:HANl< 
 
 OJILDERS' 
 
 HOISTING 
 ACHINEKY 
 
 
 California 
 3gional 
 tcility 
 
 EDITED BY 
 
 PAUL N. HASLUCK
 
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 HANDICRAFT SERIES. 
 
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 Edited by PAUL N. HASLUCK, Editor of "WORK." 
 
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 CASSELL K COMPANY, LIMITED, 43 & 45, Kast i 9 ;A Street, .Yew York.
 
 BUILDERS' 
 
 HOISTING 
 MACHINERY 
 
 Simple Lifting: Tackle; Winches; 
 Crabs ; Cranes ; Travellers ; Motive 
 Power for Hoisting- Machinery 
 
 S. 
 
 SA fl FRANCISCO, GAL. 
 
 Edited by 
 
 PAUL N. HASLUCK 
 
 Editor of "Work," '"Building World," etc. etc. 
 
 CASSELL & COMPANY, Limited 
 
 London, Paris, New York & Melbourne 
 
 MCMIV All Rig fits Reserved
 
 Library 
 
 TJ 
 
 PREFACE. 
 
 THIS Manual contains, in form convenient for every- 
 day use, a comprehensive digest of the knowledge of 
 Builders' Hoisting Machinery scattered over seventeen 
 volumes of BUILDING WORLD one of the weekly 
 journals it is uiy fortune to edit. 
 
 It may be mentioned that a series of articles from 
 the pen of Mr. Joseph Horner is incorporated in the 
 text. 
 
 Additional information on the matters dealt with 
 in this Manual, or instruction on kindred subjects, 
 may be obtained by addressing a question to BUILDING 
 WORLD, in whose columns it will be answered. 
 
 P. N. HASLUCK. 
 
 La Belle Sauvnge, London, 
 June, 1904. 
 
 733292
 
 CONTENTS. 
 
 CHAPTER p A t:E 
 
 I. Introduction : Simple Lifting Tackle . . 9 
 
 U. Hand Crabs or Winches 15 
 
 III. Travelling Crabs, Hand and Power . . 31 
 
 IV. Cranes rind Travelling Crabs : Their Details 
 
 of Construction 48 
 
 V. Applying Motive Power to Hoisting 
 
 Machinery . . . . . . .71 
 
 Index . 1)4
 
 LIST OF ILLUSTRATIONS. 
 
 FIG. PAGE 
 
 1. Side Elevation of Fixed 
 
 Pulley .... 11 
 2. Front Elevation of 
 
 Fixed Pulley ... 11 
 3. Side Elevation of Com- 
 mon Pulley Blocks . 13 
 4. Front Elevation of Com- 
 mon Pulley Blocks . 13 
 5. Differential Pulley 
 
 Blocks .... 13 
 6. Hand Crab with Cast- 
 iron Cheek ... 15 
 7. Hand Crab with Steel 
 
 Cheek .... 16 
 8. Side Elevation of Cast- 
 iron Winch Cheek . 17 
 9. Front Elevation of Cast- 
 iron Winch Cheek . 17 
 10. Wrought Winch Cheek 18 
 11. Section of Cast-iron 
 Cheek Ribbed both 
 Sides .... 18 
 12. Section of Cast-iron 
 Cheek Ribbed One 
 Side only ... 18 
 13. Elevation of Shaft 
 
 Bearings . . . .19 
 14._Section of Shaft Bear- 
 ings 19 
 
 15. Side Elevation of Sin- 
 gle-purchase Crab . 21 
 16. Front Elevation of 
 
 Single-purchase Crab . 21 
 17. Side Elevation of 
 
 Double Gear for Crab . 22 
 18. Front Elevation of 
 
 Double Gear for Crab . 22 
 19. Elevation of Another 
 
 Double Crab Gear . 23 
 20. Plan of Double Crab 
 
 Gear .... 23 
 21. Wheel Tooth ... 23 
 22. Cycloidal Teeth . . 25 
 23. Knuckle Gear . . 26 
 
 24. Arm of Pattern Wheel . 27 
 25. Arm of Pattern Wheel . 27 
 26. Arm of Machine Wheel. 28 
 27. Elevation of Wall 
 
 Winch .... 29 
 
 FJG. PAGE 
 
 28.-Plan of Wall Winch . 29 
 
 29. Front Elevation of 
 Jenny for Traveller 
 Blocks .... 34 
 
 30. Plan of Jenny for Tra- 
 velling Blocks . . 34 
 
 31. Elevation of Jenny with 
 
 Gearing . . . .36 
 
 32. Plan of Jenny with 
 
 Gearing .... 36 
 
 33. Diagram of Overhead 
 
 Crab Gear ... 37 
 
 34. Plan of Overhead Crab 
 
 Gear .... 38 
 
 35. End View of Overhead 
 
 Crab Gear . . .39 
 
 36. Overhead Crab Hoisting 
 
 Gear .... 41 
 
 37. Edge View of Cast-iron 
 
 Cheek for Hand Crab . 42 
 
 38. Elevation of Cast-iron 
 
 Cheek for Hand Crab . 42 
 
 39. Wrought Cheek for 
 
 Hand Crab ... 43 
 
 40. Plan of Light Traveller 
 
 Framing ... 49 
 
 41. End View of Light Tra- 
 veller Framing . . 49 
 
 42. Side View of Light Tra- 
 veller Framing, etc. . 51 
 
 43. Half Elevation of Built- 
 up Girders for Travel- 
 ling Framework . . 52 
 
 44. Longitudinal Section 
 of Built-up Girders for 
 Travelling Framework 52 
 
 45. Plan of Built-up Girders 
 for Travelling Frame- 
 work .... 52 
 
 46. Section of Girder . . 53 
 
 47. End Cradle for Jenny 
 
 Traveller .... 55 
 
 48. Plan of End Cradle for 
 
 Heavy Traveller . . 56 
 
 49. Section of End Cradle 
 
 for Heavy Traveller . 57 
 i 50. Section of "Box Girder . 61 
 
 51. Diagram of Load on End 
 
 Cradle .... 61
 
 viii BUILDERS' HOISTING MACHINERY. 
 
 FIG. 
 
 52. Diagram -of 
 
 PAGE 
 
 Load on 
 
 FIG. PAGE 
 
 67. End View of Rope or 
 
 End of Trave 
 
 ler Beam 
 
 61 
 
 Chain Wheel with 
 
 
 53. Diagram of 
 Truss with 
 
 Simple 
 Central 
 
 
 Guide Pulleys 
 68. Front View of Rope or 
 
 73 
 
 Load 
 
 
 62 
 
 Chain Wheel with 
 
 
 54. Diagram of Compound 
 Truss with Central 
 
 Guide Pulleys 
 69. Rope or Chain Wheel . 
 
 73 
 74 
 
 Load 
 
 
 62 
 
 70. Section of Rope In 
 
 
 55. Diagram of C 
 
 ompound 
 
 
 V-rim of Pulley . 
 
 74 
 
 Truss with I 
 
 oad over 
 
 
 71. Rim of " Waved " Rope 
 
 
 One Strut 
 
 
 63 
 
 Wheel .... 
 
 74 
 
 56. Calculation of 
 of End Cradl 
 
 'strength 
 2 Axles . 
 
 64 
 
 72. Longitudinal Section of 
 Nibbed Wheel Rim 
 
 75 
 
 57. Struts for 
 
 Timber 
 
 
 73. Cross Section of Nibbed 
 
 
 Beams 
 
 
 65 
 
 Wheel Rim . 
 
 75 
 
 58. Section of 
 
 Traveller 
 
 
 74. Plan of Nibbed Wheel 
 
 
 Axle Wheel 
 
 
 67 
 
 Rim 
 
 75 
 
 59. Section of 
 
 Traveller 
 
 
 75. Longitudinal Section of 
 
 
 Axle Wheel 
 
 
 67 
 
 Wheel Rim with Cast 
 
 
 60. Elevation of 
 
 Traveller 
 
 
 Recesses .... 
 
 77 
 
 Axle Wheel 
 
 
 67 
 
 76.-^Square-shaft Traveller . 
 
 79 
 
 61. Section of 
 
 Traveller 
 
 
 77. End Elevation of 
 
 
 Axle Wheel 
 62. Elevation of 
 
 Traveller 
 
 68 
 
 Square-shaft Driving 
 Gear .... 
 
 81 
 
 Axle Wheel 
 
 
 68 
 
 78. Plan of Square-shaft 
 
 
 63. Elevation of 
 
 Cast-iron 
 
 
 Driving Gear . 
 
 81 
 
 Bearing . 
 
 
 69 
 
 79, 80. Sliding Pinion on 
 
 
 64. Section of 
 
 Cast-iron 
 
 
 Gantry Shaft . 
 
 83 
 
 Bearing . 
 
 
 G9 
 
 81. Scarf Joint in Shaft 
 
 84 
 
 65. Cast-iron Bear 
 
 ng ! 
 
 70 
 
 82, 83. Front and Side Ele- 
 
 
 66. Single Gearing 
 
 Wheels . 
 
 72 
 
 vations of Tumbler . 
 
 85
 
 j 
 
 CW Mec/ianical Engineer. 
 
 SAN FIUNCISCO; CALj 
 
 BUILDERS' 
 HOISTING MACHINERY. 
 
 CHAPTER I. 
 
 INTRODUCTION: SIMPLE LIFTING TACKLE. 
 
 HOISTING machinery of some kind is indispensable 
 to every building and contracting firm. The limits 
 of human strength are soon passed, and the range 
 of service of the common pull-ey blocks is very 
 limited. When much heavy material has to be 
 handled the employment of unsuitable hoisting 
 machinery has a very marked effect on profits. 
 
 The principal kinds of hoisting machinery for 
 builders and contractors are the following : Pulley 
 blocks ; winches or crabs single, double, and 
 treble-geared, operated by hand or by steam, fixed 
 on the ground, or made to travel on gantries ; 
 fixed warehouse cranes, whip cranes, wharf cranes, 
 and quarry cranes, operated by hand ; fixed der- 
 rick cranes, w r orked by hand or steam ; steam 
 hoists, or hoisting engines, made semi-portable, 
 to do work in any locality, as the portable engine 
 does for agriculture ; travelling or portable cranes, 
 operated by hand or by steam, for use in large 
 yards and on wharves, with or without derricking 
 arrangements for the jib ; overhead gantry cranes, 
 with jibs, worked by hand or power, used for 
 similar purposes as the last-named, but moved on 
 a high gantry clear of lines of rails arid traffic 
 beneath ; jennies, overhead travelling cranes, or, 
 more properly, crabs, destitute of jibs, used in
 
 10 BUILDERS' HOISTING MACHINERY. 
 
 yards and in workshops, made in a wide range 
 of powers, and actuated by hand, steam, or elec- 
 tricity ; gantries, both fixed and portable, for 
 travelling crabs, made in timber, iron, and steel ; 
 lifts in warehouses and shops, actuated mostly by 
 hydraulic power. 
 
 In addition to the above-named, many other 
 types of hoisting machinery are constructed ; but 
 the list given covers the whole range of that used 
 by the builder and contractor. The construction 
 of hoisting machinery has been revolutionised dur- 
 ing the last quarter of a century, and goods and 
 materials are moved, loaded, and discharged, and 
 workshop and yard operations performed with a 
 celerity little short of marvellous. 
 
 The present intention is to consider the machin- 
 ery, not from the point of view of the maker, but 
 from that of the builders and contractors who pur- 
 chase and use it, so that instead of going exten- 
 sively into questions of stresses and the calculation 
 of certain dimensions, the types of cranes that are 
 best adapted for certain kinds of work will be con- 
 sidered, and why they are so adapted will be ex- 
 plained. The weaker points of construction, the 
 dangers incidental to working, the more vulnerable 
 parts, the question of preservation, of repairs and 
 renewals, of materials, workmanship, prices, etc., 
 will be discussed, making the handbook a very 
 practical guide for those who are not engineers. 
 In a few instances, details of construction will be 
 given, chiefly in the case of timber work, which 
 can well be prepared in a builder's own yard, and 
 in the case also of certain important details with 
 which all crane users should be familiar. 
 
 The hoisting machinery used by contractors and 
 builders is mostly operated by hand, or by steam. 
 Much of this machinery, of course, cannot be con- 
 structed by any but an engineer. Yet there are 
 some very simple types which can be made econo-
 
 SIMPLE LIFTING TACKLE. 
 
 11 
 
 mically in a contractor's own yard cranes and 
 travellers, into the construction of which timber 
 chiefly enters. There is also some of the plainer 
 work which need occasion little difficulty, and 
 there is also second-hand stuff which can often 
 be bought for the price of old iron, and altered, 
 and done up for temporary, or even for permanent 
 service. 
 
 All hoisting machinery consists, essentially, of 
 the framing and the gearing. Tiie framing in a 
 crane comprises cheeks or side frames, jib, tie- 
 rods, and post ; in a portable crane it also involves 
 
 Fie.1. Fig. 2. 
 
 Figs. 1 and 2. Fixed Pulley. 
 
 ths truck. In a crab, it consists of cheeks only. 
 Timber, iron (both cast and wrought), and steel 
 are used for these parts. Each is preferable in 
 some cases to the others. The gearing comprises 
 toothed wheels, barrel or drum, winch handles, 
 shafts, clutches., brakes, etc., everything, in short, 
 which is concerned directly with the hoisting and 
 lowering of loads, and the slewing, travelling, and 
 reversing motions of the machine. In single gear, 
 there is but one pinion and one wheel between 
 1 the winch and the barrel ; in double gear, two 
 pinions and two wheels ; in treble gear, three
 
 12 BUILDERS' HOISTING MACHINERY. 
 
 pinions and three wheels. Cranes, winches, and 
 crabs of all types are manufactured with single 
 gear, double gear, or with both single and double 
 gear. Since with increase in power the speed is 
 diminished, a keen foreman or employer will 
 always insist that the attendant shall not use a 
 high power for hoisting if a lower one will answer. 
 Further, if a crane or crab is fitted with sufficient 
 brake power, the load should always be lowered 
 with the brake, and not by means of the gearing. 
 
 The simplest element in lifting tackle is the 
 common gin-block, rubbish pulley, or monkey 
 wheel (Figs. 1 and 2), the " fixed pulley " of the 
 writers on mechanics. It is suspended by means 
 of its hook from any convenient point of support, 
 as a timber or other beam, a rope is rove over the 
 sheave, the load being suspended from one end, 
 and the hauling taking place at the other; while 
 the frame prevents the rope coming out of the 
 groove. The pulleys are made from 3 in. to about 
 22 in. in diameter. There is no mechanical gain in 
 this, since a pull equal to the load must be exerted 
 to maintain it in equilibrium. Its sole value, 
 therefore, is that by its use a change in the direc- 
 tion of motion is conveniently effected, the direc- 
 tion of the pull whether vertical or diagonal not 
 affecting the result. This type of pulley occurs 
 in the crane in the jib-wheel, which changes the 
 direction of the chain or rope at the head of the 
 jib to the vertical. It occurs also in some der- 
 ricking gear, in motion for racking a jenny along 
 a traveller, and in other parts. 
 
 Two views of a common form of pulley-block are 
 shown by Figs, 3 and 4. There may be one, two, 
 or three sheaves in the fixed block, and the same 
 number in the movable block. In each case the 
 mechanical gain is estimated by the number of 
 times the rope leads off from the lower or movable 
 pulleys. If it leads off five times, as in the figure,
 
 SIMPLE LIFTING TACKLE. 
 
 13 
 
 Fig. 3. Fig. 4. 
 
 Figs. 3 and 4. Common Pulley Fig. 5. Differential 
 Blocks. Pulley Block. 
 
 "the theoretical gain is 5 to 1. In practice it is 
 considerably less than this, because of the friction.
 
 14 BUILDERS' HOISTING MACHINERY. 
 
 The theoretical gain follows from the law of virtual 
 velocities, or the principle of work ; for in order 
 that the lower block shall be raised 1 ft. the rope 
 must be pulled out 5 ft. 
 
 Pulley-blocks are used in yards and factories for 
 almost any class of work, being readily carried 
 from place to place, and slung from beams and 
 principals. They occur in heavy cranes, in the 
 snatch-blocks, or return blocks as they are called, 
 in which the pulleys may number one, two, or 
 three. Owing to the different rates of motion of 
 the various bights of the rope, there is much slip 
 and friction between the rope and the pulleys. 
 To obviate this, White's tackle was invented, in 
 which the sizes of the pulleys are so proportioned 
 to the velocities of the rope that no slip shall take 
 place, and the friction of six separate pulleys is 
 reduced to that of two. 
 
 The differential or Weston pulley-block (Fig. 5) 
 does not run down of itself. The load has to 
 be lowered by the chain as well as lifted. This 
 is due to the excessive amount of friction devel- 
 opeda property which might appear to bs an evil 
 but one which actually contributes to the effici- 
 ency of the machine. The fixed pulleys are in one 
 casting, and an endless chain passes over these 
 and over the movable pulley below. The mechani- 
 cal advantage is due to the difference between 
 the diameters of the two fixed pulleys. Hence 
 the rule : The power multiplied by the diameter 
 of the larger pulley is equal to the weight multi- 
 plied by half the difference between the diameters 
 of the larger and smaller pulleys. These pulleys 
 are always used with chains, as ropes would slip ; 
 the sheaves are grooved out with recesses to take 
 each individual link. Like other pulley blocks, 
 they are slung from any convenient support. They 
 will lift loads up to 3 tons or 4 tons ; but they 
 are nec3ssarily very slow in their action.
 
