—-—, position of, in mould . 7
, rapping, in the mould . 62
, striking, in loam . . 14
Patterns, metal . . . . 63
Pelton water wheel . . . 722
Pendulum governor on Simplex gas
engine . . . . . 701











index. 76 3
~ PAGE - PAGE
Pendulum pump, velocity curve for 494 Plater’s tools . . . . 286
Penn’s trunk engine . 630 Plates, brands, qualities and sizes
Perfect heat engine . . 608 of iron and steel . . . 282
v , efﬁciency of . 611 ,examination of . . . 280
Petroleum, constitution and kinds of 705 ———, material of . . . . 279
engine, oil or . . 705 , rapping . . . . 67
, cycle of . . 707 ———, steel, rolling of . . . 280
——-——— , Priestman’s; con- ——, surface . . . 191
struction and working . 707 ——-—, , originating . . 21o
———- , Priestman’s ; go- , table of sizes of rivets and . 407
vernor, igniter, spray maker,start- Plugs, indicator . . . . 267
ing apparatus, vaporiser . . 708 Plumb square . _ . . 186
Piedboeuf ﬂanging press. . 300 Plummer block, casting and mould-
Pillars and struts, Euler’s formula ing . . . . . . 31
for strength of . . . . 457 Pneumatic caulking . . 322
Pin and cotter, forging a . . 106 Point of saturation . 593, 594
drill . . . . . 166 , yield . . . . 363
Pinion, bevel, making pattern of a. 60 Points, curve of saturation . _ . 594
Pinions, rules for small . . . 512 Poisson’s ratio . . . . 364
Pins in shear, strength of . . 415 Polar curves . . . . . 490
Pipe, making pattern of a . . 53 Polygon, Culmann’s funicular . 445
bend, casting and moulding . 17 of forces . . . . 464
, making pattern of a . 53 Portable drilling machine . . 310
Pipes, strength of . . . 397 hydraulic riveter . . 315
Piston, leaky; effect on indicator, Porter for forge . . . 129
diagram of . . . . 618 governor, weighted or . . 648
, machining . . . 247 Position of gates . . . . 7
pumps . . . . 730 of pattern in mould . . 7
5 rod, forging a . . . 134 Potential energy, forms of . . 47 5
————— —, machining . . . 247 Pots or compensating cylinders . 732
speeds, table of. . . 681 Power . . . . . . 479
Pit head gear . . . . 542 transmission . . . . 473
Pitch chain gearing . 544, 579 —— by
circle, line, or surface . . 510 compressed air, 545, 580
of cylinder cover bolts . . 402 transmitters . . _ . . 479
Pits for the foundry . . . 2 5- Powers, mechanical . . . 480
Pivot, anti-friction or Schiele’s . 560 Press, ﬂanging . . . . 298
Pivots . . . . . . 507 ,hydraulic,see Hydraulic press.
‘Plane, housing . . . . 45 Pressure and velocity energy, head 710
, inclined . . . . 483 curves . . . 598
Planing machine . . . . I69 elements . . . . 489
- , feed for . . 170 engines, hydraulic . . 742
-——-~—— , plate edge . . 294 gauge . . . . 694
—-—— , quick return for. . 169 machines, turbines 723, 724, 726
— tool ' . . . 171 , mean effective, per sq. inch 620
tool box . . 170 of water jet on curved ﬂoats 719
Plate bender, hydraulic. . . 298 -——— -- —— on ﬁxed plate . 717
bending rolls . . . 294 -— —— —— —— on moving plate 718
edge planing machine . 294 —— — on moving hemi-
girder, momental strength of. 435 spherical cup . . . . 718
—— moulding . . . 63 of water jet on radial-ﬂoats 719
——-——, screw . . . . . 193 of water jet on reaction
straightening rolls. . . 298 wheel . . . . 718
———, stringer . . . . 412 on teeth of wheels . 515
-——- work, boiler making and . 279 volume, and relative tem-
-———, wrist . . . . . 658 perature of steam . . . 596
764
PAGE
Pressure, wind . _ . . . 471
Priestman oil engine, see Petroleum
engine.
Prime movers . 479
Primitive elastic limit . 363
Principal, riveting a roof . 356
Principle of mechanical advantage. 481
of momentum, applied to


pressure on wheel vanes . 717
of virtual velocities. . 481
of work . . 481
Prints, core . 55
, tail . . . . 56
Problems in belt driving . 534
in Zeuner valve diagram 662
Process of making steel, Landore-
Siemens’ . . . . . 82
Process of making steel, open hearth 80

-~—— , Siemens-
Martin’s . . . . . 80
Proell valve gear . . . 658
Proﬁling milling machin . 180
Propeller, screw . . . . 688
, —--, moulding a . 25
Proportioning of structures and



machine parts by calculation . 394
Proportions of teeth . 514
Puddled bar . '76
Puddling furnace . 75
wrought iron . 74
Pulley block, Moore's . . 523
-———- , Weston’s . . 203
, brumbo . 616
, F owler’s clip . . 540
' , making pattern of a . . 51
Pulleys for belt driving . . . 5 34
for cotton rope driving . 5 36
for governor, machining . 249
for wire rope driving . . 540
Pulsometer . . . . 735
Pump, accumulator . . . 732
, donkey, velocity curve for '. 494
efﬁciencies . . 734
, force ' . 73o
, jet . . . . 711
, lifting . . . 730
—-—, pendulum, velocity curve for
, \Northington . . .
Pumping engine, Worthington high
duty . . . . . .
494
73I
732
Pumps, piston . . . 73o
Punching and shearing machines . 289
and shearing machines,
hydraulic . . ' . . '. '291
Punching machine, multiple . . 291
Pure harmonic motion . . 496


