: jgciu V , , ' ■ -•■(•.-:.■ . . ■,';, '.^ /.t ..^^ % ,x\^^ ,•0- ■ "t. >^ V V ^ ^" ^.0 V ^^ v^ ^^ 1 .0- -■t ^00^ 4-7* - "'-^'tUsi-? ••• ^ V ^-^ ^^. ^^ -c. . % «^oO /^ , % ^ s ^ * .\^ THE WESTINGHOUSE AIR BRAKE SYSTEM A complete and strictly up-to-date treatise containing detailed descriptions and explanations of all the various parts of the WESTINGHOUSE AIR BRAKE including the 8^ inch cross-compound air pump. No. 6 E T equipment. High pressure control schedule U. The K triple, L triple and L N equipment. Combined Automatic and Straight Air brake, and the 1^ inch pump governor. Compiled and Edited by the World's Leading Air Brake Experts The book also contains a complete course of catechetical instruction on all matters pertaining to the construction, care and operation of the modern Air Brake. Fully Illustrated Colored Charts PUBLISHERS FREDERICK J. DRAKE & CO. CHICAGO > 4, 0? ^?' ■ AUXILIARY RESERVOIR PRESSURE n BRAKE PIPE PRESSURE ATMOSPHERIC PRESSURE SLIDE VALVE SEAT WESTINGHOUSE TYPE K FREIGHT TRIPLE VALVE FULL SERVICE POSITION FIG. 3 Auxiliary Reservoir R I PIPE TAP Brake Pipe BRAKE CYLINDER PRESSURE AUXILIARY RESERVOIR PRESSURE f 1^^ TOP view ||1 ^P^^ ^ e^ SLIDE VALVe D BRAKE PIPE PRESSURE ATMOSPHERIC PRESSURE %r %F SLIDE VAUVe SEAT WESTINGHOUSE TYPE K FREIGHT TRIPLE VALVE. LAP POSITION. FIG. 4 AUXIUARY ReSERVOIR,„_^_ o 33 Brake Cyunder C BRAKE CYLINDER r^ESSURE AUXILIARY RESERVOIR PRESSURE n BRAKE PIPE PRESSURE ATMOSPHERIC PRESSURE i pipe tap Brake Pipe BP GRADUATING VALVE TOP view H^ FACt VIEW SLIDE VALVE r r SLIDE VALVE SEAT THE WESTINGHOUSE G-6 BRAKE VALVE. RELEASE POSITION. FIG.l ^ EQUALIZING RESERVOIR ER I^MMAIN RESERVOIR ,l. r, . ■-, .r -r.. q iSm PRESSURE ^ "^J-^Wt, FROM n ATMOSPHERIC MAIN RESERVOIR PRtSSURE 1^ P^ BRAKE PIPE PRESSURE EQUALIZING RESERVOIR PRESSURE TPIPETAP TO BRAKE PI PE BP THE WESTINGHOUSE G-6 BRAKE VALVE. RUNNING POSITION. FIG. 2 c I'O.D COPPER PIPE To Pump Governor a Gauge RED HAND OR (^ n D ATMOSPHERIC PRESSURE BRAKE PIPE PRESSURE i pipe tap From Main Reservoir MAIN RESERVOIR '^''^ PRESSURE I" PIPE TAP To Brake Pipe BP THE WESTINGHOUSE G-6 BRAKE VALVE SERVICE APPLICATION POSITION FIG. 3 _ i O D COPPER To Pump Governor RED HA» GR n n MAIN RESERVOIR PRESSURE ATMOSPHERIC PRESSURE BRAKE PIPE PRESSURE I'PIPE TAP To Brake Pipe BP EQUALIZING RESERVOIR PRESSURE THE WESTINGHOUSE G-6 BRAKE VALVE EMERGENCY POSITION i O.D. COPPER PIPE To Pump Governor a Gauge RED HAND GR FIG. 4 n n n ATMOSPHERIC PRESSURE. BRAKE PIPE PRESSURE i pipe tap From Main Reservoir MAIN RESERVOIR MR PRESSURE .'PIPE TAP To Brake Pipe EQUALIZING RESERVOIR PRESSURE BP THE WESTINGHOUSE G-6 BRAKE VALVE PLAN OF PORTS FIG. 5 8 O.D.COPPER PIPE To Pump Governor a Gauge I* PIPE- TAP To Equalizing Reservoir El Gauge black hand 'txJk GT ^arcOPPER PIPE Rotary Valve Bottom View BRAKE PIPE PRESSURE Rotary Valve Top View equalizing reservoir pressure THE WESTINGHOUSE AIR BRAKE CO. 9;^ INCH AIR PUMP » FIG. 1 GENERAL ARRANGEMENT THE WESTINGHOUSE AIR BRAKE CO. 9/2 INCH AIR PUMP DIAGRAMS FIG. 2 UP STROKE FIG. 3 DOWN STROKE D MAIN RESERVOIR PRESSURE ATMOSPHERIC PRESSURE STEAM PRESSURE STEAM EXHAUST i PRESSURES MAIN RESeRVOlR ATMOSPhEftW PRESSURE CHAMBER TRAIN PIPE Locomotive Firemen and Enginemen's Magazine. Westinghouse Air Brake Series PLATE XXXV— DISTRIBUTING VALVE, No. 6 ET LOCOMOTIVE BRAKE EQUIPMENT (Release Position — Automatic or Independent) PRESSURES ATMOSPHERIC BRAKE PIPE APPLICATIONCHAMBER AND APPUCATION CYUNDEB MR Locomotive Firemen and Enginemen's Magazine. Westinghouse Air Brake Series PLATE XXXVI— DISTRIBUTING VALVE, No. 6 ET LOCOMOTIVE BRAKE EQUIPMENT (Independent Application Position) PRESSURES MAIN RESERVOIR BRAKECVLINDER PRt55U»£ CHAMBER ] ATMOSPHERIC APPUCATION CHAMBER BRAKE PIPE AND APPIXATION CYUNDER MR Locomotive Firemen and Enginemen's Magazine. Westinghouse Air Brake Series PLATE XXXVII— DISTRIBUTING VALVE, No. 6 ET LOCOMOTIVE BRAKE EQUIPMENT (Independent Lap Position) PRESSURES MAIN RESERVOIR BRAKE CYLINDER PRESSURE CHAMBER ^ 1 mammmm i — i ATMOSPHERIC APPLICATION CHAMBER DRAKE PIPE AND APPLICATION CYLINDER MR Locomotive Firemen and Enginemen's Magazine. Westinghouse Air Brake Series PLATE XXXVIII— DISTRIBUTING VALVE, No. 6 ET LOCOMOTIVE BRAKE EQUIPMENT (Automatic Service Position) PRESSURES ATMOSPHERIC APPLICATION CHAMBER BRAKE PIPE AND APPUCATION CiUNDER MR Locomotive Firemen and Enginemen's Magazine. Westinghouse Am Brake Series PLATE XXXIX— DISTRIBUTING VALVE, No. 6 ET LOCOMOTIVE BRAKE EQUIPMENT (Service Lap Position) PRESSURES MAIN RESERVOIR APPLICATION CHAMBER PRE55URECHAMBER _ AND I ::— ] APPUCATION CYUNDER ( — ; ATMOSPHERIC BRAKE PIPE MR Locomotive Firemen and Enginemen's Magazine. Westinghouse Air Brake Series PLATE XL— DISTRIBUTING VALVE, No. 6 ET LOCO- MOTIVE BRAKE EQUIPMENT (Release Position — Independent Release After Automatic Application) PRESSURES MAIN RESERVOIR BRAKECVLlMDER PBE55UBE CHAMBER r ATMOSPHERIC APPLICATION CHAMBER BRAKE PIPE AND APPUCATION CYUNDEB MR Locomotive Firemen and Enginemen's Magazine. Westinghouse Air Brake Series PLATE XLI— DISTRIBUTING VALVE, No. 6 ET LOCO- MOTIVE BRAKE EQUIPMENT (Emergency Position) PRESSURES ATMOSPHERIC APPLICATION CHAMBER BRAKE PI PE AND APPUCATION CYUNDER MR Locomotive Firemen and Enginemen's Magazine. Westinghouse Air Brake Series PLATE XLII— DISTRIBUTING VALVE, No. 6 ET LOCOMOTIVE BRAKE EQUIPMENT (Emergency Lap Position) n PRESSURES MAIN PE5ERV0IR Z3 PRE55URE CHAMBER ATMOSPHERIC MR ^^^^rf Locomotive Firemen and Enginemen's Magazine. Westinghouse Air Brake Series PLATE XLIII— DISTRIBUTING VALVE, WITH QUICK ACTION CYLINDER CAP, No. 6 ET LOCOMOTIVE BRAKE EQUIPMENT (Release Position) PRESSURES ATMOSPHERIC APPUCATION CHAMBER AND APPUCATION CYUNDER BRAKE PIPE MR Locomotive Firemen and Enginemen's Magazine. Westinghouse Air Brake Series PLATE XLIV— DISTRIBUTING VALVE, WITH QUICK ACTION CYLINDER CAP, No. 6 ET LOCOMOTIVE BRAKE EQUIPMENT (Emergency Position) Locomotive Firemen and Enginemen's Magazine. Westinghouse Air Brake Series PLATE XLV— DISTRIBUTING VALVE AND DOUBLE- CHAMBER RESERVOIR, No. 6 ET LOCOMOTIVE BRAKE EQUIPMENT PRESSURES APPLICATION CHAMBER APPUCATION'cyUNDER ATMOSPHERIC CLOs5ED OPEN Locomotive Firemen and Enginemen's Magazine. Westinghouse Air Brake Series PLATE XLVI— E-6 SAFETY VALVE, No. 6 ET LOCO- ! MOTIVE BRAKE EQUIPMENT ; (Closed and Open Positions) * PRESSURES DFWlfJNG \fflLVE DIST. VALVE EXHAUST . DIST. VALVE EXHAUST KLUUUnu «MU»l. PiPETODlSTBIBuTISC VAlVE CICF Til AUT BBAKE ViLVE APPLlCmON CYLINDER ATMOSPMtRIC RV HPii'tTAP iyH"P'PE.TAP Locomotive Firemen and Enginemen's Magazine. Westixghouse Air Brake Series PLATE XLVII— S-6 INDEPENDENT BRAKE VALVE, No. 6 ET LOCOMOTIVE BRAKE EQUIPMENT PRESSURES EQUALIZING RESEBVOO f EED VALVE PIPE (RE5ERV0IB ' ftTMOSPniBIC Locomotive Firemen and Enginemen's Magazine. Wbstinghouse Air Brake Series PLATE XLVIII— H-6 AUTOMATIC BRAKE VALVE, No. 6 ET LOCOMOTIVE BRAKE EQUIPMENT 1 — ^ 6 i ^ ^ ^ T-' ;>:^^p is \^ ) ^.rrr'?^^*^ mB ■> ^ PfT iA jh ^ QJ H 75 > Fig. 14 — 8H'' Cross Compound Compressor. Side Elevation, '\ rod; 22^ reversing valve; 23, reversing valve chamber bush; 24, reversing valve chamber cap; 25, piston valve, 84 MODERN AIR BRAKE PRACTICE complete; 27, large piston valve ring; 28, exhaust piston valve ring; 29, small piston valve ring; 30, piston valve bolt, complete; 31, piston valve bolt nut; 33, large piston Fig. 15 — Horizontal Section of Reversing Valve Chamber. valve cylinder head ; 34, large piston valve cylinder head cap screv^ ; 35, small piston valve cylinder head ; 36, small piston valve cylinder head cap screw ; 37, upper inlet valve ; 38, lower inlet valve ; 39, upper intermediate valve; 40, lower intermediate valve; 41, upper discharge valve; 42, lower discharge valve; 43, upper inlet valve seat; 44, upper inlet valve chamber cap; 45, lower inlet valve cage; 46, upper intermediate valve seat; 47, upper intermediate valve cap; 48, lower intermediate valve cage ; 49, upper discharge valve cap ; 50, lower discharge valve; 51, i-inch steam pipe stud; 52, governor union nut; 53, stuffing box; 54, stuffing box nut; 55, stuff- ing box gland ; 56, air cylinder lubricator ; 57, upper steam cylinder gasket ; 58, lower steam cylinder gasket ; 59, upper air cylinder gasket ; 60, lower air cylinder gas- ket; 61, small piston valve cylinder head gasket ; 62, large piston valve cylinder head gasket; 63, ^-inch drain cock; \ WESTINGHOUSE CROSS COMPOUND AIR COMPRESSOR 85 64, ^-inch drain cock; 65, air strainer; 66, i-inch steam pipe sleeve; 67, lower head plug; 68, piston rod swab; 69, top head bolt and nut; 71, tee head bolt and nut; y2, 73, 74 and 75, tee head bolts and nuts ; 76, guard plate for eCCTlON A-A Fig. 16 — Vertical Section of Reversing Valve Chamber. Upper intermediate valves; ';y, lagging; 78, jacket; 79, jacket band; S2, packing nut wrench; 86, piston rod packing; 87, reversing valve rod bush; 89, upper dis- charge valve seat; 91, jacket band screw; 92, tee head bolt and nut; 99, lubricator bracket; 100, union stud; loi, union nut; 102, union swivel; 103, oil pipe to low pressure air cylinder; 104, oil pipe to high pressure air cylinder; 106, piston valve bush; 107, large piston bush. The total weight is 1,500 pounds, and the normal speed is 100 single strokes per minute, with 180 lbs. steam pres- sure and working against 140 lbs. air pressure. The drain cock 63 is intended to draw off any condensation in the steam passage a, and should always be opened when the pump is first started. The drain cock 64 connected to the low pressure steam cylinder is for the same pur- pose, and should also be opened for a short time before the compressor is started so that any condensation of steam in the cylinder may be removed. 36 MODERN AIR BRAKE PRACTICE The Governor is connected to the steam inlet at S. Steam entering passes through port a to the top head, and thence through ports a and b (Fig. i6) to the re- versing valve chamber o and main valve chamber (Fig. 13) ; e is the exhaust passage leading to the steam exhaust pipe. As it is difficult to follow the ports in these cuts, two diagrams have been prepared, as shown in Figs. 17 and 18, in which the steam valve gear is turned so as to be parallel with the cylinders in order to make the operation more easily understood, and all ports and passages are connected in the simplest possible man- ner, without regard to the actual construction of the compressor. Referring to Fig. 16, passage a communicating with cavity C and the two chambers b convey the steam from the source of supply to the operating valves, of which there are two, namely: the reversing valve and the pis- ton valve. The piston valve is a multiple piston device, consisting of a large piston at one end, a small piston at the other, with three intermediate pistons of uniform size, which will be referred to hereinafter as numbers I, 2 and 3, numbering from the small piston end of the piston valve. It is self-evident that, with five pistons mounted on a common rod and working in a cylinder, we have, in- cluding the ends, six separate chambers. In this par- ticular construction, five of these chambers have perma- nent connections as follows : The first chamber, E, behind the outer end of the small piston, to the atmosphere The second chamber, b, between the small and No. I intermediate piston, to passage a. The third chamber, i, between the No. i and No. 2 WESTINGHOUSE CROSS COMPOUND AIR COMPRESSOR 37 STCAM INLET. I Fig. 17 — Diagram of 8^" Cross-Compound Compressor. The High Pressure Steam (Low Pressure Air) Piston on Its Downward Stroke. 38 MODERN AIR BRAKE PRACTICE intermediate pistons, to the lower end of the low pres- sure steam cylinder. The fourth chamber, h, between the No. 2 and No. 3 intermediate pistons to the upper end of low pressure steam cylinder. The fifth chamber, b, between the third intermediate and the inner side of large piston to pas- sage a. The fifth chamber, b, between the third intermediate and the inner side of large piston to passage a. The reversing valve, 22, moving vertically on its seat in chamber C, controls the admission and exhaust of steam from the cavity D, behind the outer end of the large piston of the piston valve, causing it to operate horizontally, the intermediate pistons moving as follows : Intermediate piston No. 3 crosses a port connecting passage c controlling the flow of steam to the upper end of the high pressure steam cylinder, and also the exhaust into the upper end of the low pressure steam cylinder. Intermediate piston No. 2 crosses a port connecting with passage e, controlling the exhaust of steam from either end of the low pressure steam cylinder. Interme- diate piston No. I crosses a port, connecting the passage g, causing steam to be admitted to the lower end of the high pressure steam cylinder, or exhausting the same from this cylinder into the lower end of the low pressure steam cylinder. A passage z, leading from the upper end of the high pressure steam cylinder is the means of supplying pres- sure to balance the reversing valve rod. Operation, When the high pressure steam piston has nearly completed its up stroke, the reversing valve plate 18, comes in contact with the shoulder on the reversing WESTINGHOUSE CROSS COMPOUND AIR COMPRESSOR 39 rod, forcing said rod 21 to its uppermost position carrying with it reversing valve 22, the movement of which in turn not only blanks port to passage m, thereby cutting off means of exhausting steam from the cavity behind the large end of the piston valve, but also opens the port to passage n, filling this chamber D with live steam from passage a. The pressure thus exerted on the outer side of the large piston, added to the pressure on the inner side of the small piston is now greater than the pressure exerted on the inner side of the large piston, and the piston valve moves to the left, or in the direction of chamber E, which movement admits steam to the up- per end of the high pressure steam cylinder, starting the high pressure steam piston on its downward stroke. All parts have now assumed the position shown in Fig. 17. A direct communication is now established whereby live steam is supplied through passage a, chamber b, and passage c to the upper end of the high pressure steam cylinder, forcing downward the high pressure steam pis- ton and low pressure air piston to which it is rigidly connected by the piston rod, that is free to move in the necessary stuffing boxes. The downward movement causes steam to be exhausted from the lower end of the high pressure steam cylinder through passage g, cavity i and passage f, into the lower end of the low pressure steam cylinder. The latter being of materially larger volume than the former, it will be seen that the steam is thereby made to do its work expansively in the low pressure steam cylinder. At the same time — a the low pressure air piston, 9, is compressing air in the lower end of the low pressure air cylinder and forcing same through the intermediate valves 40, and 40 MODERN AIR BRAKE PRACTICE ti^ c STtAM INLET, 40 33 Fig. i8— Diagram of 8^'' Cross-Compound Compressors. The High Pressure Steam (Low Pressure Air) Piston on Its Upward Stroke. WESTIXGHOUSE CROSS COMPOUND AIR COMPRESSOR 41 passage u' into the lower end of the high pressure air cyhnder, and — b air at atmospheric pressure is being drawn into the upper end of the low pressure cylinder, through the upper air strainer and inlet valve 37. It will be observed that the steam exhausted into the lower end of the low pressure steam cylinder, and the low pressure air forced into the lower end of the high pressure air cylinder act simultaneously on the lower sides of their respective pistons. The force thus exerted results in an upward movement of the low pressure steam and high pressure air pistons. The upward move- ment causes — a steam to be exhausted from the upper end of the low pressure steam cylinder through passage d, chamber h and passage e to the atmosphere, and — b the high pressure air piston 10, to compress the air in the upper end of the high pressure air cylinder to its final pressure and to discharge it through passage v, discharge valve 41, and passage w into the main reservoir. After the low pressure steam (high pressure air) pis- ton has completed its upward stroke, as explained, the lower end of the high pressure air cylinder is, of course, filled with air compressed from the lower end of the low pressure air cylinder, and the lower end of the low pres- sure steam cylinder is filled with steam exhautsed from the lower end of the high pressure steam cylinder. However, just as the low pressure steam (high pressure air) piston has completed its upward stroke, steam is by- passed through three by-pass grooves x from the lower to the upper side of the low pressure steam piston, thereby preventing an accumulation of back pressure in the lower end of the high pressure cylinder. 42 MODERN AIR BRAKE PRACTICE At this Stage of the cycle, also, the upper end of the low pressure air cylinder is filled with air at atmospheric pressure, and the upper end of the high pressure steam cylinder is filled with live steam; but just before the high pressure steam low pressure air piston completes its downward stroke, reversing valve plate i8 engages the button end of the reversing valve rod, moving it down- ward, and carrying the reversing valve to its extreme lower position, thereby closing the port leading to pas- sage n, cutting off the supply of live steam to chamber D, and connecting passage m, cavity g, and passage 1, thereby exhausting steam from cavity D behind the outer end of the large piston of the piston valve. Since the pres- sure against the inner side of the large piston is now greater than the pressure exerted against the inner side of the small piston the piston valve moves to the right, or in the direction of chamber D, and all parts are in the position shown in Fig. i8. Live steam is now supplied from passage a, through chamber b, and passage g to the lower end of the high pressure steam cylinder, forcing upward the high pressure steam piston which, as already explained carries with it the low pressure air piston. The upward movement causes steam to be exhausted from the upper end of the high pressure steam cylinder, through passage c, chamber h, and passage d, into the upper end of the low pressure steam cylinder. At the same time a The low pressure air piston is compressing the air in the upper end of the low pressure air cylinder and forcing same through the intermediate valves y(i, and pas- sage u, into the upper end of the high pressure air cylin- der, and b air at atmospheric pressure is drawn into the lower WESTINGHOUSE CROSS COMPOUND AIR COMPRESSOR 43 end of the low pressure air cylinder, through the lower air strainer, passage r' and lower inlet valve 38. Again it will be observed that the steam in the low pressure steam cylinder, and air in the high pressure air cylinder act simultaneously against their respective pistons, steam being exhausted from the upper end of the high pressure steam cylinder through passage c, chamber h and passage d to. the upper end of the low pressure steam cylinder in which it acts expansively on the low pressure steam piston. The downward movement of the low pressure steam piston causes steam to be ex- hausted from the lower end of the low pressure steam cylinder, through passage f, chamber i and passage e, to the atmosphere and the high pressure air piston to com- press the air in the lower end of the high pressure air cylinder to its final pressure forcing same through pas- sage v', discharge valve 42, and passage w', into the main reservoir. When the pistons have moved as ex- plained, the low pressure steam high pressure air pis- ton has completed its downward stroke; the upper end of the high pressure air cylinder is filled with air com- pressed from the upper end of the low pressure air cylin- der ; and the upper end of the low pressure steam cylinder is filled with steam exhausted from the upper end of the high pressure steam cylinder. However, just before the low pressure steam (high pressure air) piston has com- pleted its downward stroke, steam is by-passed through the three by-pass grooves from the upper to the lower side of the low pressure steam piston, thereby preventing an accumulation of back pressure in the upper end of the high pressure steam cylinder. At this stage of the cycle also, the high pressure steam (low pressure air) pis- ton has completed its upward stroke; the lower end of u MODERN AIR BRAKE PRACTICE the high pressure air cyUnder is filled with air at al mospheric pressure ; and the lower end of the high pres- sure steam cylinder is filled with live steam. Here again the pump is reversed, by means of the reversing valve plate attached to the high pressure steam piston coming in contact with the shoulder of the reversing valve rod which, in turn, actuates the reversing valve, and the cycle of operation already described is repeated. INSTRUCTIONS. Piping. All pipes should be hammered to loosen the scale and dirt, have fins removed, and be thoroughly blown out with steam before erecting; bends should be used wherever possible instead of ells, and all sags avoided. Shellac or Ja:pan varnish should be applied on the male threaded portion only, and never in the socket. Do not use red or white lead. Starting and Running. The drain cocks are placed at the lowest points of the steam passages, as shown, for the purpose of draining condensed steam when the com- pressor is stopped and when starting it. They should always be left open when the compressor is to stand idle for any length of time. These drain cocks are provided with suitable union fittings, so that drain pipes may be connected if desired. In starting the compressor, always run it slowly until it becomes warm, permitting the con- densed steam to escape through the drain cocks and the exhaust, until there is sufficient pressure in the main res- ervoir (25 to 30 lbs.) to provide an air cushion. Then close drain cocks and open the steam (throttle) valve sufficiently to run the compressor at the proper speed, ac- cording to circumstances. Racing, or running at exces- sive speeds should not be allowed. The pump governor WESTINGHOUSE CROSS COMPOUND AIR COMPRESSOR 45 automatically controls the operation of the compressor when maintaining the air pressure. To Stop the Compressor, (i) Close the feed and steam valves on the sight feed lubricator, provided the compressor has a separate one, or the feed if supplied from the locomotive lubricator; {2) then close the steahi (throttle) valve; (3) open all the drain cocks on the compressor. Keep the steam valve closed, and the drain cocks open when the compressor is not working. The main reservoir cocks should also be left open when the compressor is stopped for any length of time. The com- pressor should always be stopped while the engine is over the ash pit. If kept running, ashes and dust will be drawn into the air cylinder and injure it, besides clog- ging up the air strainer. Lubrication — Air Cylinder. On account of the high temperatures developed by air compression, the variation between maximum and minimum delivered air pressures, and the necessity of preventing oil from passing into the system, one of the vital problems in efficient compressor operation is to provide a simple means for supplying lubrication to the air cylinders in proper quantity and at regular intervals. To overcome the difficulties attending the lubrication of the air cylinder of the 8^ -inch cross-compound com- pressor, two non-automatic oil cups are mounted on a bracket, which, in turn, is connected to the air cylinders by the necessary piping, thereby establishing an indepen- dent passage from each cup to the high and low pressure air cylinders respectively. This cup (Fig. 19) is of extremely simple design. The lower end is threaded for a ^-inch tapped opening, while the upper end is provided with a tight-fittirtg screw cap. 46 MODERN AIR BRAKE PRACTICE A screen prevents any dirt in the oil being carried int the cylinder. When the handle is turned, a cavity in the key, which normally forms the bottom of the oil cup, de m be f Fig. 19 — Oil Cup. posits a definite amount of oil in the air cylinders, at the same time preventing back pressure from reaching the oil chamber. The bracket may be attached to the top head of the compressor, or placed in the locomotive cab, to suit the convenience, or standard practice of any railroad. To oil the air cylinder, open its oil cup and blow out all dirt, close and fill it with valve oil, and on the down stroke of the piston open the cup to allow the oil to be drawn into the cylinder, closing the cup before the be- ginning of the up stroke. This is most easily done when the speed is moderate and the air pressure low. Valve oil only should be used in the air cylinder. A lighter oil will not last, and is dangerous. A heavier oil very soon clogs and restricts the air passages, causing the compres- sor to heat unduly and compress air slowly. Valve oil gives the best service. Judgment should determine the amount for both air and steam cylinders, it being remem- bered that the lack of a little oil when needed may result in much damage to the compressor. A swab, well oiled, is essential on each piston rod. Many master mechanics WESTINGHOUSE CROSS COMPOUND AIR COMPRESSOR 47 now consider quite essential the use of a sight feed lubricator fitting located in the cab, and connected in the piping leading from the oil well of the locomotive lubri- cator to the compressor air cylinders, and, judging from the very satisfactory results obtained, it appears to be a very effective arrangement. Fig. 20 shows a sight feed CUD Fig. 20 — Single Sight Feed Fitting. lubricator adapted for the system referred to, and it gives the engineer complete and convenient control of air cylinder lubrication, so that the minimum amount, and proper quantity of oil required may be supplied at regu- lar intervals. This sight feed lubricator can be attached to any locomotive lubricator. In order to prevent com- 48 MODERN AIR BRAKE PRACTICE pressed air from entering the oil delivery pipe between the sight feed fitting and the air cylinder, a ball check valve connection is screwed into the air cylinder. No trap should exist in the oil delivery pipe between the sight feed fitting and air cylinder. Lubrication — Steam Cylinder. The steam cylinder lubricator should not be started until all condensation has escaped from the compressor and the drain cocks closed. After closing the drain cocks start the lubricator to feed in ten or fifteen drops of oil as rapidly as possi- ble, then regulate the feed to about one or two drops per minute for each steam cylinder. No definite amount can be specified, as the amount of lubrication required depends on the work the conipressor has to do, the qual- ity of the steam, condition of compressor, and so on. Keep the lubricator feeding while the compressor is running. DISORDERS CAUSES AND REMEDIES. Compressor Refuses to Start. Cause : insufficient oil, from scant or no feed, or working water; worn main- piston rings; or rust having accumulated during time compressor has lain idle. Remedy : Shut off steam, take off cap nut, put in about a tablespoon ful of valve oil (not too much), let the oil soak down for one or two minutes, and then turn on the steam quickly. In many cases when the compressor will not start when steam is first turned on, if steam is then turned off and allowed to remain off for one or two minutes, and then turned on quickly, it will start without the use of any oil, except that from the lubricator. Compressor Groans. Cause: air cylinder needs oil. Remedy ; put some valve oil in air cylinder, and saturate WESTINGHOUSE CROSS COMPOUND AIR COMPRESSOR 49 piston swab with valve oil, then replace it on the rod. Another cause of groaning may be need of oil in the steam cylinder ; the remedy for which is an increase in the feed from the lubricator. Leakage past the air piston packing rings or past a discharge valve causes heating, destroys lubrication, and results in groaning. Piston rod packing dry and bind- ing is another cause of groaning. Uneven Strokes of the Compressor. Cause: probably I leakage past air piston packing rings and sticky air valves ; 2 unequal lift of air valves ; 3 clogged discharge valve passages ; or, 4 leaky air valves. Remedy : locate cause, if possible, and correct it by cleaning out clogged or dirty passages, adjusting lift of valves or replacing leaky valves or rings. Slozv in Compressing Air. Cause: i leakage past the air piston packing rings, due to poor fit, or wear in cylinder or rings ; 2 valves and passages dirty ; or, 3 air suction strainer clogged. Remedy : i and 2. To determine which is causing the trouble, obtain about 90 lbs. air pressure, reduce the speed to from 40 to 60 single strokes per minute, then listen at the "Air Inlet" and note if air is drawn in during only a portion of each stroke, and if any blow^s back. If the latter, an inlet valve is leaking. If the suction does not continue until each stroke is nearly completed, then there is leakage past the air piston pack- ing rings or back from the main reservoir past the air discharge valves. One of the latter leaking will cause an uneven stroke. Remedy : 3 clean strainer thoroughly. Compressor Erratic in Action. Cause: Worn condi- tion of valve motion. Remedy: Renew it. Compressor Heats. Cause: i air passages are clogged; 2 leakage past air piston rings; or, 3 the dis- 5Q MODERN AIR BRAKE 1»RACTICE charge valves have insufficient lift. Remedy : i clear air passages ; 2 renew air piston rings ; 3 regulate lift of dis- charge valves to 3% of an inch. A compressor in perfect condition will become excessively hot, and is liable to be damaged if run very fast and continuously, for a long time. Compressor Pounds. Cause: i air piston is loose; 2 compressor not well secured to boiler, or causes some adjacent pipe to vibrate; 3 the reversing valve plate, 18, is loose ; or, 4 the reversing rod or plate may be so worn that the motion of compressor is not reversed at the proper time. Remedy: repair and renew worn parts and tighten loose connections. MAINTENANCE. The air cylinder heating is a feature of air compres- sion which cannot be prevented. As an example of the normal heating, resulting from extreme duty, a 9^ -inch compressor in good order which for one hour main- tained an average speed of 174 single strokes or exhausts per minute, working constantly against 100 pounds of air pressure, was discharging the air at a temperature of 408 degrees. Higher speed or greater air pressure would have in- creased the heating, while slower speed, shorter time of test, or lower air pressure would have decreased it. Speaking generally, the speed should not exceed 149 exhausts per minute and such a speed should not be con- tinuously maintained for any considerable time, as even this speed will cause excessive heating. This is shown by another test where an average speed of about 60 ex- hausts per minute, after the main reservoir pressure was pumped up, and a maximum of 77 strokes per minute 4 WESTXNGHOUSE CROSS COMPOUND AIR COMPRESSOR 51 at the completion of an hour and fifty minutes of the test, gave a discharge temperature of 316 degrees. The fore- going show plainly the great need of good maintenance, of not wasting air either by leakage or poor handling and of giving the compressor as much time to do its work as is practicable. One of the most serious leaks is through the air cylin- der stuffing box as it not only greatly decreases the air delivered and, by the faster speed required, increases the heating, but it also causes pounding through loss of cushion. When tightening the packing, do not bind the rod, as to do so will damage both the packing and the rod. Be careful not to cross the gland nut threads. With two compressors per engine, the separate throt- tles should be kept wide open, and the speed regulated by the main compressor throttle. The purpose is to equally divide the work. If necessary to replace a broken air valve on the road or elsewhere not permitting of proper fitting, at the earliest opportunity have the repairman replace the tem- porary valve with another so as to insure the correct angle and width of valve and seat contact, the needed ground joint and the requisite lift of /^ of an inch for all valves. Never remove or replace the upper steam cylinder head with the reversing valve rod in place, as to do so will almost invariably result in bending the rod. A bent rod is very liable to cause a "pump failure." It is evident that a compressor cannot compress more air than it draws in and not that much if there is any leakage to the atmosphere about the air cylinder. Bear- ing this in mind, practice frequently listening at the "Air Inlet" when the compressor is working slowly while be- 52 MODERN AIR BRAKE PRACTICE ing controlled by the governor, and wherever a poor suc- tion is noted on either, or both strokes locate and report the fault. Any unusual click or pound should be reported as it may indicate either a loose piston or a reversing-valve plate cap screw or other serious fault. Any steam leakage that can reach the Air Inlet of the compressor should be promptly repaired as such increases the danger of water entering the brake pipe. Keeping the suction strainer clean is of the utmost importance, as even a slightly clogged strainer will greatly reduce the capacity where the speed is at all fast. A seriously or completely obstructed strainer, as by ac- cumulated frost, aggravated by rising steam, will in- crease the compressor speed and will also be indicated by inability to raise or maintain the desired pressure. It is an aid to good operation to thoroughly clean the air cylinder and its passages at least three or four times a year, by circulating through them a hot solution of lye or potash. This should always be followed by sufficient clean, hot water to thoroughly rinse out the cylinder an.d passages, after which a liberal supply of valve oil should be given the cylinder. Suitable tanks and connections for performing this operation can easily be arranged in portable form. Never put kerosene oil in the air cylin- der to clean it. THE MAIN RESERVOIR. The function of the main reservoir is to receive the compressed air delivered from the pump, and store it for use as needed. The main reservoir also acts as a catch basin for any moisture, or dirt that may be in the air. It is generally located on the engine, although in some THE MAIN RESERVOIR 53 instances it is on the tender. The minimum capacity permissible for main reservoirs is 40,000 cubic inches for freight and 20,000 cubic inches for passenger engines, and many of the leading railroads are now equipping their