 15 
 
 CHAPTER II. 
 
 HAND CRABS OR WINCHES. 
 
 HAND crabs, or winches as they are termed (Figs. 
 6 and 7), are hoisting machines employed by 
 masons and builders for hauling goods and mater- 
 ial to the uppar portions of buildings or of works 
 
 Fi.r. 0. Hand Crab with Ca^t-iron Check. 
 
 in progress. Their convenience lias in their por- 
 tability, a crab being moved easily from one part 
 of a yard to another; shear legs, a beam, or a 
 wall forms a convenient point of attachment for 
 the sheave pulley (Fig. 1) over which the rope or 
 chain which lift* t'ne load is reeved. 
 
 They are made in many sizes, their power rang- 
 ing from a single-geared winch lifting \ ton, to a 
 treble-geared winch lifting, perhaps, with double- 
 sheave blocks and snatch-block, 25 tons or 30 tons.
 
 16 BUILDERS' HOISTING MACHINERY. 
 
 These are also the cheapest kind of lifting tackle 
 which can be purchased, the parts being extremely 
 few. The cheeks of winches are made either of 
 cast-iron (Figs. 6, 8, and 9), or of wrought-iron or 
 steel (Figs. 7 and 10). The first are more liable to 
 fracture when subject to rough usage, hence it is, 
 in certain cases, as when in the midst of rough 
 work, and when required for shipment abroad, 
 
 Fig. ".Hand Crab with Steel Cheek. 
 
 good policy to pay the higher price for the 
 wrought-iron frames. 
 
 The neatest and strongest type in cast-iron is 
 that in which a central web has double ribs on 
 each side (Fig. 11). Sometimes the ribs are only 
 cast on one side, as shown by Fig. 12. Where the 
 distance stays or bolts pass through to connect 
 the frames there should be thickening bosses com- 
 ing flush, or nearly so, with the edges of the ribs. 
 These are shown at A (Figs. 8 and 9). Framings 
 other than of cast-iron are constructed with plate
 
 HAND CRABS OR WINCHES. 
 
 17 
 
 and angle wrought-iron and steel. In the case of a 
 light crab, the angle is riveted along the bottom 
 edge only (Figs. 7 and 10). In large heavy cheeks 
 the angle iron in one strip is bent round to the 
 entire outline of the cheek, and welded up at one 
 corner, and riveted on the plate. Examples of 
 this kind will be given in due course. 
 
 Fig. 8. Fig. 9. 
 
 Figs. 8 and 9. Cast-iron Winch Cheek. 
 
 When frames are plated, the shaft bearings 
 cannot be formed in the frames as in Figs. 6 and 8, 
 but must be made as separate cast-iron bosses, 
 seen in Fig. 10, and riveted on the frames. Fig. 
 13 illustrates a boss to an enlarged scale, showing 
 the mode of its attachment, A being the boss and 
 B the framing. A portion of the boss is turned 
 to fit a hole bored in the frame, and this, with 
 the bolts, prevents movement. Fig. 14 is a sec- 
 tion of the bearing shown by Fig. 13.
 
 18 
 
 BUILDERS' HOISTING MACHINERY. 
 
 In winches exposed to the weather, all bearings 
 should be bushed with gun metal, as shown in 
 Figs. 10, 13 and 14, in order to prevent the undue 
 abrasion or attrition which results from rusted 
 surfaces in contact. The length of the barrel, and 
 correspondingly the lengths of the shafts, will 
 depend on the quantity of rope or chain which has 
 to be coiled, but cost increases with length. All 
 
 Fig. 11. Section of 
 Cast - iron Cheek 
 Ribbed Both Sides. 
 
 Fig. 12. Section of 
 Cast - iron Cheek 
 Ribbed One Side 
 onlv. 
 
 Fig. 10. Wrought Winch Cheek. 
 
 winches should be firmly bolted to a stout rect- 
 angle framing of timber to keep the frames from 
 twisting in relation to one another; and the ends 
 of the timbers which carry the frames should be 
 extended 12 in. to 18 in. longitudinally to take the 
 weights used for loading the hind ends to prevent 
 the crab from overturning when at work.
 
 HAND CEABS OR WINCHES. 19 
 
 These are the principal elements of construc- 
 tion occurring in an ordinary hand winch, and they 
 occur in every crane, no matter what its type. 
 The wheels and barrel, the shafts and bearings, 
 and the brake, will be continually occurring as the 
 more complex machines are considered, and it is 
 necessary, therefore, to consider these in some 
 detail. 
 
 In the gearing of a simple hand-crab all the 
 elements which enter into the gearing of a 10-, 
 20-, or 50-ton crane are met with. The first is 
 
 Fig. 13. 
 Figs. 13 and 14. Shaft Bearings. 
 
 a simple organism ; the arrangements of the last 
 are often more or less complex. 
 
 Fig. 15 is a scale drawing of a single-purchase 
 crab, a perspective view of a similar machine being 
 shown by Fig. 7. Fig. 16 shows a side view. The 
 winch handles A A turn the first-motion shaft I, 
 carrying pinion B, which drives wheel c, keyed 
 upon the hoisting barrel or drum D, around which 
 the chain or rope is coiled. The effective diameter 
 of the barrel is the centre K of the rope or chain 
 which is coiled around it. E is the ratchet or dog 
 wheel, and F is its pawl. This wheel is keyed upon
 
 20 BUILDERS' HOISTING MACHINERY. 
 
 the barrel shaft J, and therefore revolves with the 
 barrel, the dog falling into each ratchet tooth in 
 succession. The object of this mechanism is to pre- 
 vent accidental over-running. Thus, if the load 
 were to overpower the men at the handles A A, 
 an accident would happen if the dog were not in 
 gear with the ratchet. The dog being in gear, 
 the running back of the wheels and chain would 
 be prevented, as may be seen from the figures, in 
 which the arrows show the rotation which corre- 
 sponds with hoisting. The brake wheel G (H is its 
 lever handle) is often placed within the frames, 
 being cast on the wheel c, but it is a matter of no 
 importance whether it is placed within or without. 
 Its function is the lowering of the load. Before 
 using the brake, the shaft i and pinion B are slid 
 along in the direction of the arrow, the pawl or 
 dog L being lifted off the shaft first, until the 
 pinion is out of gear with the wheel c. Or else 
 the pinion is left in gear and the handles A are 
 taken off. Then the rate of lowering is controlled 
 by the man at the lever handle H. 
 
 Looking at the arrangements, it is clear that 
 there is gain in power between the winch handles 
 A and the pinion B, and between pinion B and 
 wheel c, and between wheel c and barrel D. 
 Therefore, 
 Mechanical efficiency = 
 
 Power applied to A X radius r of A X radius of c 
 radius of B x radius of K. 
 
 Let radius r of winch handle A = 16 in. 
 
 Power of one man at handle = 15 Ib. 
 
 Pinion B = 10 teeth x 1| pitch x 4 in. per diameter. 
 
 Wheel c = 76 teeth x H pitch by 2 ft. 6^ in. diameter. 
 
 Effective diameter of drum = K = 7 in. 
 Then, taking the power of one man only 
 15 X 16 in. X 15'1 in. 
 
 - ; : = 51 / ID. 
 
 2 in. X 3'5m. 
 
 That is, one man, exerting a force of 15 Ib. at A, 
 can raise 517 Ib., a gain of power of 34'4 to one.
 
 HAND CRABS OR WINCHES. 
 
 Or two men can raise 
 
 30 X 16 in. X 15'1 in. 
 
 21 
 
 a gain of power of 69 to one. 
 
 But 15 Ib. is a fair estimate, being based on 
 the whole day's work of a man. It is found, in 
 fact, that the work of several hours can be taken 
 on a basis of 20 Ib., and, for moderate spells, 25 Ib. 
 is a maximum estimate for the power of a man at 
 a crane winch. So that the above figures may be 
 increased safely. 
 
 Fig. 15. Fig. 16. 
 
 Figs. 15 and 16. Single-purchase Crab. 
 
 The formula may take account of number of 
 teeth instead of radius, thus : 
 
 Eaclius of winch handle X power applied X 
 
 number of teeth in wheel 
 Number of teeth in pinion X radius of barrel. 
 There are two or three important facts which 
 should be noticed in connection with this calcu- 
 lation. The smaller the divisor the greater the 
 mechanical advantage. Hence, the smaller the 
 barrel, and the larger the barrel wheel, the greater 
 the power of the mechanism. It is seen that it
 
 22 BUILDERS' HOISTING MACHINERY. 
 
 must be so, from the principle of work, that power 
 is in inverse ratio to speed, that the slower the 
 lift the greater the power which is being exerted. 
 Also, the smaller the pinion the greater the gain. 
 But the practicable limits in this direction are 
 soon reached. If the barrel is made very small 
 for a given size of chain, the links, which are 
 to a certain extent rigid, are distressed. If the 
 wheel is made very large, it occupies too much 
 room, necessitating increase in the dimensions of 
 the framing and other parts. If the pinion is made- 
 very small, it is also very weak, and so good a gear 
 is not obtainable as with a pinion of moderate size. 
 
 Fig. 17. Fig. 18. 
 
 Figs. 17 and 13. Double Gear for Crab. 
 
 If the radius of the winch handle is increased^ 
 the labourers exert their power at a disadvantage. 
 As a matter of practice, winch handles have a 
 radius of from 15 in. to 17 in. ; the smallest pinions 
 seldom have less than ten or twelve teeth, and the 
 largest wheels more than 100 or 120. But, bearing 
 in mind the nature of the formulae, by introducing 
 intermediate gear, the power can be increased to 
 a very large extent. A single intermediate shaft 
 is the most common arrangement, but, in very 
 powerful winches, two such shafts are sometimes 
 used. Then the general formula would stand 
 Radius of w. handle x power x wheels 
 radius of barrel x pinions.
 
 HAND CRABS OR WINCHES. 
 
 23 
 
 It is easy to see how enormously power can be 
 increased in this manner. 
 
 Figs. 17 and 18 show the arrangement of double 
 gear for a crab. The end view to the left in Fig. 
 17 is looking at the crab from the arrow end H. 
 Here the shaft F is the first motion shaft, corre- 
 sponding with the shaft I in Figs. 15 and 16, p. 21. 
 It carries the pinion B gearing with A, as before, 
 for use in single gear. For the double gear the 
 second shaft G is used. This carries the pinion c 
 
 Fig. 21. Wheel Tooth 
 
 Fig. 20. 
 Figs. 19 and 20. Another Double Crab Gear. 
 
 and wheel D, cast together. To use the gear, the 
 shaft F, with its pinion B, is slid out of gear in 
 the direction of its arrow, and shaft B, with pinion 
 c, is slid into gear with wheel A. These move- 
 ments cause B to drive D, D carrying c with it, 
 which in turn drives A. Pawls maintain the shafts 
 in their end-long positions. E is the drum. 
 
 In many cases the gearing is not all arranged 
 at one end, the arrangement differs in some in- 
 stances, as illustrated in Fig. 19. The advantage
 
 44 BUILDERS' HOISTING MACHINERY. 
 
 of the latter is that the pinions can all be flanged 
 or shrouded, which is not practicable with the 
 arrangement shown in Fig. 17. One more pinion, 
 however, is necessary pinion E in Figs. 19 and 
 20. This always remains in gear with A, and its 
 shaft G is never slid along. The throwing in and 
 out of gear is done with the shaft F. When B 
 gears with A, c is out of gear with D, and the crab 
 is running single-geared. Wheels E and D then 
 simply run round, driven by A, doing no work. 
 When c gears with D, B is out and A is driven 
 through D and E, being then in double gear. H H 
 are the grooves for the pawl to hold the shaft F 
 endwise in either position. When the load is lifted 
 by double gear, then the efficiency is about 
 doubled, in ordinary cases, depending, however, 
 upon the proportions given to the extra wheels. 
 Suppose the extra pinions to number ten teeth and 
 twenty-four teeth respectively, then the gain will 
 be the diameter of a twenty-four-toothed wheel 
 of Ij-in. pitch being 9j in., 
 with one man, 
 
 15 x 16 in. X 475 in. x 15'1 in. _ . 
 
 2 in. X 2 in. by 3'5 in. 
 or with two men, 
 
 30 X 16 in. X 4'75 in. X 15'lin. __ 
 
 2 in. X 2 in. X 3'5 in. 
 
 Another result follows also. Since the power 
 of the arrangement increases while passing from 
 the winch shaft to the barrel shaft, these shafts 
 must be differently proportioned according to the 
 work which they have to do. The wheels, more- 
 over, must be stronger in the same ratio, the bar- 
 rel-wheel and second-motion pinion being propor- 
 tionately stronger than a first-motion pinion used 
 only for single gear. This simple winch embodies 
 a good many elementary principles ; but better 
 examples of these relations, as well as of sliding 
 pinions, will occur in the cranes proper.
 
 HAND CEABS OE WINCHES. 25 
 
 The strength of the teeth of wheels for slow- 
 running cranes is generally calculated on a statical, 
 and not on a dynamical, basis. Instead of reckon- 
 ing horse-power transmitted, a tooth is considered 
 as a cantilever subjected to a dead load. Then 
 8 or 10 is made the factor of safety. 
 
 The strength of a tooth (Fig. 21) is equal to : 
 depth B 2 X length c X strength of material 
 breadth A. 
 
 The tooth is considered a cantilever, loaded at 
 the extreme end of the length c, that being the 
 condition of maximum stress. As the teeth roll 
 on one another, the pressure approaches the root, 
 diminishing in amount. Since the depth B is the 
 principal factor in determining the strength, teeth 
 
 Fig. 22. Cycloidal Teeth. 
 
 should never be made narrower than necessity 
 demands, and a radius should always be cast in 
 the roots. In small pinions, narrow roots cannot 
 be avoided ; hence the reason why large radii are 
 generally cast in these, and why also they are 
 often shrouded, or flanged. For the same reason 
 partly, and partly because of the large amount 
 of frictional wear and tear to which they are sub- 
 jected, they are often cast in steel, phosphor 
 bronze, and delta metal. 
 
 The teeth of the wheels of cranes are formed, 
 as a rule, on one principle only, that known as 
 Willis's odontograph. The typical tooth shapes 
 are shown in Fig. 22, but those shapes vary, of 
 course, with wheels of different diameters. The 
 principle involved is, that any one wheel in a set
 
 26 BUILDERS' HOISTING MACHINERY. 
 
 which is struck out by that method will gear with 
 any other wheel of the same pitch. This is a 
 most valuable property, inasmuch as it permits of 
 the indiscriminate selection of wheels, and the 
 building up of combinations of gears without the 
 cost involved in making special wheels with teeth 
 to gear with other special wheels. Into the 
 technique of this it is not necessary to enter. In- 
 volute shaped teeth are seldom used, because it 
 is not practicable to make good interchangeable 
 gears covering a wide range of diameters with 
 these. 
 
 A form of gear which is used rather extensively 
 on cheap crabs is the knuckle gear (Fig. 23). In 
 
 Fig. 23. Knuckle Gear. 
 
 this there is not continuous rolling contact, as 
 in the odontograph teeth, but it is nevertheless a 
 very serviceable form, because, the flanks and faces 
 consisting wholly of semicircles, the roots possess 
 the greatest strength possible, and the points are 
 never likely to become fractured in consequence 
 of shock due to the wearing slack of shafts and 
 bearings. They are, however, only to be recom- 
 mended for small crabs, and not for large cranes, 
 for which the odontograph tooth should always 
 be used. Teeth should never be very long. The 
 short teeth (Fig. 22) now coming into general use 
 are to be preferred, because they are less liable to 
 fracture in the event of sudden shock. 
 
 The gearing of cranes is made from patterns, 
 and by machine. A practical man can generally
 
 HAND CRABS OE WINCHES. 
 
 distinguish between pattern-moulded and machine- 
 moulded wheels, by observing the teeth. But 
 apart from that, the shape of the arms is an almost 
 certain indication of the type of wheel. Figs. 24 
 and 25 are the arm shapes put in pattern wheels ; 
 Fig. 26, that used for machine wheels ; almost the 
 only exception to these shapes are the wheels with 
 
 Fig. 24. Fig. 25. 
 
 Figs. 24 and 25. Arms of Pattern Wheels. 
 
 plated or disc centres, which are made either by 
 pattern or machine. For the best crane work, 
 machine wheels should predominate. 
 