Index.
PAGE:
Pure iron . . . 73.
Pyrometer, Siemens’ electric. 587

, Wilson’s and Siemens’

water . . 587
Pyrometers . . 585, 587
UADRIC crank chain . . 487'
Qualities of plates . 282.
Quantity of A condensation water
required . 598
of heat . . . 585.
Quick return by belting . 534
- for planing machine . 169
returns . . 1 7 I, 173.
Quiet compressor for testing machine 374

ADIAl. drilling machine 166, 303.
Radial ﬂoats of water wheel,


pressure of water on . . 719-
teeth . . . 510
- valve gear, reversing by . 642
Radiation . . . . 582-
Radiators, relative value of . . 582
Radius link . ‘ . 247
vector . . . 490'
Rail, momental strength of steel . 434
Raising the elastic limit . 385
Rankine’s curve for expansion of


steam . . . . 607, 608-
Rapping patterns in the mould 62
plates . . 67
Ratchet brace . . . . 203
Ratio of velocities of P‘and ‘W in
kinematics . 489v
Reaction wheel . . 723.
pressure of water
jet on . . . 718-
Recess, arc of . . 512
Reciprocal stress diagrams 464.
Reciprocating machine tools. 138
Rectangular section shaft, moment
of resistance of . . . 421
Reducer for testing machine . 377
Redundant members in framed
structures . . 469'
Re-entrant angles. . . . 67
Re-evaporation, initial condensation
and . . . . 614.
Refining wrought iron . 74
Regenerative furnace 81
Regnault’s experiments. 596, 597
law ‘ . . 603
Regulation of turbines . . 724
Regulator and connections, ma-
chining '. 216
Riveting by hand, and machine,
Index.
PAGE
Relation of crank and eccentric . 637
Relative strengths of shafts . . 422
temperature, pressure, and
volume of steam . . . 596
value of good and bad con-


ductors . . . 583
value of radiators . 582
velocities in link work . 492

volume . . . .
and temperature of
ice water and steam . . . 595
Release, late; effect on indicator
diagram of . 618
Relief valves . . 686
Remelting cast iron, advantages,

&c., of . . . 2, 42
- Resilience of a bar . . . 367
————— of beams . . . 451
Resistance, limiting angle of . 560
- , moment of, see Mo-
ment of resistance.
to water through ori-
ﬁces, coefﬁcient of . . . 712
Retarded velocity . . . 474
Return connecting rod . . . 630
Reversed cycle in heat engine . 612
Reversible cycle, Carnot’s . . 608
Reversing by link motion . . 640
-———-—— by loose eccentric . . 638
by radial valve gear . 642
by shifting eccentric . 638
gear . . . . 638
valve for hydraulic engine 742
Reverted trains of wheels . 523
Revolution of ﬂy-wheel, energy of 478
. 88


Rigid links . . . .
Rigidity or transverse elasticity . 363
Rim of ﬂy-wheel, strength of . 401
Rimers, parallel and taper . . 209
Risers . . . . . . 24
Rivet, contour of head of . . 409
Riveted butt joint, double . . 411
butt joint, treble . . 411
lap joint, chain . . 409
-——--—— -— , double . . 408’
— , single 407

comparison of . . . . 321
by hand, and caulking . 286
machine, direct pattern hy-
draulic . . . .
machine, large ﬁxed hy-

316


draulic . . . . 313
machine, lever pattern . 317
. portable . 315

up boilers


7 65
. PAGE
Riveting up a girder . . . 3 56
—- a roof principal . . 3 56
—— a ship . . . 3 56
Rivets, material of . . 281
and plates, table of sizes of 407
Road wheel, casting and moulding 12
Roasting and melting copper . 83
Rods, eccentric;
‘crossed, and open, 651, 665
Rolled beam, wrought iron, mo-
mental strength of .
Rollers, anti-friction
‘ live ’

- 489,567
. 566

Rolling a tooth . . . . 512
circle . ' . . . 510
section bars . . . 279
steel plates and bars . . 28o
Rolls, plate-bending . . . 294
- , straightening . . 298
Roof principal, riveting a . . 3 56
truss, stresses in a . 465, 470
Roots" blower . . . 90
Rope gearing, cotton . . 534
: Wll'e - S39, S79
Ropes, strength of . . 397
Rotary engines : annular and eccen-
tric types . . . . . 631
Rule for steam cylinder, casting . 400
Rules for small pinions. . . 512
Rupture, modulus of . . . 436
ADDLE of lathe . . 147
Safe velocity of toothed gearing 518



Safety, factors of . . 391
valves . . . . 693
, Board of Trade rules
for . . . . . . 694
valves, dead weight . . 693
————— ' , lever loaded . 482
, spring loaded . . 693
Sand; composition and properties
of green, dry, and parting. . 4, 5
moulding; green, dry, and _
open . . . . . 5, 6_
Saturated steam, dry . 593, 594
————'—- , ——; expansion curve
of . . . . . 607
steam and other vapours,
isothermals of . . . . 608
Saturation point . . . 593, 594
———-— points, curve of . 594
Saw, hack ‘ . ' . . . 209
Sawing machine,‘ hand . . . 294
Scale, acceleration . . . 492
Scales, conversion of thermometer 585
.- 348, 353 I Scarfjoint‘. . . . . 102
- 434
766
PAGE
. Scott Russell’s straight line motion 500
Scrap iron . . . . . 41
Scrapers . . . . . 189
Scraping . . . . . 210
Screw-cutting lathe . . 141