heavy freight engines with reservoirs of 50,000 and 60,000 cubic inches capacity,, and are getting good results from the increased volume. Among the many advan- tages derived from this increased volume of air, are the prompt charging up of an empty train ; quick recharging of train pipe, and auxiliary reservoirs after an applica- tion of the brakes ; increased cooling or radiating surface by means of which the temperature of the compressed air is reduced and the moisture contained therein is better separated. The water thus trapped in the main reservoir settles to the bottom, from whence it should be drained at the end of each trip, because if it should pass into the train pipe it is detrimental in several ways, causing the pipes to rust, destroying the lubrication in the triple valves, and in winter it is liable to freeze in the pipes ; the result of which would be a stopped-up train pipe. Freight engines require a larger main reservoir than do passenger engines, owing to the fact that longer trains are handled, and a greater number of auxiliary reser- voirs are to be recharged after each application of the brakes. The question might arise, why not pump the air directly into the train pipe and thus release the brakes without carrying this large volume of air on the engine at all times? In reply it may be said that, pumping brakes off is very unsatisfactory, because the pressure would be raised so slowly in the train pipe on a long train that many of the brakes would fail to release, while at the same time the air pump would be required to supply such a large volume of air in so short a time, that it 54 MODERN AIR BRAKE PRACTICE would be liable to run hot. The pressure ordinarily car- ried in the main reservoir is 90 lbs., except in cases where special equipments are used, when the amount of pres- sure is varied to suit the conditions. The form of reser- voir found to be most efficient is of the long, slender style, as it gives greater radiating surface, and wherever possible it should be located on the engine, for the reason that when located on the tender two extra lines of hose are required between engine and tender. The amount that the pressure in the main reservoir exceeds that in the train pipe is termed excess pressure, and its purpose is to insure a prompt release of the brakes, and recharg- ing of the auxiliary reservoirs ; also to supply the other air-operated devices on the engine and train. Main reser- voir pressure begins at the discharge valves of the air pump, and ends at the engineer's brake valve. I EXAMINATION QUESTIONS AND ANSWERS Development of the Westinghouse Air Brake. Q. What is a brake? A. A device or mechanism for retarding oi stopping rotation of the wheels of a vehicle. Q. What is a power brake? A. A brake in which the operating power is supplied by mechanical means such as compressed air, vacuum, hydraulic, or spring tension. Q. What is a continuous brake? A. A brake that works simultaneously on all the ve- hicles in a train. Q. What is an air brake? A. A brake operated by compressed air. Q. What was the first or simplest form of air brake? A. The "straight air" designed and invented by Mr. George Westinghouse, Jr., about 1869. Q. Was this brake satisfactory? A. It was not; in many respects. Q. Give some of the principal reasons for its failure to give perfect satisfaction. A. (i) If an accident happened to brake pipe or con- nections permitting the air pressure to escape, it could not be detected until the engineer attempted to apply the brakes, when the air would then escape at the damaged spot, and render the brake inoperative and useless. (2) The brake could only be applied at the engineer's valve on the engine. Third, on a long train of cars brake applica- 65 06 MODERN AIR BRAKE PRACTICE tion was too slow, the time required to get the air to the rear end of the train being so great that the stop was much longer than with a short train ; likewise the time required to release the brakes on a long train was too slow, thereby causing delays in train starting. Fourth, as the supply of pressure for all brake cylinders of the train came direct from the engine, the longer the train the more cylinders there were to supply, and conse- quently the brake cylinder pressures would equalize lower on a long train than on a short train. Q. What form of brake superseded the straight air brake ? A. The plain automatic brake, designed and invented by Mr. George Westinghouse, Jr., in the year 1873. Q. Wherein was this brake an improvement over the ''straight air" brake? A. It was an indirect brake, being automatic in its action. Each car carried in an auxiliary reservoir its own storage supply of pressure for its brake cylinder, and the train pipe pressure, operating against a triple valve, held this storage of pressure from passing to the brake cylin- der. Second, any accident to, or breakage of the brake pipe and its connections on the train or engine, was shown up at once by the brake applying. The automatic applying feature of this design of brake gave it great value. Third, as a reduction of pressure in the brake pipe would cause the brakes to apply, it was made pos- sible for any of the train crew to apply the brake from any car in the train, equally as well as the engineer in his cab. Fourth, as pressure was stored in the auxiliary reservoir under each car for its individual use, that pres- sure could be passed into its brake cylinder much more quickly, with the automatic brake, than main reservoir EXAMINATION QUESTIONS AND ANSWERS 57 pressure on the engine could be sent back through the entire length of train pipe and into the cylinders of the whole train, by the straight air brake. Fifth, this feature of individual storage of braking pressure on each car made it possible to apply the brakes on a train of the ordinary length then hauled, almost as quickly as on a short train. Sixth, it also permitted as high pressures in the brake cylinders of a long train as on a short train. Q. What were the objectionable features of the plain automatic brake? A. While it gave satisfactory service on passenger trains and all freight trains of ordinary length, an emer- gency application on a long freight train, however, could not be made sufficiently sudden to prevent the slack of the rear portion of the train from running in and causing severe shocks to the cars and their lading on the rear end. Q. When and by whom was a quicker-acting brake than the plain automatic demanded? A. In 1887, by the Master Car Builders in their brake trials at Burlington, la., on the C, B. & Q. R. R. The fact was then and there developed that on long, 50-car freight trains the plain automatic brake set on the head cars first, and did not set sufficiently rapid to prevent the rear cars from running up against the forward por- tion of the train with such destructive force as to cause damage to the cars and their contents. Q. Did this occur in the service application or the emergency application of the brakes? A. Both, but with greater violence in the emergency application. Q. What form of brake then superseded the plain automatic brake? A. The quick action form, which grew out of the 68 MODERN AIR BRAKE PRACTICE Burlington brake trials. It was much quicker in its operation in emergency application and prevented the slack of the rear cars from running forward and doing damage to the lading and equipment of the" train. The quick action brake has ever since been the standard brake in steam railroad service. Q. The quick action form of brake gave a quicker emergency application ; how did it operate in service ap- plication ? A. It operated in service application in the same har- monious manner as did the plain automatic brake, and operated independently of the emergency feature. Q. What are the leading features of the quick-action | triple valve? A. First, the service feature, or part which calls into play only the piston, slide valve and graduating valve, in service application. Second, the emergency feature, or part which calls into play the emergency piston, emer- gency valve and rubber seated check valve, in addition to the piston and slide valve of the service feature. Q. Have any other improvements been introduced in air brake practice since the development of the quick- action brake ? A. Yes; although the underlying principles of the brake proper remain ; still many supplementary improve- ments have been added in recent years. Q. Describe in brief the parts that comprised the straight air brake. A. The air pump, the reservoir, the three way cock in the engineer's cab, for manipulating the pressure in and out of the brake pipe ; the brake pipe, for conveying the air back to the brake cylinders, and the brake cylinder and its attachments under the car. EXAMINATION QUESTIONS AND ANSWERS 59 Q. How were brakes applied? A. The engineer turned the three-way cock to a posi- tion which permitted reservoir pressure on the engine to pass back, through the brake pipe, into the cyHnders under the cars. If a Hght application was desired only a small quantity of pressure was allowed by the engineer to pass from the reservoir to the brake cylinders. If it was de- sired to apply the brakes harder a larger quantity of air was permitted to pass through the three-way cock to the brake cylinders. Q. How were the brakes released ? A. The position of the three-way cock handle was re- versed by the engineer, cutting off reservoir pressure on the engine, and at the same time making a connection between the brake pipe and the atmosphere, thus per- mitting brake cylinder pressure to discharge through the brake pipe and three-way cock to the atmosphere. If a partial release was desired only a part of the pressure was allowed to escape at the three-way cock. If a full release was desired, all the pressure was permitted to be discharged from the brake cylinders and brake pipe, through the three-way cock, to the atmosphere. THE WESTINGHOUSE AIR COMPRESSOR. Q. What form of air compressor did Goerge Westing- house, Jr., first use in operating the air brake? A. An old Worthington duplex water pump was con- verted and made to pump air. Q. Describe in brief the construction and operation of the old style "trigger" or straight air pump. A. This pump succeeded the Worthington. It con- sisted of a steam cylinder and air cylinder in vertical tan- dem. Steam entered the steam chest at the side, and sur- 60 MODERN AIR BRAKE PRACTICE rounded a valve which had a rotary motion imparted to it by ''trigger" device in the top head operated conjointly by steam and the usual reversing slide valve rod extend- ing down into the hollow piston rod. The operation of the air end resembled that of the later 6-inch pump. Q. Briefly describe the action of the Westinghouse 6-inch air pump. A. The action of the steam end is identical with that of the 8-inch pump. The action in the air end is as fol- lows : On the up stroke, air is drawn in at the lower suc- tion valve. On the same stroke, the atmospheric air in the air cylinder above the piston is compressed and forced out through the upper discharge valve to the main reservoir. On the down stroke, air is drawn into the up- per end of the cylinder, through the upper suction valve, and the atmospheric air in the lower end of the cylinder is compressed and forced out through the lower dis- charge valve to the main reservoir. The steam pipe from the boiler is ^^ inch in size ; the exhaust pipe is % inch, and the air discharge pipe is ^ inch. The suction pipe is l}i inch. THE 8-INCH AIR PUMP. Q. What end of the air pump is the power developed in to operate it ? A. The upper or steam cylinder end. Q. What is the lower or air cylinder end for? A. It performs the function of an air compressor. Q. How many operative parts are there in the air end of the pump, and what are they ? A. Five ; the air piston and four check valves, two of which are known as receiving valves and two as dis- charge valves. EXAMINATION QUESTIONS AND ANSWERS 61 Q. What performs the duty of compressing the air? A. The air piston. Q. Explain how this is accompHshed. A. As the piston is moving up or down in the cyUn- der, the air on one side of the piston is being compressed and deHvered out to the main reservoir, while air from the atmosphere is flowing into the cylinder on the oppo- site side of the piston. Q. Trace the flow of air in and out of the air cylinder. A. Assume the piston to be on the up stroke. Air above the piston will be compressed, and forced out into a passage under the top discharge valve which would then be lifted off its seat and allow the air to pass out under pressure to the main reservoir, while at the same time air at atmospheric pressure would pass into and fill the lower part of the air cylinder by the unseating of the lower receiving valve. The piston having completed its up stroke, now starts down, at which moment the up- per discharge valve, and the lower receiving valve both drop to their seats due to gravity. The air in the cylin- der below the piston will now be compressed, and pass out through the lower passage, under the lower discharge valve which will be raised from its seat, thence out through the pipe connection to the main reservoir. At the same time atmospheric air is passing through the up- per air inlets, filling the cylinder above the piston. Q. What is the lift of the air valves in the 8-inch pump ? ' A. The receiving valves have }i inch lift and the dis- charge valves 3^2 inch. Q. \yhy is it necessary to give the receiving valves more lift than the discharge valves ? A. This is due to the construction of the pump. As all 62 MODERN AIR BRAKE PRACTICE valves are on one side, it is necessary to remove the re- ceiving valves through the seats of the discharge valves, which necessitates that they be smaller in diameter, therefore require greater lift. Q. What is the diameter of the steam and air cylin- ders of the 8-inch pump? A. Steam cylinders, 8 inches. Air cylinders, 7^ inches. Q. What is the stroke of the pistons in the 8-inch pump? A. Nine inches. Q. What operates the air piston of the pump? A. The main piston in the steam end, which is directly connected with the air piston by the main piston rod. Q. Describe in brief the steam end of the pump. A. It is practically a small steam engine having a steam cylinder and piston, together with valves arranged to ad- mit and exhaust steam to and from either side of the piston. Q. How many operative parts are there in the steam end of the pump? Name them. A. Five ; the main steam piston, main valve, reversing valve, reversing rod and reversing piston. Q. What is the duty of the reversing valve piston ? A. To assist the smaller main valve piston in over- coming the pressure under the larger main valve piston when moving the main valve to the lower position. Q. What is the duty of the reversing slide valve? A. To admit and exhaust the steam to and from the top of the reversing piston. Q. What is the duty of the reversing valve rod? A. To raise and lower the reversing slide valve. EXAMINATION QUESTIONS AND ANSWERS 63 Q. What is the duty of the main valve pistons? A. To admit and exhaust the steam to and from the cyHnder. Q. Describe in brief the action of the steam when ad- mitted to steam cyHnder. A. Steam entering the main valve chamber passes from thence through suitable openings into the reversing valve chamber, and, assuming this valve to be in the lower position, steam will pass into a chamber above the reversing piston. As the stem of this piston is resting on top of the main valve, this valve is forced to its lower position, owing to the combined areas of reversing piston and lower piston valve both of which have boiler pres- sure upon them, which overcomes the pressure under the upper piston valve. With the main valve in its lower po- sition, the upper row of ports in the lower bushing are now open allowing steam to pass into the steam cylinder, under the steam piston forcing it up. Q. When the piston reaches the end of its upward stroke, how is its motion reversed? A. As it nears the end of the up stroke, the reversing plate attached to the top of the steam piston engages with the shoulder on the reversing rod and lifts the reversing valve to its upper position where the cavity in the valve connects two ports together allowing the steam above the reversing piston to pass to the atmosphere, while the live steam which is always between the two main valve pistons, now forces the main valve up, for the reason that the upper piston is larger than the lower. This up- ward movement of the main valve causes it to open the lower row of ports in the upper bushing, thus allowing steam to pass into the top end of the steam cylinder to drive the piston down, while at the same time the steam 64 MODERN AIR BRAKE PRACTICE ^:., ^ that is under the piston is escaping to the atmosphere by way of the lower row of ports in the lower bushing, these being now open. Q. What pressure is always present on the two inner • faces of the main valve pistons ? A. Steam pressure from the boiler when the throttle is open. Q. What pressure is always present on the two outer ends of the main valve pistons? A. Exhaust or atmospheric pressure. THE 9^-INCH AIR PUMP. Q. Wherein does the 9>4-inch pump differ from the 8-inch? A. The 9^ -inch pump has a much greater capacity, while the reversing valve gear in the steam end is much more simple. The air valves are differently located also. Q. What side of the pump are the receiving valves located on? A. On the left side, or side the air inlet is on. Q. What side of the pump are the discharge valves located on? A. On the right side, or side the discharge pipe is on. Q. What is the difference between a "right hand" pump and a ^right and left hand' pump? A. The 'right hand' pump has but one steam supply connection which is on the- right side of the cylinder, and a single exhaust connection which is on the left side of the cylinder. The "right and left hand" pumps, how ever, have a steam supply connection and an exhaust connection on each side of the cylinder. Q. In piping up a pump how can the steam supply EXAMINATION QUESTIONS AND ANSWERS 65 connection be distinguished from the exhaust connec- tion? A. The steam supply connection is the lower one, on either side, and is a smaller pipe connection than the ex- haust. Q. What are the dimensions of the 9>^-inch pump? A. Nine and one-half inch bore, by lo-inch stroke. Q. Name the operative parts of the steam end of this air pump. A. Main steam piston; main slide valve; differential pistons and connecting rod ; reversing slide valve ; and reversing valve rod. Q. What kind of a valve controls the admission and release of the steam to and from the steam cylinder ? A. A slide valve of the D type. Q. Where do the three ports in the slide valve seat lead to? A. One leads to the lower end of the steam cylinder (lower admission port) ; one leads to the upper end of steam cylinder (upper admission port) ; and the middle port is the exhaust, Q. What is the duty of the reversing valve rod ? A. To raise and lower the reversing slide valve. Q. What is the duty of the reversing slide valve? A. To admit and exhaust steam to and from the cham- ber on the right of main valve piston. Q. What is the duty of the differential pistons and connecting rod? A. To actuate or move the main slide valve over the ports in its seat. O. What is the duty of the main slide valve? A. To admit and exhaust steam to and from the pump cylinder. MODERN AIR BRAKE PRACTICE Q. What is the duty of the steam piston? A. To operate the air piston in the air cylinder. Q. Explain the passage of the air through the air end of the 9^ -inch pump. A. Assuming the piston to be on the up stroke, the air in the cylinder above the piston will be compressed and forced out through the upper passage under the upper discharge valve, unseating this valve and passing by it into the outer chamber, and thence out through the dis- charge pipe connection to the main reservoir. At the same time atmospheric air is passing through the air inlet, unseating the lower receiving valve, and passing into the air cylinder filling the space underneath the air piston. The action of the pump on the down stroke is similar to that of the up stroke, with the exception that in this case the lower discharge valve is delivering the air, while the upper receiving valve is admitting air at atmospheric pressure. Q. How many working parts are there in the air end of the 9^-inch pump? A. Five; the air piston; and four check valves, of which two are receiving, and two discharging valves. Q. What is the lift of the air valves in the g^-inqh pump, and are they interchangeable? A. The lift is 3% inch. They are interchangeable. Q. When the piston on the downward stroke has reached the bottom, how is its motion reversed? A. The reversing plate on the piston strikes the knob on the end of the reversing valve rod pulling it down, thus moving the reversing slide valve down until two ports in the seat are connected. One of these ports leads to the chamber back of the larger differential piston, and the other leads to the main exhaust port. Pressure being EXAMINATION QUESTIONS AND ANSWERS 67 now removed from behind the larger piston, it is free to be moved to the right by the Hve steam pressure, and in doing so it carries the smaller piston with it, and also the main slide valve, and thus reverses the pump. Q. What is the function of the small port leading to the chamber above the reversing valve rod in the cap nut? A. This is to prevent pressure from accumulating above the reversing rod which would prevent it from re- versing properly. It is connected at all times with the upper end of the steam cylinder, therefore, contains no pressure when the piston is on the up-stroke. O. Of what use are the small cocks? A. They are drain cocks and should be open at all times when the pump is not running to prevent conden- sation from accumulating in the steam cylinder and pas- sages. Q. How should the air pump be started? A. Slowly, to allow the condensation to escape from the steam cylinder and to accumulate sufficient pressure in the air cylinder to form a cushion for the piston. Q. How much air pressure is required to do this? A. About twenty-five or thirty pounds should be suffi- cient. Q. What else should be done at the same time that the steam throttle to the pump is opened? A. The lubricator should be started feeding freely at first, until the pump has received eight or ten drops of oil ; the feed should then be reduced to what may be con- sidered proper. Q. When should the air cylinder be oiled, and what kind of oil should be used ? A. The air cylinder should be lubricated with a small 68 MODERN AIR BRAKE PRACTICE amount of oil at frequent intervals. Valve oil should be used, as it has a good body and will stand the tempera- ture of the air cylinder. Q. Should oil ever be introduced through the air in- lets? A. No; such oiling has a tendency to gum up the air valves and passages and does the cylinder very little if any good. Q. How tight should the pump be packed? A. Just tight enough to prevent blowing. Q. How should the pump be run in descending grades ? A. With the pump throttle well open. Q. How should it be run at other times? A. Fast enough to maintain the full pressure and allow the pump governor to stop it once in a while, but it should not be run with a wide open throttle unless neces- sary to keep up the full pressure. Q. Should coal oil, or what is termed carbon oil or kerosene, ever be used to clean out or oil a pump? A. No ; it is dangerous to use it if the pump is warm, and it does not clean it as thoroughly as other more suit- able materials. Q. What should be considered as the maximum speed to run the pump? A. Not to exceed 120 single strokes per minute. Q. Why is a higher speed detrimental? A. It may not allow the cylinder to be filled with air at each stroke, and would eventually cause the pump to run hot. Q. What benefit is a well oiled swab on the pump piston rod? A. It keeps the piston rod packing lubricated, greatly 1 1 EXAMINATION QUESTIONS AND ANSWERS 69 prolonging the life of same, as well as assisting in lubri- cating the cylinders. Q. From what point of the boiler should the pump receive its steam ? A. From some high point, where dry steam can be had. THE II-INCH AIR PUMP. Q. In what respect does the ii-inch pump differ from the 9^ -inch pump? A. Principally in size, although a number of decided mechanical improvements have been made in the con- struction. Q. In what respect does the operation of the ii-inch pump differ from the 9^ -inch pump? A. There is no difference whatever, the same simple valve gear is used in. the 11 -inch pump that has been described in the 9^ -inch pump. Q. What is the lift of the air valves in the ii-inch pump ? A. Three thirty-seconds of an inch, or the same as the 95^-inch pump. Q. Are the air valves of the ii-inch pump inter- changeable with the 9^-inch pump valves? A. No ; while the valves in each pump have the same lift, they are not interchangeable, as the 11 -inch pump valves are larger in diameter. Q. What is the comparative efficiency of the ii-inch pump and 9^ -inch pump? A. Operating under similar conditions the 11 -inch pump is about 30 per cent, more efficient than the 9/^- inch pump. Q. What is the size of the steam and air cylinders of the II -inch pump? 70 MODERN AIR BRAKE PRACTICE A. The steam and air cylinders are both ii inches in diameter. Q. What is the stroke of the pistons in the ii-inch pump? A. Twelve inches. Q. What points should be observed in reference to the operation and care of the ii-inch pump? A. The same general rules as apply to the 9>4-inch pump should be followed in reference to the ii-inch pump. THE TANDEM COMPOUND AIR PUMP. Q. What is the leading feature of the Westinghouse tandem compound air pump? A. Two stages of air compression between the time of admission, and time of discharge to main reservoir. Q. Is the steam compounded also? A. It is not ; the single steam cylinder is similar to that of the 9^ and ii-inch pumps. Q. Compared with the 9^ and 11 -inch pump, what is the leading feature of the Westinghouse tandem com- pound air pump? A. While it has a steam cylinder of only 8 inches in diameter, it has an air compressing capacity equivalent to the 1 1 -inch pump. Q. What other peculiarity is there about this air pump ? A. While its steam cylinder is internally the same as that of the standard 8-inch pump, it has the valve gear mechanism and pipe connections of the special 9^ -inch pump. Q. Describe the arrangement of cylinders of the tan- dem compound pump. EXAMINATION QUESTIONS AND ANSWERS 71 A. There are three cyHnders placed vertically in tan- dem, the top one or steam cylinder being joined to the two lower, or air cylinders by a center piece, while the air cylinders are united by a thin center piece or parti- tion through which works the drum that unites the two air pistons. Q. Describe the action of the pump in compressing air. A. Assuming the pistons to be on the down stroke, air passes in through the upper air inlet on the left hand side, lifts the upper receiving valve, and passes into the upper cylinder filling the space above the descending pis- ton. When the piston has completed the down stroke and moves up this air is compressed, and lifting the upper discharge valve (upper right hand side of cylinder), is forced out past the upper discharge valve, which is also now a receiving valve for the higher pressure compart- ment, which is the annular cavity between the piston drum and the cylinder. Since the volume of this com- partment is much smaller than the low pressure volume of the cylinder from which it was received, this air is being compressed during its passage from the low pres- sure to the high pressure volumes, until when the piston reaches the upper end of its stroke the air in the low pressure clearances, passages and high pressure volume has reached the intermediate pressure of approximately 40 pounds. Q. Describe the further action of the pump. A. During the second down stroke of the piston this intermediate pressure air is further compressed until it lifts the final discharge valve, and passes out through the air discharge orifice in the center piece, and thence to the main reservoir. 72 MODERN AIR BRAKE PRACTICE Q. When air is taken at the lower end of the cylinder what takes place? A. The same operation occurs in the lower cylinder when the piston goes in the opposite direction from that d^escribed above, and as corresponding passages are designated by the same letter the operation can be read- ily followed. Q. How is the air cylinder lubricated? A. The air cylinder is lubricated by three oil cups. The upper end receives its oil from that cup placed just to the left on the upper center piece. The piston drum receives its lubrication by the oil from the cup connect- ing with a passage in the upper air cylinder and is drawn into the high pressure volume of the air as it goes from the low pressure to the high. The lower end of the air piston is lubricated by the oil cup situated on the left side of the lower center piece. Q. Why is the compound pump equal to the ii-inch air pump in air compression capacity when provided with an 8-inch steam cylinder? A. This results from the compound feature of the air cylinders. As already explained, when the pistons are moving upward, air is being forced from the cylinder above the piston to the annular cavity between the drum portion of the piston and the cylinder, the air gradually increasing in pressure as the piston advances, reaching a pressure of about 40 pounds at the termination of the stroke. This pressure under the piston and above the center piece exerts an upward force on the piston the same as does the steam under the steam piston, while at the same time the air under compression to the main reservoir is exerting only a resistance equal to the area of that portion of the upper side of the air piston ex- EXAMINATION QUESTIONS AND ANSWERS 73 posed to the air being compressed in the annular opening between the piston trunk or spool and the cylinder. Q. Does this result in economy? A. Yes ; by compounding the air end a much smaller steam cylinder can be used to operate the pump, thus causing a marked economy in steam consumption, AIR PUMP GOVERNOR. Q. What is the function of the pump governor? A. To regulate the supply of steam to the pump in such a manner that the speed of the pump will maintain the desired pressure. Q. Describe the connections of the single top gov- ernor. A. There are three ; one to the boiler ; one to the pump, and one to the main reservoir. Q. Does the main reservoir connection always lead to the main reservoir? A. No ; with the D-8 brake valve this connection leads to the train pipe. Q. Name the valves in the single top governor. A. There are two ; the steam or throttle valve, and the air valve, or pin valve. Q. Name the other important parts of the governor. A. The piston, which actuates the steam valve, the ad- justing spring and the compressing spring, also the diaphragm. Q. Describe the action of this governor. A. With the governor open, which is its normal posi- tion, air pressure enters the governor at the main reser- voir connection, and passes into a chamber below the diaphragm, this pressure increasing until it exceeds the tension of the adjusting spring above the diaphragm, 74 MODERN AIR BRAKE PRACTICE when the latter will yield and cause the pin valve to be raised from its seat. The air is now free to pass into the chamber above the governor piston which it forces down compressing the spring and seating the steam valve. Q. When the pressure beneath the diaphragm is re- duced below that for which the governor is adjusted, what will take place? A. The tension of the adjusting spring will cause the diaphragm to move down, and seat the pin valve. O. With the pin valve seated, what will cause the f steam valve to again open and supply steam to the ' pump? A. The chamber above the governor piston is always \ open to the atmosphere through a small relief port, through which the air pressure above the piston may be relieved, thus allowing the spring, with the assistance of the steam pressure under the vale to raise the piston and valve to their normal positions which will again start the pump to work. Q. What is the function of the Westinghouse duplex pump governor? A. To permit of controlling the pump with two dif- ferent air volumes, or a ready change in the pump con- trol, from one pressure to another, without the necessity of re-adjusting the governor. Q. In what respect does this governor differ from the single-top governor? A. The only difference is in the upper or air end ; two diaphragm portions are used, and a Siamese fitting, by which they are connected to one steam portion of the governor. Q. Is the principle of operation of this device the same as the single-top pump governor? EXAMINATION QUESTIONS AND ANSWERS 75 A. Yes ; the description of the operation of the single- top governor covers this device. Q. Do both of the diaphragm portions operate it at the same time ? A. No; as the adjustments of the heads differ, it re- quires different pressures to operate them ; therefore, only one head operates at one time. Q. Does it make any difference what head is set for the high or low pressure? A. No ; not as far as the governor is concerned. This is governed entirely by the way the heads are con- nected up. Q. By referring to the vent ports in the Siamese con- nection, it will be seen that one is to be plugged. What is this for? A. To prevent a needless waste of air. As the Sia- mese fitting directly connects both diaphragm portions together, one vent port is sufficient, as only one head is operating at one time. Q. What equipments is the duplex pump governor used with? . A. The High Speed Brake, "Schedule U," or High Pressure Control, and the Duplex Main Reservoir Control. Q. During the time the pin valve is unseated there is a continuous blow from the relief port. What is this for? A. This leakage, in conjunction with the flow of steam through the small port in the steam valve serves to keep the pump working slowly, to avoid the accumulation of condensation. Q. What is the purpose of the connection from below the governor piston to the atmosphere? 