 Unlimited power may be gained by the use of 
 gearing, but, of course, the reduction in speed is 
 in reverse ratio to the gain in power. Double 
 gear, therefore, is seldom exceeded. Treble gear 
 is so exceedingly slow that, though applied to not 
 a few crabs and cranes, it is intended for excep- 
 tional rather than for ordinary duty. When, for 
 regular service, power beyond the range of double
 
 28 
 
 BUILDERS' HOISTING MACHINERY. 
 
 gear is required, it is desirable to discard alto- 
 gether machinery operated by hand, and work the 
 lifting tackle by steam, hydraulic, or electric 
 power. Hence, pulley blocks and the crabs already 
 dealt with are suited mainly for casual and occa- 
 sional, and not for regular, work. Considerable 
 range of power, portability, and cheapness, the 
 fact that they require no kind of foundation, and 
 can be operated by hand, strongly recommend 
 pulley blocks and crabs, and make them popular. 
 Differential blocks range in power from J cwt. 
 to 4 tons.. Single-purchase crabs will lift from 
 8 cwt. to 1 ton ; double-purchase crabs from 16 cwt. 
 to 4 tons. If, instead of lifting directly -off the 
 barrel, the rope is passed over sheave blocks, the 
 
 
 '/A \ W% 
 
 I 
 
 \ 1 
 
 
 ^i ; v/// 
 
 
 \ \2A. 
 
 Fig. 26. Arm of Machine Wheel. 
 
 power is increased about five times, but the speed 
 is considerably reduced. Treble-purchase crabs 
 will lift from about 6 tons to 15 tons direct from 
 the barrel. Wire rope is used to an increasing 
 extent for hoisting machinery, and when it is 
 used with crabs the barrels should be larger than 
 for ordinary rope, so as to avoid strain and stress. 
 All crabs of the type so far considered are operated 
 by hand. Steam is applied to ships' winches, but 
 these are not under discussion. Steam is also 
 applied to travelling crabs on gantries, a type that 
 will be referred to later. 
 
 The gearing in the crabs already treated upon 
 occurs in other kinds of hoisting machinery, of 
 which that shown in Figs. 27 and 28 is a type. 
 Winches of this special class are intended for
 
 HAND CEABS OE WINCHES. 
 
 ig 
 
 attachment to a wall for operating a jib crane, 
 and also, variously modified, to Wellington cranes, 
 and some gantry cranes for working the jenny from 
 below. Wall jib cranes are used in warehouses 
 and in workshops, where the framed crane carries 
 no hoisting gear, but a pulley only at the jib head 
 and at the rear. Or, when the crane has a hori- 
 
 Figs. 27 and 28. Elevation and Plan of Wall Winch. 
 
 zontal jib only, the latter carries a jenny which 
 is operated by the winch. Each of these forms is 
 very useful, and each, while containing the essen- 
 tial gearing of the true crane, nevertheless differs 
 therefrom in the separation of the hoisting gear 
 from the main framing. Obviously, when a crane 
 framing is attached to the outside of the wall of
 
 30 BUILDERS' HOISTING MACHINERY. 
 
 a building, the gearing must be situated within the 
 wall to be operated by the attendant. It is usual, 
 then, to use an ordinary crab like those illustrated 
 by Figs. 6 and 7. 
 
 The construction of many of the wall cranes is 
 simplified by the use of a horizontal swinging jib 
 with diagonal tie-rods above it, and by the use of a 
 winch in a bracket bolted to the wall, as in Figs. 
 27 and 28. Single gear only may be used, as 
 shown in the figures, or double gear. All the 
 afore-mentioned crabs are of the fixed type that 
 is, though portable, they are fixed when at work. 
 They must be suitably placed for the work they 
 have to do, and they are fixed on the ground, or 
 on staging, and not directly over the work. The 
 larger travelling or overhead crabs are carried on 
 low wheels upon rails laid on traveller girders, 
 which girders are in turn mounted on end cradles 
 and wheels to travel down a gantry, the gantry 
 comprising beams laid parallel at a distance apart 
 to suit the span of the crab.
 
 CHAPTER III. 
 
 TRAVELLING CRABS, HAND AND POWER. 
 
 VARIOUS types of travelling crabs or travellers are 
 used. In them can be studied many arrangements 
 which either do not exist in the simpler fixed crabs, 
 or which exist there in a very elementary form. 
 In the simplest form of overhead traveller the 
 common differential pulley block is suspended 
 from a jenny. In others, again, the winch handles 
 are dispensed with, and the load is lifted by a 
 dependent endless chain. Many overhead crabs 
 are provided with winch handles, and platforms 
 are constructed for the men who turn the handles. 
 The traveller or travelling crane comprises either 
 a crab or a jenny which can be moved along beams 
 or girders, while the entire structure can be moved 
 bodily along gantry beams. By the combination 
 of these movements, any load within the area cov- 
 ered by crab and gantry can be lifted vertically. 
 The two dimensions which cover the area are the 
 length of the traveller beams and the length of 
 the gantry beams. The first will range anywhere 
 between 10 ft. and 100 ft. ; the second will be 
 practically without limit. One gantry will very 
 often be so long that several travellers will run 
 upon it. These are always fixed gantries. They 
 are either built up of timber framing from below, 
 or are composed of square timber balks secured 
 on the tops of wall buttresses, or on the tops of 
 iron columns, or, for the lighter travellers, on 
 corbels built into the wall. What are termed 
 travelling gantries are the Goliath cranes, in which 
 the crab rail-bearers are fixed on two vertical 
 framings, the whole structure travelling bodily 
 along rails laid on the ground level.
 
 32 BUILDERS' HOISTING MACHINERY. 
 
 Travelling crabs may be broadly classified in 
 two groups: (a) overhead travellers operated by 
 hand, and (6) overhead travellers worked by power. 
 In class (a) the travellers are worked either from 
 below or from above, those worked from below 
 being generally light, lifting from 1 to 5 tons, 
 though travellers with a lifting capacity of 15 or 
 20 tons are sometimes worked in this manner. 
 Travellers of this class are numerous, cheap, and 
 are suitable for yards and sheds where there is 
 not enough work to keep a man specially for hoist- 
 ing. The motions are operated by endless ropes 
 or chains passing over sheave pulleys of large 
 diameter, having V-rims to ensure a good bite. 
 One rope serves for hoisting and lowering, and 
 another for cross-traversing. The down traversing 
 in the smallest traveller is not done by gear, but 
 simply by pulling at one of the ropes in the dii*ec- 
 tion in which movement is required. In the heavier 
 hand travellers, however, operated from below, the 
 longitudinal traverse is worked by gear. The end- 
 less rope operating its V-grooved wheel turns spur 
 pinions and wheels, the latter being on two of the 
 travelling wheel axles. In the heaviest hand trav- 
 ellers worked from below the use of treble pur- 
 chase gear is necessary for lifting maximum loads, 
 and two chain or rope wheels are necessary, one 
 on each end of the first motion shaft, in order that 
 a couple of men shall be able to operate each 
 rope. 
 
 The majority of hand travellers are travelled 
 down the gantry either from the crab through a 
 square shaft, or by means of gearing placed on 
 one cradle. 
 
 In the Goliath cranes, in which crabs run on 
 travelling gantries, it is customary to travel by 
 means of gear placed at the base of the end fram- 
 ings. In a few cases this travelling is effected 
 from the crab through bevel gearing and shafts
 
 TRAVELLING CRABS. 33 
 
 There are several different types of power trav- 
 ellers. The first comprises travellers which run 
 on fixed gantries ; the second travellers, or 
 Goliaths, which run on travelling gantries. In the 
 latter case the gantries are moved by hand by men 
 stationed below, as in the hand Goliaths ; or they 
 are moved from the crab, and by gearing which 
 is attached, to travel along with the crab. 
 
 Power crabs are operated by steam and by 
 electricity. Steam is a very popular and long- 
 tried and proved motive power. In such trav- 
 ellers, crab and traveller are operated by means 
 of an engine and boiler fixed on the crab, and 
 moving with the crab ; but sometimes the boiler 
 and engines are fixed at one end of the traveller 
 beams, and the crab becomes then a mere travel- 
 ling jenny. Fixing the boiler and engine at one end 
 of the traveller and driving through a jenny has 
 the advantage of lessening the load on the trav- 
 eller beams by the extra weight of the crab, which 
 will often equal or exceed that of the load to be 
 lifted. More than that, there is less surging of 
 the traveller than occurs when the dead weight of 
 the crab becomes a rolling load. 
 
 The details of construction of steam crabs differ 
 considerably from those of hand crabs. The em- 
 ployment of engines and boiler necessitates a 
 larger and more substantial framing. The engines 
 are bolted to the framings on the outside, leaving 
 the inside free for gearing. The boiler is placed 
 at the back or on a foot-plate, from which the 
 attendant operates all the motions, the handles 
 for which are brought within convenient reach. 
 A water-tank, through which the exhaust steam 
 passes warming the feed water, is placed under 
 or at one side of the boiler or in front of the crab. 
 The whole of the crab should be protected from 
 the weather by a house of corrugated iron. 
 
 Steam crabs carry their boilers and engines.
 
 34 
 
 BUILDERS' HOISTING MACHINERY. 
 
 In steam crabs also provision is generally made 
 for operating the gantry, when the latter is of the 
 travelling type, directly from the crab through 
 shafts and gearing. If the power is carried to the 
 crab through a cotton rope, then a shaft running 
 along the traveller drives the crab in all its 
 motions. 
 
 Other forms are Wellington cranes and Goliath 
 cranes, of which large numbers are used. The 
 first named are operated by gearing placed on the 
 verticals, and actuating a jenny, and are often 
 
 c 
 
 Fig. 2<i. Fig. 80. 
 
 Figs. 29 and 30. Jenny for Traveller Blocks. 
 
 termed travelling gantries. The second are crabs 
 mounted on the horizontal girders, driving the 
 entire Goliath in all its motions, and may be 
 worked by hand or by steam. 
 
 For light haulage, whether in yard or workshop, 
 the overhead traveller with a jenny for the attach- 
 ment of differential blocks is very convenient. Its 
 drawback is that the action of the block is very 
 slow, and, of course, the load is somewhat limited. 
 The limit is about four tons, being equal to the 
 capacity of the largest blocks. 
 
 For light jenny travellers the girders are sjmply
 
 TEAVELLING CKABS. 35 
 
 rolled H-joists D (Fig. 29). B B are the runners, 
 and c serves for the attachment of the pulley 
 blocks. Another view of the jenny is shown by Fig. 
 30. For heavy loads and large spans timber beams 
 are used, or else built-up girders, either parallel, 
 or more generally fish-bellied and single-webbed 
 in all but the heaviest, which are sometimes 
 double-webbed. With the single girder xised for 
 the runners of the jenny the limit of span is about 
 18 ft. The traveller itself in the smallest sizes is 
 pulled along the rails by hauling at the end of the 
 suspended block, but in the larger sizes movement 
 is effected by means of an endless chain passing 
 over a sheave wheel on a longitudinal shaft, having 
 a pinion at each end, gearing with spur wheels 
 keyed on one of the running wheel axles. The 
 end cradles are made either of wrought-iron or of 
 cast-iron. When cast-iron is used, the traverse 
 girder is socketed into the castings and cemented, 
 the cement consisting of iron borings and sal- 
 ammoniac ; a single bolt is inserted for extra 
 security. Jenny crabs are made to lift loads from 
 half a ton to twelve tons, and in span up to about 
 20 ft. 
 
 Figs. 31 and 32 show a plain jenny which travels 
 on double traveller rails. The whole of the gear- 
 ing by which it is actuated is placed on the verti- 
 cals of the travelling gantry, and may be single or 
 double. One set of gearing serves for racking the 
 carriage along, another set for hoisting and low- 
 ering, guide pulleys being placed at the ends of 
 the gantry beams. In Figs. 31 and 32 there is a 
 jenny carriage A, made of cast-iron, running on 
 four double-flanged wheels B B B B. The carriage 
 is pulled along in either direction by means of a 
 chain hooked to the eyes a a. The top of the chain 
 passes along at &, and its connection with the car- 
 riage make it endless, the bights passing over 
 pulleys one at each end of the gantry. The lift-
 
 36 BUILDERS' HOISTING MACHINEEY. 
 
 Figrs. 31 and 32. Eleva- 
 tion and Plan of Jenny 
 with Gearing. 
 
 Fijr. HI.
 
 T&AVELLltfG C&ABS. 87 
 
 ing chain passes over the pulleys c c. This is 
 anchored at one end, and passes over a pulley at 
 the other, operated from the hoisting barrel on 
 the vertical below. The power is doubled by the 
 use of a fall or snatch block D, a device adopted 
 in all except the crabs of lowest power. In a con- 
 
 ffoYl id 
 
 Fif?. 33. Diagram of Overhead Crab Gear. 
 
 tractor's yard where hand power only is used, there 
 is nothing handier or cheaper than this arrange- 
 ment. Everything is operated from below, and 
 only for oiling or repairs is it necessary to send a 
 man up on the gantry. 
 
 Although the jenny is a simple arrangement, 
 yet it is so valuable that it occurs in various forms, 
 in some of the most elaborately devised cranes of 
 high power, even up to fifty tons. It is often 
 found more convenient to locate the hoisting tackle 
 away from the travelling jenny instead of upon it,
 
 38 BUILDERS' HOISTING MACHINERY. 
 
 as in the true or self-contained travelling crabs, 
 to which consideration will be given. 
 
 The gear for a typical overhead crab is shown 
 in Figs. 33 to 36. It will be observed that there 
 are two sets of gear, one for hoisting the load, 
 the other for propelling the crab along the rails ; 
 and all travelling crabs, with the exception of 
 those types already mentioned, have such distinct 
 
 Fit?. 34. Plan of Overhead Crab Gear. 
 
 sets of gear. But these gears are subject to very 
 great modifications in crabs of different kinds, 
 which modifications can be better studied after 
 discussing the typical and very common arrange- 
 ment illustrated by Figs. 33 to 36. Details of 
 frames, bearings, etc., have been omitted, in order 
 not to crowd and obscure the essential gearing, 
 which is shown with full lines.
 
 TRAVELLING CBABS. 39 
 
 Both the hoisting and the travelling gear are 
 double, few overhead crabs being made with single 
 gear only ; it is entirely hand-operated, by a man, 
 or men, standing on a platform attached to and 
 travelling with the crab. As far as this particular 
 gear is concerned, there is no provision for moving 
 the traveller itself along the gantry ; where such 
 provision is made ,the methods of effecting such 
 movements differ from each other considerably. 
 
 In Fig. 3 tli3 pitch circles of the various wheels 
 
 Fig. 35. End View of Overhead Crab Gear. 
 
 are shown in elevation ; in Fig. 34 wheels and 
 shafts are seen in plan, the positions of the shaft 
 bearings being indicated by diagonal crossing 
 lines ; Fig. 35 shows the travelling gear in end 
 view from the position A A in Fig. 34 ; and Fig. 36 
 shows the hoisting gear only in end view from the 
 position B B in Fig. 34. In these figures the pinion 
 A and wheel B are used for quick lifting. A is 
 keyed on a sliding shaft D, the endlong movement 
 of which can be arrested by means of the pawl
 
 40 BUILDERS' HOISTING MACHINERY. 
 
 grooves a, I, c, either in a position a of no gear, 
 as shown, for lowering by the brake ; or at b, with 
 pinion A in gear with B ; or in c, with pinion F 
 in gear with G. When A gears with B, the latter, 
 being keyed either upon the barrel c or upon its 
 shaft E, lifts a light load quickly. To lift a heavy 
 load slowly, the shaft D is slid along until F gears 
 with G, the pawl dropping into c ; F then drives G 
 on the same shaft as the pinion H, which in turn 
 drives the wheel B on drum c. The relative rates 
 are, in the first place : 
 
 Power X radius of winch handle x B 
 
 A x c 
 In the second case : 
 
 Power x radius of winch handle X G x B 
 
 F x H X c 
 
 The dog is kept in contact with the ratchet wheel 
 j during the lifting, so that, in the event of any 
 mishap occurring, the ratchet will hold the load. 
 When it is desired to lower by brake g on the 
 wheel G, the pawl is thrown back, the shaft D is 
 slid into its middle position, the winch handles 
 detached or the men stand clear, and, the pinion H 
 always remaining in gear with B, permits the load 
 to be lowered safely by friction, due to the pull 
 on the brake strap embracing (j. The travelling 
 gear is, as a rule, only provided with one set of 
 motions, either single or double, in the latter case 
 without any provision for alteration. In the fig- 
 ures shown the travelling gear is double only ; K 
 is the first pinion driving wheel L, next which is 
 keyed or cast the pinion M, which in turn drives 
 wheel N, keyed on the same axle Q as the driving 
 running wheels R, R. o and P are the shafts of the 
 pinion K and wheels L and M respectively. The 
 driving is done only on one pair of wheels R R, 
 the other pair of wheels s s trailing simply. In 
 the heaviest steam crabs the front and rear wheels 
 are coupled with rods, to, distribute the load
 
 TRAVELLING CEABS. 
 
 41 
 
 equally. But this is never done on hand crabs. 
 Hand-operated overhead crabs lift up to about 
 20 tons, but the majority do not exceed 10 or 12 
 tons. Spans will range up to 40 ft. or 45 ft. 
 