, change wheels foi 484




Screw cutting in lathe . . 212
gearing . . . 520, 578
, leading, of lathe . . 147
pairs . . . 485
plate . . . . 193
propeller . . . . 688
-— , moulding a . 25
tap, tempering a . . 127
, the . . . . . 483
Screwed stays . . . 335, 350
Screwing stock, Whitworth’s guide 195
tackle . . . . 191
Scriber and scribing block . . 18 5
Scroll or universal chuck . . 153
Section bars, cogging and ﬁnishing 279
, rolling of . . 279
-— , rolls for . . . 298
, modulus of . . . 417
Sections, economical . . . 433
of high speed engines . 632
Setting eccentrics. . . . 272
out a Lancashire boiler . 354
— a locomotive boiler . 352
-————~ — a marine boiler . . 342
-——— —— a vertical boiler . . 356
valves . . . . 273

Shackle, forging a . .' . 108
Shackles for testing machine. . 378
for wire rope . . . 544
Shaft couplings . . . . 502
, double-throw crank 3 forging a 129
governor, Westinghouse . 655




journals . . . . 506
-—- , formula for . . 507
—— , table of pressures on 507
———, small crank; forging a . 118
——, strength of hollow round .' 419
———, of solid rectangular . 421
———-, of solid round . . 417
of square. 419

, . .
Shafting, horsepower transmitted by 507
, counter; use of . 534
, use of . . 501, 578
Shafts, moment of resistance of, see
Moment of resistance.


Shafts, square, use of . . . 508
, steel, forging . . . 133
, strength of . . . 417

, —, by direct ex-
periment . . . . . 421

Index.


- PAGE.
Shaping machine . . . . 171
Shear, strength of pins and bolts in 415
stress . . . ‘ . . 364.
—-—- action . . ‘405
, distribution of . 437
Shearing and punching machine . 289»


force . . . 438
and bending moment
combined. . . . - . 444.
Shearing machine, hydraulic. . 291
Sheave, eccentric 3 machining . 228'
Sheer legs, stresses in . . . , 471
Shell of a boiler, riveting the '. 334
Shifting eccentric, reversing by . 638
spanner . . 209
Ships’ davits . 456-
, riveting up . . 348
Shock, loss of energy by eddies and 716-
Short columns, strength of . . 405


D slide valve 636
Shrinking of castings, warping and 69
of wood . . .
Shrouding of wheels 3 single and
double . . . . . 512
Side by side engine, Willan’s . 631
Side-lever marine engine . 630'
Siemens’ electric pyrometer . . 587
Martin’s process for making
steel. . . . . . 80‘
Siemens’, Landore- 3 process for
making steel . . . . 82:
Siemens’ water pyrometer 3 Wilson’s
and . . . 587
Sight feed lubricator, ﬁxing . . 264 _


Silicon. . . . . . 73.
Simple machines, the . . 481
roof truss, stresses in a . 465,
or Watt governor . 647
Simplex gas engine . 701
— , indicator dia-
gram for . . . . .
Simplex gas engine, method of
exhausting . . .
Simplex gas engine, pendulum

705.
701

governor for . 701
Sines, curve of . . . . 496'-
Single, double, and triple stage ex-
pansion 3 advantages of . . 621
Single eye, forging a . . . 106-
geared drilling machine . 164
riveted lap joint . . . 407
Shrouding . . . 512
webbed crank, forging a . 117
Sizes of plates and rivets . . 407
of steel plates, maximum . 282
Skimming gate . . . . 38

Ina’ex. 767
PAGE PAGE
Sleeve for governor, machining . 253 Spindles, main andexpansion valve;
Slide bar and connections, machin- machining . . . . . 224
ing . . . . . . 232 Spiral mill . . . . . I76
Slide bar, pressure on . . . 448 Split pins, gauge of . . . 277
‘blocks, machining . . 238 Spray maker for Priestman oil

-——— rest of lathe . . . . 147
valve, distribution of steam by 636






—- , double ported . 6 54
—— —-, , back cut
off . . . . . . 654
—— ——-, ‘expansion . . . 262
-—_., , lap of. . . . 636
-— , lead of . . . 638
' , leaky; effect on indica-
tor diagram . . . . 618
, long D . . 636
-— ——, main; machining . 262
—-— —, normal . . . 636
, short D . . . 636
Slider-crank chain, double . . 487
, single . . 486
Sliding pairs . . . . 485
Slip of belts. . . . . 530
Slope, virtual . . . . 716
Slot drilling machine . . . 168
Slotting machine . . . . 173
Small pinions, rules for. . . 512
Smelting copper, roasting and . 83
Smithing and forging . . . 88
Smith’s blast . . . . 90
hearths . . . . 88
tools. . . . . 93
, boiler . . . 284
Smith, the . . . . . 88
Softening a casting . . . 36
Solid forging versus welding . . I 15 .
friction, laws of . . . 555
3 round shaft, strengthof . 417
Spanner, forging a . . . 108
, shifting . . . . 209
Special drilling machine . . 304
Speciﬁc heat 585
at constant pressure
and constant volume. . . 60 3
, method of ﬁnding . 586
of superheated steam 604



heats of a gas . . . 602
of substances, table of 586
volume . . . . 594
Speed cones. . . . . 534
of belts . . . . 530
of cutting tools . . . 142
of lathe . . . . 143
of mills . . . . 177
Spiegeleisen . . . 80
Spindle for governor, machining . 252