76 MODERN AIR BRAKE PRACTICE A. This is the drip pipe connection to the chamber im- mediately below the piston, for the purpose of permitting any steam that may leak past the steam valve, or any air that may leak past the piston, to escape to the atmos- phere. AUTOMATIC LUBRICATION. Q. What is the object of the automatic air cylinder oil cup? A. To automatically lubricate the air cylinder of the air pump, instead of by hand. Q. In what manner does the automatic cup better per- form the lubrication of the pump than a hand oiler? A. With the hand oiler, a considerable quantity of oil is given the pump at one time to last the entire trip, while the automatic oil cup is subject to alternate suction and compression strokes of the air piston, and just the required amount of oil is regularly and continuously fed to the air cylinder. Q. Describe the construction and operation of the No. I automatic oil cup. A. It consists of a brass body having an internal chamber in which the oil is placed. A small regulating valve stem passes down through this chamber. This valve stem can be adjusted from the top by simply pull- ing off the cap which fits into the top of the body. A small lock nut on this valve stem, guards against the feed adjustment changing. When the valve is slightly raised oil passes drop by drop into the small chamber below. This chamber connects through a passage to the cap, and by means of small holes in this cap to the atmosphere, thus bringing said chamber always under atmospheric pressure. EXAMINATION QUESTIONS AND ANSWERS 77 Q. What is the function of the ball valve in the lower part of the cup ? A. When the air piston descends, the suction causes this valve to rise, and the air will pass through the holes in the cap and by way of the passage into the body, and as this air passes on into the pump cylinders, any oil that may have dropped from the regulating valve onto the top of the nut holding the ball valve in position, is drawn into the pump cylinder, thus lubricating it. As soon as the piston starts on the return, or up stroke, the ball valve promptly seats itself, thus preventing any air from being discharged to the atmosphere through the oil cup. Q. What is the purpose of the four holes drilled up through the cup? A. These holes connect with a circular groove in the base, and are thus connected with each other. This groove also connects with the passage leading from the pump cylinder to the top of the ball valve, and during the up stroke of the air piston, compressed air is forced into the grooved canal in the base, and thence to the ver- tical drilled holes or passages in the body, and as the temperature of compressed air is always sufficiently high to heat the oil cup the oil is thus kept liquid even in cold weather. Q. Describe the construction and operation of the No. 2 automatic oil cup. A. This cup is composed of a steel base screwing into the air cylinder of the air pump, to which is connected a brass oil reservoir. A brass cap fits the top snugly. Oil is contained in the inner chamber. The operative parts are a valve, valve spring and needle feed stem On the down stroke of the air piston the valve is drav^ from its seat by suction, compressing the spring, a slight 78 MODERN AIR BRAKE PRACTICE amount of air is drawn in to the cup, and oil is drawn past the needle and down into the air cylinder. The temperature of the oil in the cup is kept warm by the same means as in No. i, that is, the admission of warm air to passages cast in the body. Q. What is the principal difference between this cup and No. i cup? A. No. I has an adjustable feed, while No. 2 has a fixed feed. PUMP GOVERNOR DISORDERS. Q. If trouble is experienced in the regulation of main reservoir pressure how may the engineer ascertain whether or not the defect is in the steam, or air portion of the governor? A. By examining the vent port of the governor. If it is found to be open and air flowing freely from it, it in- dicates that the air end of the governor is all right and that the trouble must be in the steam end. Something is preventing the piston from seating the steam valve. Q. If this trouble is experienced on a day when the weather is very cold, where would we usually find the trouble ? A. The drain or waste pipe is probably frozen up. Q. Is that the only defect that could cause such a trouble ? A. No ; a blind gasket in this pipe, or the pipe clogged with dirt or gum or otherwise closed, would cause it. This allows the steam that may leak by the stem of the steam valve to accumulate under the piston, holding it up against the air pressure above it. Q. Sometimes a governor that has been working prop- EXAMINATION QUESTIONS AND ANSWERS 79 perly will develop a continual blow from the vent port. What would be defective in this case? A. The diaphragm valve would be unseated in this case, probably due to dirt or foreign matter on its seat. Q. Should the vent port be plugged to prevent the loss of air? A. No ; to do so would probably cause the governor to stop the pump. As the diaphragm valve would continue to leak, and as there would be no outlet for the air, it would accumulate above the piston until there was suffi- cient to drive it down, which would stop the pump. Q. If the governor stops the pump properly, but fails to start it again when the pressure is slightly reduced, what may cause the trouble? A. The diaphragm valve being rigid, instead of hav- ing the proper amount of side play, a partly or entirely stopped-up vent port, or the piston packing ring being a very tight fit and stuck in the lower end of the cylinder. Q. How does the rigid diaphragm valve cause such trouble ? A. By not seating properly it allows air pressure to feed down on top of the piston holding it down. Q. How should the packing ring fit the cylinder? A. It should be a neat working fit and as near air tight as possible, as leakage by this ring would be a waste of air, and would have a similar effect as an enlarged vent port. Q. Some governors are observed to have a heavy flow of steam from the waste pipe at all times. What would cause this? A. The piston stem being a very loose fit, and the upper side of the steam valve not making a very good joint. Q. What is the standard main reservoir pressure on 80 MODERN AIR BRAKE PRACTICE grades less than one and one-half per cent? On grades of one and one-half per cent and over? A. Ninety pounds and no pounds. Q. Where duplex governors are used, what should be the difference in adjustment of the two heads as regards pressure ? Ao Twenty pounds. Q. What is the allowable variation of the governor in controlling pump? A, Theoretically there should be no variation. GAUGES. I Q. What is the purpose of the different air gauges used on the engine? A. To properly indicate the air pressures in the dif- ferent parts of the brake system. Q. What pressure does the red hand on the duplex gauge indicate? What pressure does the black hand indicate ? A. Red hand — main reservoir; black hand — chamber *'D" pressure. Q. Where duplex gauge is used on brake cylinder, as with No. 6 E T equipment, what does red hand indicate ? What does black hand indicate? A. Gauge No. i. Red hand, main reservoir pressure; black hand, equalizing reservoir pressure. Q. What pressures are indicated by Gauge No. 2? A. Red hand, brake cylinder pressure; black hand, brake pipe pressure. Q. Which gauge hand shows the amount of reduction being made during a service application of the brakes? A. Black hand. Gauge No. i. EXAMINATION QUESTIONS AND ANSWERS 81 Q. Why, then, is the black hand of Gauge No. 2 neces- sary? A. To show brake pipe pressure when engine is second in double-heading or a helper. Q. What pressure is indicated by the red hand of Gauge No. 2 when operating the automatic or indepen- dent brake valve? A. Brake cylinder pressure. Q. How can you test principal air gauge to prove prob- able correctness? A. By means of a test gauge attached to train pipe- hose on tender. Place brake valve in full release for the red hand, and in running position for the black hand. THE WESTINGHOUSE 8>^-INCH CROSS-COMPOUND AIR COMPRESSOR. Q. What are the principal advantages of this compres- sor as compared with all other types of locomotive air compressors ? A. Economy in steam consumption and great air com- pressing capacity. Q. Explain in a general way the design of the 8^ -inch cross-compound compressor as compared to the 9^ -inch and 1 1 -inch Westinghouse compressors. A. It has two steam and two air cylinders placed side by side, the steam cylinders vertically above the air cylin- ders and joined by a suitable center piece. O. How are the steam cylinders designated? A. High and low pressure steam cylinders. Q. How are the air cylinders designated? A. High and low pressure air cylinders. Q. What are the dimensions of the steam cylinders? i 82 MODERN AIR BRAKE PRACTICE A. The high pressure steam cylinder is 8^x12 inches, the low pressure steam cylinder, 14^x12 inches. Q. What are the dimensions of the air cylinders? A. The low pressure cylinder is 14^x12 inches; the high pressure air cylinder, 9x12 inches. Q. Why do the high pressure cylinders vary in diam- eter, while the low pressure cylinders are of the same size? A. In view of the boiler pressure being greater than the maximum air pressure desired, it does not require a high pressure steam cylinder as large in diameter as the high pressure air cylinder. This permits of greater econ- omy in steam consumption and more uniformly balances the steam and air forces acting on the various pistons. Q. How are the cylinders relatively located? A. The low pressure air cylinder is under the high pressure steam cylinder; the high pressure air cylinder is under the low pressure steam cylinder. Q. How are the high pressure steam piston and low pressure air piston joined? A. By a hollow piston rod, the same as those in gy^ and ii-inch compressors. Q. How are the low pressure steam piston and the high pressure air piston joined? A. By a solid piston rod. Q. Have the low pressure steam piston and the high pressure air piston and rod any mechanical connection to the valve gear? A. No ; they are simply floating pistons. Q. How many inlet valves has the low pressure air cylinder? A. Four. Q. Where are they located ? I EXAMINATION QUESTIONS AND ANSWERS 83 A. Two each in the top and bottom heads of the cyHnder. Q. How many intermediate valves? A. Four. Q. What is the purpose of the intermediate valves? A. They perform the same duties between the low and high pressure air cylinders as the discharge valves do be- tween the high pressure air cylinder and the main reser- voir. Q. Where are they located? A. Two each in the top and bottom heads of the low pressure air cylinder. Q. How many discharge valves has the high pressure air cylinder? A. Two. Q. Where are they located? A. Outside of and near the top and bottom of the high pressure air cylinder. Q. Where is the steam valve gear located? A. In the top head of the high pressure steam cylinder. Q. Does a single valve mechanism serve to operate the entire compressor? A. Yes. Q. What are the operative parts of the valve gear? A. A piston valve, reversing valve and reversing valve rod. Q. How many pistons has the piston valve? A. Five. Q. What are the purposes of the five pistons? A. The two outer or differential pistons perform the same duties, and in the same way, as the main valve pistons of the 9^ -inch compressor. The three inter- mediate pistons, all of equal diameter, govern the flow L 84 MODERN AIR BRAKE PRACTICE of steam through the admission and exhaust ports of the steam cyhnders, thus corresponding to the main (slide) valve of the 9%-inch compressor. Q. How many steam ports are there in the piston valve seat? A. Five. Q. To what do they connect? A. Beginning at the right-hand port, the ports connect to the steam cylinders as follows : the top of high pres- sure cylinder ; top of low pressure cylinder ; exhaust ; bottom of low pressure cylinder, and bottom of high pressure cylinder respectively. Q. Name the operating pc.rts of the compressor. A. The reversing valve and the reversing valve rod; the piston valve, which performs the same duties as the differential pistons and slide valve of the 9^-inch com- pressor; the inlet valves, the intermediate valves, in the pasages connecting the high and low pressure air cylin- ders ; the discharge valves ; the high pressure steam pis- ton and its rod ; the low pressure steam piston and its rod; the low pressure air piston, and the high pressure air piston. Q. How does the piston valve perform the same duties as the differential pistons and main (slide) valve of the 9^-inch compressor? A. The five pistons are so arranged that the two outer (differential pistons) when moved actuate or move with them the three intermediate ones over the ports in their seat, perrjiitting the passage of steam to and from the cylinder ports in a similar way to that accomplished with the slide valve. O. Where is the steam pipe connection to the com- pressor ? y EXAMINATION QUESTIONS AND ANSWERS 85 A. At the steam inlet, at the right of the high pres- sure steam cyHnder. Operation, Steam Portion. Q. Where does steam enter the compressor? A. Through the passage leading to the top head to main valve chambers ; also through the port into the chamber containing reversing valve. Q. What is the duty of the reversing valve? A. To admit and exhaust steam from the chamber, at the right of the piston valve. Q. When the high pressure steam piston is at the bottom of its stroke, what position will the reversing valve be in? A. Down. Q. In what position is the low pressure steam piston at this time? A. Up. Q. Do the high and low pressure pistons always move in opposite directions and at the same time? A. Yes. Q. With the reversing valve down, what takes place? A. The chamber at the right of the piston valve is open to the exhaust through a port, and cavity in revers- ing valve, and exhaust port. The larger piston of the piston valve having a greater area exposed to the pres- sure in the chamber than the smaller piston at the oppo- site end of the piston valve, moves the piston valve to the right. Q. With the piston valve in the position just de- scribed, what takes place in the steam cylinders? A. With steam pressure from the boiler always pres- ent in the main valve chambers, steam is admitted to the 86 MODERN AIR BRAKE PRACTICE bottom end of the high pressure steam cyhnder, from the chamber on the left, carrying its piston upward; at the same moment the steam in the top end of the high pressure cyHnder is expanding into the top end of the low pressure cylinder, forcing its piston downward. During the down stroke of this piston, the bottom end of the low pressure cylinder is open to the exhaust. Q. Upon completion of the piston stroke just de- scribed, what takes place? A. As the high pressure piston approaches the upper end of its stroke, the reversing plate strikes the shoulder on the reversing valve rod, forcing it and reversing valve upward. This movement closes the port to the exhaust and uncovers another port, allowing steam to flow to the chamber at the right of the larger piston valve. Since live steam is always in the top chambers, and exerts its pressure against the inner surfaces of the largest and smallest of the piston valve pistons, and since now the larger piston has full steam pressure on its outer face, the resulting pressure on it will be balanced, while the small piston has steam on its inner face, and the chamber on its outer face is open to the exhaust, there is an unbalanced pressure on the right of the small piston so that it will be forced to the left. Q. What follows the movement of the piston valve to the position just described? A. Steam is admitted to the top end of the high pres- sure cylinder from the chamber on the right, driving its piston downward. At the same time, the steam under the high pressure piston expands into the bottom end of the low pressure cylinder, carrying its piston upward. The top end of the low pressure cylinder is now open to the exhaust I EXAMINATION QUESTIONS AND ANSWERS 87 Operation, Air Compressor Portion. Q. How is the air taken into the bottom end of the low pressure air cyHnder? A. When the high pressure steam piston is moved up- ward, the low pressure air piston, being connected to the same piston rod, is also carried upward, and air is drawn in through the lower strainer into the lower passage ; the lower inlet valves lift and the air passes into the cylinder through inlet ports. Q. While this is going on, what is taking place in the top end of the low pressure air cylinder? A. Air above the piston is being compressed during its upward movement and forced past the upper interme- diate valves, through a passage into the top end of the high pressure air cylinder, the piston of which is mean- while traveling downward. Q. What takes place in the bottom end of the low pressure cylinder when the piston reaches the upper end of its stroke? A. When the piston starts downward, the inlet valves are forced to their seats, and the air below the piston is compressed until it can raise the lower intermediate valves against the air pressure in the high pressure cyl- inder acting on their upper side, when it is forced through ports to the lower end of the high pressure air cylinder, the piston, in the meantime, being drawn up- w^ard by steam pressure under the low pressure steam piston. Q. What takes place in the top end of the low pres- sure air cylinder at this time? A. The upper intermediate valves drop to their seats and prevent back flow of air from the top end of the 88 MODERN AIR BRAKE PRACTICE high pressure air cylinder, and air is drawn through the upper air strainer into a passage past the upper inlet valves — and through a port into the top end of the low pressure air cylinder. At the same time the high pres- sure air piston is moving upward (compressing the air admitted from the top end of the low pressure air cylin- der to the top part of the high pressure air cylinder), until its pressure in the passage is sufficient to lift the upper discharge valve against the main reservoir pres- sure holding it to its seat, and air then flows through passages to the air discharge and the main reservoir. Q. What takes place when the low pressure air piston reaches the lower limit of its stroke and starts upward? A. The lower intermediate valves drop to their seats so that air from the high pressure air cylinder cannot flow back into the low pressure air cylinder ; at the same time the high pressure piston is forced downward by the low pressure steam piston, compressing the air (that has been forced into the high pressure air cylinder from the low pressure side), lifting the discharge valve, when it will be forced through port and passage to the air dis- charge and main reservoir. Q. It has been stated that the high pressure piston is forced downward by the low pressure steam piston. Is there any additional force exerted on the piston at this time? A. Yes. During the time the high pressure air piston is moving down the low pressure air piston is moving up and compressing the air into the upper end of the high pressure air cylinder. The gradual increase of air pressure on top of the piston exerts a downward force on the piston the same as does the steam above the low pressure steam piston. When the compressor mechan- EXAMINATION QUESTIONS AND ANSWERS 89 ism is reversed, the action is simply a repetition of that just described. Q. What pressures are exerted on the pistons as they reach the lower end of the stroke? A. Steam piston has from 25 to 40 pounds of steam pressure per square inch (dependent upon boiler pres- sure) and air piston about 40 pounds of air pressure. Q. What is the intermediate air pressure on the under side of the high pressure air piston as it starts on its downward stroke? A. About 40 pounds. Q. What is the pressure on the piston when it starts on its "upward stroke? A. The same ; about 40 pounds. Q. In how many stages is the air compressed? A. Two. Q. What is meant by ''two stages"? A. The final pressure at which the air leaves the com- pressor is obtained by two separate compressions. The first "stage" is when air, at atmospheric pressure, in the low pressure air cylinder is compressed and delivered to the high pressure air cylinder at the "intermediate" pres- sure. The second stage is when the air at the interme- diate pressure in the high pressure air cylinder is com- pressed, and delivered to the main reservoir at the final or high pressure. Q. What type of air valves are used in the 8^-inch cross-compound compressor? A. Inlet valves and discharge valves are of the 11- inch compressor standard. Intermediate valves are of the 9>^-inch compressor standard. ■Q. What is the lift of all air valves? A. ^2 inch. 90 MODERN AIR BRAKE PRACTICE Q. How can the air inlet valves be removed? A. Top valve is accessible by removing cap nuts, and ■bottom one by removing the valve cages. i Q. How are the upper intermediate valves removed? ^ A. By taking out the cap nuts. Q. How are the lower intermediate valves removed? A. By unscrewing valve cages. Q. How are the discharge valves removed? A. By removing cap nut and by taking out valve cage. Q. What provision is made for lubricating the piston | rods of the compressor? A. Swabs, which should be kept well lubricated with oil. Q. How many oil cups has the compressor, and where are they located? A. Two; located on the high pressure steam cylinder head. Q. What do they lubricate? A. One the high pressure air cylinder; the other the low pressure air cylinder. Q. How many drain cocks has the compressor, and where are they located? A. Four; located in the steam cylinders. Q. What is their purpose? A. The ^-inch cock drains the steam inlet chamber: the other cocks drain the top and bottom ends of the low pressure steam cylinder and the bottom end of the high pressure steam cylinder. Q. When should these drain cocks be open? A. At all times when the compressor is not running, to prevent condensation from accumulating in the cylin- ders and passages, and when starting it. EXAMINATION QUESTIONS AND ANSWERS 91 Q. In general, how should this compressor be ope- rated ? A. The same as the older standard Westinghouse compressors. Q. What decided advantages has the cross-compound as compared to other types of locomotive air compres- sors? A. (a) Economy in steam consumption. (b) Great air compressing capacity at compara- tively low speed. (c) The compressor is less susceptible to pounding and strains incident thereto. (d) Less packing ring leakage in both the steam and air cylinders. Q. What contributes largely to the steam economy? A. Compounding the steam, and less low packing ring leakage. Q. What contributes largely to air capacity? A. A low maximum pressure in the low pressure air cylinder; less differential pressure on opposite sides of the pistons, as compared to older types of air compres- sors, and full stroke of high pressure steam and low pressure air pistons, and valve gear, regardless of high or low main reservoir pressure. O. Why is the packing ring leakage less in the low pressure air cylinder? A. Because, as already explained, the pressure in this cylinder never exceeds 40 pounds. Q. Why is the packing ring leakage less in the high pressure air cylinder? A. As the air is compressed to main reservoir pres- sure on one side of the piston, it is being built up to about 40 pounds on the other side (a result of compress- k 92 MODERN AIR BRAKE PRACTICE ing the air from the low pressure to the high pressure air cylinder), hence the differential is 40 pounds less than would be the case with simple compressors having one side of the piston exposed to main reservoir pres- sure and the other to atmospheric pressure. Q. Why is the packing ring leakage less in the high pressure steam cylinder? A. While steam is exerting its force on one side of the ^ high pressure piston, the other side is subjected to such | back pressure as obtains from expansion into the low pressure steam cylinder. Q. Why is the packing ring leakage less in the low pressure steam cylinder? A. Because while the exhaust side of the piston is open to the atmosphere, the steam pressure on the oppo- site side of the piston is, as the name of the cylinder implies, comparatively low. 2 Q. Why cannot the results as stated in the four pre- I ceding questions be accomplished with simple compres- ' sors? ' A. Because with such type of compressors there is a high differential pressure on opposite sides of the pis- tons. In the steam cylinder the piston has high steam pressure on one side and is open to the atmosphere on the other, while one side of the air piston is working against main reservoir pressure and the other is ex- posed to atmospheric pressure. Q. In what way does full stroke of the low pressure air piston increase the capacity of the compressor? A. As the maximum air pressure in this cylinder never exceeds 40 pounds, the air occupying the clearance space when the piston starts on its return stroke, quickly ex- pands down to atmospheric pressure, permitting the tak- EXAMINATION QUESTIONS AND ANSWERS 93 ing in of free air more promptly and with much less piston movement than is possible when main reservoir pressure in the cylinder must expand to that of the at- mosphere. Q. In what way does this low pressure affect the ope- ration of the valve gear ? A. Against this low pressure the high pressure steam and low pressure air pistons always make their intended and full traverse, thus insuring full movement of the valve gear regardless of the high main reservoir pressure. Q. Is the stroke of the low pressure steam, and high pressure air pistons affected by high and low main reser- voir pressure? A. Yes, to some extent, though such is of little im- portance, as it can in no wise interfere with the valve gear or govern the quantity of free air taken into the compressor. Q. What is the comparative air compressing capacity of the 8^-inch cross-compound and 95^-inch compres- sors? A. Under the same operative conditions the cross- compound has a little more than three times the capacity of the 9^-inch compressor. Q. What is the steam consumption of the 8>^-inch cross-compound compressor when supplying the same volume of air as the 9^ -inch compressor when working at its maximum capacity? A. The 85^-inch cross-compound uses about one-third the amount of steam required by the 9>^-inch com- pressor. Q. How should the air compressor be started? 94 MODERN AIR BRAKE PRACTICE A. Slowly to allow the condensation to escape from the steam cylinders. Q. What else should be done at the same time that the steam throttle to the compressor is opened? A. The lubricator should be started feeding freely at first, until the cylinders have received eight or ten drops of oil; the feed should then be reduced to an amount sufficient to properly lubricate the compressor. Q. What kind of oil should be used? A. A good quality of valve oil. Q. When should the air cylinders be lubricated and what kind of oil should be used? A. The air cylinders should be lubricated with a small amount of valve oil at occasional intervals. Q. Why should valve oil be used? A. Because it has a good body and will stand the tem- perature of the air cylinders. Q. Describe the construction and operation of the oil cup. A, The cup has an air-tight fitting cover and plug cock or key, which is operated by the handle, the key having a recess or cavity in one side. When the handle is in a vertical position, the cavity fills with oil. When the handle is horizontal, the oil flows from the cavity into the oil pipe and finds its way to the air cylinder. Q. Should oil ever be introduced through the air in- lets or strainers? A. No; such oiling has a tendency to gum up the air valves, passages or strainers, which, in time, may restrict the flow of air sufficiently to reduce the capacity of the compressor. Q. How tight should the piston rods be packed? A. Just tight enough to prevent leakage. EXAMINATION QUESTIONS AND ANSWERS 95 Q. What benefit is derived from well-oiled swabs on the piston rods? A. They keep the piston rods lubricated and assist in oiling the cylinders. Compressor Disorders and Remedies. Q. What is the cause if, when starting the compres- sor, it short strokes or 'Mances"? A. Low pressure on the reversing valve allowing it to drop of its own weight ; too much lubrication or a bent reversing valve rod. Q. What could be the trouble if the compressor be- gins to pound badly after running rapidly for some time? A. The compressor may be lacking in lubrication. It may also have worked the bolts loose that fasten it to its bracket. If the bracket is weak or loose on the boiler, it would cause the same trouble. O. Are there any other causes for the compressor pounding ? A. Yes ; too much lift of the air valves ; tight packing rings in the piston valve, or loose nuts on the piston rods in the air cylinders. Q. If the compressor stops in service, from an un- known cause, what might be the trouble? A. Loose nuts on the piston rod in the low pressure air cylinder; a bent or broken reversing valve rod; the rod disengaged from the reversing valve plate; a loose reversing valve plate; bad packing rings on the main valve, or a dry compressor. Q. What method should first be tried to start the compressor ? 96 MODERN AIR BRAKE PRACTICE A. Close the compressor throttle for a short time, then open it quickly. Q. If this fails to start the compressor, what other method might be tried ? A. Tap the steam cylinder head lightly. Q. What should first be examined if the compressor fails to start? A. The nuts on the piston rod of the low pressure air cylinder, which can be done by removing the plug in the center of the lower cylinder head. If the trouble is not located, next examine the reversing valve rod, by re- moving the reversing valve cap. Q. In the case of loose nuts on the piston rods in the low, or high pressure air cylinders, how should the trouble be remedied? A. In all cases where possible the compressor should be removed from the locomotive and proper repairs made in the air brake room. Very poor results are lia- ble to be obtained when this work is done without removing the compressor from the locomotive. Using a hammer and chisel to tighten up these nuts is very bad practice, as it does not draw them tight, and often fractures the end of the rod. Q. What will cause a blow in the cross-compound compressor ? A. Loose rings on the low pressure piston, or on either of the pistons of the piston valve ; reversing valve not having a good bearing on its seat ; reversing valve rod not fitting snugly in the reversing valve bushing; -reversing valve, or piston valve bushing not fitting neatly ; or top head gasket leaking between the ports. Q. If, in handling a long train, the compressor gets hot, what should cause the trouble? EXAMINATION QUESTIONS AND ANSWERS 97 A. Unusually high main reservoir pressure ; bad pack- ing rings on the air pistons, the packing in the stuffing boxes being too tight ; too little lift of, or stuck air valves ; the ports and passages being badly gummed or clogged up, or clogged up air strainers. Any or all of these troubles would produce the effect mentioned. If the compressor and its air pipes are in good condition, it should not run hotter than that caused by the natural heat of compression. Q. Should the compressor run hot, what should be done? A. First reduce its speed, then put a small quantity of good oil in the air cylinders, and continue to run the compressor slowly until it cools down. Q. How can bad packing rings on the low pressure air piston be determined? A. By noticing the suction at the air inlets. The suc- tion should be good nearly the entire stroke if the pack- ing rings are in proper condition. Q. If the low pressure air piston packing rings are found in good condition, what should next be done? A. Ascertain if the air valves have the proper lift (3^ inch). Q. In fitting new air valves, what rules should be followed? A. The valve should have a ^ood bearing on the seat, but not too wide. In removing the top of the valve to give the required lift, it should be filed squarely, that it may have a full bearing where it strikes the stop. Q. What will result from bad packing rings in the high pressure air cylinder? A. If the leakage is serious, it will have a tendency to slightly slow up the speed of the compressor. 