 Overhead travelling crabs are constructed in 
 various ways. Cheeks are made of cast-iron, or 
 are plated, as in the fixed crabs. Two views of 
 a cast-iron cheek are shown by Figs. 37 and 38. 
 When plated, the web is sometimes made of thick 
 
 Fig. 36. Overhead Crab Hoisting Gear. 
 
 plate, and only a, bottom flange riveted on ; the 
 web is made of thin plate, and flanged all round. 
 The latter is preferable to the former, because the 
 frames are stiffened materially by the riveting of an 
 angle iron round them, and because the angle 
 forms" a suitable basis for bolting shaft bearings. 
 When the angle is riveted to the bottom only, then 
 boss bearings are necessary, and these contain no 
 provision for the taking up of wear as divided
 
 1'2 BUILDERS' HOISTING MACHINERY. 
 
 bearings do. Moreover, boss bearings are con- 
 sidered rather objectionable in crane work, because 
 whenever a shaft has to be removed, as, for in- 
 stance, to replace a fractured pinion by a new 
 one, often one cheek at least has to be taken 
 away bodily, since there is no other way to remove 
 any shaft. Bosses are cheaper, of course, than 
 divided bearings, but they give trouble subse- 
 quently. When boss bearings are used, it is desir- 
 
 Fig. 38. 
 Figs. 37 and 38. Cast-iron Cheek for Hand Crab. 
 
 able to arrange shaft diameters so that the shaft 
 can be drawn out endwise. Then it is usually 
 practicable to key a small wheel on the shaft when 
 inserted part of the way through the frames. 
 
 The frames of many of the heavier crabs are 
 of a composite character, being made mainly of 
 plating, but having cast-iron cheeks bolted on to 
 carry the main shafts, a single casting carrying 
 two or three distinct bearings. This facilitates the 
 fitting and boring of the bearings, and generally
 
 TRAVELLING CRABS. 43 
 
 makes a more rigid framework. But it is not often 
 adopted in small crabs. 
 
 Figs. 37 and 38 illustrate a cast-iron cheek for 
 a hand crab, and Fig. 39 one of wrought-iron or 
 steel. The first contains provision for single 
 travelling gear only, the second for double gear. 
 
 Cast-iron being a rather brittle material, is 
 liable when used in crane work, to fracture under 
 the sudden and severe stresses which often occur 
 in braking and in slipping of the chain and surg- 
 ing of framings. Many casi^iron framings arc 
 
 Fig. 39. Wrought Cheek for Hand Crab. 
 
 much lighter than they ought to be, or the metal 
 is badly arranged, and angles are left too keen. 
 But if w T ell proportioned and designed, cast-iron 
 frames are more rigid than those of wrought-iron, 
 and the expense involved in fitting angle irons and 
 in the attachment of separate bearings is saved, 
 because the bearings are made in the casting 
 itself. 
 
 Figs. 37 and 38 show a well-proportioned frame 
 lightened out in the vicinity of the neutral axis, 
 and well ribbed everywhere with good radii. A A
 
 44 BUILDERS' HOISTING MACHINEEY. 
 
 are the axle bearings, B is the barrel bearing, c 
 is the bearing for the first motion pinion shaft, 
 D that for the intermediate and brake-wheel shaft, 
 and E that for the first motion travelling pinion 
 shaft. A A c E are divided bearings, B and o are 
 solid. The metal below B and in the ribs adjacent 
 is thickened because it is in tension, which cast- 
 iron is weak to withstand. The divided bearings 
 are in cast-iron as shown, or lined with brasses. 
 Brass bearings are not so desirable in slow-run- 
 ning hand crabs as in steam crabs. Often, how- 
 ever, brass is used for the bearings c and E, even 
 in hand crabs, because they are of small bore, and 
 the shafts revolve several times faster than those 
 in the other bearings. A curved rib is cast on 
 at F. The object of this is to receive a piece of 
 sheet iron which is bolted to it, extending from 
 cheek to cheek, and which receives the bearings 
 for the pawl. 
 
 In the wrought^iron or steel cheek (Fig. 39) the 
 angle A, bent to the outline of the cheek, should 
 properly be welded up into one piece rather than 
 be made in separate pieces mitred at the corners. 
 It is riveted, the rivets being spaced at from 3-in 
 to 4-in. centres ; B B are the axle bearings, c is the 
 barrel bearing, D the bearing for the first motion 
 pinion shaft, E the bearing for the intermediate 
 shaft, F the first motion travelling pinion shaft, o 
 the intermediate travelling shaft, the gear being 
 double. The bearings B B c G are boss bearings, 
 which pass through holes bored in the frame, 
 being bolted to the frame through flanges. DBF 
 are ordinary plummer blocks bolted to the angle. 
 All or any of these bearings may be in iron, or 
 brass bushed. Such a frame depends for its stiff- 
 ness more on the size of angle, and the method of 
 its fitting and riveting, than on the thickness of 
 the plate. The fitting of the bearings also must 
 be good quite apart from the holding power of
 
 TRAVELLING CRABS. 45 
 
 the bolts. The portions of the bosses which pro- 
 ject through the frames should be turned, and fit 
 closely into holes bored in the plate. The bottoms 
 of the plummer blocks should be planed, and a 
 light rough cut be taken off the top angle. Bolts 
 must be turned, and bolt holes drilled. These are 
 the essentials of good fitting in such a cheek. 
 
 In the true travellers, the main bearers are 
 supported at their ends by means of cradles, which 
 are short beams attached to, and at right angles 
 with, the main bearers. These are provided with 
 flanged wheels, which travel down the rails that 
 are fixed to the gantry beams. The essential 
 framing is that consisting of a couple of parallel 
 main beams, supported at the ends, and loaded at 
 intermediate points with the crab and its load ; and 
 two cradle beams, supported near the ends, the 
 wheels being the points of support, and loaded at 
 two intermediate points by the main beams and 
 their load. 
 
 The method of calculating the strength of these 
 beams is similar to that employed for beams in 
 general. As will be shown later, the forms and 
 sections used in their construction differ very 
 widely. The first essential in these, after absolute 
 strength, is stiffness, not only depthwise, but side- 
 ways. The beams cannot be tied anywhere except 
 at the ends, because there must be a clear-way 
 between for hoisting. They must therefore be 
 stiff enough in themselves. This stiffness is im- 
 parted in various ways in some cases by utilising 
 a platform girder ranged alongside the main girder, 
 and connecting the two tog-ether. For single- 
 webbed beams the top and bottom flanges are made 
 sufficiently wide to impart side stiffness. In heavy 
 travellers, the double-webbed or box form of 
 girder is used ; in these the two webs reinforce 
 each other, and the flange plates are wide. 
 
 Another difficulty to be guarded against is that
 
 46 BUILDERS' HOISTING MACHINERY. 
 
 of cross-working of the traveller. The longer the 
 span, the more liable is the traveller in going down 
 the gantry to irregular diagonal movements, and 
 this causes hitching and fracture of the flanges of 
 the wheels. Such accidents are generally pre- 
 vented by the use of a broad wheel base (that is, 
 distance from centre to centre of wheels) on the 
 cradle. There can seldom be any objection to a 
 long wheel-base, and the length should be in due 
 proportion to the span of any traveller. 
 
 Another matter which is not always under con- 
 trol is the method of attachment of the main beams 
 to the cradle beams. If there is sufficient head- 
 room, it is always best to bolt the ends of the 
 former directly on top of the latter, because of 
 the intensity of the bending moment over the ends. 
 It sometimes happens, however, that this method 
 is- not available, because it would not leave suffi- 
 cient head-room for the crab. In such case one 
 of two devices is available: either place the 
 cradles over the ends of the main beams, in which 
 case the whole stress on the latter has to be sus- 
 tained by bolts ; or abut the main beams against 
 the perpendicular faces of the cradles and rely on 
 bolts and rivets. But lightness as well as strength 
 is required in a crab and traveller, even more than 
 in a crane. The dead weight of the crab and 
 traveller is nearly always greater than that of the 
 load to be lifted. Hence, while ample strength 
 and stiffness should be provided, the minimum of 
 weight consistent with stability should also be 
 secured. Some travellers are much heavier than 
 they need be, not because they are unnecessarily 
 strong, but owing to bad designing and injudicious 
 arrangement of material. 
 
 In another class of crabs and travellers driven 
 by steam, the engine and boiler are located in a 
 building elsewhere, and the power is transmitted 
 by means of a longitudinal line of rhafting running
 
 TRAVELLING CRABS. 47 
 
 down one wall of the shop, in a line v/ith the 
 fixed gantry. This drives a square shaft along 
 the traveller girder on which the crab moves, and 
 operates the motions of the crab through worm 
 gearing or bevel wheels. This movement is the 
 reverse of that in which the crab is made to drive 
 a travelling gantry, and there is little essential 
 difference in the methods by which these move- 
 ments from traveller to crab, or from crab to 
 traveller, are transmitted. 
 
 Instead of using a square shaft along the gantry, 
 a cotton rope running at a high speed is a favour- 
 ite method employed to transmit power from a 
 distance to the traveller. When electricity is used 
 as the motive power, then the dynamo is situated 
 in any convenient locality away from the traveller, 
 and a rod conveys the current thence alongside 
 the gantry, whence it is taken up by a brush on 
 the crab connected to the electric motor. Then 
 belt gearing is used to reduce the speed as 
 required. 
 
 The motions of many overhead travellers are 
 operated from one end, from levers brought to a 
 cage within which the attendant sits. The method 
 is applied to crabs actuated by square shafts and 
 cotton ropes, and to jenny crabs operated by 
 either method. The advantages are that the 
 maximum of head room is obtainable in this way, 
 more especially when a jenny is used, and that 
 the attendant can from his cage see the work 
 below much better than from a platform on crab 
 or traveller. Such an arrangement consequently 
 is used very extensively.
 
 CHAPTER IV. 
 
 CRANES AND TRAVELLING CRABS: THEIR DETAILS OP 
 CONSTRUCTION. 
 
 THE framework of a traveller consists of main 
 beams or girders with or without truss rods, and 
 end cradles with their attachments. Timber may 
 be used for the beams, in which case trussing is 
 necessary. Timber gantries are well adapted for 
 contractors' use, and are cheaper than those made 
 of iron or steel ; but for permanent structures, and 
 for shipment abroad to hot countries, iron or steel 
 is always to be preferred. The use of timber for 
 beams is economical in the case of builders and 
 contractors, because the timber work can be con- 
 structed in the yard ; a crab can be bought new, 
 or cheaply at second-hand, and the gantry made 
 to suit the firm's requirements. The timber 
 gantry must always be trussed, but in ironwork 
 trussing is not indispensable. 
 
 For light work the rolled H-joists make good 
 beams, and for the heavier class of travellers the 
 beams are built up of plate and angle iron in such 
 a way as to be self-sustaining. The strength is 
 obtained by increasing the depth of the parallel 
 girders, or by making girders of fish-bellied form, 
 suitable stiffeners being inserted to prevent buck- 
 ling. Travellers intended to lift light loads and 
 with narrow spans are generally made with girders 
 of rolled H-sections ; they are cheap, and the 
 absence of truss rods gives increased head room. 
 
 The riveting of the rails to the girders increases 
 their stiffness, and sometimes plates are riveted 
 to the top and bottom flanges with the same inten- 
 tion. Traveller beams of H-section are occasion-
 
 DETAILS OF CONSTRUCTION. 
 
 ally used for wide spans, in which case they are 
 generally trussed. The struts may then be formed 
 of flat bars riveted to the sides of the beams, the 
 truss rods, being flat bars. This method of con- 
 struction is desirable when lightness is sought in 
 
 ... 
 
 long-span travellers. Such joists can also be 
 trussed with round rods, cast-iron struts being 
 bolted to the bottom flange or to blocks of timber 
 inserted between the flange and strut.
 
 50 BUILDERS' HOISTING MACHINERY. 
 
 Illustrations of some types of iron and steel 
 girders used on travellers are given by Figs. 40 
 to 42. Figs. 40, 41, and 42 show the cheapest 
 type of framing for light travellers used for geared 
 crabs, Fig. 40 being a plan of one end, Fig. 41 
 an end view, and Fig. 42 a side view. The main 
 gird3rs consist of two joists A A of H-section upon 
 which the crab travels on rails, and two end cradles 
 B which support the joists, and travel on rails C 
 down ths gantry beams D. The supports of the 
 gantry may consist of continuous beams if in a 
 yard, of masonry corbels if in a shop, or of con- 
 tinuous timber beams upon or against the walls. 
 In these figures the cardinal dimensions are the 
 span or distance from centre to centre of gantry 
 rails, the wheel base w of the end cradles, and the 
 cantres x of the crab wheels. , 
 
 These dimensions vary widely as the require- 
 ments of a firm vary, but they are the main ele- 
 ments in the settlement of the other dimensions, 
 and also of the general methods of construction 
 adopted. The first and most important is the 
 span ; on this depend the depth and cross-section 
 of the joists A A, and also the question of the 
 employment of joists at all, or of the more elabor- 
 ately built-up girders of plate and angle. There 
 is no rule limiting the use of joists on the one 
 hand, or of plate girders on the other. At ex- 
 tremes there is no question as to the most suit- 
 able selection, but in a large number of cases local 
 conditions must determine the choice. Joists can 
 be had up to 12 in. deep at ordinary prices, and 
 they can be superimposed to increase depth. But, 
 in the latter case, dead weight becomes unduly 
 increased, and plated girders can be built of less 
 weight with equal strength. 
 
 For light travellers, however, joists are cheaper 
 and quite as good girders. The wheel base w 
 should be of a good length, the governing con-
 
 DETAILS OF CONSTRUCTION. 
 
 dition being the prevention of cross working. The 
 larger the span, therefore, the more reason is 
 there for increasing the wheel base. The wheel 
 base, and the weight of the girders A A, of the crab 
 on them, and of the maximum load lifted, together 
 determine the depth and sectional area of the end 
 cradles B. 
 
 With increase in span and load the rolled joist 
 gives place to built-up girders. These are either 
 parallel or fish-bellied, single- or double-webbed. 
 They are parallel for 
 short spans and mo- 
 derate loads, bellied 
 in other conditions. 
 The advantage of the 
 latter consists in the 
 attainment of the 
 maximum strength 
 with the minimum 
 of dead weight. It 
 is a form, therefore, 
 adopted for most 
 heavy travellers of 
 long span. It is, of 
 course, essentially a 
 double parabolic 
 outline, but this is 
 for practical purposes merged in a regular curve. 
 
 Figs. 43 to 46 illustrate a girder of this type, 
 the numerous rivets being the only omission. Fig. 
 
 43 is a half elevation, Fig. 44 a longitudinal sec- 
 tion on the plane a a, and Fig. 45 a plan view on 
 the top flange to which the crab rails are attached. 
 The girder is solid-webbed and single-webbed, as 
 shown in section in Fig. 46. The web A is in two, 
 three, or more lengths, dependent on the total 
 length and depth of the girder. In Figs. 43 and 
 
 44 there are three plates, jointed at a on each side 
 of the centre. The top and bottom flange plates 
 
 Fig. 42. Side View of Light 
 Traveller Framing, etc.
 
 BUILDERS' HOISTING MACHINERY.
 
 DETAILS OF CONSTRUCTION". 
 
 and the angles also have to be jointed. These 
 parts always break joint. The top flange plate B 
 and the bottom one c are each in two lengths in 
 this example, and jointed at & midway between 
 the web joints a. At D the angles break joint away 
 from both a and &. At each joint there are cover- 
 ing plates ; E E for the web A ; P B 1 are covers for 
 the flanges B and c, while the angle joints have 
 covering angles H H. In all such joints the area 
 of the covering pieces and the rivet section must 
 be ample, and the joints must be 
 arranged wide apart. At cer- 
 tain intervals stiffeners G G G are 
 riveted down the girder webs. 
 Without these the webs would 
 crumple and twist out of shape, 
 even though strong enough as 
 beams by calculation. 
 
 To make the beams rigid 
 enough without stiffeners, it would 
 be necessary to increase the web 
 thickness A, thus adding by 
 perhaps 50 per cent, to dead 
 weight. By the use of these 
 stiffeners or struts placed at 
 intervals of a few feet apart, the 
 thin webs (rarely exceeding from 
 t s ff in. to tV m - i n thickness) are 
 amply reinforced and buckling is 
 prevented. 
 
 The stiffeners are usually of T-section, though 
 angles are often used. They may be set up close 
 to the web A, but the usual practice is to lay them 
 against packing pieces d d, which cost no more 
 than the setting of the angles, while they add to 
 the rigidity of the web. At a web joint as at a, 
 the joint plates E serve also as packings. The 
 method of setting out the stiffeners, seen in section 
 in Fig. 46, is better than simply joggling the 
 
 Fig. 46. Section 
 of Girder.
 
 54 BUILDERS' HOISTING MACHINERY. 
 
 stiffeners over the longitudinal angles, because 
 some extra support is thereby afforded to the 
 flange plates. 
 