708
engine . . . . .
Spring, weak indicator; effect on



diagram of . . . . 618-
Spring.loaded safety valve . . 693.
Springs, helical; deﬂection of . 426'
, , strength of . 425
Sprues . . . . 38
Spur gearing . . . 509, 578.
wheel, making patterns of . 58
teeth, mill for . . 178
Square centreing . . . . 150~
drift . . . . 205
shaft, strength of . . 419
shafting, use of . . 508-

Stamping die . . . . 123.
, forging by . , 122
, —, examples
of . . . . . . 125
Stanhope levers . . . . 496
Star feed for lathe . . . 160'-
Starting apparatus, Priestman oil
engine . . . . . 708-
States of matter, three . . . 591
Static friction, co-eﬂicient of . 5 5 5.
Stationary engine, example of . 681

Stay, girder . . - 335, 348-
, gusset; and longitudinal . 330
-_-, palm . . - - 335
, screwed - 335: 350'
, tubes . . . - 351
Steam and water, mixtures of . 598-
cylinder, large; casting and
moulding . . . . 21
, machining . . 257



distribution by slide valve . 636



——, dry saturated . 593, 594
, eﬂiciency of . . 602
engine indicator . . . 616-
—— , Tabor . . 616~
—-—— , losses in the . . 613
hammer . . . . 97~
, force of blow of the 98, 101
, forging by . . 117
, ice and water ; relative tem-



peratures and volumes of . . 595
lap of slide valve . . 638i
, latent heat of . 592
—— port area . 681
, superheated; speciﬁc heat of 604.
-—-— used, horse power in terms of 626-

cylinders, casting rule for . 400-
Index.








PAGE ' PAGE
Steam, wet saturated . . 593, 594 Strength of pins and bolts in shear 415
Steel castings . . . 2, 42 —- pipes . . . . 397
, composition of . . . 77 —- riveted joints,see Riveted
— or iron, test for . . . 83 joint.
— plant, Bessemer . . . 79 — ro es . . . . i 397
-—— , cementation . . 78' — —- shafts, see Shafts.
—— , Siemens Martin’s . 80 —— by direct experi-
-—‘—— plates and bars, rolling of . 280 ment . . I . 421
rail, momental strength of . 434 — shear sections . . 415
—-- shafts, forging . . . 133 —-——- — short columns . . 405
tempering . . . 83, 125 —— —— structures . . . 361
---, Whitworth’s compressed . 82 ——'- —— suspension link . -. 405
Steeple engine . . - . 630 —-—-—-— —- teeth . . . . 514
Stephenson’s link motion . . 640 —— — thick cylinders . . 399
Stepped gearing . . . . 518 —— wire rope . . 397, 539
Stern tube and stem bush . . 689 Strengths of different shafts, rela-
Stock and dies . . . . 192 tive . . . . . 422
Stock, \Nhitworth’s guide screwing 195 Stress action, bending . . . 426
Stone breaker . . . . 498 ' , classiﬁcation of . 394'
Stop valve, casting and moulding. 31 , combined, see Com-
Stopping off . . . . 64 bined stress action.
Storage, electric transmission by . 551 action, compressive . . 404 '
Stores of energy, natural . . 476 -—-— , tensile . . . 395
Straight line motion, see Parallel —— , torsional. . . 417
motion. —— , shear . . . 405
Straightening roll, plate . . 298 area, virtual . . 430, 431
Strain, deﬁnition of . . . 361 caused by heating and cooling 368
diagrams, stress and . . 385 —— by impulsive load . 368
measuring . . . . 381 ——-, deﬁnition of; and kind of . 361
Strainingcylinderoftesting machine 376 diagrams, reciprocal . . 464
Strap and connecting rod end ; , line of limiting . . . 430
machining . . . . 243 , shear; distribution .of . '. 437
, eccentric; machining . . 228 strain diagrams . . 385
Straps, brake . . . 569 , tensile; by centrifugal force 400
Stream horse-power, measurement , working; decision of . . 393
of . . . . . . 714 Stresses, breaking . . . 392
Strength, momental, see Momental , , average . . 394
strength. ———, , table of . . 393
of belts . . . . 529 — in jib of a crane . . 468
—-——— —- bolts . . . . 402 —— in sheer legs . . . 471
-——— —— chains. . . . 397 ———- in simple roof truss . . 465
———-— -—— cotter joint . . ., 415 -—— in suspension bridge chain 466
—-— — coupling bolts . . 422 ——— in Warren girder . . 466'
—— — crane hooks . . 454 -—-—— in wire rope . . 542
-——— — cylinder cover bolts . 403 tensile and compressive, '
——-——— — cylinders . . . 397 nature of . . . . . 366'
—— —- ﬂat surfaces in boilers . 451 Strickling, striking, sweeping, or
—— -- fly-wheel rim . . 401 loam boards . . . . 61
-——-— — furnace tubes . . 460 Striking a pattern in loam . . 14
—--—— — helical springs . a. 425 Stringer plate or tie bar . . 412
—— — keys . . . . 423 Stroke adjustment in hydraulic
-———- —long columns . . 457 engine . . . . . 744v
——— — machine parts . . 361 Structures, braced or framed. . 463'
— materials . . . 361 of three dimensions,
—- pillarsand struts, Euler’s framed . 471.

formula for . . . . 457 ————-, strength of . 361
Index.
7 PAGE
Struts, Euler’s formula for strength of 456

Stud ﬁxing . , . . . 214
Sturtevant fan . . 90
Suction or lifting pump . . 730
" , tube for jonval turbine . 724
Sulphur‘ . . . . . 73
Sun and planetwheels . . 523
Sunk keys '. . . . . 504
Superheated steam, deﬁnition of . 594