98 MODERN AIR BRAKE PRACTICE Q. If the packing rings are found to be defective, how should new rings be fitted to the cylinder? A. The rings should be filed or scraped, to a good bearing all the way around the cylinder. The ends should be filed off so that the ring will fit the smallest part of the cylinder, the ends coming as close together as possible and work free. They should also be a neat fit in the piston grooves. Q. Is it poor practice to fit rings to a cylinder that is slightly out of round, or not of the same diameter its entire length? A. Yes. Q. What should be done if the cylinder is found, from wear, to be smaller in one part than another? A. It should be re-bored. If this is not done, the rings will permit the air to churn from one end of the cylinder to the other, greatly reducing the efficiency of the compressor, and at the same time contribute largely to excessive heating. Q. If the air ports or passages are gummed up, how may they be cleaned out ? A. By working a strong, hot solution of lye, or potash, and water through the air cylinders. If the engine is to remain in the round house long enough, the air cyl- inders and ports may be filled with this solution and allowed to stand until it has cut the gum. If the time will not permit of this, then the solution should be worked through the compressor by running it slowly, to the main reservoir ; then worked through the compressor a second time, after which a quantity of fresh water sufficient to thoroughly rinse the compressor should be worked through it. The piston rods should then be re- packed (unless metallic packing is used) and the pipe 1 1 EXAMINATION QUESTIONS AND ANSWERS 99 joints tightened. Kerosene or coal oil must not be used, as it frequently explodes under pressure, and at best does not do the work thoroughly. Q. If the compressor makes irregular strokes or "goes lame/' where would the trouble be? A. Probably with the air valves. Q. What would be the trouble? A. A valve may be stuck or broken. Q. If an inlet valve was stuck open or broken, what would result? A. Air would be drawn into the low pressure cylinder and on the return stroke of the piston, blown back to the atmosphere. Q. If an inlet valve were stuck closed,- what effect would it have? A. No serious effect. As there are two inlet valves at each end of the low pressure air cylinder the valve still in g^ood condition would permit the cylinder to be supplied with air. Q. If an intermediate valve was stuck open or broken, what would result? A. Air would churn back and forth between the high and low pressure air cylinders, and no air would be taken in at the inlet valves at the end of the low pressure cylinder having the stuck or broken intermediate valve. Q. If an intermediate valve was stuck closed, what effect would it have? A. Little, if any effect. There being two intermediate valves at each end of the air cylinders, the valve still in good condition would answer the requirements. Q. What would be the effect if the upper discharge valve was stuck or broken? A. Main reservoir pressure would always be on top 100 MODERN AIR BRAKE PRACTICE of the high pressure air piston and cause the compressor to work slowly. Q. What would be the effect if the lower discharge valve was stuck or broken? A. Main reservoir pressure would always be under the high pressure air piston, causing the compressor to work slowly. Q. What could be done out on the road to get the, compressor to work regularly? A. If a valve is stuck, tapping lightly on the outside of the compressor will often dislodge it. If the valve continues to stick, it should be removed, and the foreign matter cleaned off. Though the trouble may be reme- died it should be reported upon arrival at the terminal, and the compressor thoroughly cleaned, as gummed-up valves indicate a bad condition of the air cylinders. Q. If a compressor is in good condition, yet is slow in pumping up air pressure, where might the trouble be ? A. The air strainers may be partially clogged up, which in most cases is the source of this trouble, as it will not permit the low pressure cylinder to be filled with air at each stroke of the piston. Strainers are at times deceiving in external appearance as they may be polished bright and appear to be clean and yet the small perforations may be partially clogged up with dirt. Q. In the event of the low pressure steam piston or high pressure air piston becoming disabled, can the com- pressor still supply air? A. Yes — as under such conditions the compressor be- comes single-acting, the same as the 9^-inch compres- sor. Q. How would the compressor then operate ? A. Air would be taken into the low pressure air cylin- Examination questions and answers IOj. der in the usual manner and forced through the high pressure cyHnder to the main reservoir. O. What main reservoir pressure could be obtained in this way? A. 40 to 50 pounds. Main Reservoir. Q. What is the function of the main reservoir? A. To receive and store the compressed air delivered by the air pump. Q. Does the size of the main reservoir affect the ope- ration of the brakes? A. It does. It should be large enough to contain a sufficient volume of air to promptly charge up the train pipe and auxiliaries when empty. Q. What is the minimum size reservoir permissible for freight and passenger engines? A. A capacity of 40,000 cubic inches for freight and 20,000 cubic inches for passenger. O. Are there any freight engines equipped with reser- voirs of a capacity greater than 40,000 cubic inches? A. Yes; many of the leading railroads are equipping their heavy freight engines with reservoirs of 50,000 and 60,000 cubic inches capacity, and are getting good results from the increased volume. Q. Why is a reservoir of large capacity desirable? A. It permits of carrying a large volume of air with which to promptly charge up an empty train, or to re- charge the train pipe and auxiliary reservoirs after an application of the brakes. Q. Are there any other benefits received from the use of a large main reservoir? A. Yes ; it acts as a cooling or radiating chamber for 102 MODERN AIR BRAKE PRACTICE the air after it leaves the pump, thereby reducing the temperature of the air and allowing it to pass through the brake valve into the train pipe at a moderate temper- ature. Q. What benefit is received by cooling the air before it leaves the main reservoir? A. It separates the moisture from the compressed air and causes it to settle in the reservoir, whence it can be readily drained out. Q. What might be the result if this water is not caught in the main reservoir, but goes back through the brake valve into the train pipe? A. Water passing into the train pipe is very detri- mental, as it causes the pipes to rust, and in getting into the triple valves it destroys the lubrication. In the win- ter time, water in the train pipe is very dangerous, as it is liable to result in a stopped-up train pipe. Q. Why do freight engines require a larger main res- ervoir volume than passenger engines? A. This is owing to the longer trains handled and greater number of auxiliary reservoirs to recharge after an application of the brakes. Q. Why cannot air be pumped direct into the train pipe, and thus release the brakes? A. The process is too slow, and on a long train many of the brakes would fail to release; another objection is that the pump would be required to do a great amount of work in a very short time, which would probably cause it to run hot. Q. How much main reservoir pressure is carried? A. Ordinarily 90 pounds, although local conditions, and the use of special equipments govern the amount carried. EXAMINATION QUESTIONS AND ANSWERS 103 Q. Is not main reservoir pressure sometimes called excess pressure? A. Yes ; the amount of pressure in the main reservoir above that in the train pipe is called excess pressure. Q. What is excess pressure used for? A. To insure a prompt release of brakes and recharg- ing of the auxiliary reservoirs ; also, to supply the vari- ous air operated devices on the engine without affecting the train pipe pressure. Q. Where is the starting and ending point of the main reservoir pressure in the brake system? A. It starts at the discharge valves of the pump and ends at the engineer's brake valve. Q. What effect does water have in the main reservoir ? A. It occupies space that should be filled with air, and in doing so reduces the capacity of the reservoir. Q. How often should the main reservoir be drained? A. At the end of each trip. In suburban or switch- ing service, every 24 hours. Q. Where does the water come from that is found in the main reservoir? A. From the atmosphere. Atmospheric air always carries in suspension more or less moisture, which is de- livered into the main reservoir with the compressed air, and is condensed into water. Q. Does leakage at the pump stuffing box affect the amount of water collected in the main reservoir? A. But very little, as experiments have proven that the amount received through the stuffing box is very small. 104 MODERN AIR BRAKE PRACTICE THE ENGINEER S BRAKE VALVE. The engineer's brake valve is the device on the engine by means of which the engineer is enabled to charge up, and keep charged, the trainpipe and auxiliaries; apply the brakes, and keep them applied, release the brakes and keep them released, and to do these several things he has either to place the main reservoir in communica- tion with the train pipe, or open the train pipe to the atmosphere, or shut off all communication, as the case may be, according to whether he is applying or releasing the brakes, keeping them set, or running along. There are just four things that constitute the essen- tial parts to a modern Westinghouse brake valve, and they are : the rotary valve, the handle that controls the rotary, the equalizing discharge valve, and the feed valve attachment, or train pipe governor. Of course there are gaskets, springs, packing rings, the equalizing reservoir, etc., but they are matters of detail. There are five positions in which the handle of the brake valve can be placed. The first, or extreme left position is full release, and is the position the handle should always be in when re- leasing brakes, or when it becomes necessary to charge up quickly, for in this position the air from the main reservoir flows through the largest ports in the rotary, direct to the trainpipe. The second position is called running position, .because the handle should be carried in this position while run- ning along, for the reason that in this position the ro- WESTINGHOUSE ENGINEER'S BRAKE VALVE 105 tary valve is placed so that all the air that passes from the main reservoir into the trainpipe must go through the feed valve attachment, and this attachment will only allow seventy pounds of air to get into the trainpipe (if set correctly, and unless the high-speed apparatus is be- ing used), it enables the pump to maintain an excess pressure in the main reservoir, for if the pump gov- ernor is set at ninety pounds, and the feed valve set at seventy, there will naturally be twenty pounds greater pressure in the main reservoir than in the trainpipe be- fore the pump is stopped by the governor. Another reason why the handle must always be carried in running position while the train is running along, is because whenever the pressure in the trainpipe leaks down below the standard of seventy pounds, the feed valve will open automatically and allow the main reser- voir pressure to again flow into the trainpipe until that pressure is restored, when it will automatically close itself, and allow the pump to again create the "excess" in the main reservoir. The third position of the brake valve is lap, and when the handle is in this position all ports are closed, so that no air can pass either into the trainpipe or out of it. After applying the brakes, the handle should be brought to lap carefully, and held there until it is desired to fur- ther reduce the trainpipe pressure or release the brakes, as the case may be, and when releasing the brakes the handle must be placed on full release position for a few seconds, according to the length of train and the amount of excess carried before it is allowed to rest on running position. The fourth position is called service application posi- tion because in this position the air is allowed to escape 106 MODERN AIR BRAKE PRACTICE gradually from the train pipe. In this position the air on top of the equalizing discharge valve is allowed to escape through the small preliminary exhaust port in the seat of the rotary so gradually that a sudden reduction on the trainpipe is prevented, for as the pressure on top of the discharge valve is allowed to escape, the trainpipe pres- sure below gradually forces it from its seat and thereby opens the trainpipe exhaust. If the handle is left in service position until ten pounds is drawn from the top of the dis- charge valve and then placed on lap, the valve will not seat until a fraction over ten pounds has escaped from the trainpipe, when the pressure on top will then be the greatest and force the discharge valve back to its seat, and thereby close the trainpipe exhaust. The fifth position is called emergency application po- sition, because when the handle is iv this position the rotary connects the main trainpipe supply port with the main exhaust port and the air is allowed to escape from the trainpipe, direct to the atmosphere, regardless of the equalizing discharge valve, and this sudden reduction of trainpipe pressure allows the triples to be forced to their full stroke, and thus causes the quick action, or emergency application. Emergency position should never be used except in case of danger. In applying the brakes with the quick-action triple, it is not only necessary to reduce the train-pipe pressure lower than that in the auxiliary, but it is absolutely nec- essary that the reduction be made gradually to prevent the emergency action. The old-style brake valve, or three-way cock, Fig. 21, has only three positions, viz : application, lap and release. The passage ways through the plug of the valve are designated by the marks on the plug. When the handle D-8 BRAKE VALVE 107 is turned to the right, communication is estabHshed be- j tween the main reservoir and the brake pipe to the brake C3iinders. When the handle is reversed (turned to the Fig. 21 — Three-Way Cock Form of Brake Valve. left), the former communication is cut off and a new one Imade, establishing communication between the brake cylinders and brake pipe to the atmosphere. I D-S Brake Valve. — As the D-8 brake valve is now largely superseded by the F-6 and G-6 it will not be nec- ;essary to enter into details in describing it, except to 'point out the differences between the two types of brake valves. , The D-8 brake valve uses the pump governor to con- ]trol the train pipe pressure of seventy pounds, and the connection is made at V, Fig. 22, the excess is controlled by what is known as the excess pressure valve (19, Sec. ^3, of Fig. 22). When the handle of the D-8 brake valve is in full re- lease position the pump will shut off at seventy pounds, loa -MODERN AIR BRAKE PRACTICE Fiof. 22 — D-8 Brake Valve and the pressure in the main reservoir and train pipe would be the same, but if the handle is in running posi- tion the excess pressure valve will not open to admit air D-8 BRAKE VALVE 109 into the train pipe until there is twenty pounds in the main reservoir, and as it requires twenty pounds to hold this valve open, the train pipe will get a pressure of seventy pounds before the pump will shut off, thus leav- ing an excess pressure of twenty pounds in the main reservoir. If the handle is placed on lap while the train pipe pressure is below seventy pounds, the pump will run the main reservoir pressure up to boiler pressure, for the governor cannot shut the pump off unless there is seventy pounds in the train pipe ; on the other hand, if the handle is in running position no air can get into the train pipe until there is twenty pounds of excess in the main reser- voir, and as a consequence the many leaks that commonly occur in the main reservoir and train pipe connections cause the brakes to creep on before the pressure can be restored to keep them off. It is mainly on this account that the F-6 brake valve was invented, for with this valve the pump governor is controlled by the main reservoir pressure, and will stop the pump at ninety pounds in the main reservoir, no matter in what position the handle is, and, as the train pipe pressure is controlled by the feed valve, whenever that pressure falls below the standard of seventy pounds, if the handle is in running position the feed valve will open and let the main reservoir pressure in, and thus keep the brakes from dragging. Another difference between the two kinds of brake valves is that with the D-8 valve, when making a serv- ice application, the air from cavity D over the equalizing discharge valve, 17, is exhausted to the atmopshere through a separate little port in the casing, marked h in Sec. 2 of Fig. 23, whereas the preliminary exhaust h, 110 MODERN AIR BRAKE PRACTICE in the F-6 valve, is connected with the main or emer gency exhaust, marked k in Sec. 2 of Fig. 25, thus mak 1 Sec. 4 I Fig. 23— D-8 Brake Valve and Rotary. ing one port less through the casing of the F-6 brake valve. Therefore there are the following differences between F-6 BRAKE VALVE 111 the D-8 and the F-6 brake valves : ist, with the D-8 valve the excess pressure is gotten before the train pipe begins to charge, if the handle is in running position ; 2nd, with the D-8 valve the train pipe pressure is controlled by Fig. 24 — Engineers' Brake Valve, F-6 Type. the pump governor, instead of the feed valve attach- ment, as it is with the F-6; 3rd, with the D-8 valve, if the handle is left in either lap, service or emergency position, the pump will run the main reservoir pressure 112 MODERN AIR BRAKE PRACTICE Up to boiler pressure, or will shut off when there is only seventy pounds in the main reservoir if the handle is left in full release from the starting of the pump, whereas with the F-6 valve, the pump will be shut off by the gov- ernor, if properly set, when the main reservoir reaches ninety pounds, no matter what position the handle of the valve is in ; 4th, with the F-6 valve the excess pressure is gotten after the train pipe pressure is pumped up; 5th, with the D-8 valve, if the excess pressure valve should happen to be in bad order, and it usually is, if the handle was left on lap for any considerable length of time after making a service application, the main reservoir pressure would be raised so high that, with a short train, when the handle was thrown to release position the auxiliaries would be overcharged, and the wheels slid on the next application, unless the engineer was very careful, whereas with the F-6 valve the most that could get in the auxili- aries, if the governor was correct, would be ninety pounds ; 6th, when an emergency application is made with the D-8 valve, the black hand on the gauge will rise instead of fall, because in this position the equaliz- ing port to cavity D is open to the main reservoir pres- sure. The construction of the D-8 valve, with these differences, is the same as the F-6 or G-6, except that the D-8 has an excess pressure valve, while the F-6 or G-6 has a feed valve attachment, which will be explained in regular order. F-6 Brake Valve. — The parts of the F-6 brake valve are as follows : the handle, which controls the rotary, is marked 8, in Sec. i, Fig. 24. The lug, 9, is forced out by a spring, 10, so that the handle may be stopped in any desired position, and when placing the handle in any of the positions be sure that the lug in the handle is right F-6 BRAKE VALVE 113 up against the lug on the brake valve, for the reason that the rotary valve is moved in exact accord with the handle. If either lug is worn the movement of the ro- tary will be correspondingly changed when the lugs are against each other; 12 is the stem to one end of which the handle is fastened by nuts 6 and 7, and the other is dove-tailed or keyed into the top of the rotary, so that whatever way the handle is turned the rotary has to turn with it; 13 is a small leather gasket for the purpose of preventing any air from leaking out around the stem, as main reservoir pressure is always on top of the ro- tary and under the shoulder of stem 12, forcing it up against the casing. This gasket sometimes gets gummed up so badly that it causes the handle to move very hard ; 14 is the rotary valve, and 3 is the rotary valve seat; 18 is the equalizing discharge valve, which controls the train pipe exhaust m and n. The action of the discharge valve has already been explained under the head of serv- ice application position. As cavity D above the discharge valve is very small, it is necessary to have a greater volume of air to control it than the cavity alone will contain, and this greater volume is supplied by a little drum, or equalizing reser- voir, which holds about 500 cubic inches of air, and is located, usually, under the footboard of the cab. It is connected to the brake valve at T ( Sec. i ) , and from T to cavity D there is a connecting passage, as shown by s in Sec. 3, and as the little drum is always charged equally with cavity D, whenever the pressure in cavity D is reduced it is also reduced in the little drum. This greater volume is needed above the discharge valve to compensate for the volume in the train pipe. When the handle of the brake valve is placed in service 114 MODERN AIR BRAKE PRACTICE m position the rotary shuts off the main reservoir and also cavity D from the train pipe, and allows the air to escape from cavity D by way of port e, groove p and preliminary exhaust port h to the atmosphere through the main ex- Fig. 25— F-6 Brake Valve — Rotary and Seat. haust k, and when the handle is moved to lap it closes the preliminary exhaust, and thus holds the little drum pres- sure at whatever it was reduced to, as shown by the ,1 F-6 BRAKE VALVE 115 black hand of the gauge, and when the train pipe has ex- hausted until it becomes less than the pressure in cavity D the discharge valve is forced to its seat by the pressure in the little drum, and stops any further flow of air from the train pipe. Nos. 34 to 46 in Sec. 3 of Fig. 24 all refer to the old style feed valve attachment as used on the F-6 brake valve. The essential parts are the supply valve, 34, valve spring, 35, diaphragm piston, 37, regulating spring, 39, regulating nut, 41. When the rotary is in running position, the operation of the feed valve is as follows : the regulating spring being set at seventy pounds tension, it forces the piston up against the stem of the supply valve and raises it off its seat, causing the main reservoir pressure to flow from the top of the rotary down through port j in the rotary Sec. 4, Fig. 25, and through port f in the rotary seat Sec. 3, Fig. 24, through a passage, f, and under the supply valve to the top of the diaphragm piston, then through a port (shown by dotted lines, and marked i,) Sec. 2, Fig. 25, which leads off the top of the piston into the train pipe by way of the main supply port, as shown by dotted lines in Sec. 2. As the rotary is now in posi- tion so that the large cavity, c, as shown in Sec. 4, 'Fig. 24, connects the main supply port with the equalizing port g (which passes through the rotary seat into cavity D), the air that is passing from the top of the rotary through the feed valve into the train pipe, is also filling cavity D, and the little drum, by way of ports g and s, as shown in Sec. 3, Fig. 24. While Fig. 24 shows full release position, still ports s and g are fully shown, and if the handle is moved to running position the port through the rotary that regis- 116 MODERN AIR BRAKE PRACTICE ters with port e in Sec. 3, would be in register with port f ; port g is indicated by dotted Hnes. In running position, when the train pipe and little drum are charged up to seventy pounds, there is also seventy pounds on top of the diaphragm piston, and as the regulating spring is set at a fraction less than seventy, the air pressure forces it down and allows the supply valve to seat and shut off the main reservoir from the train pipe. But as soon as the pressure in the train pipe falls below seventy, the piston is again forced up by the regulating spring and keeps the supply valve open until the pressure is again restored in the train pipe. The feed valve attachment is in operation only, when the handle of the brake valve is in running position. The course of the air through the brake valve in full release position is as follows. : the return pipe from the main reservoir is connected to the brake valve at X, and passes directly to the top of the rotary through passage A, then through port a in the rotary into cavity b in the rotary seat and under a bridge in the rotary (which now stands midway over cavity b), and on over the seat of the rotary, through large cavity c, direct into the main supply port, I, to the train pipe. In passing over the rotary seat the air also passes down through the equal- izing port g, into cavity D, and from cavity D through port s into the little drum ; and as the feed valve is cut out when the handle is in full release, both the little drum and train pipe pressure would charge up to main reser- voir pressure if the rotary was left in full release. In full release position, port j in the rotary registers with port c in the seat, so that cavity D charges faster in ^uU release than in running position. G-6 BRAKE VALVE 117 The little drum is simply an enlargement of cavity D and the same pressure is in both. The Warning Port, through which the air is heard es- caping as long as the handle remains in full release, is a small port through the rotary about the size of a pin, which allows the main reservoir air to whistle through it to warn the engineer that he is liable to overcharge his train pipe. It should always be kept clean. The black hand of the gauge is piped to the little drum at W, Sec. I, Fig. 24, as stud 17 is tapped into pipe 15 which connects the little drum with cavity D by way of port s. The red hand of the gauge, and also the pump gover- nor are piped to the main reservoir pressure at R. To make an emergency application the handle must be moved to the extreme right, when the large cavity, c, in the rotary will connect the main supply port, 1, of the train pipe with the main exhaust port, k, and allow the air in the train pipe to exhaust directly into the at- mosphere. G-6 Brake Valve and New Slide Valve Feed Valve. — The G-6 brake valve is identical with the F-6, with the exception of the feed valve. In the new slide valve feed valve the only material change is that a slide valve controls the flow of air from the main reservoir into the train pipe, which allows the pressure to be raised much quicker than it can be with the old style feed valve. The working parts of the new slide valve feed valve are as follows : all of the essential parts of the old style feed valve are retained, see Fig. 27, with slight modifica- tion, for 64 is the diaphragm piston, which, instead of having a rubber diaphragm has two sheet-brass dia- phragms, 57, on the piston head, supported by a ring, 63 ; 118 MODERN AIR BRAKE PRACTICE Fig. 26 — G-6 Brake Valve. 67 is the regulating spring ; 65 the regulating nut ; 59 a small valve corresponding exactly with supply valve 34 in the old style feed valve, and 60 is the spring which controls valve 59. By reference to Fig. 26, Sec. 3, it will be seen that there is a slide valve, 55, attached to a piston, 54, and this piston is forced forward by a spring, 58. The action of the new slide valve feed valve is as fol- lows : When the handle of the rotary is in running posi- \ SLIDE VALVE FEED VALVE 119 tion, main reservoir pressure drives the slide valve and piston back, which uncovers a port in the slide valve seat that connects with feed port i, and as the slide valve does not move until the train pipe is fully charged, it causes the pressure to be restored very quickly after it has been reduced from any cause. The reason the slide valve does not move until the pressure is restored is because the piston has no packing rings, and the air is allowed to circulate by it through a small passage that leads to the supply valve chamber, 63 62 6& Fig. 27 — Slide Valve Feed Valve. from which it passes under the cut-off valve across the diaphragm into feed port i, and when there is a pressure of seventy pounds on the diaphragm it moves away from the supply valve and allows it to seat, when the circula- tion by the piston is stopped, causing the pressure to equalize on both sides of the slide valve piston, when spring 58 moves the slide valve and closes communica- tion between the main reservoir and the train pipe. Whenever train pipe pressure falls below seventy the 120 MODERN AIR BRAKE PRACTICE diaphragm forces valve 59 off its seat and the same action is repeated as before. The H-6 automatic brake valve, and the S-6 independ- ent brake valve will be discussed in the section devoted to the No. 6 E. T. Equipment, EXAMINATION QUESTIONS AND ANSWERS 121 WESTINGHOUSE ENGINEER S BRAKE VALVE. Q. What is the engineer's brake valve for ? A. For the purpose of enabling the engineer to prop- erly charge, set and release brakes, and control the flow *of main reservoir and train pipe pressure. Q. What style of brake valve is now in general use? A. The equalizing discharge type. Q. What advantage is gained by its use? A. It permits the engineer to make light, uniform re- ductions throughout long trains, sufficiently fast to cover all leakage grooves, yet not fast enough to obtain quick action; and automatically closes off the discharge grad- ually, thereby preventing the release of the head brakes of the train. Q. What are the essential parts of the engineer's brake valve ? A. The rotary valve and the handle which controls it, the equalizing discharge valve, the feed valve attach- ment, or train pipe governor, and the equalizing reser- voir. Q. What is the purpose of the rotary valve? A. To open and close the ports in the brake valve. Q. What is the handle of the brake valve for? A. To control the movement of the rotary valve. Q. What is the equalizing discharge valve for? A. To open and close the train pipe exhaust port according to the pressure above or below it. Q. What is the equalizing reservoir intended for? 122 MODERN AIR BRAKE PRACTICE A. To maintain a large volume of air on the upper side of the equalizing discharge valve, in order to com- pensate for the volume of air in the train pipe, which is on the under side of the equalizing discharge valve. Q. How many positions are there for the brake valve handle to be placed in ? A. Five; as follows: i, full release position; 2, run- ning position; 3, lap position; 4, service application; 5, emergency. Q. Name the different types of Westinghouse engi- neer's brake valves now in use. A. The D-8, the F-6, the G-6, the H-6 automatic, and the S-6 independent. D-8 BRAKE VALVE. ,„i,_ Q. In what respect does the D-8 valve differ from the F-6 or G-6 type of brake valve herein described ? A. The principal difference is in the train pipe con- trolling device. With the D-8 valve an excess pressure valve is used, while the F-6 and G-6 have a feed valve device to control the train pipe pressure. Q. Are the positions of the brake valve handle of this valve the same as with the F-6 or G-6 pattern ? A. Yes. Q. Are the ports in the rotary valve and seat the same in this valve as with the F-6 or G-6? A. Yes ; practically the same, although slight modifi- cations have been made in the general arrangement of the F-6 and G-6 valves to permit of better wearing surfaces. Q. What is the object of the excess pressure valve? A. To permit excess pressure to accumulate in the EXAMINATION QUESTIONS AND ANSWERS 123 main reservoir, and to allow air to feed into the train pipe after the excess pressure has been attained. Q. In what position of the brake valve does the excess pressure valve operate? A. Running position. Q. How much excess pressure does this valve main- tain? A. Ordinarily 20 pounds, this being governed by the tension of the spring on the back of the valve. Q. With the brake valve in running position, will air pass to the train pipe until the excess pressure is ob- tained ? A. No; in order for air to pass to the train pipe, it must unseat the excess pressure valve ; therefore, it can- not pass through unless the air pressure exceeds the ten- sion of the valve spring. Q. With the D-8 type of brake valve, what volume of air is the pump governor connected to? A. To the train pipe volume. * Q. If the handle of the D-8 brake valve is placed on lap position while the train pipe pressure is below 70 lbs., what will be the result? A. The pump will run main reservoir pressure up to boiler pressure. Q. Why is this ? A. Because the governor cannot shut the pump off unless there is 70 lbs. pressure in the train pipe. F-6 BRAKE VALVE. Q. Name the different pipe connections to the F-6 valve. A. I, Main reservoir; 2, train pipe; 3, equalizing res- 124 - MODERN AIR BRAKE PRACTICE ervoir ; 4, pump governor and red hand of air gauge ; 57 black hand of gauge. Q. How many positions are there in which air is ad- mitted to the train pipe, and what are they? A. Two. Full release and running position. Q. How many positions are there in which the train pipe pressure can be discharged? Name them. A. Two. Service application and emergency position. Q. What is lap position? A. Lap position is the position in which all ports in the brake valve are closed. Q. What is lap position used for? A. To hold the brakes on after an application, or to prevent main reservoir pressure from passing into the train pipe when the train has parted, or the conductor has applied the brakes with the conductor's valve; also, when coupling to air brake cars. Q. In what respect does the F-6 brake valve differ from the D-# type ? A. Principally in the use of the feed valve attach- ment, in place of the excess pressure valve, although a number of general mechanical improvements have been made in the valve. Q. What improvement is the feed valve attachment over the excess pressure valve ? A. The feed valve is a device which controls the train pipe pressure, maintaining the standard amount regard- less of the excess pressure in the main reservoir, which the excess pressure valve would not do. It is also more sensitive in its action and permits of a convenient method of adjustment- also, is broader in the limits of adjust- ment. Q. With the brake vaive in running position, is it EXAMINATION QUESTIONS AND ANSWERS 125 necessary to accumulate the excess pressure before air can pass to the train pipe, as it is with the D-8 type? A. No; this is one of the decided advantages of this valve. With excess pressure valve, considerable trouble was had from the brakes creeping on during the time the pump was raising the excess pressure necessary to open the valve. Q. How many types of feed valves are there? A. Two known as the poppet type of feed valve and the slide valve feed valve. Q. What type of feed valve is used with the F-6 brake valve ? A. The poppet type of valve. Q. What is the difference between the F-6 brake valve and the G-6 valve? A. Only in the use of the slide valve feed valve, as described in the following pages. Q. What is full release position of the brake valve used for? A. To allow main reservoir pressure to flow quickly and directly into the train pipe, thereby insuring a prompt rise of pressure and the prompt release of the brakes and recharging of the auxiliary reservoirs. Q. Describe the warning port, and its location. A. It is a small port about the size of a pin, and passes through the rotary. Q. What is the function of the warning port? A. By allowing the air to whistle through it warns the engineer when he is liable to overcharge his train pipe. It should always be kept clean. Q. To what reservoir is the black hand of the gauge piped ? A. To the equalizing reservoir. 126 MODERN AIR BRAKE PRACTICE Q. What pressure does the red hand of the gauge indicate ? A. Main reservoir pressure. G-6 BRAKE VALVE. Q. Describe the passage of the air through the brake valve when in full release position. A. Air from the main reservoir flows through the largest ports in the rotary, direct to the train pipe. Q. What volume of air is at all times in the chamber above the equalizing piston? A. The equalizing reservoir, or little drum, volume. Q. What is the object of having the equalizing reser- voir always connected to the chamber above the equaliz- ing piston? A. This is to increase the volume of air of the equal- izing piston. Q. Why is this necessary? A. Without the equalizing reservoir, the volume of air above the equalizing piston would be so small that it would be difficult to reduce the pressure gradually, Which is required during service brake applications. Q. Is it understood that in all cases, when this chamber is being charged, that the equalizing reservoir is also being charged? A. Yes ; they are at all times in direct communication with each other. Q. What is the cause of the blow from the direct ex- haust opening of the brake valve when in full release position ? A. This is due to the warning port being open, in the rotary valve, and which is always open to the direct ex- EXAMINATION QUESTIONS AND ANSWERS 127 haust when the brake valve handle is in full release position. Q. What is the object of having this air escape when the handle is in this position? A. To make a noise and attract the engineer's atten- tion to the fact that the brake valve is in full release po- sition, and that it must be moved to running position to prevent the train pipe from becoming overcharged. Q. What air pressure is escaping to the atmosphere through the warning port? A. Main reservoir pressure. Q. What will happen if the brake valve is left in full release position? A. The train pipe and main reservoir pressure will equalize, thereby causing the train pipe to become over- charged. Q. Why would the train pipe be overcharged if it con- tains the same pressure as the main reservoir ? A. This is owing to the pump governor being con- nected to the main reservoir volume of air, with this style of brake valve, and which is always adjusted for a pressure above the standard train pipe pressure. Q. To what position must the brake valve handle be moved to prevent the train pipe from becoming over- charged ? A. Running position. Q. What are the conditions while the brake valve is in running position? A. In this position all the air that passes from the main reservoir into the train pipe must pass through the feed valve attachment thus enabling the pump to main- tain an excess pressure in the main reservoir. 