 The construction of the joints of parallel girders 
 is identical with that illustrated in the fish-bellied 
 girder, and need not therefore be shown separately. 
 Parallel girders cost less per ton than bellied ones, 
 and are frequently employed. But as span and 
 weight increase, it is always better, in order to 
 secure lightness combined with maximum strength, 
 to supply the bellied form, a practice which is 
 rarely departed from. For the widest spans the 
 box girder is usually selected. This is essentially 
 two single-webbed girders placed at a distance 
 of from 6 in. to 10 in. apart, and rigidly connected 
 with flange plates. These are much superior to 
 the single-webbed form, because they are much 
 more rigid to resist the side deflections due to 
 the irregular movements of the crab and its load 
 when working. The main beams cannot be braced 
 together at any point away from the ends, the 
 most that can be done in some cases being to insert 
 gussets at the union of the main beams with the 
 cradles. They are therefore entirely independent, 
 and must be rigid enough in themselves to with- 
 stand side deflections, as well as those in a vertical 
 direction, and for this reason the box girders are 
 preferred for long spans and heavy loads. 
 
 The end cradles, of travellers are made of 
 timber, cast-iron, wrought-iron, or steel. Timber 
 and rolled H-irons are employed for light trav- 
 ellers, cast-iron often for those of moderate weight, 
 and structures built up of wrought-iron and steel 
 for the heaviest. In each case cast-iron bearings, 
 either solid or divided, are employed to carry the 
 gantry wheels. In most instances the traveller 
 beams are bolted on top of the cradles, an arrange- 
 ment which is very suitable, and which gives the 
 maximum of head room. Ocrasionallv it is necen-
 
 DETAILS OF CONSTBUCTION. 5o 
 
 sary to reverse this by bolting the beams below 
 the cradles, as when the roof is too low to permit 
 of the usual arrangement ; in other cases they are 
 bolted against the cradles. 
 
 Fig. 47 shows an end cradle of cast-iron, suit- 
 able for jenny travellers, lifting up to about 1 ton 
 or 30 cwt. A is an H- joist, along which travels 
 the jenny from which pulley blocks are suspended. 
 B is a casting suitably cored, and c c are the 
 
 Fig. 47. End Cradle for Jenny Traveller. 
 
 gantry wheels keyed on axles which run in bear- 
 ings in si This form is cheap, light, and strong 
 enough for its purpose. The jenny used on such 
 a traveller is shown by Fig. 29, p. 34. 
 
 In Figs. 40, 41, and 42, a cheap form of cradle 
 is shown. The cradle B is formed of channels (see 
 Fig. 42), placed back to back, with a clear space 
 between them, and riveted together with covering 
 plates. For a light traveller, the running wheels 
 are often placed outside as shown, the axles 
 passing through bearings G o, bolted or riveted to B.
 
 56 
 
 BUILDEBS' HOISTING MACHINEEY. 
 
 Figs. 48 and 49 show a type of end cradle which 
 is at once strong, cheaply constructed, and suit- 
 able for the heavier travellers. Fig. 48 shows the 
 cradle in plan, with the ends of the two traveller 
 beams, of the type seen in Fig. 43, bolted upon it ; 
 and Fig. 49 is the same in section in front of one 
 of the wheels. Two joists of H -section A A are 
 riveted together at a distance apart sufficiently 
 wide to clear the travelling wheels B B, the union 
 being effected with a covering plate c on top. 
 End plates D D, riveted to the ends through angles 
 a (Fig. 49), make a stiff boxed structure. Bear- 
 ings E E, of cast-iron, bolted to A A, carry the axles 
 of the wheels B B. F is the timber of the fixed 
 
 
 Fig. 48. Plan of End Cradle for Heavy Traveller. 
 
 gantry, G G are the ends of the traveller beams. 
 In heavy cradles the wheels are inside the framing 
 as in Fig. 48, the arrangement outside, as in Figs. 
 40 to 42, being only adapted for lighter ones. In 
 the heaviest travellers the end cradles are stiff 
 boxed girders, built up with plate and angle iron. 
 
 It is not difficult to determine the strength of 
 any longitudinal traveller beams or end cradles 
 for a given span and load. A knowledge of mathe- 
 matics, beyond that involved in the calculation of 
 moments of inertia for given sections, is not neces- 
 sary ; and in the case of simple joists and com- 
 binations of channels even this can be dispensed 
 with, because the leading firms supply particulars, 
 which may be accepted as perfectly reliable, of the 
 strengths of joists under different conditions of
 
 DETAILS OF CONSTEUCTION. 
 
 57 
 
 loading-. It is well, however, to be able to form 
 a workable estimate of the strength of any vital 
 portion of a traveller such as the beams, tie-rods, 
 and axles, and examples of the calculations relat- 
 ing to them are here offered. 
 
 The margin of strength allowed in most parts 
 of crane work is exceptionally large. In theory 
 
 Fig. 49. Section of End Cradle for Heavy Traveller. 
 
 the loading may appear to be dead loading ; but 
 in practice it is very severe live loading, consisting 
 of impact, shock, stresses imposed suddenly and 
 removed as suddenly, and wear and tear of the 
 severest kind. All parts of a crane will fail at 
 some time or other, under ordinary as well as 
 under extraordinary stresses, and the practice of 
 well-established crane-making firms is largely built
 
 58 BUILDERS' HOISTING MACHINERY. 
 
 on the lessons taught by such failures. The know- 
 ledge gained by such experience renders it a by 
 no means difficult matter to successfully design 
 special cranes to meet special requirements. The 
 following calculations are based on sound practice. 
 There is no law by which to fix the exact 
 relationship between the depth and the span of 
 a traveller beam. Different materials and methods 
 of construction, together with different conditions 
 of head room, considerably affect the proportion. 
 Broadly speaking, an economical depth for a trav- 
 eller girder is from V.-r to -/o of the span. But to 
 show the extent to which this proportion may vary 
 under different conditions, two samples may be 
 quoted, both of which are taken from existing 
 cranes. One is a 10-ton traveller of 10-ft. span 
 only. The girder section used is a rolled joist 
 
 10-in. deep, giving a proportion of " 12 to 1. 
 
 The other is a 6-ton traveller of 65-ft. span, having 
 a plate and angle girder with double flange plate?. 
 The depth of the girder is 2 ft., giving a propor- 
 
 65 
 tion of 2 = 32'5 to 1. The section of a traveller 
 
 girder may therefore vary considerably, provided 
 its material is properly arranged to meet the 
 stresses that come upon it. Traveller girders ara 
 usually considered as beams loaded in the centre 
 and supported at the ends. The bending moment 
 on the centre section of a beam of this kind is 
 
 represented by the formula , where : 
 
 w = weight or load. 
 
 L =] length or span. 
 
 Care must be taken to add the weight of the 
 crab or jenny to the load lifted, and the weight 
 of the girders themselves must be taken into ac- 
 count as a distributed load. An example will mako 
 this a little clearer. Given a traveller to lift 10
 
 DETAILS OF CONSTRUCTION. 59 
 
 tons on a span of 50 ft., with a girder depth of 
 2 ft. 6 in., what section should the girders have? 
 Putting the weight of the crab at 4 tons, and the 
 weight of the girders at 3 tons each, then : 
 Bending moment on one girder due to half the load, 
 and half the weight of crab 
 
 7 tons x 50-ft. span _ , . 
 
 = 87'5 foot-tons. 
 4 
 
 Bending moment due to weight of girder = 
 
 3 tons x 50-ft. span _, , , 
 
 = 1875 foot-tons. 
 
 o 
 
 Total bending moment at centre of one girder = 
 
 87'5 + 18'75 = 105-25 foot-tons. 
 
 Dividing this bending moment by the effective 
 depth of the girder, the load upon the flange area 
 is found to be =_ 
 
 105-25 foot-tons 
 
 25ft. =42 tons. 
 
 If the girders are made of steel, 6 tons per square 
 inch may be safely imposed upon the flange area. 
 This will mean an area of 
 42 tons 
 
 TtoS = ' sq " in " 
 
 to be made up in flange plate and angles. Using 
 two angles, each 3 in. x 3 in. x f in., and one 
 plate 15 in. x f in., the area will = area of two 
 angles 3 in. x 3 in. x f in. minus one f-in. rivet 
 hole each = 3'65 sq. in. Area of one plate 
 
 15 in. x f in. - two |-in. rivet holes = j^L^JJl- 
 
 7'58 sq. in. 
 
 The width of the flange plate (15 in.) is just half 
 the depth of the girder, and is a good proportion 
 for traveller beams. The web plates in this case 
 may be made J in. thick. It is not usual to reckon 
 on the webs taking any of the bending moment ; 
 they have their work to do in resisting shearing 
 actions, and as, a rule they have ample area for 
 this. A web plate must have some body in it to
 
 60 BUILDEES' HOISTING MACHINERY. 
 
 withstand buckling and corrosion ; when these are 
 allowed for, it will be found that the webs are 
 safe enough in shear. Two webs should be used, 
 and the girder should be built as a box section 
 (Fig. 50). The underside of the girder may be 
 curved to enclose a parabola in its outline. The 
 depth at the ends can be made to suit their attach- 
 ment to the end cradles. 
 
 Another way of calculating the sections of 
 beams is from the moment of inertia of a section. 
 This is similar in principle to that just used 
 namely, the dividing the bending moment by the 
 depth but it is not so quickly done, and the 
 results are more exact. But the rule given and 
 worked out is suitable for ordinary work. 
 
 To estimate the strength of an ordinary end 
 cradle section is a simple matter. It is usually 
 considered as a beam supported at the ends and 
 loaded at the two points where the main girders 
 are attached. The maximum bending amount to 
 be sustained is that due to the weight imposed at 
 A (Fig. 51), multiplied by the horizontal distance 
 between A and B. The weight at A is made up of 
 two items, one of them being due to half the 
 weight of one main girder, and the other due 
 to the proportion of the weight of the crab and 
 load when right home at the end of the traveller 
 (see Fig. 52, where T signifies tons, and the load 
 is assumed to be 14 tons, consisting of weight of 
 crab, 4 tons, with a load of 10 tons). To find the 
 load at a in this figure, multiply the weight at b 
 by the distance c, and divide by the span, thus : 
 Load at a = 
 
 14 x 46 
 
 = say 13 tons, 
 ou 
 
 As this load is carried by two girders, a load of 
 
 = 6T> tons is imposed upon the end cradle by 
 
 one girder ; half the weight of one girder must be
 
 DETAILS OF CONSTRUCTION. 
 
 (31 
 
 added to this, bringing the total up to 6'5 + 1'5 = 
 8 tons at point A in Fig. 51. The bending moment 
 in this case is then : 
 
 8 tons x 27 iu. = 216 inch-tons. 
 
 The cradle section may be proportion-ad in the 
 same way as that in the main girder, that is, by 
 dividing the bending moment by the effective 
 depth, and arranging a flange area to suit. If 
 channel or joint sections are used, the modulus 
 
 ; 
 
 .-23-n r-*a'--| 
 
 90- 1 
 
 Fig. 51. 
 
 Fig. 50. 
 
 Fig. 52. 
 
 Fig. 50. Section of Box Girder. Fig. 51. Diagram of 
 Load on End Cradle. Fig. 52. -Diagram of Load on 
 End of Traveller Beam. 
 
 of the section multiplied by the stress per square 
 inch on the material equals the bending moment 
 acting upon the section. Thus, selecting say two 
 channels, each 10 in. deep by 4 in. wide, having 
 a combined modulus of section of 44, the stress 
 
 21 6 
 per square in. will = = 4'9. 
 
 The wheel bases of traveller end eradles are 
 generally about one-fifth to one-sixth of the main 
 span, but this calculation is only approximate.
 
 62 BUILDERS' HOISTING MACHINERY. 
 
 As a rule, if the cradles are well stayed, the 
 longer the base the better the crane travels, as 
 a short-base crane is apt to get jammed across 
 the track. 
 
 Traveller beams of timber have to be trussed, 
 
 Fig. 53. Diagram of Simple Truss with Central Load. 
 
 the trussing transmitting the bending stres&es into 
 tensional stresses in the tie-rods. The following 
 examples will illustrate the methods of calculation 
 adopted. Trusses are simple, or compound ; and 
 the loads are central or otherwise. 
 
 Consider first a simple truss with a central load. 
 Take, for instance, a 10-ton traveller of 36-ft. 
 span ; the load on the beams would be about 
 16 tons, allowing 6 tons for the weight of crab, 
 etc. This means 8 tons on each beam (Fig. 53). 
 When the load is in the centre the reaction at 
 each end of one beam would equal half the load 
 on it that is, 4 tons. With some definite scale, 
 say i in. to the ton, mark this, reaction on a line 
 perpendicular to the beam, then draw another 
 line parallel to the beam until it cuts the tie-bar, 
 as at left-hand end of figure ; by scaling the length 
 
 Fig. 54. Diagram of Compound Truss with Central Load. 
 
 of this horizontal line the compression on the 
 beam is obtained ; by scaling the line correspond- 
 ing to the tie-bar the tension on the bar can be 
 measured, as in the figure. 
 
 The compression on the central strut is equal
 
 DETAILS OF CONSTKUCTION. 63 
 
 to the load that is, 8 tons. The proportioning of 
 the sizes of the different members of the system 
 is simply the equating of areas to safe loads on the 
 materials used, care being taken that in the case 
 of round tie-bars having screwed ends, the area 
 under the thread of the screw is equal to the area 
 of the main bar, unless, as in the case of small 
 trusses, the bar area is slightly in excess in order 
 to avoid the expense of swelling the end for the 
 screwed portion. 
 
 Consider, secondly, a compound truss with the 
 load central (Fig. 54), the load is as in the last 
 example, and the reactions as before. The ten- 
 sions in the end tie-bars will also be obtained 
 in the same way as before. The compression on 
 
 ~m 
 
 Fig. 55. Diagram of Compound Truss with Load over one 
 Strut. 
 
 the beam is most readily obtained by multiplying 
 the action at one end by half the span, and divid- 
 ing by the depth of the truss, thus : 
 4 tons x 18 ft. 
 
 4 It = 18 tons. 
 
 As this is the compression on the beam, it is also 
 the tension on the bottom tie-bar. 
 
 Ths compression on the central struts is found 
 by dividing the load on the beam by the number 
 
 , . 8 tons 
 
 of struts, = c - = 4 tons compression on 
 
 _ struts 
 
 each strut. It will be noticed that the central 
 counter-braces do not come into action until the 
 load moves from the central position. 
 
 Consider, thirdly, a compound truss with the 
 load directly over one strut (Fig. 55), and the load
 
 BUILDEKS' HOISTING MACHINERY. 
 
 will be as before. The reactions on the supports 
 will be in inverse proportion to the distance of 
 the supports from the load, so that there is one- 
 third of the load = say, 2'6 tons on the farthest 
 support, and two-thirds of the load = 5'3 tons on 
 the nearest support. The tensions on the end 
 tie-bars and compression on the beam can be 
 obtained by the same method used for the simple 
 truss. 
 
 The compression on the strut immediately 
 under the load is equal to the load 8 tons; the 
 
 
 MR 
 
 e'r 
 Fig. 56. Calculation of Strength of End Cradle Axles. 
 
 compression on the other strut is equal to the 
 reaction at the farthest support 2'6 tons. In the 
 case now under consideration the counter-brace 
 A (Fig. 55) comes into play as a tension member. 
 The load upon it can be obtained by marking with 
 the scale of tons the compression on the farther 
 strut, using as. a starting-point the junction of the 
 three tie-bars with it, then drawing a line parallel 
 to the counter-brace from the point obtained until 
 it meets the horizontal bottom tie-bar ; the length 
 of this line represents the tension in the counter- 
 brace ; the length of the horizontal line of the
 
 DETAILS OF CONSTEUCTION. 65 
 
 triangle formed gives the tension in the horizontal 
 tie-bar. 
 
 The axles for the end cradles should have ample 
 strength, or trouble will be experienced when 
 travelling. They should be calculated for strength 
 in the wheel and also in the bearings. Taking the 
 diameter in the bearings first (see Fig. 56), it is 
 necessary, in order to have a rigid axle, to reckon 
 on a bending moment due to the load on the bear- 
 ing = 4 tons multiplied by half the length of the 
 bearing = 2 in., = 
 
 4x2 = 8 inch-tons. 
 Dividing this bending moment by 5 tons per square 
 
 Fig. 57. Struts for Timber Beams, 
 inch for wrought iron, a modulus of section will 
 
 o 
 
 be required of = 1'6. 
 
 This is obtained by fixing the diameter at 2f (the 
 modulus of section of a round bar is equal to dia- 
 meter cubed x '0982). The diameter in the wheel 
 boss must be calculated by considering the axle 
 as a beam the span of which is the distance be- 
 tween the bearings, and which is subjected to a 
 distributed load if the wheel boss extends through- 
 out the whole length as it should do. In this case, 
 the bending moment is 
 
 8 tons x 7 in. . , 
 
 = 7 men-tons. 
 
 8 
 
 This happens to come out less than the diameter 
 in the bearings, which would not do because the 
 wheel must pass over the portion in the bearing 
 in order to be placed in position. It is usual,
 
 66 BUILDERS' HOISTING MACHINERY. 
 
 therefore, to make the centre portion of the axle 
 slightly larger in diameter in order to facilitate 
 the passing of the wheel into place, and also to 
 form a slight shoulder on the axle to take side 
 working, and so prevent the wheel working loose 
 on its key from this cause. The driving axles must 
 also be calculated for a twisting moment according 
 to conditions, or method of driving. 
 