, speciﬁc heat of 604



Supporting workin lathe . 150
Supports for cores . 39
Surface condenser . 686
' ' for horizontal
‘compound pumping engine . 684
, pitch . . 510
plates 183, 191
, originating . . 210
in boilers, strength of ﬂat . 451
Surfacing in lathe .. . . 147
Suspension bridge chain, stress in . 466
—— link, strength of 405
ABOR steam engine indicator 617
Tackle, block and . 482
, screwing . . 191
Tail prints . . 56
,Tap, screw ; tempering a . 127
'Taper rimer . . 209
Tapping a cupola . 4o
Taps, screw . . . 192
Taylor’s machine vice . . 182
Teeth of wheels . . . . 510
— , backlash in . 514
———— — —————, clearance of . 514
-——— — -——--, helical . 518
-———— — - , involute . 517
~-——- —- ———, mortice . . 518
--——-~ -— --——, names of parts of. 514
———— — —-——, pressure on . . 515
———- — , proportions of . 514
— —— , radial . . 510
— - , strength of . . 514

Telo-dynamic transmission of power 5 39
Temperature . . 584
, absolute zero of . 589
and volume, relative, of
ice, water, and steam . 595
—-———'~ pressure and volume, re-
,lative, of saturated steam . . ‘596
pressure and volume, curve
of ditto . . . 598


Tempering a chisel or drill . . 126
a screw tap . 127
—- colours . 83, 125
-—-——— steel 83, 125

769
PAGE
Templates and jigs . 274
Tensile stress action . . 395
caused by centrif. force 400




stresses, nature of . . 366
Tension and bending combined . 453
-- elements . . . . 489
, coefﬁcients of fric-
tion in . . . . . 528
in belts, centrifugal . . 530
of belts . 527
Test diagrams, automatic . 384.
for iron or steel . . . 83
requirements by Admiralty . 388
Testing machine, cement . 370
, Emery . . 376
-——— , Kennedy’s . . 372
——-— , lubricant . 563
—-— , shackles for . 378
-— , Thurston’s torsion 378
--—- , \Verder . 370
——- , VVicksteed’s . 372
, ; fulcra of. 375
machines . . . 369
Theorem, Culmann’s . . . 446
Theoretical indicator diagram, cal-
culation of work and horse power
from . . . . 625
Theories, bending . 437
Theory of'beams . . . 427
of compounding . . 614
of heat; caloric or material,
dynamical . 581
of machines . . 480
Thermal unit, British . 479, 585
Thermodynamics, ﬁrst law of . 600
, second law of . 612

Thermometer scales, conversion of 585
Thermometers . . . 584
Thomson’s turbine, construction of 726

, efﬁciency of . 726-
Thread bottom, diameter and sec-
tional area of bolt at . . 402
Threads, Whitworth . . . 192
Threecylinderengine,Brotherhood’s 6 31
states of matter . . 591
Throttling versus variable expansion 6 50
Throw of eccentric . 637
Thrust bearing 506, 688
Thurston’s torsional testing machine 378

Tie bar . 412
Tilt hammer . . . 78v
Time and distance bases (\Yeloc.) . 491
Tin, zinc, &c. . . . . 8
Toggle joint, velocity curve of; and
application of . 498
Tongs, forging a pair of . 113.
3D



Index.
7 7 0
PAGE
Tool box for planing machine . 170
holders for lathe . . I 57
Tools, boiler-maker’s . 283
-_-—, boiler-smith’s . 284
, erector’s . 202
—-—-, ﬁtter’s . . 186
, lathe . . I 56
——, machine . . . I 37
—— 3 advantage of . . 288
, marking off. . . 183
-———, moulder’s 4o
----, pattern-maker’s . . 45
—-——, planing machine . . 171
-——-, plater’s . 286
—-——-, smith’s . . . . 93
Tooth 3 ﬂank, addendum, &c., of . 514
gearing, safe velocity of . 518
, rolling a . . . . 512
Topography of indicator diagram . 618
Torsion and bending combined . 461


and compression combined 463
, angle of . . . . 424
Torsional stress action . . . 417
testing machine . . 378
Total head of water . . . 71 1
heat of steam . . . 597
Toughening cast iron . . . 3
Tower high-speed engine . 633
Tractive force of locomotive . . 693
Train of gearing . . . . 481
Trains, epicyclic . . . . 521
, reverted . . . . 523
Trammels . . . 18 5 '
Transfer of heat . . . . 581
Transformation of energy . . 477
Transmission dynamometer . . 576
of power . . . 473
, advantages,
&c., of various methods of. . 577
of powerbybelting, 526, 579
by compressed

air . . . . 545,, 580
of power by cotton
ropes - - ' 534, 579
of power
by electricity 549, 580
of power by electricity
direct or by storage . . .
of power by electricity,
efﬁciency of . . .
of power by electricity,
examples of . . .
of power
55I
55I
554
by hydraulics, 549, 580
—-——---——~ of power
by wire ropes: 539, 541:
S79


PAGE
Transmission, telodynamic . . 539
Transmitters of power . . 479
Transverse elasticity, modulus of . 363
Travelling crane driven by cotton
rope gearing
crane

driven. by square
shafting 509
crane driven by wire

rope gearing . . . 543
Treble geared lathe 157, 159
riveted butt joint . 41 1
Trials, brake . 5 56
Triangle of forces. . 464
Trip gear, Corliss . 657
-—— , Proell. . 658