128 MODERN AIR BRAKE PRACTICE Q. How many ports in the rotary valve seat are open in running position? A. Two ; one leading to the feed valve attachment, and the other to the chamber above the equalizing piston. Q. With this attachment what pressure is allowed in the train pipe, and what pressure in main reservoir ? A. Seventy pounds in train pipe, and 90 pounds in main reservoir, unless the high speed apparatus is in use. Q. Why w^ill the train pipe not become overcharged with the brake valve in running position? A. Because, in this position all air which enters the train pipe must pass through the feed valve attachment which controls the train pipe pressure, as this valve auto- matically closes off when the desired pressure is ob- tained. Q. What air pressure is always present above the rotary valve? A. Main reservoir pressure. Q. When is the running position of the brake valve used ? A. While running over the road when the brakes are not being operated, in order that the feed valve may control the train pipe pressure. Q. What is lap position used for? A. To prevent the main reservoir pressure from enter- ing the train pipe, or the train pipe pressure from pass- ing through the valve to the atmosphere. Q. Are there any ports open to the brake valve on lap? A. No; all communication through the brake valve is cut off. Q. After applying the brakes how should the handle be brought to lap? 1 EXAMINATION QUESTIONS AND ANSWERS 129 A. It should be brought to lap carefully, and held there until it is desired to further reduce train pipe pres- sure, or release the brakes as the case may be. Q. When releasing the brakes how must the brake valve be handled ? A. The handle should be placed on full release for a few seconds, according to the length of the train and the amount of excess pressure carried, before it is allowed to rest on running position. Q. Describe the conditions when the brake valve is in service application position. A. In this position the air on top of the equalizing discharge valve is allowed to escape so gradually that a sudden reduction of train pipe pressure is prevented. Q. In making a service brake application does it re- quire that the brake valve handle be left in application position any longer to make a lo pound reduction on 40 cars than it would with 10? A. No ; for in service position the volume of air which is reduced always remains constant, that being the air pressure in the chamber and the equalizing reservoir. Q. If the brake valve handle is left in service position until 10 pounds is drawn from the top of discharge valve, and then placed on lap, what is the result? A. The valve will not seat until a fraction over 10 pounds has escaped from the train pipe, when the pres- sure on top will then be the greatest, and force the dis- charge valve back to its seat, thereby closing the train pipe exhaust. Q. When should emergency position be used? A. Only in case of danger. Q. What conditions prevail in the brake valve during an emergency application? . 130 MODERN AIR BRAKE PRACTICE A. In this position the rotary connects the main train pipe supply port with the main exhaust port thus allow- ing the air to escape from the train pipe direct to the atmosphere regardless of the equalizing discharge valve. Q. What effect does this sudden reduction of train pipe pressure have on the triple valves? A. It allows them to be forced to their full stroke, thus causing quick action or emergency application. Q. With the brake valve handle in emergency posi- tion, does any air pressure escape from the train. pipe at the train pipe exhaust fitting? A. No; in emergency position of the brake valve the equalizing piston does not move; therefore no air can escape from the train pipe exhaust. Q. What precautions must be observed in applying brakes with the quick action triple? A. The reduction in train pipe pressure should be made gradually in order to prevent an emergency appli- cation. Q. Sometimes a very noticeable flash occurs at the train pipe service exhaust when releasing brakes, as though the equalization piston had raised. It is a notice- able fact that this never occurs with a long train, but only with the light engine or a few cars. What causes it? A. When the valve handle is placed in full release po- sition, the supply to the train pipe is much greater than that to the equalizing reservoir, thus charging the cham- ber under the equalizing piston faster than the chamber above it. This causes the piston to rise until the pres- sures equalize. 1 PLAIN TRIPLE VALVE ISI THE TRIPLE VALVE. One of the most important parts of the automatic air brake system is the triple valve, so called from the fact that it performs the three-fold function of, (a), charging the auxiliary reservoir located under the car, (b), apply- ing the brake, and (c), releasing the brake. As has been already explained, the automatic air brake requires an auxiliary reservoir under each car, and in this reservoir a sufficient volume of compressed air is stored ready for use in applying the brake. In the brake cylinder is where the air pressure is applied to the piston acting upon the brake levers and rods, but the triple valve ope- rates or controls the passage of the compressed air from the auxiliary reservoir, near which it is located, into the brake cylinder during the application of the brake; and it also releases the pressure from the brake cylinder, passing it to the atmosphere locally under each car when the engineer desires to release -the brakes. This being done the triple valve again automatically assumes the position in which air passes through it to recharge the auxiliary reservoir, ready for another application. PLAIN TRIPLE. Fig. 28 shows a sectional view of the Westinghouse new style plain triple, the parts of wliich are designated as follows : 23 is called the triple piston ; 24 is the slide valve ; 25 is the graduating valve ; 26 is the graduating m MODERN AIR BRAKE PRACTICE to AUXILIARY RESERVOIR PiPLTAP TO TRAIN Pif Fig. 28 — New Style Plain Triple-Valve. stem, and 2^ is the graduating spring ; 32 is the U spring over the slide valve. The casing is so shaped that one part of it forms a cylinder for the triple piston to move in, and is marked PLAIN TRIPLE VALVE 133 B, and adjoining it is a chamber having a flat side (called the slide valve seat), for the slide valve to move on, and is marked C. The flat side of this chamber, which forms the seat on which the slide valve rests, has two ports cut through it ; the one marked f leads to the brake cylinder, and the other, marked h, leads to the atmosphere. In the slide valve there are also two ports, one passes through the valve, as shown by the letters 1, p-p, and the other is a groove cut in the bottom of the valve, and marked g, and when the valve is moved toward the left end of Chamber C (in other words, moves down), the port through the valve marked p connects with the port in the seat marked f, so that the air in the auxiliary can pass through the valve, and valve seat and on through pipe connection X directly into the brake cylinder; and when the slide valve is in the opposite end of Chamber C the groove g in the bottom of the slide valve connects the two ports f and h together, so that one end of the groove rests directly over the port leading to the brake cylinder, and the other end rests over the port leading to the atmosphere, thus forming a direct opening between the brake cylinder and the atmosphere; therefore, as the triple is so connected to the auxiliary by pipe connection Y that the auxiliary pressure is always in direct com- munication with chamber C, in which the slide valve moves, and as the port in the seat marked f is the only way for the air to get in or out of the brake cylinder, with this kind of a triple, it is very evident that when the slide valve is moved along on its seat until the port in the valve marked p-p comes opposite the port in the seat marked f, the air in the auxiliary is free to pass into the brake cylinder, and apply the brake. And when the slide 134 MODERN AIR BRAKE PRACTICE valve is forced back again to its original position, as shown in Fig. 28, the air in the brake cylinder is free to pass out to the atmosphere through ports f , g, h and ex- haust port k, and thereby release the brakes. Therefore, as the flow of air from the auxiliary to the brake cylin- der, and from the brake cylinder to the atmosphere is dependent upon the movement of the slide valve, it is necessary to understand how this movement is accom- plished. The stem of the triple piston extends into chamber C, in which the slide valve moves, and the valve is hung on this stem; there is a packing ring, 30, around the triple piston, making a tight joint against the walls of cylinder B, and as one end of this cylinder is always open to chamber C (which always contains auxiliary pressure) and the other end of cylinder B is always open to the train pipe, the triple piston stands between the auxiliary and train pipe pressure at all times, and if these pres- sures are equal, and the piston is in full release position, as shown in Fig. 28, should the pressure on the train pipe side of the piston become lower than that on the slide valve side, the piston would be moved by the aux- iliary pressure, and of course draw the slide valve with it, causing the port in the valve marked p to come oppo- site the port in the seat marked f , and allow the air from the auxiliary to pass into the brake cylinder and set the brake. To release the brake it is necessary to force the slide valve back to the position it occupied before the brake was set, as shown in Fig. 28. To do this the pressure stored in the main reservoir is used, because when the engineer places his brake valve in full release position the main reservoir pressure PLAIN TRIPLE VALVE 135 quickly raises the pressure on the train pipe side of the triple piston and forces it back to the position shown in Fig. 28, and, as the slide valve has to go back with it, the groove g in the bottom of the valve is placed so that one end of it rests over the port marked f in the valve seat, and the other end rests over the port marked h in the valve seat, consequently the air in the brake cylinder is free to pass out to the atmosphere through ports f , g, h and through a passage around the casing to the triple exhaust marked k. The air having thus escaped from the brake cylinder the heavy spring in the cylinder, marked 9, in Fig. 33, drives the brake piston back from the levers, which allows the brake shoes to drop away from the wheels and the brake is released. The whistling noise heard when the brakes are releas- ing on passenger cars is caused by the air escaping through the small ports in the triple (on freight cars the air exhausts through the pressure-retaining valve on top of the car), and if this whistling is weak, when releas- ing after a full application has been made, it indicates that either a portion of the air has already escaped from from the cylinder through a bad packing leather around the brake piston, or there is too much piston travel, which allowed the air to expand in the cylinder more than it should have done; in other words, a high pressure will rush out quicker than a low pressure. Having set the brakes and released them, it now be- comes necessary to recharge the auxiliary reservoir, to be ready for the next application. The brake cylinder gets its power from the auxiliary, and the latter must always be kept charged ready to meet I all demands made upon it by the cylinder. If the auxil- 136 MODERN AIR BRAKE PRACTICE iary is only partly charged, the force with which the brakes set will be correspondingly weak. It should be borne in mind that just as soon as the slide valve moves to let the air out of the brake cylinder it opens the feed groove between the train pipe and aux- iliary to admit air again into the auxiliary. Reference to Fig. 28 will show the course of the air from the train pipe through the triple to the auxiliary. Beginning at the point indicated by W, the air travels through a passage a-a, in the casing, to a chamber indi- cated by A, and from this chamber there are two open- ings, c, c, which allow the air to pass into the cylinder in which the triple piston moves, as indicated by B. As the air passes from chamber A it strikes the plain side of the triple piston, and forces it to the extreme end of cylinder B, and as the piston is supposed to be a tight fit in cylin- der B, the only chance the air has to get into the cham- ber G is by passing through a small groove cut in the wall of cylinder B, as indicated by m. This is called the "feed groove." As this groove m is only as long as the head of the piston is thick, it will be seen at once that the piston must be all the way back before the air can enter this^roove. It will be noticed, also, that the piston forms a seat only about half way from its center to its outer edge ; in other words, there is a shoulder on the slide valve side of the piston, and this necessitates another groove to be cut in this shoulder, which is shown by the letter n. The air can now pass from cylinder B by way of the feed grooves, m and n, into chamber C, and over the top of the slide valve through the pipe connection Y into the auxiliary. Owing to the smallness of the feed groove in the triple through which the air oasses to get into the auxiliary, PLAIN TRIPLE VALVE 137 the train pipe will naturally fill quicker than the auxil- iary, and cause the pump to stop temporarily, but as soon as the train pipe pressure is again lowered by the air passing through the feed grooves into the auxiliary, the pump will again start, and continue to compress air until every bit of space is filled to seventy pounds. If the main reservoir, train pipe or auxiliary reservoir leaks, while the brake valve is in the position just de- scribed, the pump will not stop at all, and a great many lealcs will very soon wear a pump out. A few important things to remember when charging up a train are : first, leaks of any kind will prevent get- ting the required pressure in the time it should be gotten, and bad leaks will prevent it entirely. Second, the strainer and feed grooves in the triple must be kept clean to allow the air to pass freely. Third, the packing ring around the triple piston must be a good fit to prevent the auxiliary charging too rap- idly, and to insure against charging too quickly is the reason for having a shoulder on the slide valve side of the piston, for if any air leaks around the packing ring it cannot enter the auxiliary except through the second feed groove, as shown by n in Fig. 28, unless the shoulder on the piston has a bad seat. A still greater reason for having the packing ring, 30, tight, is to insure the brake against "sticking," as it will if the train pipe pressure equalizes with the auxiliary without moving the slide valve. The reason for having the feed grooves so small in the triples is to allow all the auxiliaries on the train to charge as nearly together as possible, and also to assist in making the triple sensitive to the slightest reduction of train pipe -jptiessure, for, if the feed groove was large, 138 MODERN AIR BRAKE PRACTICE when the air was drawn from the train pipe a consider- able amount of air from the auxiHary would flow back into the train pipe before the piston moved ; but, as it is, the feed groove is so small and so short that it requires less than a two pound reduction to cause the triple pis- ton to move and shut off communication between the auxiliary and train pipe. For the same reason (sensitiveness) the piston pack- ing ring must have a good fit, or else the auxiliary and train pipe pressures will equalize, and thereby fail to move the piston when desired in setting or releasing the brakes. This is especially true on long trains. (See "K'^ triple valve.) If everything was tight, and all the parts working as they should, and train pipe pressure was kept constantly at seventy pounds, a one hundred car train could be charged as quickly as could one car, as under such per- fect condition the air will pass through the feed grooves at the rate of one pound a second, but as this is never the case in actual practice, it ordinarily takes about five minutes to charge up a short train of ten cars, and about twelve to fifteen minutes for a train of thirty or forty cars, with comparatively no train pipe leaks, and where there are leaks it, of course, takes much longer. Train pipe leaks should be carefully guarded against. There are three kinds of applications, as follows: ''full service," "partial service" and "emergency." The method of making a full service application has just been de- scribed. Partial service application is made possible by means of the graduating valve, 25, see Fig. 28, as for in- stance if a reduction of 10 pounds is made on the train pipe the triple will automatically lap itself as soon as a fraction over 10 pounds has left the auxiliary. i PLAIN TRIPLE VALVE 139 This is done as follows : when the train pipe pressure is reduced below that in the auxiliary the triple pistoi? moves and carries with it the graduating valve, which, as will be seen by reference to Fig. 28, is connected di- rectly to the stem of the triple piston by a small pin, as shown by the dotted lines, and, when the piston moves, the graduating valve is carried from its seat in the slide valve and opens port p, so that when the slide valve is in service position the auxiliary air can pass through the slide valve by way of ports 1 and p, then through port f in the seat of the slide valve and on through pipe con- nection X direct into the brake cylinder. As only ten pounds are drawn from the train pipe, just as soon as a fraction over ten pounds flows from the auxiliary, the train pipe pressure being now the strongest forces the triple piston towards the auxiliary end of its cylinder, but it can only force it a very short distance, for the reason that the distance between the end of the slide valve and the shoulder on the stem of the piston is only three-sixteenths of an inch, and when the piston has moved this distance it is stopped by the slide valve, be- cause the auxiliary pressure, aided by the U spring, is firmly holding the slide valve, on account of the friction being greater on the slide valve seat than it is around the edge of the triple piston, and when the piston is thus stopped by the slide valve, the graduating valve is now back on its seat, and no more air can flow from the aux- iliary into the brake cylinder, until the train pipe pres- sure is again reduced and the graduating valve again un- seated by the movement of the triple piston. The slide valve does not move when the second re- duction is made, but stands in the same position it as- sumed on the first reduction. Consequently, as soon as 140 MODERN AIR BRAKE PRACTICE the graduating valve is unseated the air will again flow into the brake cylinder; but when the air in the brake cylinder finally becomes as strong as it is in the auxiliary (or equalizes) the pressure in the auxiliary no longer falls below that in the train pipe, and therefore the grad- uating valve remains off its seat, because the triple pis- ton does not now move back as it did when the first re- duction was made, as the pressure in the train pipe is now as low or lower than it is in the auxiliary, and the brakes are now fully applied. Hence a full service application can be made without the graduating valve, but in making a "partial service application," this valve is a very important factor. If the engineer simply wants to slow his train up, but does not want to come to a full stop, he can draw off any amount of air from the train pipe he desires, and when he laps his brake valve, the triple valve will, by means of the graduating valve, let a corresponding amount of air from the auxiliary into the brake cylinder and automatically lap ports 1-p-p in the slide valve, but if the engineer should draw his train pipe pressure down below the point at which the auxiliary and brake cylinder equalize, he would not only be wasting the train pipe pressure, but would have trouble when it came time for him to release his brakes, as will be explained later on. As has already been mentioned, the third kind of an application is called the "emergency." When this kind of application is made it is only in case of danger, and therefore it is desired that the air in the auxiliary should be passed into the brake cylinder as quickly as possible, and in order to do this it is necessary to have the slide valve entirely clear the port in the seat through which the air has to pass. PLAIN TRIPLE VALVE 141 In making ordinary stops this very quick action is not required, and in order to prevent the sHde valve making the full stroke, there is a projection on the train pipe side of the triple piston which strikes against the gradu- adng stem, 26, and as this stem is held to its seat by the graduating spring, 27, the strength of this spring com- bined with the pressure in the train pipe causes the triple piston to stop, and in doing so the slide valve is held in such a position that port p is in register with port f , and of course the brakes are applied gradually. But if the pressure in the train pipe is reduced sud- denly, the auxiliary pressure causes the triple piston to strike the graduating stem a hammer blow and over- comes the tension of the spring so that the slide valve entirely clears the port in the seat, and the auxiliary [pressure immediately equalizes with the brake cylinder. (This refers to the plain triple. The emergency action of the quick-action triple will be described later on, and also the action of the "K" triple.) The U spring, 32, is placed over the slide valve for the reason that if the brake is applied and all the air is let out of the train pipe, and the car cut off from the engine, the brake could not be "bled" off by the release valve on the auxiliary if the slide valve could not be lifted off its seat by the brake cylinder pressure, but as there is a slight lift to the slide valve for this purpose, the U spring is required to reseat the valve, so that when the auxiliary is again recharged no air can get under the slide valve and pass out to the atmosphere through port h in the valve seat. If there is a great deal of oil on the slide valve seat it will prevent the slide valve from being forced up by brake cylinder pressure, when a single car is being "bled 142 MODERN AIR BRAKE PRACTICE off," and the brake cannot be released at all until the air finally leaks out around the packing leather in the cylinder. In such a case the release signal is very handy. QUICK ACTION TRIPLE VALVE 143 THE WESTINGHOUSE QUICK ACTION TRIPLE VALVE. Fig. 29 shows this valve in release and charging posi- tion, and the parts are numbered as follows : A. Train pipe connection. B. Auxiliary reservoir connection. Fig. 29 — Quick-Action Triple in Release and Charging Position, 144 MODERN AIR BRAKE PRACTICE . C. Cylinder connection. 3. Slide valve. 4. Triple piston and stem. 5. Triple piston packing ring. 6. U or slide valve spring. 7. Graduating valve. 8. Emergency valve piston. 9. Emergency valve seat and guide. 10. Rubber seated emergency valve. 12. Check valve spring. 14. Check gasket. 15. Check valve. 21. Graduating stem. 22. Graduating spring. 23. Triple gasket. The air passages and ports are described in the text. The feed groove, i, is now open. The parts contained in the quick-action triple which are not in the plain triple are shown in Figs. 29, 30, 31 and 32, and are indicated as follows: The emergency piston is marked 8 ; the guide for this piston, which also forms a seat for the emergency valve, is marked 9; the emergency valve is 10; the check-valve spring is 12; the check valve is 15, the gasket which separates cham- ber X from chamber Y is marked 14. This gasket, it will be noted, extends clear across the triple, but a por- tion of it is cut away just over the emergency valve, so that when that valve is unseated, as it is in an emergency application, the air in chamber Y can pass into chamber X and the brake cylinder, and another hole is cut in this same gasket at e, so that the train pipe pressure, which QUICK ACTION TRIPLE VALVE 145 enters the triple at A, can pass freely into chambers f and h. RELEASE AND CHARGING. The quick-action triple has five positions : release, charging, service, lap and emergency. Fig. 30 — Quick-Action Triple in Service Position. Release and charging positions are really one and the same, and are shown in Fig. 29. While the air is being released from the brake cylinder by way of the ports in the slide valve seat, etc., as previously illustrated in Fig. 146 MODERN AIR BRAKE PRACTICE 28, the auxiliary is being charged by way of the feed grooves described in Fig. 28 as m and n, but in Fig. 29 they are marked i and k. By referring to Fig. 29, and following the course of the arrows it will be seen that after the air enters the triple at A it passes through a passage in the casing, to a chamber having two openings into the cylinder contain- ing the triple piston, and from this cylinder the air passes through the two feed grooves marked i and k, on into the slide-valve chamber, and instead of entering the aux- iliary at the pipe connection Y, as in Fig. 28, it passes right on through the slide-valve chamber into the auxil- iary, so that whether it is a plain or quick-action triple the auxiliary pressure is always on the slide-valve side of the triple piston, and train pipe pressure is on the op- posite side. SERVICE POSITION. In this position, shown in Fig. 30, it will be seen that the triple piston has moved in its cylinder until the pro jection j strikes against the graduating stem, which stops it, and in making this movement the stem of the piston has drawn the slide valve to a position which places the port marked w, z-z in register with the port in the seat marked r, thus allowing the auxiliary pressure to pass into the brake cylinder through pipe connection C and set the brake. LAP POSITION. Lap position, Fig. 31, means that all ports are closed, and the reason why the triple automatically laps itself is due to the fact that when the slide valve is moved to i A QUICK ACTION TRIPLE VALVE 147 service position the graduating valve is held off its seat at w by the triple piston and when the pressure in the auxiliary becomes slightly less than train pipe pres- sure the piston is forced back by the train pipe pressure until the graduating valve strikes its seat in the slide BnkeC:rtBfe( Fig. 31 — Quick-Action Triple in Lap Position. valve, and stops the flow of the auxiliary air into the brake cylinder. The reason the slide valve is not moved when the graduating valve moves is because the auxiliary and train pipe pressure are so nearly equal that the friction 148 MODERN AIR BRAKE PRACTICE of the slide-valve seat, combined with the tension of the slide valve spring (marked 6), prevents it, and as this keeps the exhaust port closed, and the position of the triple piston keeps feed groove i closed, all ports are now closed and the valve is said to be on lap. The triple will not lap itself unless the auxiliary pres- sure has a chance to get lower than train pipe pressure, which means that if an engineer reduces his train pipe pressure below the point at which the auxiliary and brake cylinder pressures equalize, the only means of holding the air in the brake cylinder (aside from the packing leather around the brake piston and the closing of the triple exhaust) is the check valve, 15, or the pack- ing ring, 30, of the triple piston, for while it is true tha^: the piston would seat against gasket 23, still this gasket so soon becomes hard that it cannot be relied upon to stop the auxiliary pressure from flowing back into the train pipe. The reason the check valve has to be depended upon to keep the brake cylinder pressure from flowing back into the train pipe, after an extra heavy reduction has been made, is because the air in chamber Y will reduce as fast as the train pipe pressure is reduced, on account of the volume in Y being so small that the slightest pos- sible leak in the seat of the check valve will let it out, and after the train pipe pressure has been drawn down sufficient to allow the auxiliary and brake cylinder to equalize, the leak from chamber Y is supplied by the brake cylinder, for whenever the pressure in Y becomes less than that in the brake cylinder the emergency valve, 10, is forced off its seat by the brake cylinder pressure until it equalizes again with chamber Y, when the spring, 12, reseats valve 10, which is done very quickly, conse- J QUICK ACTION TRIPLE VALVE 149 quently if the train pipe pressure was entirely exhausted and the check valve leaked very badly the brake cylinder would very quickly be robbed of its pressure and let the brake off. It is, therefore, very bad practice to ever re- duce the train pipe pressure below the point at which the auxiliary and brake cylinder equalizes, except in an emergency. EMERGENCY POSITION. A sudden reduction of train pipe pressure is necessary to cause the triple to assume emergency position. When a sudden reduction is made it causes the triple pistion, 4, to strike the graduating stem, 21, such a hammer blow that the graduating spring, 22, is unable to stop it from making its full stroke, and as it has now traveled further than it did in service position, the slide valve has also been moved a correspondingly greater distance on its seat, which brings a big slot, or in some triples, a removed corner (not shown) in the slide valve over a port in the seat (indicated by dotted lines behind port Z), and allows the auxiliary pressure to fall on the emergency piston, 8, which strikes the stem of valve 10 and forces it from its seat (which is kept closed by spring 12 and the train pipe pressure in Y), and valve 10 being thus unseated, the air from Y rushes into the brake cylinder. As all this is done so very quickly that the train pipe pressure has as yet reduced but very little, the remain- ing train pipe pressure forces the check valve up and also rushes into the brake cylinder until it equalizes with what is left in the train pipe, when spring 12 reseats the check valve, preventing the air in the brake cylinder from flowing back into the train pipe. 150 MODERN AIR BRAKE PRACTICE At the same time that the big slot in the back of the sHde valve reached its position over the port in the seat leading to the emergency piston, another small port in the slide valve, marked S in Fig. 31, is placed in register Fig. 32 — Quick-Action Triple in Emergency Position. with port r in the valve seat, taking the place of port Z, which allows the auxiliary pressure to flow into the brake cylinder on top of what went in from the train pipe. The opening around the emergency valve is so much larger than port S in the slide valve that virtually no QUICK ACTION TRIPLE VALVE 151 air enters the brake cylinder from the auxihary until the check valve closes on the charge received from the train pipe. It is this air from the train pipe that gives the added percentage of brake power after an emergency applica- tion ; for the air which enters the brake cylinder from the train pipe has the same effect as shortening the pis- ton travel, because it forces the auxiliary pressure to equalize just that much higher than it would if the brake cylinder was empty when the auxiliary pressure started to flow into it. On account of the train pipe pressure having two out- lets (one by way of the brake valve, and the other by way of valve lo) when an emergency application is made, it is reduced so suddenly that the next triple i& thrown into quick action, because the pressure that was holding that triple to release position immediately rushes back into the empty space just created in the train pipe by the first reduction, and the triple is left without suflicient train pipe pressure to hold it, when the pressure on the auxiliary side of that triple piston drives it to emergency position, which in turn creates a vacancy in the train pipe on that car which the next car tries to fill, and so on, till all the brakes on the entire train are set in emer- gency. The new passenger triple valve, style L, now being made by the Westinghouse Air Brake Company, is ar- ranged to operate with two auxiliary reservoirs for the purpose of enabling the engineer to gradually release and quickly re-apply the car brakes. 