 Fig. 57 illustrates the method usually adopted 
 for the strutting of timber beams. The struts A A 
 are of cast-iron, designed to withstand compres- 
 sion. The tie-rods are of round bar, with forged 
 eyes welded on, and drilled to receive the pins in 
 the struts, the pins being in shearing stress. The 
 main rods are attached at their outer ends to cap 
 castings B on the ends of the beams. These ends 
 of the rods, which are screwed, pass through holes 
 cored in lugs on the outsides of the caps, and are 
 each tightened with a nut. The pins for the 
 attachment of the bracing rods to the timber 
 beams pass through cast-iron plates c c bolted to 
 the timbers. Flat bars are often used for tension 
 rods, and timber for struts. The latter withstand 
 compression as good as those of cast-iron, but they 
 have a heavier appearance and are only suitable 
 for small gantries. A builder who constructs his 
 own timber work can save expense by using tim- 
 ber struts. Single strutting or trussing is adopted 
 for traveller girders up to about 30 ft. span, double 
 trussing between 30 ft. and 40 ft., treble trussing 
 over 40 ft. 
 
 The platform arrangements of crabs and trav- 
 ellers vary with conditions. It is desirable to have 
 a platform running along at least one side of a 
 traveller, except in those of small dimensions 
 worked from below. In the case of traveller crabs 
 worked from an end cage, a platform along one 
 r:ide, for purposes of lubrication and examination, 
 will suffice. The platform is frequently omitted
 
 DETAILS OF CONSTRUCTION. 67 
 
 in steam crabs, the driver standing upon the foot- 
 plate of the crab and running it back to the end 
 of the gantry when the day's work is over; when 
 head room is limited, boiler and tank are suspended 
 from the crab, one on each side of the gantry. 
 
 In hand crabs, platforms for the men to walk 
 on while turning the winch handles are generally 
 put on both sides of the gantry. If this is not 
 done, the crab must be surrounded with a platform, 
 which is in one respect preferable, because the 
 men are then better able to overlook the work 
 
 Fig. 58. Fig. 59. Fig. CO. 
 
 Figs. 58 to 60. Sections and Elevation of Traveller Axle 
 Wheels. 
 
 beneath. Sometimes, too, in addition, a narrow 
 platform is run along each side of the traveller. 
 Platforms should always be guarded with hand- 
 railings. The railing is of gaspipe of about 1 in. 
 diameter, and the stanchions are light forgings 
 with feet for bolting to the timber, and holes for 
 the gaspipe to pass through. The flooring boards 
 are either supported on platform girders, which 
 are made either of rolled joists or of timber beams, 
 running in a longitudinal direction outside of, and 
 parallel with, the main beams, or they are carried 
 on iron brackets, which are built up of plate and 
 angle and bolted to the beams.
 
 68 
 
 BUILDERS' HOISTING MACHINERY. 
 
 The platform, when attached to and travelling 
 with the crab, must go completely round it so as 
 to afford access from one side to the other. It is 
 supported on stiff angles, which are bolted to any 
 conv-enient points of attachment on the crab fram- 
 ing, and it must be surrounded with handrailing. 
 
 The axle wheels of travellers are made either 
 of cast-iron or of steel ; in the heaviest travellers 
 the centres are of cast-iron and the tyres of Bes- 
 semer steel, which are checked and shrunk on the 
 
 Fig-. 61. 
 
 Figs. 61 and G2. Section and Elevation of Traveller Axle 
 Wheel. 
 
 centres. These axle wheels are shown in Figs. 58 
 to 62. The cast-iron or cast-st-sel wheel (Figs. 58 
 to 60) is made with a solid centre web in preference 
 to arms. Arms are not so conducive to security of 
 working as solid plate, because the metal in the 
 rim is always in excess, as shown in the sectional 
 views, partly for strength and partly to allow for 
 wearing down of the tread. 
 
 The shrinkage stress-as between the arms and 
 rim are therefore not equal, and, though fracture 
 may not occur at the time of casting, it is likely 
 to happen afterwards under moderate stress, be-
 
 DETAILS OP CONSTRUCTION. 
 
 (19 
 
 cause the metal is in a permanently overstrained 
 condition. The evil may be lessen-ed by careful 
 regard to proportioning and by the use of large 
 radii. But these precautions are often neglected, 
 and therefore it is always safer, except for very 
 light loads, to have plated wheels ; but even for 
 light loads also it is best to be on the safe side. 
 
 The plated wheel is frequently stiffened by cast- 
 ing arm-like ribs on both sides of the plate (Fig. 
 60). These ribs give additional support to the 
 rim, which is subject to much stress not only from 
 the dead load, but also from diagonal stress acting 
 
 Fig. 63. Fig-. 64. 
 
 Figs. 63 and 64. Cast-iron Bearing. 
 
 against the flanges, due to cross working of the 
 traveller or crab. The difference between an iron 
 and a steel wheel, each of which is made as in 
 Figs. 58 and 60, is that the latter for equal loading 
 may be about from 30 to 50 per cent, lighter than 
 the former. It is not a usual practice to turn the 
 treads of wheels, but it is often insisted on in 
 high-class work, and conduces to smooth running. 
 The compound wheel (Fig. 61) is only required 
 for heavy pressures and severe duty. Fig. 62 
 shows another view of Fig. 61. It is the best 
 possible form of wheel, but is expensive. The tyres 
 A are weldless, rolled from Bessemer steel blanks, 
 and these are turned and bored carefully to suit
 
 70 
 
 BUILDERS' HOISTING MACHINERY. 
 
 the turned cast-iron centres B. The turning fit 
 is sufficiently easy to permit of the tyre, when at 
 a low red heat, dropping over the raised check 
 on the rim. Wh-en dropped over in this condition, 
 the tyre as it cools grips the centre so tightly that 
 bolt or rivet fastenings are not required. The 
 depth of the check averages T V in. The centres 
 must be massive and solid webbed ; arms are quite 
 unsuitable. Both web and rim must be thick, us 
 shown proportionally in the figures. 
 
 Kails used for travellers 
 and traveller crabs are 
 of the flanged type. 
 They are bolted direct 
 to the wood or to 
 steel beams. In the 
 latter case wood pack- 
 ing is frequently in- 
 serted. They may be 
 bolted down direct 
 or through clips 
 pressing on the rail 
 flanges. 
 
 The cast-iron bearings for the axles of end 
 cradles are usually of the forms shown in Figs. 63 
 and 64 (plate bearings) or Fig. 65 (dead-eye bear- 
 ings). These last are easily fitted, and as the 
 motion of the axles is but slow, the bearings are 
 seldom brass-bushed except in power travellers. 
 Bearings of the type shown in Figs. 63 and 64 are 
 of cast-iron, riveted and bolted between the chan- 
 nels A, chipping strips being used, because chan- 
 nels that are nominally alike vary slightly in width 
 and in thickness of flange ; by using strips, there- 
 fore, the work of chipping to a fit is often dimin- 
 ished. The bearings are properly bored after 
 being fitted and bolted into 
 
 Fig. Go. Cast-iron Bearing.
 
 CHAPTER V. 
 
 APPLYING MOTIVE I OWER TO HOISTING MACHINERY. 
 
 THE methods by which the motive power is made 
 to operate travellers and crabs may now be con- 
 sidered in detail. 
 
 Beginning with the simplest, Fig. 66 shows the 
 design of single gearing adopted for the longi- 
 tudinal travel of travellers operated from below, 
 a rope wheel turned by an endless rope depending 
 therefrom. Its shaft operates the bevel pinion B, 
 and wheel c ; B has its bearings in the boss of the 
 bracket D bolted to the traveller beam E ; c is 
 keyed on the shaft F which runs the whole length 
 of E, having its bearings at G G, which are also 
 bolted to E. There will be one or more inter- 
 mediate bearings like G at intervals along the 
 beam to support F. Two pinions H H at the ends 
 of F drive wheels j J, keyed on the axles of the 
 travelling wheels K K. The travelling wheels at 
 the other end simply follow those, being ungeared. 
 In heavy travellers, double gear is used instead 
 of the single gear shown in Fig. 66, an inter- 
 mediate pinion and wheel coming between H and K. 
 
 The rope and chain wheels A, used for operat- 
 ing travellers from below, are always as light as 
 it is possible to cast them. Metal massed in these 
 wheels would be in the wrong place, because there 
 is practically no stress on them, and it would only 
 add to dead load on the shafts and beams. These 
 wheels are worked by ropes and by chains; a. 
 wheel with a smooth rim being used for rope, and 
 one with a nibbed rim for chain, because a rope 
 will bite on a smooth rim, -but a chain will slip. 
 The general proportions of both wheels are alike,
 
 72 
 
 BUILDERS' HOISTING MACHINERY. 
 
 and the same patterns are generally used, the only 
 difference being in the rims. 
 
 Figs. 67 to 69 illustrate the general outlines of
 
 APPLYING MOTIVE POWEE. 
 
 chain or rope wheels. The arms are light, and the 
 rim is of V -section, with a radius in the bottom, 
 so that the rope or chain instead of lying close 
 to the bottom of the rim is gripped between the 
 sides of the V (Fig. 70), which arrangement materi- 
 ally assists the bite. Sometimes rope wheels are 
 
 Fig. 67. 
 
 Figs. 67 and 68. Rope or Chain Wheel with Guide Pulleys. 
 
 " waved " that is, the V looked at edgewise is 
 curved lengthwise at the bottom (Fig. 71), so that 
 the bending or biting effect between the rim and 
 the rope may be increased. This is a desirable 
 provision when the ropes and the wheels are large, 
 but it is not necessary for small ropes. 
 
 The nibs cast on for chains are of the form 
 shown in Fig. 72. They are about f in. wide in the
 
 74 BUILDERS' HOISTING MACHINERY. 
 
 middle, standing about \ in. high, are rounded off 
 towards the ends, and are placed from 1^ in. to 
 2 in. apart. Fig. 72 is a longitudinal section of the 
 V - rim, Fig. 73 is a cross section, and Fig. 74 is a 
 
 Fig. 6!). Rope or Chain Wheel. 
 
 plan. To accommodate a large chain, the rim of 
 the wheel should be cast with recesses into which 
 the links of the chain will drop bodily (Fig. 75). 
 The pitching out must be accurately done, other- 
 wise the chain will ride in the wheel instead of 
 dropping into the recesses, and the difficulty of 
 obtaining this accurate fitting increases with the 
 size of the wheel, or with the arc of contact with 
 
 Fig. 70. 
 
 Fig. 71. 
 
 Fig. 71. 
 
 Fig. 70. Section of Rope in V-rim of Pulley. 
 Rim of Waved Rope Wheel. 
 
 the chain. The best way is to pitch the centres 
 of the recesses accurately, and to allow consider- 
 able clearance between the chain links and these 
 recesses.
 
 APPLYING MOTIVE POWER. 75 
 
 The dimensions of rope and chain wheels vary 
 from 2 ft. to 5 ft. in diameter. The metal in the 
 rims ranges from J in. to f in. thick, and the arms 
 are made as light as possible, consistently with 
 reasonable rigidity. If large bosses have to be 
 cast, as when the wheels of this kind have to fit 
 over sleeves, the arms being cast also, the shrink- 
 age of the bosses is liable to cause fracture in the 
 arms. It is better, therefore, to split the boss in 
 the mould and bond it subsequently. 
 
 Figs. 68 and 69 illustrate the two general 
 
 Fig. 73. 
 
 yv 
 
 Fig. 74. 
 
 Figs. 72 to 74. Longitudinal Section, Cross Section, and 
 Plan of Nibbed Rim. 
 
 designs on which rope wheels are made. The first 
 is of cast-iron, with curved arms, this curving 
 diminishing any tendency to fracture ; the second 
 is made with wrought-iron arms cast into rim and 
 boss, and hence is termed a spider wheel. Fig. 68 
 is suitable for wheels up to about 2 ft. 6 in. dia- 
 meter, Fig. 69 for the larger wheels. In both 
 figures the details are suitably proportioned. The 
 bite of a rope on a smalt pulley is increased by 
 the employment of guide pulleys as in Fig. 68, 
 which are not necessary in larger wheels. But it 
 is proper in any case to have swinging rope guides, 
 as in Fig. 69, to coerce the rope and prevent it
 
 76 BUILDEES' HOISTING MACHINERY. 
 
 from getting off the pulley groove during working. 
 This guide is a T-shaped forging dependent from 
 the spindle, being bored at the top to fit over the 
 pulley spindle, and maintained at a suitable dis- 
 tance by distance pieces at the ends of the bottom 
 horizontal. The rope passes between the two 
 horizontal members. The manner in which the 
 T-shaped sling is supported and bent inwards to 
 the wheel is seen in Fig. 68. 
 
 One disadvantage of the crab worked from 
 below is that ropes or chains hang down in the 
 way of the work, and of the workmen on the floor 
 below ; but this would only be objectionable in 
 some cases. This type of crab is suitable for 
 occasional service, but for constant duty the types 
 before referred to are preferable. 
 
 The numerous class of travellers which are 
 operated from above embrace the square-shaft, 
 both hand and steam ; the cotton-rope ; and the 
 electrical types. The square-shaft traveller is the 
 oldest; the steam comes next in point of time, 
 and is followed by the cotton-rope and the elec- 
 trical types. The cotton-rope traveller is steam- 
 driven, but the engine is not on the traveller or 
 crab, but is situated elsewhere. The square-shaft 
 type is, in the hand travellers, driven from the 
 crab gearing, as also are the steam travellers 
 proper ; or a steam-driven square gantry shaft 
 will operate both the traveller and the crab. In 
 some few cases the longitudinal movement of a 
 traveller is not worked from the crab, but by 
 means of gearing on the end cradles. This is not 
 a good arrangement, because it entails loss of 
 time, though the construction of the crab is 
 simplified. 
 
 When putting up a traveller, the choice of type 
 and of motive power must be largely governed by 
 the conditions which exist in the factory or works. 
 If sufficient engine power is available, it might
 
 APPLYING MOTIVE POWER. 77 
 
 be better to utilise it for driving by rope or square 
 shaft. If there is a dynamo already in the place, 
 or if it is intended to set up a dynamo for any 
 purpose, such a>s lighting, the same machine or 
 another might also be employed for driving the 
 traveller. 
 
 In increasing motive power when that power 
 is steam, the cost of shafting and belting, etc., 
 for transmission, and of oil and repairs, becomes 
 a serious item, while the extension of electrical 
 power involves nothing more than the laying down 
 of new dynamos, motors, and conductors. The 
 
 . 75. Longitudinal Section of Wheel Rim with Cast 
 
 waste due to friction in hundreds of yards of shaft- 
 ing and shaft fittings is enormous; that due to 
 heat losses in dynamos and motors does not cost 
 money for renewals, as in the case of steam 
 driving. 
 
 For hoisting, even mpre than for the driving 
 of machine tools, it is desirable that electricity 
 should be employed rather than steam power trans- 
 mitted by belts, shafts, or ropes, because hoisting 
 is in most shops of a very intermittent character, 
 and belts, shafts, or ropes run continuously. The 
 electrical plant, requiring no time to develop 
 power, is, therefore, far better fitted for such in- 
 termittent Avork. Electricity is, too, more adapt 
 able and more economical than steam, as motors 
 can be set down and worked anywhere ; but a 
 steam engine must be near its boiler, because the 
 farther it is away the larger is the percentage cf
 
 78 BUILDEKS' HOISTING MACHINERY. 
 
 wasted steam ; it must also be kept at work, with 
 an expenditure of power out of all proportion to 
 the results., though only one or two machines out 
 of a shopful are running. 
 
 In smoothness, of running, a high-speed crab, 
 whether driven by rope or electricity, is superior 
 to a steam-driven crab, because to the latter is 
 transmitted from the engine a more or less oscil- 
 latory motion. But the worm-drive on high-speed 
 travellers is always very smooth, while the longi- 
 tudinal travel is equally so. Another advantage 
 of high-speed driving is that the load due to the 
 crab, which is dead load on the beams, is lessened 
 by the absence of the boiler, engines, and tank. 
 This load, though advantageous in a balance crane, 
 is undesirable in a crab. There is little difference 
 in the motor arrangements, whether belts or gear 
 wheels are used for transmitting motion from the 
 end of a traveller to its crab. The substitution of 
 one motor method for th other can be easily 
 effected at a small cost. 
 
 If a quick-speed power traveller is required, 
 and the laying down of electrical power at some 
 future time is contemplated, the best traveller to 
 obtain is one of the rope-driven type, either with 
 belt or with clutch arrangements. In such circum- 
 stances, a motor can always be substituted for 
 the rope drive ; but, with a steam crab, tha cost 
 of conversion either into ropa drive or into elec- 
 trical drive would be nearly prohibitive, because 
 engines and boiler would be useless, the, bevel- 
 gear between the square shaft and the crab would 
 have to be replaced with worm gear, and the whole 
 of the driving and reversing gear at the end, 
 whether wheels or belts, would have to be entirely 
 new. 
 