Triple expansion marine engine . 68 5
stage expansion, advantages of 621


Trunk engine, Penn’s . . 63o
Truss, roof 3 with ﬁve cells . . 470
, simple roof 3 stresses in a . 465
Tube beader and cutter . 326
expander . 324
ignition in gas engine . . 700
Tubes, boiler stay . 351
, furnace . 347
3 Fairbairn’s, and

Bdard of Trade rules for . 460
, Galloway . 332
, Marriotte’s . . 588
T ubulous or water-tubeboileis 337, 3 56

Tumbler bearing . . 509
Turbine, Fourneyron . 723
, Girard . 724
, _Ionval . . 724
, reaction wheel. . 723
, Thomson’s . 726
Turbines . .' . 723
, classiﬁcation of . 727
, comparative efﬁciency of
different . . . . . 726
, fundamental equation for . 728

, path of water in . 726
Turning pairs . 485
Turret-head lathe . . 200
Twin mills . . 176
Twist drill . . . . . I66
—— —-——, form of cutting edge of 197
———— ——-—- grinder. . . 197
NDERSHOT water wheel . 721
Uniform forces, work done by 366
Uniform strength, beams of . . 452
Universal chuck . . 153
ﬂanging press . 300
—————— joint, I-Iooke’s or . . 504
—--——— milling machine . 179
Use of linkwork . . 496,
-—- ofmachine tools on locomotive
boilers . . . - .
of machine tools on marine
boilers . . .
of machine tools on ships


-—— of shafting . 501,
Uses of drilling machine .
‘ -— of friction
ACUUM gauge . . .
Value of good and bad con-
ductors, relative . .
Valve, back-cut-off . . .
; double ported

, Corliss . . .
, Cornish double beat
diagram, Zeuner’s . .
, fundamental
diagrams, Zeuner’s; pro-
blems in . .
gear, Corliss .
for high duty
thington engine . . .
gear for oscillating engine .


‘Wor:

index.
PAGE
577
318
- 319
. 320
578
303
- 569
694
- 583
652
654
656
. 636
660
661
. 663
657
732
644
for Worthington pump 7 3 1
--—— ——, Hackworth’s . . 643
-———— , Joy’s . . . 642
— ——, Marshall’s . . 643
-—— ——-, Proell . 658

...——
, radial; reversing by



642
-— , Walschaert’s . . 643
, grel . . . . . 735
, gridiron . . . . 654
guide bracket, machining . 228
, Meyer expansion . . 6 52
-——, , double ported 6 54
, reversing, for hydraulic
engine . . . . 742
rod; machining . 226
setting . . . 273
, slide, see Slide valve.
Valves, relief . 686
, safety . . . . 693
Vane, best form of water wheel . 719
Vaporiser for Priestman oil engine
Vapours, isothermals of, steam and
other . . .
Variable expansion . . .
by automatic cut
off

expansion by linking up
—— gear, Meyer
versus throttling
forces, work done by
Vector, radius .


708
. 608
650
- 657
. 651
. 652
6 5o
. 366
. 490


7 7 I
PAGE
Velocity . . . 473
accelerated . 473
curves 490
energy, head pressure and. 711

of water through oriﬁces . 712
ratio of crank and connect-
ing rod . . . . 490
ratios in kinematics . . 489
, safe; of toothed gearing . 518
Velocities in linkwork, relative . 492
, principle of virtual . 481
Vent holes for moulds . . . 6
Ventilated buckets for water wheels 720


Venting foundry ﬂoors . . 39
Vertical boilers . 337
milling machine . 180
Vice, instantaneous grip . 187
, leg . . . . 186
—, machine, Taylor’s . 182
, parallel . 187
Virtual centre . 490
slope. . 716
stress area. . . 430
velocities, principle of . 481
Viscosity of oils . . . . 562
Volume, constant; speciﬁc heat at 603
, relative, of steam and water 593
, , temperature and;
of ice, water, and steam . . 595
, relative temperature pres-
sure and; of steam . . . 596
, relative; temperature, &c.,
. 598
- 594
curves of . . . .
, speciﬁc, deﬁnition of
Volumetric elasticity, modulus of . 363
498
504
643




AGON brake . . .
\Nall box and wall bracket
Walschaert’s valve gear



Warping and shrinking of castings 69
of wood . . . 43
\Narren girder, stresses in . 466, 467
\Naste of fuel . . . 698
l/Vater and steam, mixtures of . 598
— , relative volumes
and temperatures of ice . 595
discharge from oriﬁces . 711
._-__-_ , co-
eflicients of . . . 712
energy, Froude’s experi-
ments on . . . ~ . . 711
, latent heat of . . . 591
pyrometer; \Nilson’s and
Siemens’ . . . . 587
, total head of . 711
wheel, breast . 720
772

PAGE
Water wheel, overshot . . 720
-—-, Pelton . 722
--—- -—-, sluice governor . 720
———~- —--~---, undershot . 721

vane, best form of . 719
--—, ventilated buckets for 720
, weight and impulse
machines .