152 MODERN AIR BRAKE PRACTICE TRIPLE VALVE^ AUXILIARY RESERVOIR AND BRAKE CYLINDER COMBINED. Figure 33 illustrates a freight equipment. The brake cylinder, 2, is bolted directly to the auxiliary reservoir, 10, and while the supply pipe, b, runs through the auxiliary and into the cylinder, still the air in the auxil- iary cannot get into the cylinder except by way of the ports in the triple, as previously described, for the left end of pipe b is connected with the triple at C, as shown in Fig. 31. The gasket between the auxiliary and brake cylinder is not for the purpose of ^separating them, but is to make the cylinder air-tight at that end, and when the brakes are set, the other end of the cylinder is made air-tight by the packing leather, 7, around the piston head, 3, which is held to its place by the expansion ring, 8, and fol- lower, 6. Spring 6 is to force the piston back when the air is let out of the cylinder. To prevent the brakes from setting on account of train- pipe leaks, there is a small leakage groove, a, cut in the wall of the cylinder for about three inches from the extreme left end, or pressure head, so that any small amount of air that might be let into the cylinder through the triple, from any cause, would escape to the atmos- phere, instead of pushing the piston out, by passing through the leakage groove by the piston head, and out around piston 3. The Release Valve 17 or "bleeder," is for the purpose of drawing the air from the auxiliary, and when a car is set out, and especially when a brake is cut out, the release valve should be held open until all the air in the auxiliary has escaped, for if any air is left in it the QUICK ACTION TRIPLE VALVE 153 Fig. 23 — Triple Valve Auxiliary Reservoir and Brake Cylinder Combined. .64 MODERN AIR BRAKE PRACTICE I brake will again set whenever the trainpipe pressure is reduced lower than that in the auxiliary. Whenever a brake cannot be released from the engine, but has to be "bled off," either at the auxiliary, or by the release signal valve inside the car, always cut that brake out at the first opportunity and drain the auxiliary. Where cars are equipped with the new release signal the brakeman can keep a brake off that is inclined to stick, until the train is in a safe position to allow him to get down and cut the brake out. If the auxiliary release valve leaks and it cannot be stopped by one or two quick jerks, to dislodge the dirt that is causing it to leak, cut the brake out, as no air can accumulate in the auxiliary, making that brake worthless, and the leak is drawing air from the train- pipe, which affects the rest of the brakes. Should the release valve become clogged so that no air could be drawn through it, remove the drain plug ii in the under side of the auxiliary. This plug will not have to be re- moved, of course, where a car is equipped with the release signal as the brake cylinder can be emptied inde- pendent of the action of the triple, by simply opening the valve of the release signal. Pressure Retaining Valve. This device illustrated by Fig. 34, is for the purpose of retaining a certain amount of pressure in the brake cylinder after the triple valve has been moved to release position. It is attached as follows: Into the triple exhaust a small pipe is connected and extends from the triple to the top of the car at the end where the hand-brake staff is, and onto this pipe is at- tached the retaining valve at the connection marked X. PRESSURE RETAINING VALVE 155 The handle 5 controls a plug 6 similar to the cutout plug 13 in the plain triple. When the handle is turned as shown in Fig 34, port c through the plug is in register with port b-b, and the air which comes from the triple Ml^ 1 1 Fig. 34 — ^Pressure-Retaining Valve in Retaining Position. X. Triple exhaust connection. 5 Handle. 4. Retaining valve weight. 6. Cut-out plug. exhaust is forced against the seat of the valve 4, which raises and allows the pressure to escape to the atmos- phere through port d. As port d is controlled by valve 4, the air will exhaust only while this valve is up, and as the weight of the valve, combined with the size of the ports, requires a pressure of fifteen pounds to keep it up, just as soon as the pressure in the brake cylinder has been reduced to a fraction less than fifteen pounds to the square inch, the valve will seat and retain the re- maining pressure in the brake cylinder until the handle is turned down. When the handle is turned down it brings port a in register with the lower part of b, and 156 MODERN AIR BRAKE PRACTICE port c is turned to register with port e, and thereby allows all the air in the brake cylinder to escape to the atmosphere. Therefore if the handle of the retainer is kept turned down the engineer can release the brakes from the en- m Fig. 34a — Three-Position Retaining Valve for Heavy Freight Cars. gine, but if the handle is turned up (unless the brake leaks off) it will stay set until the handle is turned down. Retainers were formerly made to hold only ten pounds in the brake cylinder, but are now made to hold fifteen or fifty pounds. With the retainer handle turned up, the second appli- cation of the brakes will give a much higher brake- cylinder pressure, if the auxiliary has been allowed time PRESSURE BETAINING VALVE 157 enough to recharge, because the pressure that is already in the cyHnder will force the auxiliary to equalize much higher than it would if the cylinder was empty to start with (in the same manner that the emergency applica- tion causes an added pressure on account of the train pipe pressure entering the cylinder before the auxiliary pressure has a chance to get in). For this reason it is best to apply the brakes and recharge the auxiliaries as soon as possible after passing the summit of a mountain grade, and besides it gives an increased reserve of brake power. 158 MODERN AIR BRAKE PRACTICE THE "K" TYPE FREIGHT TRIPLE VALVE. The Westinghouse Air Brake Company at frequent intervals, adds new and improved apparatus to its air brake equipment, after having first subjected the new- device to the most rigid, and severe test in the workshop. In view of the fact that air brake construction, like all other branches of the useful arts, is continually advancing it is plainly evident that the man whose daily duties re- quire him to care for, and operate the air brake, must study if he would keep pace with the march of progress. One of the most important of these recent additions is the device known as the *'K" triple valve. The "K" type triple valve differs from the standard quick action triple valve in three particulars: First, it allows a small amount of train pipe pressure to be vented into the brake cylinder when a service application is made, regardless of the location of the triple in the train. Second, it automatically retards the release of the brake cylinder pressure when the K triple is located within thirty cars from the engine. Third, it retards the charg- ing of the auxiliary reservoir when the K triple is located within thirty cars from the engine. By venting a small amount of train pipe pressure into the brake cylinder during a service application, it pro- duces a much higher braking power than is produced by the standard quick action triple, and this feature is primarily intended to cause the brakes throughout the train to be applied as nearly uniform as possible. The uniformity of application and release was the point in view when this triple was made and the increased brake THE K TRIPLE VALVE 159 power was merely incidental, in fact, in view of the many old styl-e quick action triples which are now in use, it would be preferable if the uniform application could be secured without having to apply the brakes harder in service with this triple than with the old style quick action triple. ^5^, X*.. Fig. 35 — The Type "K" Freight Triple Valve. The retarding of the brake cylinder pressure is pro- duced by holding the brakes applied on the head end of the train until the rear end brakes have had a chance to release, and as the force of the train pipe pressure would be materially decreased if the auxiliary feed groove in the triples on the head end of the train were 160 MODERN AIR BRAKE PRACTICE wide open, it was therefore necessary to temporarily choke the feed groove on the head cars so that the train- pipe pressure instead of rushing into the auxiliary will have to keep moving toward the rear end of the train, thereby driving those triple pistons to release position before the pressure in the trainpipe has had a chance to expand into the auxiliary reservoir. The choking of the triple feed groove on the head cars is produced by the trainpipe pressure overcoming the retarding spring in the triple, thereby moving the piston beyond the normal position, which closes the regular feed groove and allows the auxiliary to receive trainpipe pressure by way of a restricted opening through the slide valve. The latest type of K triple has a re- stricted feed groove on the back of the piston, doing away with port i. The importance of this restricting of the feed groove will be easily understood when it is remembered that with the ordinary Westinghouse Automatic Engine Equipment on a 50-car train with a 50,000 cubic inch main reservoir, a 9^-inch pump carrying a 70-pound train line pressure and a 100-pound main reservoir pres- sure, after a trainpipe reduction of 20 pounds, when the handle of the brake valve is thrown to full release posi- tion it will raise the trainpipe pressure in ten seconds to about 78 pounds on the first oar, 57 pounds on the 25th car and only 53 pounds on the last car. Consequently if the head brakes were allowed to release immediately when the handle was thrown to release position, the result would be that the rear brakes would either give the train a fearful shock or else pull it in two. The new valve is at present manufactured in two sizes, the "K-i" for use with 8-inch freight-car brake cylinders, 161 corresponding with the H-i (F-36), and the "K-2'' with lO-inch freight-car brake cyHnders, corresponding with the H-2 (H-49). The K-i will bolt to the same reser- voir as the F-36, and the K-2 as the H-49. Each valve is marked with its designation on the side of the valve body, and the K-2 may be distinguished from the K-i by the fact that it has three, as compared with tzvo, bolt holes in the reservoir flange. Also, in order to distin- guish the type K valves from the old standard type, their exterior being similar when they are attached to the auxiliary reservoir, a lug is cast on the top of the valve body, as shown in Fig. 35. This enables anyone to locate them at once. With the K-2-A triple the retarding Spring is contained inside of triple casing, thereby avoid- ing the danger of having it broken off. Figure 36 is a vertical cross section of the K-2 triple valve, and the names of the various parts are as follows : 2, Valve Body; 3, Slide Valve; 4, Piston; 5, Piston- Packing Ring; 6, Slide- Valve Spring; 7, Graduating Valve; 8, Emergency Piston; 9, Emergency- Valve Seat; 10, Emergency Valve; 11, Emergency- Valve Rubber Seat; 12, Check- Valve Spring; 13, Check- Valve Case; 14, Check- Valve-Case Gasket; 15, Check Valve; 16, Air Strainer; 17, Union Nut; 18, Union Swivel; 19, Cylinder Cap; 20, Graduating-Stem Nut; 21, Graduating Stem; 22, Graduating Spring; 23, Cylinder-Cap Gasket; 24, Bolt and Nut; 25, Triple- Valve Cap Screw; 26, Drain Plug ; 27, Union Gasket ; 28, Emergency- Valve Nut ; 29, Retarding-Device Bracket ; 30, Retarding-Device Screw ; 31, Retarding-Device Stem; 32, Retarding-Device Washer; 33, Retarding-Device Spring; 34, Retarding- Device- Stem Pin ; 35, Graduating- Valve Spring. Figure 37 shows the relative position of the ports and 162 MODERN AIR BRAKE PRACTICE cavities in the slide valve, graduating valve, and slide valve seat of the K--2 Triple Valve. As it is difficult to show all of these in a single section, diagrammatic cuts of the valve in each of the principal positions have been used, all ports and passages having been so arranged as to place them in one plane. In preparing these cuts, the actual proportion and mechanical construction of the valve has been disregarded for the purpose of making the connections of ports, and operation, more easily understood. 1 Fig. 36 — The K-2 Triple Valve. The retarding groove in the exhaust cavity of the slide valve has now been changed to a round port, in order to insure the opening of that port when the triple is in Re- tarded Release position. 163 EXPLANATION OF FIGS. 36 AND 37. Referring to Fig. 36, the branch from the brake pipe connects at union swivel 18. The retarding-device bracket 29 projects into the auxihary reservoir, and by- its construction free communication exists between the auxihary reservoir and chamber R, in which the sHde- valve 3 and graduating valve 7 operate. The retarding- device stem 31, through its extension into chamber R, and the action of its spring 33, forms the stop against which the stem of piston 4 strikes when it moves to the release position (from right to left in the cut, it being shown in full-release position). The opening marked "To Brake Cylinder" comes op- posite one end of the tube which leads through the auxiliary reservoir to the brake cylinder, when the valve is bolted in place on the end of the auxiliary reservoir. This opening in the triple valve leads to chamber X over the emergency valve 10, and under the emergency piston 8. Also, it leads through port r to the seat under slide valve 3 (Fig. 37). The emergency piston 8 and the parts below it are the same as in the older quick- action freight triple valve. Port y (shown by dotted lines) connects chamber Y, between check valve 12 and emergency valve 10, with port y in the valve seat (Fig. 37)- Port t connects the slide-valve seat with the chamber above emergency piston 8. Port p is the exhaust port to the atmosphere. Port / in the slide valve begins at the face, as shown by the top view, Fig. 37, and passes around other ports in the valve to a smaller opening in the top. (Note: — This port j does not exist in the K-I Triple Valve, as will be explained later.) Port is sim- 164 MODERN AIR BRAKE PRACTICE r FACE VIEW GRADUATIN6 VALVE . UH b\f i>f' FACE VIEW TOP VIEW SLIDE VALVE. ^^^^^^^^^^^^^^^-^^^1 ^0 af!.v.-:::.-.v.D ^-^m^^^^-^^^-^^^-^-:^-^^^ SLIDE VALVE BUSH. Fig Z7 — Slide Valve, Graduating Valve and Slide-Valve Seat of K-2 Triple Valve. Note. — The latest type K triple does not have port I, i)ut has a groove on the back of the piston as a feed groove for retarded charg^e-up. THE "k" triple valve 165 ilarly arranged, except that openings in top and bottom are alike in size. Port q runs directly through the slide valve, but is smaller at the top than at the face of the valve, and the smaller part is out of center with the larger part. Ports ^ and z run through the valve and connect with cavities in the face ; port z also has a cavity at the top. The face view of the graduating valve shows that it has a small cavity v. This valve is of the slide-valve type, and it seats on the top of the slide valve, where it controls the upper ends of ports z, q, o, and /. The purpose of the cavity v is to connect the upper ends of ports and g in a service application, as explained in detail later. As shown by the face view of the slide valve, n is a long e^ivity having a narrow extension at the right hand end. This cavity connects the ports through which the air escapes" from the brake cylinder in releasing. Port h is cut diagonally from the face till it just cuts into edge, at the top of the slide valve. It admits auxiliary- reservoir pressure to port t in an emergency, application. With this explanation, and by occasional reference from the diagrammatic views to those in Fig. 37, the same ports being lettered alike, a clear understanding will be obtained of both the operation and actual arrange- ment of ports of the triple valves. FULL RELEASE AND CHARGING POSITION. Fig 38 is a diagrammatic view of the triple valve in this position Air from the trainpipe flows through passage e, cylinder cap /, and ports g to chamber h; thence through feed groove i, now open, to chamber R above. the slide valve, which is always in free communi- 166 MODERN AIR BRAKE PRACTICE cation with the auxiliary reservoir. The feed groove i is of the same dimension as that of the old standard H-i (F 36) triple valve, which is designed to properly charge the auxiliary reservoir of an 8-inch brake cylinder, and prevent any appreciable amount of air from feeding back into the trainpipe from the auxiliary reservoir during an application. For this reason, the feed groove of the Fig 38— K-2 Triple — Full-Release and Charging Position. K-2 triple valve is made the same size as the K-i, so that it is necessary in the K-2 triple to increase the charging port area, through which the air can feed into the auxiliary reservoir, sufficiently to enable it to handle the greater volume of the auxiliary reservoir of a lO-inch brake cylinder. In order to do this, the small port / is added to the slide valve of the K-2 triple valve only ; this 167 port registers with port 3; in the slide-valve seat, when in the full release position. Air then passes from cham- ber Y, through ports y and / to chamber R, and the aux- iliary reservoir. Trainpipe air in a raises check valve 15 and supplies chamber Y with air as fast as it is required. Port j is so proportioned that the rate of charging the auxiliary reservoir of a 10-inch brake cylinder is made practically the same as that of the 8-inch, which in full release is fed through the feed groove i only. In the following description, the K-2 triple valve only is re- ferred to; the operation of the K-i is exactly the same except for the absence of port ;'. Air flows from the trainpipe to the auxiliary reservoir until their pressures become equal, when the latter is then fully charged. QUICK-SERVICE POSITION. To make a service application of the brakes, air pres- sure is gradually reduced in the trainpipe, and thereby in chamber h. As soon as the remaining pressure in the auxiliary reservoir and chamber R becomes enough greater than that in chamber h, to overcome the friction of the piston 4 and graduating valve 7, these two move to the left until the shoulder on the end of the piston stem strikes against the right-hand end of the slide valve, when it also is moved to the left until the piston strikes the graduating stem, 21, which is held in its place by the compression of the graduating spring, 22. The parts of the valve are then in position shown in Fig. 39. The first movement of the piston closes the feed groove i, preventing air from feeding back into the trainpipe from the auxiliary reservoir, and also opens the upper end of port z in the slide valve, while the movement of the lat- 168 MODERN AIR BRAKE PRACTICE ter closes the connection 'between port r and the exhaust port p, and brings port z into partial registration with port r, in the slide valve seat. Auxiliary reservoir pres- sure then flows through port z in the slide valve and port r in the seat to the brake cyHnder. Fig- 39 — ■K-2 Triple— Quick Service Position. ./V^the same time, the first movement of the graduating vah e connected the two ports o and q in the slide vahe, by the cavity v in the graduating valve, and the movement of the slide valve brought port o to register with port 3; in the slide valve seat, and port g with port t. Consequently the air pressure in chamber Y flows thrc^ugh ports y, 0, v, q and t, thence around the emer- gency piston 8, which fits loosely in its cylinder, to cham- THE "k" triple valve 169 ber X and the brake cylinder. When the pressure in chamber Y has reduced below the trainpipe pressure remaining in a, the check valve raises and allows train- pipe air to flow by the check valve and through the ports above mentioned to the brake cylinders. The size of these ports is so proportioned that the flow of air from the trainpipe to the top of emergency piston 8, is not sufficient to force tiie latter downward and thus cause an emergency application, but at the same time takes con- siderable air from the trainpipe, thus increasing the rapidity with which the trainpipe reduction travels through the train. With the ordinary quick action triple valve in a serv- ice application, all of the trainpipe reduction has to be made at the brake valve, and the resulting drop in pressure passes back 'through the train at a rate depend- ing on its length, size of trainpipe, number of bends and comers, etc., which cause friction and resistance ; also a much heavier apj51ication of head than of rear brakes is caused at the beginning of the application, thereby running the slack in, which- is liable at low speeds to be followed by the slack running out suddenly when the re?>r brakes do apply, causing loss of time and difliculty in making quick slow downs and accurate stops, and, with very long trains, results in such serious losses through leakage grooves and feed grooves as to lose much braking power and even prevent some brakes from applying. With this new triple valve, only a small part of the reduction is made at the brake valve, while eacti triple acts momentarily as a brake valve to increase the reduction under each car, thereby rendering the re- sistance !and friction lin the trainpipe of much less ejiect, and hastening the application throughout the train. 170 MODERN AIR BRAKE PRACTICE This is called the "Quick-Service" feature, and by means of it the rapidity of a full service application on a 50-car train is increased about fifty per cent. The rapid reduc- tion of trainpipe pressure moves the main piston 4 quickly to the service position and cuts off any flov^ back from the auxiliary reservoir through the feed groove to the trainpipe; it rapidly drives the brake-cylinder piston beyond the leakage groove, and prevents loss of air through it; and yet permits applying v^ith as moderate a brake force as desired. It also greatly reduces the train- pipe reduction necessary at the brake valve for a certain brake-cylinder pressure, due to the fact (i) that part of the reduction takes place at each triple valve and (2) that the air taken from the trainpipe into the brake cylinder gives a little higher pressure than if the auxil- iary-reservoir pressure alone were admitted, thus re- quiring a smaller trainpipe reduction for the same cylin- der pressure. FULL-SERVICE POSITION With short trains, the trainpipe volume, being com- paratively small, will reduce more rapidly for a certain reduction at the brake valve than with long trains. Un- der such circumstances the added reduction at each triple valve by the quick-service feature, might bring about so rapid a trainpipe reduction as to cause quick action and an emergency application, when only a light appli- cation was intended. (The emergency application is ex- plained later.) But this is automatically prevented by the triple valve itself. By Fig. 39, it will be noted that in the quick-service position, port ^ in the slide valve and port r in the seat do not fully register. Neverthe- less, the opening is sufficient to allow the air to flow THE K TRIPLE VALVE 171 from the auxiliary reservoir to the brake-cyHnder writh sufficient rapidity to reduce the pressure in the auxiliary reservoir as fast as the pressure is reducing in the train- pipe, v^hen the train is of considerable length. But if the trainpipe reduction is more rapid than that of the auxiliary, the difference in pressures on the two sides of piston 4 soon becomes sufficient to slightly compress the \ BP la Fig. 40 — K-2 Triple — Full Service Position. graduating spring, and move the slide valve to the posi- tion shown in Fig. 40, called ''Full Service!' In this position, quick service port 3; is closed, so that no air flows from the trainpipe to the brake cylinder; the trainpipe reduction being sufficiently rapid, there is no 172 MODERN AIR BRAKE PRACTICE need of the additional quick-service reduction, so the triple valve cuts it out. Also, ports z and r are fully open, and allow the auxiliary-reservoir pressure to reduce more rapidly, so as to keep pace with the more rapid train- pipe reduction. ^1 v/?///////////y///////A Fig. 41 — K-2 Triple — Lap Position. LAP POSITION When the trainpipe reduction ceases, air continues to flow from the auxiliary reservoir through ports z and r to the brake cylinder, until the pressure in the chamber R becomes enough less than that of the trainpipe to cause piston 4 and graduating valve 7 to move to the right until the shoulder on the piston stem strikes the THE "k" triple valve 173 left-hand end of slide valve 3. As the friction of piston and graduating valve is much less than that of the slide valve, the difference in pressure which will move the piston and the graduating valve, will not be sufficient to move all three ; consequently, the piston stops in the posi- tion shown in Fig. 41. This movement has caused the graduating valve to close port z, thus cutting off any further flow of air from the auxiliary reservoir to the brake cylinder. Consequently, no further change in air pressures can occur, and this position is called "Lap," because all ports are lapped, — -that is, closed. If it is desired to make a heavier application, a further reduction of the trainpipe pressure is made, and the operation described above repeated, until the auxiliary reservoir and brake cylinder pressures become equal, after which any further trainpipe reduction is only a waste of air. About twenty pounds trainpipe reduction will give this equalization. RETARDED RELEASE AND CHARGING POSITION. The K triple valve has two release positions, full- release and retarded-release. Which one its parts will move to when the train brakes are released, depends upon how the trainpipe pressure is increased ; if slowly, it will be full release, and if quickly and considerably, if the triple is located within 30 cars from the engine, it will be retarded-release. It is well known that in a freight train, when the engineer releases the brakes, that the rapidity with which the trainpipe pressure increases on any car depends on the position of the car in the train. Those cars towards the front, receiving the air first will have their trainpipe pressure raised more rapidly than 174 MODERN AIR BRAKE PRACTICE those in the rear. With the old standard apparatus, this* is due to two things : ( i ) the friction in the trainpipe ; (2) the fact that the auxihary reservoirs in the front at once begin to recharge, thus tending to reduce the pres- sure head by absorbing a quantity of air and holding back the flow from front to rear of the train. The re- tarded-release feature of this new triple valve overcomes the second point mentioned, taking advantage of the first while doing so. The friction of the trainpipe causes the pressure in chamber h to build up more rapidly on triple valves towards the front than those in the rear. As soon as its pressure is enough greater than the auxiliary-reser- voir pressure, remaining in chamber R after the applica- tion above described, to overcome the friction of piston, graduating valve, and slide valve, all three are moved toward the right until the piston stem strikes the retard- ing-device stem, 31. The latter is held in position by the retarding-device spring, 33. If the rate of increase of the trainpipe pressure is small, as, for example, when the car is near the rear of the train, the triple valve parts will remain in this position, as shown in Fig. 38, the brakes will release and the auxiliary reservoirs recharge as described under 'Tull Release and Charging." If, however, the triple valve is near the head of the train, and the trainpipe pressure builds up more rapidly than the auxiliary reservoir can recharge, the excessive pres- sure in chamber h will cause the piston to compress re- tarding-device spring, 33, and move the triple-valve parts to the position shown in Fig. 42. Exhaust cavity n in the slide valve now connects port r leading to the brake cylinder, with port p to the atmos- phere, and the brake will release; but as the small ex- tension of cavity n (see Fig. 37) is over port p, dis- THE "k" triple valve 175 charge of air from the brake cyHnder to the atmosphere is quite slow, in this way the brakes on the front' end of the train require a longer time to release than those on the rear. This feature is called the ''Retarded Re- lease," and although the triple valves near the locomotive commence to release before those in the rear, as is the ' Wy/////////////m/A W/^////////////^^m Fig. 42 — K-2 Triple — Retarded-Release Position. case with the H-triple valve, yet the exhaust of brake- cylinder pressure in retarded-release position is suffi- ciently slow to allow the rear brakes to release first. This permits of releasing the brakes on very long trains at low speeds with less danger of a severe shock or break in two than with old style triples. 176 MODERN AIR BRAKE PRACTICE At the same time, the back of the piston is in con- tact with the end of the sHde-valve bush and, as these two surfaces are ground to an accurate fit, their contact effectually cuts off communication between chambers h and R through feed groove i, preventing air from feed- ing through from the trainpipe to the auxiliary reser- voir by this path. Also, port / in the slide valve registers with port y in the slide valve seat, and pressure in cham- ber Y can flow through ports y and / to the chamber R and the auxiliary reservoir. Chamber Y is supplied with air under these circumstances by the check valve 15 rais- ing and allowing trainpipe air to flow past it. The area of port / is about half that of feed grove i, so that the rate that the auxiliary reservoir will recharge is much less than wlien the triple valve is in full-release. The groove on the back of the piston now takes the place of port I. As the auxiliary-reservoir pressure rises, and the pressures on the two sides of piston 4 become nearly equal, retarding-device spring 31 forces the piston, slide valve, graduating valve, and retarding device stem back to the full release position shown in Fig. 38, when the remainder of the release and recharging will take place as described above under "Full Release and Charging." These features of the new valve are always available, even when in trains with the old standard triple, the beneficial results being in proportion to the number of new valves present in the front end of train. EMERGENCY POSITION. Emergency Position is the same with the K triple valve as with the H type. Quick action is caused by a sudden and considerable reduction in trainpipe pres- THE K TRIPLE VALVE 177 sure, no matter how caused. This fall in trampipe pres- sure causes the difference in pressures on the two sides of piston 4 to increase very rapidly, so that the friction of the piston, slide valve and graduating valve is quickly and greatly overcome, and they move to the left with such force that when the piston strikes the graduating stem, it compresses graduating spring 22, forcing back the stem and spring, until the piston seats firmly against W//M/// / /M m BP a Fig. 43 — K-2 Triple — Emergency Position. the gasket 23, as shown in Fig. 43. The movement of the slide valve opens port t in the slide-valve seat, and allows auxiliary reservoir pressure to flow to the top of emergency piston 8, forcing the latter downward and opening emergency valve 10. The pressure in chamber y being instantly relieved, allows trainpipe air to raise 178 MODERN AIR BRAKE PRACTICE the check valve 15 and flow rapidly through chambers Y and X to the brake cylinder, until brake-cylinder and trainpipe pressures equalize, when both check valve and emergency valve are forced to their seats by the spring in the former, preventing the air in the cylinders from escaping back into the trainpipe again. At the same time port ^ in the slide valve registers with port r in the slide-valve seat, and allows auxiliary-reservoir pressure to flow to the brake cylinder. But the size of ports s and r is such that very little air gets through them before the trainpipe has stopped venting into the brake cylin- der. This sudden discharge of trainpipe air into the brake cylinder has the same efifect on the next triple valve as would be caused by a similar discharge of trainpipe air to the atmosphere. In this way each triple valve ap- plies the next, thus giving the quick and full applica- tion of all brakes, made heavier than full service appli- cation through the greater amount of trainpipe air ad- mitted to the brake cylinders. The rapidity with which the brakes apply throughout the train is so much increased that in a 50-car train it re- quires less than three seconds ; the brake-cylinder pres- sure is also increased approximately twenty per cent with 8 inch brake cylinders. The release after an emergency is effected in exactly the same manner as after a service application, but re- quires a longer time, owing to the higher brake-cylinder pressures and lower trainpipe pressures. To change a standard type H triple valve to the type K, it is necessary to add the retarded-release feature and to make the necessary changes in the controlling valves, body, and check-valve case. THE "k" triple valve 179 MANIPULATION. I No Special instructions are required by the engineers to handle trains partially or wholly fitted with the K triple valve. The automatic brake valve should be handled as good practice requires with the H triple valve. Some of the most important details are as follows : Make the terminal brake tests, and check the results indicated by noting how well the brakes hold in the first running application, and be governed accordingly in sub- sequent applications. Before attempting to release have an ample excess pressure for the length of train, and in releasing leave the handle of the automatic brake valve in release posi- tion until the rear brakes have had time to release. As return to running position will cause triple valves in retarded-release position to change to full-release posi- tion, the brake-valve handle should not be moved from release too soon. However, with short trains the usual early return to running position will prevent unnecessary retardation of release. the automatic SLACK ADJUSTER. The question of correct piston-travel is of the highest importance, and the automatic slack adjuster is for the purpose of keeping it as nearly uniform as possible, which should be eight inches when running. 180 MODERN AIR BRAKE PRACTICE SLACK ADJUSTER COMPLETE. I Fig. 44 shows how the adjuster is attached to the pres- sure head of the brake cylinder. One end of cyUnder lever (5) is bolted to a cross head, which moves in a guide (4) that is bolted to the pressure head of the cylin- der. The cross head is held to its place by a threaded rod (i), which has a ratchet nut where its opposite end extends through the adjuster body (3), and when it is desired to reduce the piston travel, it is done by moving the cross hea-d away from the cylinder head a distance equal to the amount of slack to be taken up ; and to in- crease the travel move the cross head toward the cylinder. When no air is in the cylinder the threaded rod can be turned either way with a wrench, and four turns of the rod will equal one inch of piston travel. In running along, whenever the piston travel exceeds eight inches the adjuster automatically takes up one thirty-second of an inch every time the brake is released, and therefore whenever new shoes are put on (which ne- cessitates letting the adjuster well back), the brake should be fully applied and whatever travel the piston shows over 6^ inches should be taken up by turning the ratchet nut, as the running piston travel is from one to two inches greater than it is when the car is standing still. Don't try to turn the ratchet nut while the brake is set, and never alter the dead levers or bottom rods unless, with all adjuster slack out, the piston-travel is less than 55^ inches, or when the adjuster has been taken up to its limit and the travel is too long, and not then in the latter case if any brake shoes need renewing. Fig. 45 illustrates the adjuster in cross section. 