 The square-shaft drive is suitable for gantries 
 of moderate length and for moderate speeds. But 
 for long gantries and high speeds it is not so well
 
 APPLYING MOTIVE POWER. 
 
 suited as the rope drive. The latter can be of 
 unlimited length, the former should not be more 
 than about 200 ft. Rope driving 
 is quieter than shaft driving. 
 Wire, hemp, and cotton are used ; 
 and speeds range between 2,000 
 ft. and 5,000 ft. per minute, 2,000 
 ft. being a usual rate. 
 
 The steam traveller is the best 
 type for use out-of-doors in yards, 
 docks, and harbours ; but it is 
 not desirable inside buildings, be- 
 cause of the sulphur, steam, and 
 dust given off. For such situa- 
 tions any of the other methods of 
 driving are preferable. 
 
 Square-shaft and electrically 
 driven travellers are sometimes 
 made to work from below, with 
 dependent chains. In such cases, 
 the chains pass over pulleys, 
 from which the operating clutches 
 on the traveller are controlled. 
 Such an arrangement is not de- 
 sirable, and is only adopted when 
 ths work is of so intermittent a 
 character that there is not suffi- 
 cient of it to keep a man con- 
 stantly aloft. 
 
 Fig. 76 shows the general ar- 
 rangement of the working of a 
 square - shaft traveller from a 
 crab. The same method will 
 serve alike for hand or steam. 
 Substantially the same arrange- 
 ment would be used if the 
 traveller were driven from 
 
 'M- / 
 
 a square 
 
 shaft 
 
 running down one of the gantry beams, the 
 direction of driving being reversed. In Fig. 76,
 
 80 BUILDEES' HOISTING MACHINERY. 
 
 A is one of the traveller beams, single-webbed and 
 fish-bellied ; B B are the end cradles, plated, 
 against which the beams fit by abutment ; c c are 
 the gantry beams against the walls of the shop ; 
 D is the square shaft driven by the sliding or 
 sleeve-bevel wheel E, from the crab gear through 
 F'. The wheel E travels with the crab, having its 
 bearings in a bracket on one side of the crab, the 
 journals being indicated by diagonal lines, and the 
 revolution of the wheel turns the shaft D in its bear- 
 ings at the ends of the beam. The shaft D is 
 supported by the tumbler bearings F F, which have 
 their bearings on the sides of the beam A. The 
 radius described by the bearings when knocked 
 over by the passage of the wheel E is indicated by 
 dotted half-circles. The motion of the shaft is 
 communicated to the running wheels G G through 
 two sets of gear, one at each end. Each set com- 
 prises two pinions A' B' and two wheels c' D', by 
 which power is gained. The wheel D' is keyed in 
 the axle of G. 
 
 Heavy shaft-driven travellers are sometimes 
 driven by bevel wheels and reversing clutches, 
 arranged at one end of the gantry. There is an 
 advantage in the adoption of such an arrangement, 
 besides that of permitting the attendant to over- 
 look properly the operations going on below, as 
 it is one in which rope or electrical driving can 
 be afterwards substituted with the minimum of 
 expense. In this type of traveller the rotation of 
 the square shaft is transmitted through bevel 
 gearing to the shaft which is driven parallel there- 
 with, above the end cradle, and the substitution 
 of a motor for the square shaft would be the only 
 alteration necessary, the reversing bevel gearing 
 being retained for the operation of the several 
 motions. 
 
 When a traveller and a crab are driven in this 
 way from a square shaft running down one of the
 
 APPLYING MOTIVE POWEE. 
 
 81 
 
 gantry beams, the arrangement referred to, and 
 one which is frequently adopted, is that shown 
 
 in Figs. 77 and 78. Fig. 77 shows an end elevation 
 of the gear ; Fig. 78 shows a plan view, all ad- 
 jacent details being omitted, and the location of 
 
 F
 
 82 BUILDERS' HOISTING MACHINERY. 
 
 the journals being indicated by diagonal lines. In 
 this design each distinct motion is operated by 
 a separata set of gears on one shaft on the end of 
 the traveller, over the end cradle. 
 
 In Fig.s. 77 and 78 A is the longitudinal down 
 gantry shaft, and B is the bevel wheel which slides 
 on ths shaft with the movement of the traveller. 
 This wheel gears into another bevel wheel c, which 
 has its bearing in a bracket bolted to the end 
 cradle, the shaft D of which has a bevel wheel E 
 at its upper end, which gears with and drives a 
 bevel wh-ael F on the shaft G, that carries the differ- 
 ent gears for actuating the several motions that 
 namely of longitudinal travelling H, of cross-trav- 
 ersing J, and of hoisting K. In these gears the 
 mode of operation is that of friction cones, or 
 friction clutches. The sliding of either of the 
 double-ended clutches L L L to right or left drives 
 the shaft in one direction or the other. The bevel 
 wheels run loosely, the clutches only having key- 
 ways which slide on feather keys in the shaft. 
 
 When the clutch L is in gear with the clutch on 
 a pinion the two are as one, and are driven by 
 the feather key. The pinion which is engaged 
 with the clutch drives the larger wheel on the 
 shafts M N or o, which operate the several motions 
 through other wheels and pinions. The shaft N 
 drives the running wheel p through the inter- 
 mediate gear Q R s T u, and the shafts M and o 
 operate the traversing and lifting motion through 
 sliding worms, and worm wheels on the crab. 
 All the bevel wheels are half shrouded that is, 
 they have flanges or caps reaching to the pitch 
 planes, and turned on their edges, and these roll 
 against one another in continual contact during 
 the operation of the gears. The advantages are 
 twofold the strength of the teeth is slightly in- 
 creased, and the motion is rendered smoother and 
 more regular, These flanges are an important
 
 APPLYING MOTIVE POWEE. 
 
 83 
 
 detail in good practice, which should never be 
 omitted in high-speed hoisting gearing. The same 
 addition is to be observed in the spur wheels Q 
 to T. The whsel v is not driven by gear, but 
 trails only. The rail level is indicated by the 
 dotted line w, and the end cradle by the dotted 
 outlines x. A projected view of wheel v is shown. 
 The gantry shafts, which are used for driving 
 to or from traveller crabs, are almost invariably 
 made of square bar iron or steel. Steel is gener- 
 ally used now, because a smalLer size can bs used 
 
 Fig. 80. . Fig. 79. 
 
 Figs. 79 and 80. Sliding Pinion on Gantry Shaft. 
 
 than in wrought iron, thus reducing dead weight 
 while retaining equal strength. The shafts are 
 made square because they have to drive or be 
 driven through bevel gearing, one wheel of which 
 must revolve, either driving or being driven by 
 the shaft as it revolves. The sliding wheel is 
 cored and slotted, or cored only, and filed out to 
 make an easy sliding fit on the shaft, but not so 
 easy as to permit of much slop and backlash 
 (Figs. 79 and 80). These shafts are not tooled, 
 but are left black. A coarse file may be passed 
 over them, but nothing more. As the shafts are 
 generally longer than the standard length of bars, 
 one, two, or more joints have to be made in them. 
 These are of the scarf form, that shown in Fig. 81 
 being as good as any other, and the most easily
 
 BUILDEES' HOISTING MACHINERY. 
 
 made. In making such a joint as this, the scarfs 
 are formed by slotting in a machine, and the 
 rivets have countersunk heads. The size of bars 
 used will range from If in. in light hand and 
 power travellers, to 2^ in. and even 3 in. in the 
 larger power travellers. 
 
 As the shafts are of great length in proportion 
 to diameter, it is necessary to afford them support 
 at several points intermediate between the end 
 bearings. But, as they have to be traversed con- 
 stantly from end to end by the sleeve bevel wheel 
 which slides along, the bearings cannot be rigid, 
 but must be of a type which can be easily moved 
 aside momentarily to allow the wheel to pass. 
 
 Fig. 81. Scarf Joint in Shaft. 
 
 This is the tumbler type, and is found in modified 
 forms in all travellers. Some of the tumbler bear- 
 ings are much more complicated than others, and 
 are the subject of patents. They all belong to one 
 of two types ; one is that of a lever or levers 
 thrust over by the passage of the bevel wheel 
 removing the supporting bearing from the shaft 
 momentarily, the support being returned auto- 
 matically as soon as the wheel has passed and left 
 the bearing clear. The other is a bearing moving 
 vertically, thrust downwards by the passage of 
 the wheel, and returning immediately afterwards. 
 The commonest type of tumbler, which is cheap 
 and efficient, is shown in Figs. 82 and 83. It con- 
 sists of a bell crank lever A, pivoted in a bearing
 
 APPLYING MOTIVE POWER. 
 
 85 
 
 B, on the sides of the gantry beams c, and having 
 recesses at its free ends to receive the turned 
 portions of the shaft. As the crab comes along 
 it knocks over the bearing which is uppermost, 
 causing the horizontal lever arm, with its bearing, 
 to rise up and take the position of the displaced 
 vertical bearing immediately after the passage of 
 the wheel. The lever arms are maintained in a 
 vertical position by the resting of the horizontal 
 arms upon supports bolted to the traveller sides. 
 
 Fi. 82. Fig. 83. 
 
 Figs. 82 and 83. Tumbler. 
 
 feen in Fig. 76. The mechanism is efficient ; but 
 the d-etails will vary in different cases. In the 
 lighter travellers the ends of the tumblers are 
 simply cored out, as shown in Figs. 82 and 83, 
 and not machined, but cleaned out a little with 
 the file. For the rapidly revolving and heavy 
 shafts, bearings are made of brass or phosphor 
 bronze, bored and fitted into the ends of the cast- 
 iron tumblers. 
 
 The driving of travellers and crabs -from a 
 square gantry shaft seems a somewhat clumsy 
 device. The shaft must be heavy and of large
 
 86 BUILDERS' HOISTING MACHINERY. 
 
 size to resist torsional stress, and it must be 
 supported in tumbler bearings at intervals. This 
 increases weight and expense, and absorbs much 
 power. Moreover, very long gantry shafts are 
 objectionable, because of their tendency to twist 
 and their great weight. It is for these reasons 
 that the cotton rope and electrical drives have 
 found so great favour. 
 
 Thsre is little difference between the gearing 
 of an electrical and of an ordinary crab or trav- 
 eller, and electricity can be applied to almost any 
 well-constructed hoisting machine, with a few 
 necessary alterations. The traveller picks up the 
 electric current from a conductor running down 
 the length of the shop, which through a motor or 
 motors on the traveller drives the first motion 
 shaft in place of the cotton ropa, or square shaft, 
 of an ordinary machine. 
 
 A common difference between a square-shaft 
 traveller and a rope or electrically driven traveller 
 is that the shaft is driven at a slow speed, and 
 that the latter two are driven at a very high speed. 
 In the first case it is not necassary to effect much, 
 or even any, reduction in speed between the shaft 
 and the crab ; in the latter two cases it is necessary 
 to do so, in order to bring the rates of lifting, 
 travelling, or traversing, within workable and safe 
 limits. 
 
 A rope must be driven at a high speed to 
 develop its dynamical force, and an armature must 
 generally revolve at a high speed. Ropes run at 
 rates ranging from about 1,500 to 3,000 ft, per 
 minute, and armatures revolve at from 700 to 
 1,200 ft. per minute. The reduction of soeed be- 
 tween the first driving shaft and the crab is nearly 
 always effected by worm gearing, in some cases, 
 however, by spur gearing. General practice 
 favours the former, but there are exceptions, and 
 single-threaded worms have, until recently, been
 
 APPLYING MOTIVE POWER. 87 
 
 most generally used ; but double and even treble- 
 threaded worms are now successfully employed, 
 th-3 idea being to reduce the excessive friction 
 which occurs between the gears. Single-worm fric- 
 tion, however, has its advantages, and the method 
 has its advocates., because the friction is so great 
 in amount that the crab can never run and turn 
 the worm through the wheel, which can happen 
 in double- and treble-threaded worms. When the 
 latter are used, therefore, it is necessary to fit a 
 brake to the gear. 
 
 The reversing mechanism for each motion (lon- 
 gitudinal, cross-traverse, and lifting) must, both 
 in shaft- and rope-driven travellers, be effected 
 either through belting or clutches: the clutches 
 being of the general type and arrangement illus- 
 trated by Figs. 77 and 78, and the belting, when 
 used, being open and crossed for each motion, in 
 order to run the operating shafts in reverse direc- 
 tions. In electrical travellers each of these 
 methods is employed, as well as another method 
 which is* not practicable with square-shaft-driven 
 travellers namely, the use of reversing motors, 
 but the opinions of engineers and electricians are 
 divided as to the advantages, of this method. One 
 advantage is that the use of reversing motors does 
 away with the intermediate gear of clutches and 
 wheels, or belts and pulleys. 
 
 When it is a question of converting an existing 
 rope- or square-shaft traveller, it is perhaps as well 
 to employ a continuous-running motor; but when 
 a new driving system is being designed, the knock- 
 ing out of the reversing gear is worth considera- 
 tion. Electricians, generally object to the use of 
 reversing motors, but the experience of several 
 competent engineers has demonstrated their prac- 
 tical utility in the driving of overhead travellers. 
 
 There are two ways in which the motions of 
 travellers and crabs are regulated by the atten-
 
 88 BUILDERS' HOISTING MACHINERY. 
 
 dant; one is by means of levers, another through 
 hand wheels. These may operate friction clutches 
 in gearing, or belts. Clutches are either of the 
 claw or of the friction type, the latter running with 
 less shock than the first. Claw clutches are not 
 suitable for the high speeds of rope- or electrically- 
 driven travellers, notwithstanding that they are 
 used for slow-running cranes. 
 
 Practice is pretty equally divided between belt 
 driving and friction cone driving for power, rope, 
 and electrical travellers. Both are durable ; both 
 have the advantage of effecting a gradual start 
 and a gradual stoppage, and both, being operated 
 by levers or by hand wheels, are under perfect 
 control ; both possess the very desirable charac- 
 teristics of yielding under excessive and dangerous 
 stress, the clutches slipping within each other, and 
 the belts slipping on their pulleys, while possessing 
 ample grip for all legitimate duty. 
 
 The sizes of cones, the angle of cones, and the 
 length of drive of belts, cannot be determined by 
 theoretical considerations, but are settled solely 
 by practice, according to the duty which they have 
 to perform. The holding powers of clutches, 6 in. 
 or 8 in. in diameter, is sufficient for loads of from 
 five to ten tons, and the angle of cone is about 
 1 in 6. If the angle were much less than this it 
 would cause seizing ; if it were much greater it 
 would impair the frictional power. For operating 
 these clutches, either a hand lever or a screw 
 movement is employed. The lever is more rapid 
 in its action, but the screw holds more securely, 
 and should be generally adopted. 
 
 Levers alone are used for belt shifting. Belt 
 driving is rather more gradual as regards increase 
 of speed than clutch driving ; but trouble may 
 occur in consequence of the slipping of the belts, 
 which is generally caused by too short a drive. 
 A long drive, which is easily obtained in the
 
 APPLYING MOTIVE POWER. 89 
 
 belting for most machine tools, cannot be got on 
 a traveller. But the short drive should be used 
 under tho most favourable conditions possible, and 
 the belts must be kept tightly strained ; this is 
 not the best way of running a belt, it is true, but it 
 is ths only way possible in traveller driving. Tho 
 best kind of belting must bo used, for inferior 
 qualities will give perpetual trouble by stretching, 
 iraying, and cracking in consequence of the high 
 spoed at which they are run. 
 
 The arrangement of the belting varies in trav- 
 ellers by different makers. But generally there is 
 a first motion drum, and from this all the traveller 
 and crab motions are driven. The lifting shaft is 
 driven by two pairs' of pulleys, each pair being 
 fast and loose. The larger pair is used for lifting, 
 the smaller pair for lowering the reversal of the 
 latter being accomplished by crossing the lowering 
 Holt. The traversing shaft is driven by three 
 pulleys and two belts, one belt open and the other 
 crossed, driving on the outer pulleys, the middle 
 pulley being the loose one. The longitudinal 
 travelling is done by a drive on to pulleys on an 
 intermediate spindle, and gear wheels are used 
 to reduce speed and gain power. Such an arrange- 
 ment of belt driving will be suitable for a motor- 
 driven or a rops-driven traveller. With a motor 
 drive the end pulleys will be belt connected ; with 
 a rope drive the rope will run over grooved pulleys 
 in the place of the belt pulleys. 
 
 Electrical crabs are driven through one or more 
 motors. The former method is the most common. 
 The motor is set on one end of the traveller, and 
 the motions of the crab are operated through 
 levers. The object in using three motors is to 
 have each one proportioned to the particular work 
 which it has to do, that is, lifting, travelling, and 
 cross traversing. No intermediate gear is re- 
 quired. Motors are connected to the first motion
 
 90 BUILDERS' HOISTING MACHINERY. 
 
 drum by means of a belt drive. The objection to 
 this is the shortness of the drive, which is liable 
 to cause considerable slip. The motor is usually 
 fixed on a sliding base plate for adjustment. 
 
 A method of driving permitting instant connec- 
 tion with, and disconnection from, th-3 motor, is 
 the Hollick friction gear, by means of which the 
 movement of the motor can be instantly switched 
 off from the hoisting drum. The armature shaft is 
 provided at one end with a paper-covered friction 
 pulley. This is run in contact with a cast-iron 
 pulley on the same shaft as the first pinion which 
 drives the gear for the hoisting drum. The two 
 are kept in contact by means of a third pulley, 
 which is maintained in contact with the paper 
 pulley by means of two adjustable links. 
 