. . . . 720
with curved or radial
vanes, pressure of water jet on . 719

Water-tube or tubulous boilers . 337
Watt governor, simple or . 647
Watt’s parallel motion . 499
Weak indicator spring, effect on
diagram . . . . 618
Weight machines (water wheel) . 720
Weighted or Porter governor . 648
Welding by ﬁre . . . . 102
by electricity, Bernardos’
process . . . . 327
, Thomson’s process 327
versus solid forging . . 115
Werder testing machine . . 37o
high-speed engine . . 633




Westinghouse shaft governor . 655
Weston’s clutch . . . . 569
pulley block . . 203
Wet saturated steam . 593, 594
Wheel and axle . 481

, compound . . 483
moulding, bevel . . . 34
by machine . . 31
teeth . . . . . 510




—— , bevel . . . . 520
—-——— , spur; mill for . . 178
trains, epicyclic . . . 521
-——- , reverted . . . 523
Wheels, internal or annular . . 514
, mitre . . . . . 520

—-— of lathe, change . . . 147

——, sun and planet . . 523
Wheel-vanes, turbine . 724, 726
, water . 719
Whirlpool chamber of centrifugal
pump . . . . . 728
White cast iron . . . . 1
-—--— metal . . . . . 85
White’s straight-line motion . . 510
transmission dynamometer 576
Whiton’s-chuck . . . 152
Whitworth compressed steel . . 82
guide screwing stock . 19 5

quick return, velocity
curve for . . . . . 492
threads . . . 192
Wicksteed’s testing machine . . 372

Index.
PAGE;
Willan’s side by side engine . . 631
Wilson’s and Siemens’ water pyro-
meter . . . . . 587
Wind pressure . . . 471
Wire drawing, effect upon indicator
diagram of . . . . 618
Wire rope, and
strength of _ . . 539
———, gearing . . 539, 579
, pulleys f0 . 540
construction

__-


--—- ———, shackles for . 544.
—— —-—, stresses in . . . 542
—-—— transmission, uses of . 541
Wbhler’s law . . . . 390
Wood for pattern making . . 43
used by engineers. . . 87
' , warping and shrinking of . 43
Wood-turner’s lathe . . 46
Work and horse power from indica:



tor diagram . . . . 625
done by uniform and variable
forces . . . . 366
during evaporation . 600
—-~-— in deforming a bar . 366-
for lathe, centreing . . 151
lost in friction . . . 5 58

—-——, principle of. . . . 481
stored in hydraulic accu-
mulator . . . . . 738
supported in lathe . . 150
Working stress, decision of . . 393
valve for hydraulic lift . 742
Worm gear, jack with . . . 205
gearing . . . 520
--—- wheel, casting and moulding a 10
, hobbing a . . ‘274
-—~— , making pattern for . 58
Worthington high duty engine . 731






; valve
gear . . . . . . 732
~-—-— pump . . . 731
Wrist plate . . . . . 658
Wrought iron, brands of . . 76
, casting of . . 87
-—--, reﬁning and puddling 74
YIELD point . . . . 363
ERO, absolute, of temperature 589
Zeuner diagrams applied to
link motion . . . .
Zeuner diagrams applied to Meyer
valve . . . . . 664
expansion curve . 608
valve diagrams, see Valve
diagrams

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IGINAL SOLE MAKERS OF
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Sizes, Prices, and particulars on application.

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‘ SONNBNTHAL 85 00...
85 QUEEN VICTORIA STREET, LONDON,
SELIG,
EC.
THE ‘SUNDALE’ MILLING MACHINE.
With Automatic Vertical, Horizontal, and Transverse
Feeds.
All Feeds are reversible without changing the belt. All Feeds can be operated
simultaneously or separately. The table can be swivelled to various angles.
With the Vertical and Angular Milling Attachment, the Machine can also be used
' for Boring, Drilling, Facing, Keyseating Shafts, Rack Cutting, &c., and with the Cir-
cular table, operated by worm wheel and dividing arrangement, Spur Gears, Hollow-
faced Worm Wheels, &c., can be cut.


Makers of
LATHES, DRILLING MACHINES
(Radial and other).
Makers of
PLANING, SCREWING, and other
Machine Tools.


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SOLE LIGENIS’EES:
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85 QUEEN VICTORIA STREET, LONDON, E-Oi
3 E
‘CHAPMAN & HALL’S
SCIENCE PUBLICATIONS.
ADAMS (HENRY), M. Inst. C.E., .M. [.Mcch.E., F.S.I., &c., Professor W'Engineering at
the City of London C alleg' ——
KEY TO EXAMINATIONS OF SCIENCE AND ART DE-
‘ ~PARTMENT. Subject IIL—BUILDING CoNsTRUcTioN. Crown 8vo. 4s.
MILLS (F.), F.R.A.S.
ELEMENTARY PHYSIOGRAPHIC ASTRONOMY. Crown
8vo. 1s. 6d. '
ADVANCED PHYSIOGRAPHY. Crown 8V0. 4s. 6d.
‘ALTERNATIVE ELEMENTARY PHYSICS. Second Edition.
Crown 8vo. 2s. 6d.
1*: These books are specially adapted to meet the requirements of the Syllabus of the
Science and Art Department.
MILLS (F.), F.R.A.S.,' and NORTH (19.)—
QUANTITATIVE ANALYSIS (Introductory Lessons on). Crown
8vo. 1s. 6d.
HANDBOOK OF QUANTITATIVE ANALYSIS. Cr. 8vo. 3s.6d.
WRIGHTSON (PROF. [OI-IN), M.R.A.C., F.C.S., &c.; Examiner in Agriculture to the
Science and Art Department; Professor of Agriculture in the Normal School of
Science, 69%., ﬁre.
PRINCIPLES OF AGRICULTURAL PRACTICE AS AN
INSTRUCTIONAL SUBJECT. With Geological Map. Second Edition. Cr.
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FALLOW AND FODDER CROPS. Crown 8V0. 5s.
LE comm" (]OSEPH)—
IIEVOLUTION AND ITS RELATIONS TO RELIGIOUS
'lHOUGt-IT. Crown 8vo. 6s.
PRA TT (R .), Head Master, School of Science and Art, Barro w-z'n- Furness.
SCIOGRAPHY, OR PARALLEL AND RADIAL PROJEC-
TION OF SHADOWS. Being a Course of Exercises for the use of Students in
Architectural and Engineering Drawing, and for Candidates preparing for the Ex-
aminations in this subject and in Third Grade Perspective. With numerous Plates.
Oblong 4to. 7s. 6d.