2y is the ratchet nut which is attached to the threaded rod: THE SLACK ADJUSTER 181 Fig. 44 — Automatic Slack Adjuster Complete. )S2 MODERN AIR BRAKE PRACTECE DESCRIPTION OF FIG. 44. 5. Cylinder lever. 1. Threaded rod. 3. Ratchet-nut wheel casing. 2. Adjuster cylinder. a and b. Pipe connection between brake cylinder and adjuster cylinder. THE SLACK ADJUSTER 163 Fig. 45— Automatic Slack Adjuster. 184 MODERN AIR BRAKE PR.-^TICE i DESCRIPTION OF FIG. 45c 2'j. Ratchet-nut wheel. 22. Pawl. a. Projection for lifting pawl. 23. Piston. 21. Release spring. I THE SLACK ADJUSTER 185 22 is the pawf which moves the ratchet nut; 23 is the piston, to which the pawl is attached, and 21 is the spring which drives the piston back after the cyHnder pressure has escaped from in front of it, and as the adjuster cyHn- der is connected to the brake cylinder by a smiall pipe, whenever the air in the brake cylinder forces the brake piston out eight inches, brake-cylinder pressure is ad- mitted against piston 23, which forces the pawl back so that it engages the ratchet-nut wheel, and when the air is released from the brake cylinder the air in the adjuster cylinder (11) escapes through the non-pressure end of the brake cylinder, and spring 21 pushes the piston and pawl forward, thus turning the ratchet-nut wheel the dis- tance of two teeth, which takes up one thirty-second of an inch of piston-travel. The pawl is released by striking a projection (a), which keeps it up. , Fig. 46 illustrates the degree of angularity at which the port in the brake cylinder should be tapped according to the size of the cylinder. As this port is only one-eighth of an inch, it may easily becomic clogged, sc that if the adjuster fails to work you should at once ascertain if the air passages are open between the brake and adjuster cylinders by loosening the union swivel on the adjuster cylinder connection. Whenever the adjuster has operated to the limit of the screw and the pawl fails to release, so that the ratchet-nut cannot be started back with a wrench, if it be the old style adjuster, remove the ratchet-nut cover and carefully pry the piston outward until the pawl can be raised, then slack back the nut about a turn, which will let the piston return to the end of its cylinder and keep the pawl free from the ratchet nut as before. An improvement has lately been added by inserting a 186 MODERN AIR BRAKE PRACTICE PORTJO BE.sfFROM, PRESSURE HEAD. '^ORa: o -5^ c. - o — «<*, SI :^PIPE TAR 37 Fig. 46— Automatic Slack Adjuster— Size of Cylinder Port. DESCRIPTION OF FIG. 46. The illustration shows the angularity at which the brake-cylinder port should be drilled for the different sized cylinders. conductor's valve 187 stop screw next to the ratchet-nut casing, which holds the threaded rod a short distance from its extreme travel, so that in case the pawl sticks it is only necessary to back out the stop screw, when the pawl will release itself auto- matically. The adjuster cylinder should be cleaned and oiled every time the brake cylinder is oiled. THE conductor's VALVE. The conductor's valve is an additional stop cock at- tached to the trainpipe of each passenger car. There is a branch pipe running from the trainpipe up through the body of the coach, usually in the toilet room, and on this branch pipe is a stop cock, or valve, so that in case the conductor is unable to signal the engineer, or an emergency arises making it necessary to stop the train as quick as possible, the conductor can let the air out of the trainpipe by simply opening this valve. If he wishes to make a gradual stop he has only to open the valve gradually, but if he wishes to stop quick, he must open the valve quick, and also must hold it open until the train is stopped, for if the engineer should fail to lap his brake valve, as soon as the conductor's valve was closed the brakes would release, on account of the main reservoir pressure driving the triples to release position. 188 MODERN AIR BRAKE PRACTICE TYPE L TRIPLE VALVE. This triple valve has the usual brake-pipe auxiliary- reservoir, and brake-cylinder connections, also an addi- tional connection for a supplementary reservoir. Fig 47 shows a view of the type L triple valve, with the safety valve in place. In order that trains mav be con- trolled easily and smoothly when running at either high or low speeds, and that stops may be made quickly and with the least liability of wheel sliding, the brake ap- ^ paratus must provide the following essential features of operation: A small brake-pipe reduction must give a moderate brake-cylinder pressure and a moderate but uniform re- tardation on the train as a whole. It must be possible to make a heavy service reduction quickly, but without liability of quick action. It must be possible to graduate the release as well as the application of the brakes. To insure the ability to obtain brake applications in rapid succession, and to full power, a quick recharging of the auxiliary reservoirs is necessary. This feature also enables the engineer to handle long trains in heavy grade work with a much greater factor of safety than hereto- fore, and eliminates the need for retaining valves. For high-speed trains, a high brake-cylinder pressure available for emergency applications is imperative, in order to provide a maximum braking power, when the shortest possible stop is required to save life or to avoid sudden danger. 4 TYPE L TRIPLE VALVE 189 The Westinghouse Air Brake Co. claim that they have met the above requirements by the development of the type L triple valve. This triple valve is of the quick- action, automatic, "pipeless" type, and is intended for use only in high-speed passenger service. The L valve Fig. 47— The Type L Triple Valve. forms a part of the LN Passenger Car Equipment, v^hich is designed throughout to meet the service conditions out- lined above. Being of the quick action type it possesses the following important features: 190 MODERN AIR BRAKE PRACTICE 1st. Quick Recharge (of auxiliary reservoirs), by which a rapid recharging of the brake system is secured, thus making it possible to obtain full braking power im- mediately after a release has been made and permitting as many applications and releases in quick succession as may be desired, without materially depleting the system,. 91 M 23 aT aa as ao Fig. 48— The Type L Triple Valve. 2nd. Quick Service^ by which a very quick serial service action of the brakes throughout the train is se- cured, similar to that in emergency applications, but less in degree. This makes certain the prompt and uniform application of all the brakes in the train, correspondingly increasing the rapidity and effectiveness of any given brake-pipe reduction, and thereby practically eliminating the need for the harsher emergency application, except in cases of actual danger. 3rd. Graduated Release, which permits of partially or entirely releasing the brakes on the entire train at will. 4th. High Emergency Cylinder Pressure, which i TYPE L TRIPLE VALVE 191 greatly increases the available braking power in emer- gency applications over the maximum obtainable with a full service reduction. With this, as with all quick-ac- tion triple valves, a portion of the air contained in the brake pipe is vented to the brake cylinder in emergency applications, thus providing for the quick serial operation of the brakes in the usual way. This, in itself increases the brake cylinder pressure thus obtained, considerably above the maximum pressure, possible in ordinary service applications. The high emergency pressure feature referred to still further increases this em^ergency pressure, and the high cylinder pressure thus obtained, is retained without re- duction, until released. This is accomplished by the use of a supplementary reservoir in addition to the ordinary auxiliary reservoir. The supplementary reservoir is approximately double the size of the auxiliary reservoirs. Its function is to assist in obtaining the graduated release of the brakes, and the high emergency cylinder pressure, and the way in which this is accomplished will be explained later on. This feature makes it possible to use the equipment as a high speed brake, when carrying 90 lbs. brake pipe pressure, and obtain better results than when using no lbs. pres- sure with the old standard equipment in steam road service. Fig. 48 shows a vertical cross section of the valve, and the names of its various parts are as follows : 2, Valve Body; 3, Slide Valve; 4, Piston; 5, Piston Ring; 6, Slide Valve Spring; 7, Graduating Valve; 8, Emergency- Valve Piston; 9, Emergency- Valve Seat; 10, Emergency- Valve ; 11, Rubber Seat for Emergency- Valve; 12, Check- Valve Spring; 13, Check- Valve C'^e; 14, Check- Valve Case Gasket; 15, Check Valve; '6, 192 MODERN AIR BRAKE PRACTICE Emergency Valve Nut; 17, Graduating- Valve Spring; 18, Cylinder Cap; 19, Graduating-Spring Nut; 20, Graduat- ing Sleeve; 21, Graduating Spring; 22, Cylinder Cap Gas- FACE VIEW GRADUATING VALVE. PLAN VIEW i c 9 c D© © 1 c ^ > <^o ® ( m ) FACE VIEW SLIDE VALVE. ® (ZD t © @ 00 SLIDE VALVE SEAT. Fig, 49 — Graduating Valve, Slide Valve, and Slide- Valve Seat. Type L Triple Valve. ket; 23, Bolt and Nut for Cylinder Cap; 24, Bolt and Nut for Check- Valve Case; 25, By-Pass Piston; 26, By-Pass Piston Ring; 27, By-Pass-Valve; 28, By- Pass-Valve TYPE L TRIPLE VALVE 193 Seat ; 29, By-Pass-Valve Spring ; 30, By-Pass Valve Cap; 31, By-Pass-Piston Cap; 32, Strainer; 33, E-7 Safety Valve. Figure 49 illustrates the actual arrangement of ports, and cavities, in the graduating valve, slide valve, and slide valve seat, of the type L triple valve. Owing to the impossibility of showing all of the ports and con- Fig. 50 — Full-Release and Charging Position. necting passageways in any single illustration, figures 51, 52, 53, 54 and 55, are presented, and each shows in a diagrammatic way, the relations of the various parts to each other, for the different positions of the triple- valve piston. The actual proportions and mechanical construction of the parts have been disregarded, in order to make the connections, and operation more intelligible to the student. The letters designating the ports and passages appear- 194 MODERN AIR BRAKE PRACTICE ing on Figures 48 to 55 inclusive, correspond through- out, but the reference numbers on Fig. 48 do not exactly correspond with those on the diagrammatic views. The various connections shown in Fig. 48, and the ports in Fig. 49 will, however, be made clear, by comparison with the diagrammatic views shown in Figures 50 to 55. Referring to Fig. 49, it will be noticed that the Fig. 51 — Quick-Service Position. ports in the plain view of the slide valve seat are as fol- lows : r leads to the brake cylinder ; t, to the top of the emergency piston ; p, to exhaust ; x, to the supplementary reservoir ; y, to the check valve case and chamber Y ; b, to the safety valve, and c, to the space behind the by-pass piston. The registration of the parts is most readily followed, and understood, by reference to, and comparison with TYPE L TRIPLE VALVE 195 the diagrammatic drawings, Figures 50 to 55, in which the connections to the triple valve are as follows: a — Brake Pipe. X — Supplementary Reservoir. C — Brake Cylinder. p — Exhaust. b — Safety Valve. R — Auxiliary Reservoir. OPERATION OF THE TYPE I, TRIPLE VALVE. CHARGING. Referring to Figures 48 and 50, air from the brake pipe enters the triple valve through the passages a, e, g, and h, to the face of the triple valve piston (which is then forced to release position as shown), thence through the feed groove i to chamber R and auxiliary reservoir. Brake-pipe air in passage a also raises the check valve 15, and entering chamber Y flows thence through the ports y and ; into chamber R and the auxiliary reservoir. This check valve then prevents any back flow of air from the auxiliary reservoir to the brake pipe. At the same time, port k registers with port x and the air in chamber R also flows through these ports into the supplementary reservoir. Both the auxiliary and supplementary reser- voirs are thus charged at the same time and to the same pressure from the brake pipe through the two different channels already mentioned. When in this position, air from the brake cylinder, entering the triple valve at C, flows through passage r, port n, large cavity W (Fig. 49), in graduating valve, and ports m, and p, to the atmosphere, thus releasing the brakes. 196 MODERN AIR BRAKE PRACTICE SERVICE APPLICATION. The ports of the triple valve being in release, and charging as shown in Fig. 50, a service reduction in brake-pipe pressure, reduces the pressure in chamber h, and on the face of the triple valve piston, below that in the auxiliary reservoir on the opposite side of the piston. The higher auxiliary reservoir pressure therefore forces the piston in the direction of the lower brake-pipe pressure, carrying with it the attached graduating valve. The first movement of the piston closes the ports /, m and k, thus shutting off communication between the brake pipe, and the auxiliary and supplementary reservoirs, and closing the exhaust passage from the brake cylinder to the atmosphere. The same movement opens port z and connects ports q and 0, in the main slide valve through the small cavity v in Fig. 49 in the graduating valve. The spider or lugs on the end of the piston stem, then engage the end of the main slide valve, which is carried along with the piston, and graduating valve, as the re- duction continues. This brings the parts into quick service position shown in Fig. 51. Service port 2 in the slide valve, registers with brake cylinder port r, in the seat, thus allowing the air in the auxiliary reservoir to flow to the brake cylinder, and ap- ply the brakes. At the same time the quick service ports, o and q, and the small cavity v, in the graduating valve, connect passage y, leading from chamber Y in the check yalve case with passage r leading to the brake cylinder. This allows air from the brake pipe to lift the check valve, and flow through the above mentioned ports to the brake cylinder. This constitutes the quick service action of the triple valve, in that it causes a slight, but TYPE L TRIPLE VALVE 197 definite reduction in brake pipe pressure locally, at each valve. The effect of a reduction in brake-pipe pressure, made at the brake valve, is thus quickly and uniformly transmitted from car to car throughout the train. The amount of air vented from the brake pipe to the quick service ports is not great for two reasons ; first, because the ports and the passage v^ays are small; second, be- cause in the movement of the slide valve 3 to full Fig. 52 — Full-Service Position. service position, the quick service port y is restricted as it approaches this position and completely closed just before service port z is fully open, as shown in Fig. 52. The amount of opening given the service port in any case, depends upon the rate of reduction in brake pipe pressure as compared with that of the auxiliary reservoir. If the former is at first rapid, as compared with the 198 MODERN AIR BRAKE PRACTICE latter, which would be ;the case with short trains, the higher auxiliary pressure moves the piston at once to Full-Service Position, Fig. 52, thus automatically cut- ting out the quick-service feature where it is not needed. When in Full-Service Position, Fig. 52, the service port z is fully open, and the quick-service port is closed. This stops the flow of air from the brake pipe to the cylinder and the quick-service action ceases. As shown in the cut, the graduating spring is compressed slightly when the piston is in full service position. In any case where the brake pipe reduction is so rapid, that the quick service feature is of no advantage, the difference of pres- sure on the two sides of the triple valve piston becomes at the same time sufficient to compress the graduating spring, and automatically close the quick service »port as explained above. But if the brake pipe reduction is less rapid, or slow, as in the case of long trains, or moderate service reductions, a partial opening only of the service port is sufficient to preserve a balance between the pres- sure on the two sides of the triple valve piston. The service port connecting the auxiliary reservoir to the brake cylinder, is much larger than the quick-service port connecting the bi-ake pipe to the brake cylinder. This serves to effectually prevent an emergency application, when only a service application is desired. It also guards against the brake-pipe reduction being continued, due to the quick-service port remaining open, after the reduc- tion has been stopped at the brake valve. During the time the slide valve 3 remains in Quick or Full-Service Positions, as shown in Figures 51 and 52, the cavity q connects the brake-cylinder port r with port h, leading to the safety valve. This safety valve, known as the E-7 (see Figures 47 and 48), is ordina- TYPE L TRIPLE VALVE 199 rily set for 62 lbs. In an emergency application, however, the safety valve is entirely cut off from the cylinder, as explained under the heading ''Emergency." LAP. After a sufficient brake-pipe reduction has been made, the brake-valve handle is lapped, and further escape of air from the brake pipe is prevented. When the flow Fig- S3 — Service-Lap Position. cf air from the auxiliary reservoir to the brake cylinder has reduced the pressure on the reservoir side of the triple-valve piston slightly below that remaining on the brake-pipe side, the pressure in the brake pipe, assisted by the graduating spring, will move the piston, and graduat- ing valve to service-lap position, shown in Fig. 53. In this position all of the ports are blanked by the grad- 200 ' MODERN AIR BRAKE PRACTICE uating valve, and the flow of air to the brake cyHnder is stopped. Further movement is prevented by the shoul- der of the piston stem striking the end of the slide valve 3, as shown in the cut. The slight difference of pressure which was sufficient to move the piston and small grad- uating valve is unable to overcome the added resistance of the slide valve, and the parts remain in the position shown. It should be noted that the slide valve 3 remains in Service Position, a movement of the piston and gradu- ating valve being all that is required to lap the valve. Consequently, when in this position, only a slight re- duction in brake-pipe pressure is required to again bring the piston and graduating valve into Service Position. It is evident that the exact position of the main slide valve in Lap Position depends upon whether its previous position was that of quick service (Fig. 51), or full service (Fig. 52). If the former, the lap position as- sumed would be that of quick-service lap (Fig. 53). If, however, the valve had moved to full service, the posi- tion would be that of full-service lap. The main piston being in service-lap position (Fig. 53), the pressure on both sides of it must be equal. If the brake-pipe pres- sure is increased in order to release the brakes, the higher pressure on that side of the piston causes it to move the graduating and slide valves to the extreme right to re- lease, and recharging position, previously described (see Fig. 50). The air, which was prevented from leaving the supplementary reservoir by the former movement of the slide valve to service position, and which consequently remained at its initial pressure, while the auxiliary reser- voir pressure was being reduced, now flows into the aux- iliary reservoir and helps to recharge it. During this operation, as well as while graduating TYPE L TRIPLE VALVE 201 the release of the brakes, described under the next heading, the pressures on the brake pipe and auxihary reservoir sides of the triple-valve piston are always m balance. This is important, since it insures an imme- diate response of the brakes to any reduction, or in- crease in brake-pipe pressure, irrespective of what oper- ation may have occurred just preceding. If the brake-valve handle is moved to Running Posi- tion and left there, the brake-pipe pressure is fully re- stored and the piston remains in Release Position ; the brakes being thereby fully released and the auxiliary and supplementary reservoirs fully recharged. GRADUATED RELEASE. - Suppose, however, that after the brakes have been applied, only sufficient air is permitted to flow into the brake pipe to move piston 4, with the slide, and grad- uating valves, to release position (Fig. 50), and the brake-valve handle is returned to lap. Then the flow of air from the supplementary reservoir, through ports X and ^, to the auxiliary reservoir, continuing after the rise in brake-pipe pressure has ceased, the pressure on the auxiliary reservoir side of the triple-valve piston will be raised slightly higher than that on the brake-pipe side, and cause the piston, and its attached regulating valve, to move to the left, to graduated release position shown in Fig. 54. In this position the brake is only par- tially released, and a portion of the air pressure originally in the brake cylinder still remains there. In this way, the brake cylinder pressure may be released in a series of steps, or graduations, and the operation is known as grad- 202 MODERN AIR BRAKE PRACTICE uated release, and may be repeated as desired, until the brake-pipe pressure has been fully restored, and the ex- haust of air from the brake cylinder completed. The' amount of reduction in the brake cylinder pressure for any given graduation depends upon the amount of air pressure which has been restored in the brake pipe. The recharge of the brakes is similarly proportioned. Fig. 54 — Graduated-Release-Lap Position. EMERGENCY. When the brake-pipe pressure is reduced suddenly, or its reduction continues to be more rapid than that in auxiliary-reservoir pressure, the piston is forced to the extreme left and compresses the graduating spring. The parts are then in Emergency Position, as shown in Fig. TYPE L TRIPLE VALVE 203 55. In this position air from the auxiHary reservoir en- ters the brake cylinder passage r through the port «? in the main slide valve, instead of port ^ as in service appli- cation. Port / in the seat is also uncovered by the end of the main slide valve, thus admitting air from the auxil- iary reservoir, through port t to the top of the emergency piston. Fig- 55 — Emergency Position. The air pressure thus admitted to the top of this piston, pushes it down and forces the rubber seated emergency valve from its seat. This allows the brake pipe air in pas- sage a to lift the emergency check valve, and flow through chambers y and x to the brake cylinder C, in the ordinary way. At the same time port d, in the main slide valve, registers with port c in the seat. This allows air from behind the by-pass piston to flow through ports c, d and n to r, and the brake cylinder. As there is no pressure 204 MODERN AIR BRAKE PRACTICE in the brake cylinder at this instant, the by-pass piston, with its attached by-pass valve is forced to the left by the auxiliary reservoir pressure acting against its opposite face. The air contained in the supplementary reservoir then flows past this valve into the passage way leading to the auxiliary reservoir. It thereby adds to the latter, the volume of the supplementary reservoir. This gives in effect an auxiliary reservoir pressure vol- ume approximately three times the size of the one that supplies air to the brake cylinder in a service application. Air from the supplementary reservoir continues to flow to the auxiliary reservoir until the pressures in the latter, and in the brake cylinder have risen nearly to that re- maining in the supplementary reservoir. Communication between the two reservoirs is then closed by the by-pass valve returning to its seat. This action of the triple valve in the emergency appli- cations permits the pressure in the brake cylinder to rise to within a few pounds of maximum brake-pipe pressure, a much higher pressure being secured in emergency applications than is possible with the standard auick- action triple valve. Further more it will be noted by reference to Fig. 55 that cavity q has traveled past the brake cylinder port r, so that the latter is no longer connected to the safety valve h. Hence, there is no escape of air from the brake cylinder after an emergency application of the brakes. Not only, therefore, is the emergency pressure considerably higher than that formerly secured by the use of the old standard High-Speed Brake, but it is held without diminution until the brakes are released. TYPE L TRIPLE VALVE 205 INSTALLATION AND MAINTENANCE. The triple valve is usually bolted to the pressure head of the brake cylinder,, to which all the pipe con- nections are permanently made. In removing the valve, no pipes need to be disconnected, the loosening of the three bolts which hold it in place being all that is re- quired. Hence, the name 'Tipeless," as applied to this valve. Care should be taken in locating the valve to have it free from obstructions which would render in- spection or removal difficult. It should be placed as far as possible above the general level of the piping so that no pockets are formed in the latter. If this point does not receive proper attention, trouble may be ex- perienced in cold weather from the freezing of water in the pipes or valve itself. Under ordinary service conditions, the triple valve should be thoroughly cleaned and lubricated once in three months. The proper interval is best determined for each particular case by a careful inspection and trial. Where conditions are severe and the triple valve exposed to extremes of weather, dirt and so on, more frequent inspections will no doubt be found necessary. Where the valve is protected, and not sub- jected to hard usage the interval may be lengthened. The use of heavy grease or other lubricants which will "gum" and cause the valve to work stiff, or clog the ports, should be avoided. Too light a lubricant or one that does not possess sufficient "body,^' is not satisfactory, as it will not thoroughly lubricate the parts or last as long as necessary. Special lubricants made for this pur- pose will give the best results. Before installing the triple valve all of the piping should be thoroughly hammered and blown out, in order 206 MODERN AIR BRAKE PRACTICE to loosen and remove all scale and foreign matter. This is especially important in new installations. After the piping is completed all of the joints should be thoroughly tested with soap suds, under pressure, and made air tight. Particular attention should be given to the safety valve and its strainers, in order that no dirt or scale can reach the safety valve seat and prevent it from properly closing. The by-pass piston should also receive atten- tion to insure that it is working freely in its bushing. Never remove the movable parts of the triple valve while it is on the car. If the valve is not working properly, or needs cleaning and oiling, take it down and replace it by a valve in good condition. All cleaning and oiling should be done at a bench, by a competent man; where the liability of damage to the internal parts of the valve is least. Any attempt to take the triple valve apart while still on the car is almost sure to result in a large percentage of valves being injured by care- less handling, or dirt getting inside the pipes, or valve. If repairs are necessary the valves should be sent to the shops, where the facilities for doing the work are best. The complete LN equipment includes a type L valve triple valve, with safety valve, a supplementary reservoir and a cut-out cock. At times, however, cars equipped with this schedule must be operated in trains with cars having the old standard equipment (P triple valves), as for instance during the transmission period when a change is being made from the old standard to the LN schedule. During this time the cut-out cock between the triple valve and supplementary reservoir should be closed. The new valves will then work in perfect harmony with the old. In fact, if old and new equipments are to be TYPE L TRIPLE VALVE 207 in service together for any considerable length of time, the cut-out cock and supplementary reservoir may be omitted entirely, as v^ell as the safety valve, furnished with the triple valve. If the equipment is used with 70 pounds brake-pipe pressure, no other change is neces- sary, and only the addition of the ordinary High-Speed Reducing Valve is required for High-Speed Service (no pounds brake-pipe pressure). In such cases where the conditions of service demand, there would, of course, be the same necessity for a Pressure-Retaining Valve, as with the Type P Triple Valve. An improved safety valve is used with the type L triple valve, one size of safety valve being adapted for the different sizes of L triples. The parts of this safety valve, as shown in section in Fig. 56 are, 2, body; 3, cap nut; 4, valve; 5, valve stem; 6, spring; 7, regulat- ing nut; 8, exhaust regulating ring; 9, lock ring. This safety valve is located on the side of the triple, and connected to the brake cylinder through the triple valve. Its function is to prevent abnormal brake cylin- der pressure during service applications of the brake. This safety valve is in connection with the brake cylinder at all times, except during an emergency appli- cation. There are two adjustments, maximum and minimum, and its operation is as follows : As the air from the safety valve port b in the triple valve enters chamber A, of the safety valve, and its pressure becomes sufficient to overcome the tension of spring 6, valve 4 is moved upward, closing the upper end of ports d in the valve bushing and opening chamber B to the atmosphere through ports c in the body, thereby permitting air to flow from chamber A through chamber j B and ports c to the atmosphere. (Only one each of MODERN AIR BRAKE PRACTICE ports c and d are shown in the cut.) As the air pres- sure below valve 4 decreases, the tension of spring 6 forces valve 4 downward, which restricts the opening through ports c to the atmosphere and opens ports d to Fig. 56— Safety Valve Used With Type L Triple Valve. spring chamber E. Air now being permitted to enter chamber E, assists spring 6 in forcing valve 4 to its seat quickly. As chamber E is opened to the atmosphere at TYPE L TRIPLE VALVE 209 all times through ports f in the body, air in chamber E will escape to the atmosphere and again allow the air pressure in chamber A to overcome spring 6 and raise valve 4 from its seat — this action causing the valve to open and close quickly with a pop action. The function of the exhaust regulating ring 8 is to regulate the size of the opening through ports f, and f, thus controlling the range of opening and closing of valve 4- When this ring has once been placed in proper position it is securely held there by lock ring 9. The valve is adjusted by removing cap nut 3, and screwing regulating nut 7 up or down, after which the cap nut must be replaced and securely tightened in order to hold nut 7, and prevent escape of air from chamber E through the cap nut joint. The safety valve should be adjusted to open at 62 lbs. pressure ; and it should close at 58 lbs. As previously explained this range is regu- lated by means of exhaust regulating ring 8, which can be screwed up or down until ports f have the proper area of opening. 210 MODERN AIR BRAKE PRACTICE THE TRIPLE ^^ALVE. Q. What relation does the triple valve bear to the automatic air brake? A. It is a very Important and essential part of the system. Q. In general, what is the function of the triple valve ? A. It controls the passage of the compressed air from the auxiliary reservoir into the brake cylinder during an application; and it also releases the pressure from the brake cylinder at the will of the engineer. After release, the triple valve again assumes the position in which the air can pass through it to recharge the auxiliary reservoir. PLAIN TRIPLE. Q. Name the operative parts of the plain triple valve. A. This valve consists of a piston, slide valve, gradu- ating valve, graduating stem, graduating stem spring and slide valve spring. Q. How many positions are there to a plain triple, and what are they? A. Four; release, service, lap and emergency posi- tions. RELEASE POSITION. Q. What is the normal position of the triple valve? A. Release position. Q. What is the purpose of release position of the valve ? EXAMINATION QUESTIONS AND ANSWERS 211 A. To allow the auxiliary reservoir to be charged, and to exhaust the air from the cylinder to permit the brakes to release. Q. Explain how the air passes through the triple valve in order to charge the auxiliary reservoir? A. Air enters from the train pipe connection, passes through a port into graduating stem case, thence through another port to the piston chamber. The piston being in release position, and the feed port in the bushing being open, the air is free to pass through this port, also another port on the piston shoulder to the slide valve chamber, thence through pipe connection to the auxiliary reservoir. Q. When the auxiliary reservoir is fully charged, how do the pressures stand on the opposite sides of the triple valve piston? A. Equal; in other words equalized. SERVICE APPLICATION POSITION. Q. With the auxiliary reservoir charged and the valve in release position, what must be done to cause the piston to move to service application position? A. The train pipe pressure must be reduced below that in the auxiliary reservoir. Q. How much of a train pipe reduction should be made to cause this valve to move to application position ? A. Not less than 5 pounds. Q. Explain what takes place as the triple valve piston moves to service position? A. As the piston starts down, the first slight move- ment causes it to close the feed port and unseat the graduating valve. A shoulder on the end of the triple piston stem, then becomes engaged with the end of the 212 MODERN AIR BRAKE PRACTICE slide valve, causing it to be moved to service position, in which the exhaust cavity is no longer in communica- tion with the brake cylinder port, but a port in the slide valve is now in register with a port in the seat, which leads to the brake cylinder. Q. As the piston moves toward service position, what resists its movement and prevents it from moving the full length of its cylinder? A. The graduating stem, with which the knob on the plain side of the triple valve piston becomes engaged, as the piston reaches service position. Q. What is the duty of the graduating stem and spring ? A. To act as a bumping post for the triple valve piston, which will prevent it from going to the emer- gency position during service application. Q. Explain the flow of air through the triple valve in service application position. A. A port on the slide valve is in register with a port in the seat; therefore, as the graduating valve is un- seated, auxiliary reservoir pressure, which always sur- rounds the slide valve, is free to pass through ports in the slide valve to the graduating valve seat and thence through other ports to the brake cylinder. Q. If 5 pounds of pressure is reduced from the train pipe, how much will leave the auxiliary reservoir? A. Just a little more than 5 pounds. Q. Why will just a little more than 5 pounds leave the auxiliary? A. Owing to the reservoir pressure expanding into the brake cylinder as long as the graduating valve is open, which eventually will cause the auxiliary pressure to become a little lower than that which remains in the I EXAMINATION QUESTIONS AND ANSWERS 213 train pipe. The train pipe pressure then being the greater of the two causes the triple valve piston to move forward sufficiently to seat the graduating valve and prevent any further flow of air from the auxiliary reservoir to the brake cylinder. LAP POSITION. Q. What is lap position of the triple valve? A. The position in which the graduating valve is closed. O. Does the slide valve move after the first reduction has been made? A. No; not until the brakes are fully applied or re- leased. O. What takes place when the second reduction is made in the train pipe? A. The triple piston again moves until it reaches the graduating stem, unseating the graduating valve, and allowing auxiliary pressure to pass to the brake cylinder in equal amount to that reduced in the train pipe, when the piston will move forward, and again seat the gradu- ating valve. Q. Does the triple valve piston move with every re- duction that is made in the train pipe? A. Yes ; every considerable reduction, and by so doing it unseats the graduating valve. Q. How much of a reduction will be required to fully apply the brake in service? A. About 20 pounds if the piston travel is adjusted properly. Q. How much pressure will that develop in the brake cylinder ? A. About 50 pounds. 