 When the centres of the pulleys are in line the 
 pulleys are in frictional contact. But a slight 
 movement of the outer pulley up or down will break 
 the contact, and the driving pulley will cease run- 
 ning, being out of contact with th-3 paper pulley on 
 the armature shaft. Contact is broken by levers and 
 links. The pushing over of a large lever moves 
 the short levers and the links, causing the centre 
 of the outer wheel to turn in an arc round the 
 centre of the driving-wheel shaft, thus throwing 
 the first pulley out of the line of centres and 
 breaking the contact 
 
 Very few data are as yet available for estimat- 
 ing the relative economy and efficiency of trav- 
 ellers actuated by ropes and by electricity, but so 
 far the balance of evidence is in favour of elec- 
 tricity. Some practical men believe that effective 
 electrical hoisting machinery has yet to be de- 
 signed. Electrical driving is at present in the 
 crude stage ; instead of adapting machines to its 
 special requirements, it is used for machinery that 
 has been designed for an altogether different 
 motive power. An analogous case is that of the
 
 APPLYING MOTIVE POWER. 91 
 
 early railway carriage, which was a very slight 
 adaptation of the then familiar stage-coach. Up 
 till recently the practice has been to drive all 
 motions of a traveller from one motor ; it is now 
 beginning to be understood that this is somewhat 
 akin to driving a machine from shafting and 
 pulleys, or a crane from a flyrope or square shaft, 
 each of which is running constantly, whether the 
 machine or crane is, or is not, being used. At 
 any rate, engineers are feeling their way to bettor 
 designs, and it is probable that in this, as in other 
 departments of engineering, much may be learnt 
 from America, where the advantages of electrical 
 driving are more appreciated than they are in 
 this country, and where it is more extensively 
 applied. 
 
 The power required to drive the ropes alone 
 for travellers is considerable, and this is constant 
 even when the traveller is at rest. Mr. John Barr 
 found that the power to drive the ropes for two 
 travelling cranes, with the ropes running at 2,200 
 ft. and 1,570 ft. par minute respectively, varied 
 from 5'9 indicated horse-power in the first to 6'3 
 indicated horse-power in the second, per 100 ft. 
 length of shop. The ropes formerly used for driv- 
 ing the travellers in the erecting shop at Horwich 
 ran at a speed of 3,880 ft. per minute. Thece were 
 eaeh If in. diameter and 600 ft. long, weighing 
 3 cwt., and each absorbed with its pulleys 15'5 
 horse-power. 
 
 The power absorbed in driving shafts and belt- 
 ing nearly always forms a large proportion of the 
 total power used. The table* on p. 92 will give 
 some idea of this. 
 
 One of the objections sometimes urged againrt 
 electrical driving is that the attendants lack tech- 
 nical knowledge ; and a graver accusation is that 
 the original designers of the machines do not 
 possess that theoretical and practical acquaintance
 
 BUILDERS' HOISTING MACHINERY. 
 
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 with the subject which is absolutely necessary to 
 success in machine construction. The designing of 
 a good electrical traveller requires the co-operation 
 of the electrician and the mechanical engineer ; 
 neither of them alone appears to be able to design 
 an efficient traveller. 
 
 The almost general practice hitherto has been 
 to copy a rope-driven or square-shaft traveller in 
 all, or nearly all, its details, and then to substitute 
 the motor for the usual method of driving. This
 
 APPLYING MOTIYE POWEE. S3 
 
 plan may not be open to objection when it io 
 required to convert existing travellers, but it will 
 not be on such lines that the successful machine 
 of the future will be arranged. In such machines 
 it is probable that intermediate gear will be aban- 
 doned, and that one motor will drive one particular 
 motion, each being reversible by the same motor, 
 without intermediate gear. Further, in an elec- 
 trical traveller provision must be made for the 
 gradual starting of th3 machinery. This is accom- 
 plished by inserting a resistance, which permits 
 the flow of only just sufficient current to start th? 
 motor. As the load is taken on, the resistance is 
 gradually cut out, either by the movement of the 
 switch in the hand of the attendant or by an 
 automatic governor. The prevention of sparking 
 under wide variations of load is an essential re- 
 quirement, and so also is the making of the brushes 
 self-adjusting for wear. In such matters the elec- 
 trician can render valuable aid to the mechanical 
 engineer.
 
 INDEX. 
 
 Armature Shaft, 90 
 
 Axle Wheels of Travellers, 63 
 
 Axles for End Cradles, 65 
 
 Barrel-shaft Crab, 21 
 
 Beams, Calculating Sections of, 
 6J 
 
 , Gantry, 31 
 
 , Main, 46 
 
 , Timber. Strutting, 66 
 
 -, Traveller, Depth of, 58 
 
 , Load of 6-3 
 
 , Span of, 58 
 
 , Strength of. 56 
 
 , Trussing, 62 
 
 Bearings, Boss, 42 
 
 , Brass, 44 
 
 , Cast-iron, 44, 70 
 
 , Dead-eye, 70 
 
 , Diameter of, 65 
 
 , Divided, 44 
 
 , Plate, 70 
 
 . Shaft, 18 
 
 Belt Driving, 88 
 
 Bending Moment, 53, 59 
 
 Blocks, Differential Pulley, 23 
 
 , Double-sheaved, 16 
 
 , Gin, 12 
 
 , Pulley, 9. 12, 14 
 
 , Snatch, 16 
 
 , Weston Pulley, 14 
 
 Boss Bearings. 42 
 
 , Wheel, Diameter of, 65 
 
 Box Girders, 54, 56, 60 
 
 Brake Wheel Crab, 23 
 
 Brass Bearings, 44 
 
 Cast-iron Bearings, 44, 70 
 
 Cheek for Hand Crab, 43 
 
 Chain Wheels, 71, 75 
 
 Cheeks, Hand Crab, 41, 43 
 
 Clutches, 88 
 
 , Claw, 83 
 
 , Friction, 88 
 
 Cones, Clutch. 88 
 
 Cotton Rope Drives, 86 
 
 Crab, Barrel-shaft of, 23 
 
 , Brake Wheel of, 20 
 
 , Double-gear, 23 
 
 . Double-purchase, 23 
 
 Driving, from Square Gan- 
 try, 85 
 
 , Electrical. 86, 89 
 
 _ Frames of, 11, 17, 42 
 
 . Gear, Dog in, 20, 40 
 
 , Overhead, 38 
 
 Crab Gearing, 12, 19 
 
 , Hand. 15 
 
 , , Cheeks of, 41-43 
 
 , , Travelling, 31, 32 
 
 , High Speed, 78 
 
 , Overhead, 31, 41 
 
 , Platform of, 66 
 
 , Power, 31, 33 
 
 , Single-purchase, 19, 28 
 
 , Steam, 33 
 
 , Travelling, 31 
 
 , Treble-purchase, 28 
 
 , Weight of, 60 
 
 Cradles, End, Axles for, 63 
 
 , , for Traveller, 54 
 
 , , Load on, 60 
 
 , , Strength of, 56, 60 
 
 , Wneel Base of, 61 
 
 Cranes, Construction of, 48 70 
 
 , Derrick, 9 
 
 , Framing. 11 
 
 , Gantry, 9, 29 
 
 , Gearing, 12, 23 
 
 , Goliath, 31, 32, 34 
 
 , Portable, 9 
 
 , Quarry, 9 
 
 , Travelling, 9, 31 
 
 , Wall, 30 
 
 , Warehouse, 9 
 
 , Wellington, 29, 34 
 
 __' Wharf, 9 
 
 , Whip, 9 
 
 Crane-jib, 29 
 Cycloidal Teeth, 25 
 
 Dead-eye Bearings, 70 
 Derrick Cranes, 9 
 Derricking Gear Pulley, 12 
 Differential Block, 28 
 Divided Bearings. 44 
 Dog. Crab Gear, 20, 40 
 Doublesheave Blocks, 16 
 Drives, Belt, 83 
 
 , Cotton Rope. 86 
 
 -, Electrical, 86 
 
 , Rope, 79 
 
 -, Shafting, 91 
 
 Worm, 78 
 
 Electrical Crabs, 86, 89 
 
 Driving, 86 
 
 Travellers, 78. 86. 87 
 
 End Cradles (see Cradle, EnJ) 
 Engines, Hoisting, 9 
 Fish-bellied Girders, 51, 54
 
 INDEX. 
 
 Fixed Pulleys, 12, 14 I Odontograph, Willis's, 25 
 Flange Plate, 59 Overhead Crab, 31 
 Frames, Crab, 11. 17, 42 Gear, 38 
 
 , Crane, 11 
 . Traveller 48 
 
 , Hand-operated, 41 
 Travelling Crabs, 41 
 
 Friction Gear, Hollick, 90 
 
 Parallel Girders, 51, 54 
 
 Gantries 10 
 
 Pattern Wheel Arms, 27 
 
 , Timber, 48 
 
 Pinion, Sliding, on Gantry 
 
 Travelling, 41 
 Gantrv Beams, 31 
 
 Shaft, 83 
 Plate Bearings, 70 
 
 Cranes, 9. 29 
 
 , Flange, 59 
 
 . t grafts 83 
 
 , Web, 58 
 
 , Square, Driving Crabs.etc., 
 from, 85 
 
 Plated Wheel, 69 
 Platforms of Crabs and Travel- 
 
 Gearing (see also Crab, etc.) 
 , Hollick Friction, 90 
 , Knuckle, 28 
 , Wheels. 71 
 Gin-block 12 
 
 lers, 66 
 Portable Cranes, 9 
 Power, Applying, 71 
 Crabs, 33 
 
 Travellers, 31, 33 
 
 Girder, Box, 54, 56, 63 
 , Built-up, 51 
 , Depth of, 58 " 
 
 , Fish-bellied, 51, 54 
 
 Pullev Blocks, 9, 12, 14 
 , Derricking Gear, 12 
 , Differential, 28 
 _; Fixed, 12, 14 
 
 , Parallel 51, 54 
 
 , Guide, 75 
 
 , Single-webbed, 51 
 , Solid-webbed, 51 
 
 , Jib Wheel, 12 
 , Rubbish, 12 
 
 , Span of, 58 
 
 , V-rim, 73 
 
 Stiffeners, 53 
 , Traveller, 50 
 
 Quarry Cranes, 9 
 
 Webs, 53 
 
 Rails, Riveting, 48 
 
 Goliath Cranes, 31, 32, 34 
 
 Reversing Mechanism, 87 
 
 Guide Pulleys, 75 
 
 Rim, Nibbed, 74 
 
 Guides, Swinging Rope, 75 
 
 of Waved Rope Wheel, 73 
 
 
 Riveting Rails, 48 
 
 Hani Crabs (see Crab) 
 
 Rope, Cotton, 86 
 
 Handle, Winch, 22 
 
 Driven Traveller, 86 
 
 Hand-operated Overhead Crabs, 
 
 Guides Swinging, 75 
 
 41 
 
 Wheels, 71, 75 
 
 Hoisting Engines, 9 
 
 , Wire, 23 
 
 Gear, 39 
 
 Rubbish Pulley, 12 
 
 Hoists, Steam, 9 
 
 
 Hollick Friction Gear, 90 
 
 Scarf Joint in Shaft, 83 
 
 
 Shaft-driven Travellers, 83 
 
 Jib Crane, 29 
 
 Shafts, 84 
 
 Wheel Pulley, 12 
 Jenny Crabs, 9, 35 
 
 -, Armature, 93 
 , Bearings for, 18 
 
 Gearing, 35 
 
 , Gantry, 83 
 
 Travellers. 34, 55 
 
 -, , Sliding Pinion on, 83 
 
 Joint, Scarf, 83 
 
 ., Scarf Joints in, 83 
 
 
 Single-purchase Crab, 19, 23 
 
 Knuckle Gear, 26 
 
 Single-webbed Girder, 51 
 
 
 Sliding Pinion on Gantry Shaft, 
 
 Levers, Belt-shifting, 88 
 
 83 
 
 Lifting Tackle, 12 
 
 Snatch-blocks, 16 
 
 
 Solid Webbed Girder, 51 
 
 Main Beams, 46 
 
 Span of Girders, 58 
 
 Machine Wheel Arms, 27 
 
 in Travellers, 50, 51 
 
 Masons' Hoisting Machinery, 15 
 
 of Traveller Beam, 58 
 
 Mechanical Efficiency, 20 
 
 Square Gantry, Driving Crabs, 
 
 Mechanism, Reversing, 87 
 Monkey Wheel, 12 
 
 etc., from, 85 
 Square-shaft Drive, 78, 81 
 
 Motive Power, Applying, 71 
 ^ , Increasing, 77 
 
 Travellers, 76, 79, 86, 87 
 Steam Crabs, 33
 
 BUILDERS' HOISTING MACHINERY. 
 
 Steam Hoists, 9 
 
 - - Traveller, 79 
 
 Steel Cheek for Hand Crabs, 43 
 
 Stiffeners, Girder, 53 
 
 Strength of Crane Work, 57 
 
 End Cradle, 56, 60 
 
 Traveller Beam, 56 
 
 Struts, Traveller, Compression 
 
 of, 63 
 
 Strutting Timber Beams, 66 
 Swing Hope Guides,- 75 
 
 Tackle, Lifting, 12 
 
 , White's, 14 
 
 Teeth, Cycloidal, 25 
 - -, Wheel, 25 
 
 , , Size of, 26 
 
 -, , Strength of, 25 
 
 Timber Beams, Strutting, 62 
 
 Gantries, 43 
 
 Traveller, 31 
 
 , Axle Wheels of, 68 
 
 Beams, 31 
 
 , Depth of, 58 
 
 , Load of, 60 
 
 , Span of, 58 
 
 , Strength of, 56 
 
 , Trussing, 62 
 
 -, Driving, from Square Gan- 
 try, 85 
 
 , Electrical, 79, 86, 87 
 
 End Cradles, 54 
 
 . , Wheel Base of, 61 
 
 Framework, 43 
 
 Gearing, 86 
 
 Girders, 50 
 
 Hand, 79 
 
 Jenny, 34 
 Platform, 66 
 Power, 33 
 Quick-speed, 78 
 Rope-driven, 86, 87 
 Shaft-driven, 80 
 Span in, 50, 51 
 Square-shaft, 76, 79-86, 87 
 
 Traveller, Steam, 79 
 Travelling Crabs, 31 
 
 , Overhead, 41 
 
 Cranes, 9, 31 
 
 Gantries, 31 
 
 Wheels, 71 
 
 Treble Gear, 11 
 Treble-purchase Crabs, 28 
 Truss, Compound, with Central 
 
 Load, 63 
 
 Trussing Traveller Beam, 62 
 Tumbler, 84 
 
 V-rim of Pulley, 74 
 
 Wall Cranes, 30 
 
 Jib Cranes, 29 
 
 Waved Rope Wheel, Rim of, 73 
 
 Warehouse Cranes, 9 
 
 Web Plate, 59 
 
 Webs, Girder, 53 
 
 Wellington Crane, 29, 34 
 
 Weston Pulley Block, 14 
 
 Wharf Cranes, 9 
 
 Wheel Bases of Traveller End 
 
 Cradles, 61 
 Boss Diameter, 65 
 Wheels, Axle, of Travellers, 63 
 
 , Chain, 71, 75 
 
 , Gearing, 71 
 
 , Machine, Arms of, 27 
 
 , Monkey, 12 
 
 , Pattern, Arms of, 27 
 
 . Plated, 69 
 
 , Rope, 71, 75 
 
 , Teeth of, 25 
 
 , Travelling, 71 
 
 , Waved Rims of, 73 
 
 Whip Cranes, 9 
 White's Tackle, 14 
 Willis's Odontograph, 25 
 Winch Handle, 22 
 Winch (see Crab) 
 Wire Rope, 28 
 Worm-driving, 78, 87 
 Wrought-lron Crab Cheek, 43 
 
 PIUXTKD BY CASSKLL AND COMPANY, LIMITED, LA BELI.E SALVAGE, K.C
 
 HANDICRAFT SERIES (continued). 
 
 it Lusnions ana squaos. u pnoisienng an c.<tsy 
 
 I'pholstering Footstools, Fenderettes, etc. 
 
 r. Mattress Making and Repairing Renovating 
 
 ling and Laying Carpets ana Linoleum. Index. 
 
 Upholstery. With 162 Engravings and Diagrams. 
 
 Contents. Upholsterers' Materials. Upholsterers' Tools and Appli; 
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 Chair. Upholstering Couches and Sofas. 
 Miscellaneq s Upholstery. Fancy Upholstery, 
 and Repairing Upholstered Furniture. Plannin 
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 Bags. Portmanteaux and Travelling Trunks. Knapsacks and Satchels. Leather Orna- 
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 Harness Making. With 197 Engravings and Diagrams. 
 
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 Important New Series of Practical Volumes. Edited by PAUL 
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 Contents. Materials used in Metal Plate Work. Geometrical Construction 
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 Tools and Appliances Used in Metal Plate Work. Soloering and Brazing. 
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 Work. Examples of Practical Pattern Drawing. 
 
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