SCHA UERJWANN (F. L.)—
WOOD-CARVING IN THEORY AND PRACTICE, as applied
to Home Arts. With 124 Illustrations. Second Edition. Imperial 8vo. 5s.
OLIVER (PROFESSOR)—
ILLUSTRATIONS OF THE VEGETABLE KINGDOM. New
and Cheaper Edition. 109 Plates, coloured. Royal 8V0. 16s.
GOWER (A. R.)—
PRACTICAL METALLURGY. With Illustrations. Crown 8V0. 3s.
DOUGLAS (]0HN)-— .
SKETCH OF THE FIRST PRINCIPLES OF PHYSIO-
GRAPHY. With numerous Illustrations. Crown 8vo. 6s.

LONDON:
CHAPMAN 8c HALL, Ltd., Agents to the Science 8c Art Department.
(the (BoIbsmitbs’ Gompanv’s
TECHNICAL 81 RECREATIYE INSTITUTE,
NEW GROSS, $-13-

. qfbairman at‘ @nhernnm:
THE PRIME WARDEN OF THE WORSHIPFUL
COMPANY OF GOLDSMITHS.
Deputy Qlbatrman:
SIR FREDERICK ABEL, BART., K.C.B., D.C.L., F.R.S., D.Sc.,
I HON. MEMBER INST. C.E. AND ME.
@etretarg:
J. s. REDMAYNE, B.A.

(technical ano (Beneral Glasses.
THE educational facilities offered to Students are amongst the most
complete in London. N0 expense has been spared in the equipment of
the laboratories, workshops, and class-rooms, and the tuition is of the
highest character, the courses of instruction being both theoretical and
practical. Special Honours Classes are formed in most Lecture subjects.

T/ze EDUCATIONAL WORK is divided among Z/ze following Departments,
wil/z Slaﬁ’ of doom‘ sixty [nslxuez‘ors :—
ENGINEERING AND MECHANICAL!
Head—W. J. LINEHAM, M. l. Mec.E., and fourteen Assistants.
WORKSHOP CLASSES. LECTURES.
Carpentry, General. Applied Mechanics.
,, Building. Building Construction.
,, Household. Carpentry and Joinery.
,, Teachers in Training, Brickwork and Masonry.
Fitting and Machining. Mach?“ Drawmg-
Pattern Making Practical Solid Geometry.
1 b. Steam and other Heat Engines.
P u_m _mg' Mechanical Engineering. ‘
Smithing. ‘ . Plumbing. '
Brick Cutting. Gas-making Apparatus.

Chemistry: Head-—A. G. BLOXAM, F.I.C.
Practical and Theoretical Inorganic and Organic Chemistry.
Technical Laboratory Work. Tanning. Gas Manufacture.
Practical and Theoretical Photography.
Electrical Engineering‘ : Head—H. H. SIMMONS, A. I.E. E.
Practical Laboratory and Lecture Courses.
Mathematics and Physics: Head—O. GLYNNE JONES, B.Sc.Lond.
Mathematics. Theoretical Mechanics.
Electricity and Magnetism. Physics.
[Continued
THE GOLDSMITHS’ INSTITUTE, New Cross,‘ SE.
( Continued).
School of Art (Day and Evening) .: Head—j. HILL.
Nude Life. Design. Modelling. Wood Carving, etc.
Commercial and Civil Service : Head—G. E. CLARK.
General Commercial Subjects. _
Languages. Civil Service. Practical Telegraphy.‘
Music: Head—DR. CHURCHILL SIBLEY.
Theory of Music. Piano. Violin. Solo 'Singing. Mandoline.
Institute Choir and Orchestra, etc.
Miscellaneous and Women’s Classes:
Botany. Hygiene. Physiology. Ambulance.‘ 'Dressmaking. '
Cookery. . Laundry. Millinery, etc.

REDUCTIONS OF FEES TO ARTISANS.—Certain classes at the Institute
are open to a limited number of bona ﬁde artisans and handicraftsmen
making application in September of each year, on payment of half the
ordinary fees. Particulars will be forwarded upon application.
N

WW‘-
The Classes are open to all, irrespective of Membership.

ADVANTAGES OF M EMBERSHIP.
Library (Lending and Reference). Cinder Running Track.
Technical Museum. Reduced Admission to Concerts and
' Reading and Writing Rooms. Saturday Entertainments.
Social and Club Rooms. Large Swimming Bath.
, Free Organ Recitals. Refreshment Rooms.
Two Recreation Grounds.
GYMNASIA FOR BOTH SEXES.

SUBSCRIPTIONS PER ANNUM :
Non-Students. Students.
Men ............................... .. 12/_ 7/-
Women ......................... .. 9/-
5]-

'LIST OF CLUBS AND SOCIETIES
. _ (Open to Members only).
Athletic and Harriers. I Cycling.
Chess and Draughts. 5 Lawn Tennis.
Football (Association and Rugby). ' Ramblers (Men).
Cricket. Ramblers (Women).
Parliamentary Debating. ‘ Swimming (Men).
Literary (Men). Swimming (Women).
literary (Women). Volunteer Company.
Engineering. Choir and Orchestra.
Electrical Engineering‘. shorthand.
Chemical. Provident.
French. Camera.
Rowing‘. Quoits and Bowls.
Boxing.
\f
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