214 MODERN AIR BRAKE PRACTICE Q. How much pressure will remain in the auxiliary reservoir in this case? A. About 50 pounds, as the auxiliary reservoir and brake cylinder pressure always stand equal when brakes are fully applied. Q. How will the triple valve operate if the train pipe pressure is reduced more than the amount required to equalize the auxiliary and brake cylinder pressures? A. The triple valve piston will drive the graduating stem down, compressing the graduating stem spring, and traveling the full length of its cylinder, until it rests upon the leather gasket. Q. With the triple valve in application position, what must be done to cause it to move to release position ? A. The train pipe pressure must be made greater than the auxiliary reservoir pressure. Q. How can this be accomplished? A. Either by increasing the train pipe pressure until it is greater than the auxiliary reservoir pressure, or the auxiliary reservoir pressure may be reduced below that which is in the train pipe. EMERGENCY APPLICATION POSITION. Q. What is the fourth position of the triple valve? A. Emergency position. Q. What is the object of the emergency position of the triple valve? A. To allow the air to pass from the auxiliary reser- voir to the brake cylinder quickly. Q. What must be done to cause the triple valve piston to move to the emergency position? A. A sudden reduction of air pressure must be made in the train pipe. EXAMINATION QUESTIONS AND ANSWERS 215 Q. Explain the operation of the triple valve as it moves to the emergency position. A. The quick reduction made in the train pipe causes the auxiliary reservoir pressure to drive the piston down quickly, the knob on the triple valve piston to strike the graduating stem with considerable force, driving it down and compressing the graduating stem spring. This movement of the piston has caused the slide valve to be moved downward until it entirely uncovers a port in the slide valve seat, thereby permitting auxiliary reservoir pressure, which is always present in chamber e, to pass directly to the brake cylinder. This, brings about a quick equalization of the auxiliary reservoir and brake cylinder pressures. Q. Does the emergency action of this triple valve give any greater braking power in the brake cylinder than would be obtained if a full service application were made ? A. No ; the only benefit received from the plain triple valve in emergency is that a quicker application of the brake will be had. Q. Are there any more than one type of plain triple valve ? A. Yes ; there are several different types in service, but the two standard types now furnished are the H-24 and F-46. Q. What is the principal difference in these two types of valves? A. Only in the sizes of the ports and the various operative parts. Q. Why must different size ports be used in these different valves? 216 MODERN AIR BRAKE PRACTiCE A. Because they are used with different size cylinders and reservoirs. Q. What are the dimensions of the graduating spring used in the plain triple valve ? A. Phosphor bronze spring wire, number 14 B. W. G., 83-1000 inch in diameter, 12 coils, 2^ inches, free height, 25-64 inches inside diameter. WESTINGHOUSE QUICK ACTION TRIPLE VALVE. Q. How many, and what are the positions of the quick action triple valve? A. Five; release, charging, service, lap and emer- gency. Q. In what respect do the passenger and freight car triple valves differ? A. With passenger car triple valves, heavier graduat- ing stem springs are used and a different style of emergency valve piston. There is also a difference in the size of the slide valve and various ports throughout the valve. Q. Name the different parts of the quick action triple valve. A. Slide valve, triple piston, piston packing ring, slide valve spring, graduating valve, emergency piston, emer- gency valve, check valve spring, check valve, graduating stem, and graduating stem spring. Q. How many complete sets of operative parts has the quick action triple valve? A. Two; the service parts and the emergency parts. Q. Name the parts of the quick action triple valve that operate during service application? A.- The triple valve piston, the slide valve and grad- uating valve. EXAMINATION QUESTIONS AND ANSWERS 217 Q. How can the freight car triple valves be distin- guished from the passenger car triple valve other than by the lettering on the triple valve body? A. By the exhaust outlets. All freight car triples have two exhaust outlets, while the passenger car valves have but one. Q. What are the dimensions of the graduating stem springs used in the passenger car triple valves? A. With the F-27 and F-29 type of valves, the springs are made of wire 8-100 of an inch in diameter, 13^ coils, 2^ inches free height, and 29-64 inches inside diameter, while with the freight triple valves F-36 and H-49, wire of 49-1000 of an inch in diameter is used, 16 coils and 2^ inches free height, the inside diameter being 29-64 inches. Q. Why are heavier graduating springs used on pas- senger cars than on freight cars? A. Owing to the shorter train pipe of a passenger train the triple valve pistons move more quickly and require more resistance to stop them in service position. RELEASE AND CHARGING POSITIONS, Q. What can be said of these positions? A. They are really one, and the same. Q. Explain why. A. While the air is being released from the brake cylinder by way of the ports in the slide valve seat, the auxiliary is being charged by way of the feed grooves. Q. What is the time required to charge an auxiliary reservoir from zero to 70 pounds? A. With triple valve in proper condition and 70 pounds of pressure maintained in the train pipe it will require approximately 1^4 rninutes. 218 MODERN AIR BRAKE PRACTICE Q. What controls the flow of air from the train pipe to the auxiHary reservoir? A. The feed ports in the triple piston bushing and in the piston seat. Q. What is the object in making the feed groove so small ? A. In order to permit of a uniform charging of all auxiliary reservoirs in a long train, also to prevent auxiliary reservoir pressure from passing back into the train pipe during service brake application. Q. As was described, the F-29 triple valves are used in connection with larger reservoirs, the F-27 with smaller. Is it possible to charge both reservoirs in the same length of time? A. Yes; because the feed ports are made in propor- tion to the size of the reservoir with which the triple valve is to be used. Q. What must be done to cause this valve to move to application position? A. The train pipe pressure must be reduced below that which is in the auxiliary reservoir. SERVICE APPLICATION POSITION. Q. Explain the action of this triple valve after a light service application is made. A. The train pipe pressure being reduced below that in the auxiliary reservoir and chamber m, the greater pressure on the auxiliary side of the piston causes it to move to the left. By so doing, the feed port is closed, cutting off connection between the auxiliary reservoir and train pipe, the graduating valve unseats and the slide valve moves until a port in the slide valve is EXAMINATION QUESTIONS AND ANSWERS 219 brought in register with a port in the slide valve seat, which leads to the brake cylinder. Q. What causes the triple valve piston to stop when it reaches this position in which the ports in the slide valve and the seat are in register? A. The resistance of the graduating stem and spring with which the knob on the triple valve piston becomes engaged when it reaches this position. Q. Explain the flow of air through the triple valve in service application position. A. With the triple valve in service application posi- tion, the auxiliary reservoir pressure, which is always present around the slide valve, is free to pass through ports in the side of the slide valve by the graduating valve which is unseated, thence through ports in the slide valve, and the seat, to the brake cylinder. Q. How much air will pass from the auxiliary reser- voir during this service application? A. Just a trifle more than the amount which was re- duced in the train pipe. Q. With the graduating valve open as shown, why will not the auxiliary pressure continue to flow to the brake cylinder? A. Because, as the pressure in the auxiliary reservoir expands into the brake cylinder, and becomes a trifle lower than that which remains in the train pipe, train pipe pressure causes the triple piston to move forward sufficiently to seat the graduating valve, thereby stop- ping any further flow of air from the reservoir to the brake cylinder. LAP POSITION. Q. With the triple valve in lap position, what occurs if another light reduction in train pipe pressure is made ? 220 MODERN AIR BRAKE PRACTICE A. The triple piston will again move back until it en- gages the graduating stem, thus unseating the graduat- ing valve, which will allow auxiliary reservoir pressure to again pass through to the brake cylinder in amount equal to that reduced in the train pipe, when the piston again seats the graduating valve. Q. Does the slide valve move with every reduction in train pipe pressure? A. No ; the slide valve of the triple valve moves only once with a brake application. The piston and graduat- ing valve;, however, move with every reduction. Q. What is meant by the term ''application of an air brake ?" A. From the time the brake is first, applied until fully released. This might be made with one or more train pipe reductions. Q. If, during a service brake application, the pressure in the train pipe is reduced below that at which the aux- iliary reservoir and brake cylinders will equalize, how will the triple valve operate? A. The piston will move to the left until it strikes the body gasket, and will remain in this position as long as the auxiliary reservoir pressure is above that in the train pipe. Q. Do we get any further braking power by this movement ? , A. No; braking power cannot be increased after equalization has once taken place between the auxiliary reservoir and brake cylinder, no matter how much more air may be reduced in the train pipe. Q. With the triple valve in application position, what must be done to cause the same to move to release posi- tion ? EXAMINATION QXJESTIONS AND ANSWERS 221 A. The pressure in the train pipe must be made greater than that which is in the auxihary reservoir. Q. How can this be accompHshed ? A. Either by the engineer charging up the train pipe until the pressure exceeds the reservoir pressure, or by the train men reducing the auxihary reservoir pressure below that in the train pipe. Q. What two things does the triple valve do when it moves to release position? A. It opens the feed port in order to again allow the auxiliary reservoir to recharge, and opens the exhaust port from the brake cylinder to the atmosphere, permit- ting the brakes to release. Q. Explain how the air escapes from the brake cylinder to the atmosphere when the triple valve is in release position. A. A cavity in the slide valve connects cylinder port and exhaust port together, thereby permitting the air to leave the brake cyMnder and escape. Q. After having made a brake application and re- duced the auxiliary reservoir pressure to 50 pounds, what will be the time required to recharge the auxiliary reservoir again to 70 pounds pressure? A. Not less than 35 seconds if the train pipe pressure is fully restored to 70 pounds. EMERGENCY APPLICATION POSITION. Q. With the auxiliary reservoir fully charged, what must be done to cause the triple valve to operate in emergency ? A. A quick reduction of pressure must be made in the train pipe. 222 MODERN AIR BRAKE PRACTICE Q. Explain the operation of the triple valve in emer- gency. A. A sudden reduction of train pipe pressure causes the triple piston to move out so quickly that the grad- uating stem spring cannot withstand the impact of the knob on the triple valve piston, but yields, so that the piston moves to the limit of its travel. In this position, the removed corner of the slide valve uncovers a port in the slide valve seat, which admits air from the slide valve chamber to the chamber above the emergency piston, which results in forcing the emer- gency piston down and unseats the emergency valve. With the emergency valve unseated, air pressure in the chamber, above the check valve, escapes to the brake cylinder which then permits train pipe pressure to raise the check valve and also pass to the brake cylinder until the train pipe and brake cylinder pressures equalize, when the check valve reseats. A port of the slide valve and another port in the seat are in direct communica- tion, which will, therefore, allow auxiliary reservoir pressure to pass to the brake cylinder until the pressures become equalized. Q. At what pressure will the auxiliary reservoirs and brake cylinders equalize with an emergency application and proper piston travel? A. About 60 pounds. Q. As it is understood that train pipe and auxiliary reservoir pressures both pass to the brake cylinder dur- ing an emergency application, what volume of air reaches the cylinder? A. A small amount of auxiliary reservoir pressure is admitted to the brake cylinder as the service port is tjassing over the cylinder port, but the air pressure from EXAMINATION QUESTIONS AND ANSWERS 223 the train pipe is the first to reach the cylinder in any considerable volume. It will be noted that the port in the slide valve is restricted in size. This is for the pur- pose of permitting the train pipe pressure to reach the cylinder before any great auxiliary reservoir volume can pass to the brake cylinder. Q. What advantage is gained by having the triple valve piston make ja. joint with the graduating cap gasket when in emergency position? A, This is to prevent auxiliary reservoir pressure from leaking into the train pipe past the triple valve piston packing ring. Q. In releasing the brake after an emergency appli- cation, is a higher train pipe pressure required than would be necessary if the brakes were fully applied in service ? A. Yes; to release brakes after an emergency appli- cation, the train pipe pressure must be raised above 60 pounds ; whereas, with a full service application, the brakes can be released with a little over 50 pounds train pipe pressure. THE PRESSURE RETAINING VALVE. Q. What is the purpose of the pressure retaining valve ? A. Its purpose primarily is to retain a limited, pre- determined amount of pressure in the brake cylinders of the train, in heavy grade service, thereby holding the speed of the train in check during the time the auxiliary reservoirs are being charged. Q. Does it not also perform other useful duties? A. Yes ; it permits of a much safer handling of the train, the maintenance of a more uniform rate of speed 224 MODERN AIR BRAKE PRACTICE I down heavy grades, and causes a great saving in air pressure, which means less labor for the air pump. It also gives an increased cylinder pressure and higher braking power, with a lower consumption of air pres- sure. Likewise, it permits of a greater reserve in stop- ping power for emergencies. Q. Briefly describe the construction of the pressure retaining valve? A. It consists of a weighted valve enclosed in a casing, and seated in a passage way. This valve is screwed on the opposite end of a pipe coupled to the exhaust port of the triple valve. Q. Describe its operation when the handle is turned down, pointing to the ground. A. When the handle is pointing downward, pressure escapes from the brake cylinder, through the triple valve, passes through the retaining valve pipe to the re- taining valve, where it escapes freely to the atmosphere. In this position the valve is non-operative and performs no useful work. Q. When the handle of the retaining valve is turned horizontal, how does it operate? A. When the handle is turned up, pointing in a hori- zontal line, the direct outlet from the retaining valve pipe is closed, and a passage way is made through the cock to the under side of the weighted valve on its seat. All pressure over 15 pounds will hold the valve lifted from its seat and escape through a small port from the cage enclosing the weighted valve. The weighted valve is so proportioned that it will seat when only 15 pounds pressure is exerted upon it. Thus the last 15 pounds are retained in the brake cylinder, which is sufficient to steady the train while the brakes are being recharged EXAMINATION QUESTIONS AND ANSWERS 225 Q. The retaining valve tlien merely performs the use- ful service of holding 15 pounds in the brake cylinder? A. Not only this, but the passage way out of the cas- ing to the atmosphere is so small that considerable time is consumed in discharging the entire brake cylinder through the small port. This renders the release of the brake much slower, and exerts a retarding effect which also gives more time for the auxiliary reservoir to recharge. Q. Is this small escape port in the cap, or cage, the same size for all retaining valves? A. No; it is 1-16 inch for retaining valves used on 6, 8 and loinch cylinders, and }i inch for 12, 14 and 16-inch cylinders. These port sizes give a restriction, which requires about 30 to 60 seconds for the full cylinder pressure to escape down to the amount limited by the weighted valve. Q. Describe the construction of the three position retaining valve. A. It has two separate weighted valves, one of the ordinary form., the other being of an inverted cup shape, resting upon the top of the ordinary weight. Q. How does this valve operate? A. When the handle points downward, the valve is inoperative, and brake cylinder pressure escapes freely to the atmosphere through the large release port of the valve. Q. When the handle is turned half way up, at an angle of 45 degrees, how does the valve operate? A. The large release port is cut off, and both weights now resist the escape of brake cylinder pressure through the retaining valve, and as their combined weights have 226 MODERN AIR BRAKE PRACTICE a, resistance equal to 50 pounds of pressure, that amount is retained in the brake cy Under. Q. Why is it necessary to retain such a high pressure ? A. Experience has proved it desirable, on high capacity steel cars, to hold this amount continuously in the brake cylinders in heavy grade service, on account of the low percentage of braking power on these cars when loaded. Q When the handle is turned up to horizontal posi- tion, how does the valve operate? A. The heel, or projection, on the handle strikes a pin which, in being forced upward against the inverted cup weight, lifts that weight from the top of the other weight, thus permitting the latter to perform its usual function of retaining 25 pounds in the brake cylinder. RETAINING VALVE DISORDERS. Q. Is the retaining valve of any decided advantage in driver brake operation? A. It would be were it not for the fact that driver brake packings generally leak badly, and the numerous connections in the brake cylinder pipe frequently become loose and cause leakage. With these avenues of escape for pressure, the retaining valve is unable to perform its intended function. The driver brake retaining valve has almost entirely given way to the combined automatic and straight air brake which overcomes this leakage difficulty. Q. If there is a steady leakage of pressure at the re- taining valve exhaust while brakes are released, should the trouble be looked for in the retaining valve? A. No ; the trouble will generally be found in the rub- ber seated emergency valve in the triple. EXAMINATION QUESTIONS AND ANSWERS 227 Q. If the retaining valve handle has been turned up in operative position, brakes then released, and after a few moments the handle is turned down and no air escapes, is the fault in the retaining valve? A. No; it is either in a leaky joint or connection in the pipe, or in the brake cylinder packing. Q. Should air refuse to pass through the retaining valve with handle turned down, and brake remain set, where should the trouble be looked for? A. At the exhaust port. It may be stopped up by accumulation of dirt, pipe scale, or cuttings. Some- times insects build and stop up the port. THE K TRIPLE VALVE. O. In what respect does the type K triple valve differ from the standard quick action triple? A. It has three additional features known as quick service, uniform release and uniform recharge. Q. Why are these added features necessary? A. To meet modern conditions of freight service. Q. Why is the older type (F-36 or H-49) triple valve not satisfactory on trains consisting of more than 50 cars? A. Being originally designed for trains of not more than 50 cars it is unable to handle the increased volume of air required on longer trains. Q. How are the F-36 and H-49 triple valves at present designated ? A. The H-i, and H-2 triples. Q. With the same discharge opening at the brake valve why do the type *'K" triple valves apply more promptly and uniformly than the old standard types? A. The Quick Service feature of the "K" valve makes « M0«» ... ..«. ,.„„„ a supplementary brake pipe reduction at each triple s^alve. Q. How is this supplementary or local brake pipe re- duction obtained? A. When a brake pipe reduction is made at the brake valve, the first triple valve moves to quick service posi- tion, in which position a port is open from the brake pipe to the brake cylinder, which permits the brake pipe air to flow to the brake cylinder, making a local brake pipe reduction which affects the next valve, causing a rapid serial application throughout the train. Q. Does air flow from the auxiliary reservoir to the cylinder at the same time it flows from the brake pipe to the cylinder ? A. Yes. The service port from the auxiliary reser- voir to the cylinder is open when the quick service port is open. Q. What controls the opening of the quick service port ? A. The triple valve slide valve, and graduating valve. Q. Is the quick service feature operative with short trains ? A. No. This feature automatically goes out of service when the brake pipe pressure is being reduced at the proper rate. Q. What increase of brake cylinder pressure is ob- tained by use of the quick service feature? A. About one pound higher equalization under nor- mal conditions of piston travel and cylinder leakage. O. What other advantages are obtained from the quick service feature in addition to the higher cylinder pressure ? A. The application of all brakes with light brake pipe li EXAMINATION QUESTIONS AND ANSWERS 229 reductions; time of application is reduced about one- half; also a uniform application is obtained throughout the train. Q. Is less air consumed in handling a train equipped with quick service triple valves than would be the case with valves not having this feature? A. Yes. A considerable portion of the brake pipe air which is ordinarily discharged to the atmosphere enters the brake cylinders, therefore not requiring as heavy brake pipe reductions to obtain the same cylinder pres- sure as would be the case where auxiliary reservoir air alone enters the cylinder, but chiefly because, for a given train and speed, the same stop can be made with a much lighter brake pipe reduction with the "K" valves, due to uniform application throughout the train. Q. Is the advantage of the quick service feature ob- tained where quick service triples are mixed in a train with triple valves not having this feature? A. Yes. The advantages obtained are in proportion to the number of quick service triple valves in the train. Q. Will the discharge of air from the brake valve ex- haust with a given reduction be as long with a train of quick service triple valves as would be the case if the train was equipped with triple valves not having the quick service feature? A. No. The time of discharge from the brake valve would be reduced about one-half. Q. How many service positions has the type "K" triple Valve? A. Two: Quick Service and Full Service positions. Q. From an external view what distinguishes the type **K" valve from other types? A. A lug or fin cast on the top of the valve body. 230 MODERN AIR BRAKE PRACTICE Q. What is the object o'f the Uniform Release feature of the ^'K" triple valve? A. To provide a uniform release of brake cylinder pressure through the entire train and prevent the severe shocks, and possible break-in-twos often experienced with a long train equipped with triple valves not having this feature. Q. When the brake valve is placed in release position in order to release the train brakes, on what portion of the train do the triple valves move to release position first? A. On the head end. Q. Why do the valves on the head end move to re- lease position before those on the rear end? A. Owing to the prompt rise in brake pipe pressure on the head end when the brake valve is placed in release position and the slow rise of pressure on the rear end. Q. What prevents the pressure from raising promptly on the rear of a long train if a high pressure exists in the main reservoir at the time the brake valve is moved to release position? A. The frictional resistance to the flow of air through the long brake pipe combined with its many bends makes it impossible to raise the pressure promptly on the rear end. Q. How many release positions has the type "K" triple valve? A. Two: Normal and Retarded Release. Q. How do these two positions differ, insofar as the release of brake cylinder pressure is concerned? A. In normal release position, the exhaust opening is large, which permits of a prompt fall of brake cylinder pressure; in retarded release position, the exhaust open- EXAMINATION QUESTIONS AND ANSWERS 231 ing is small, which restricts the fall of brake cylinder pressure. Q. What controls the movement of the valve to nor- mal or retarded release position? A. The rate of rise of brake pipe pressure as compared with that in the auxiliary reservoir. If this is slow the valve moves to normal release position; if quick, the valve moves to retarded release position. Q. Explain briefly the uniform release feature of the "K" triple valve. A. Connected to the auxiliary end of the triple valve body is a casing in which is a stem and spring so located as to stop the triple piston and slide valve in normal release position when the brake pipe pressure is raised gradually. However, if the rise in brake pipe pressure is sufficiently prompt to increase it materially above the auxiliary reservoir pressure the differential pressure thus set up will be sufficient to move the triple piston and slide valve to retarded release position, compressing the retarding spring. Q. What difference in pressure between the brake pipe and auxiliary reservoir is required to compress the retarding spring, and cause the valve to move to retarded release position? A. About three pounds. Q. In releasing the brakes on a fifty-car train or longer, with the brake valve held in release position, about how far back in the train will the valves move to retarded release position? A. About thirty cars immediately back of the engine. Q. Why will the valves beyond this point not go to retarded release position? A. Because with a long train it is impossible to raise 232 MODERN AIR BRAKE PRACTICE the brake pipe pressure three pounds above the auxiliary reservoir pressure for more than thirty cars back in the train. Q. If the head triple valves move to release first, why are not the head brakes released first? A. The restricted exhaust opening of the "K" valve in retarded release position causes the brake cylinder pressure to fall sufficiently slow as to permit the rear triples of a long train to move to normal release position and discharge the brake cylinder pressure to five pounds on the rear in approximately the same time the cylinder pressure on the head end is reduced "to five pounds. What other feature does the "K" triple valve possess that is valuable at the time brakes are being released? A. The uniform recharge feature. Q. What is meant by uniform recharge? A. The recharging of the auxiliary reservoirs on the head, and rear of the train at approximately the same rate. Q. Why is this necessary? A. To prevent the reapplication of the head brakes, when the brake valve is moved from release to running position, as would occur, if the head auxiliary reservoirs were overcharged. Q. If the feed grooves of triple valves in the trains are the same size, why will the head auxiliary reservoirs charge faster than the rear ones? A. When the brake valve is placed in release position, the brake pipe pressure on the head end is raised promptly above that in the auxiliary reservoirs, whereas the brake pipe pressure on the rear is raised slowly, this difference in brake pressure resulting in the head reser- voirs charging more promptly than those on the rear. EXAMINATION QUESTIONS AND ANSWERS 233 Q. How does the "K" triple valve permit a uniform recharge when the brake pipe pressure is higher on the head end than on the rear end? A. The charging ports and grooves are so arranged that with the triple valves in retarded release position (as would be the case where the brake pipe pressure is high), a small opening is had from the brake pipe to the auxiliary reservoirs ; when the valves are in normal re- lease position, a large opening is had from the brake pipe to the reservoirs. This difference in sizes of charging openings compensates for the difference in brake pipe pressure at the two ends of the train. Q. Is any other benefit obtained by retarding the re- charge of the head auxiliary reservoirs? A. Yes. It permits a greater volume of air to flow to the rear, insuring a higher pressure and a more prompt release of the rear brakes. Q. Does the retarded recharge feature interfere with the proper handling of trains on grades? A. No. The retarded release feature combined with the quick service feature more than compensates for the retarding of recharge on the head end, and the uniform recharge more evenly distributes the brake work on the train. Q. With all cars equipped with "K" triple valves, can the brakes on long trains be released at low speed with- out danger of a break in two. A. Yes. The retarded release feature operating on about thirty of the head brakes will be sufficient to keep the slack from running out. Q. If a number of "K" triple valves are located in the rear of a long train of old type of triple valves will 234 MODERN AIR BRAKE PRACTICE the slack run out on the head end due to the retarded release feature of the *'K" triple valves ? A. No. "K" triple valves on the rear of long trains do not go to retarded release position. Q. With "K" valves scattered through a train equipped with old type of triple valves, would the higher cylinder pressure obtained with the *'K" triple valves be sufficient to cause trouble? A. No. The ordinary variation in piston travel found on different cars in the train results in a greater differ- ence in cylinder pressure than would be had between the type *'K" triple valves and old type triple valves. Q. Will ''K" triple valves work in perfect harmony with old style triple valves? A. Yes. They not only work in harmony, but greatly improve the action of the older type. Q. How should a brake be bled off by hand if there is air pressure in the brake pipe ? A. The release valve on the auxiliary reservoirs should be held open only until the discharge of air is heard at the retaining valve. Q. What will be the effect if the release valve is held open after air commences to discharge from the retain- ing valve? A. The triple valve will move to retarded release posi- tion and be much slower in releasing the brake. Q. How should the brake be released by hand if there is no air in the brake pipe ? A. The release valve should be held open until all the air is exhausted from the brake cylinder. Q. Is there any difference in the emergency parts of a "K" triple valve as compared to the old type quick action triple valves? I I EXAMINATION QUESTIONS AND ANSWERS 235 A. No. All parts are the same and interchangeable. Q. How man}? sizes of "K" triple valves are there? A. Two: The K-i and K-2. Q. What sizes of brake cylinders are these used with? A. The K-i for 8-inch cylinder, and the K-2 for loinch cylinders. Q. Can the features of the type "K" valve be incor- porated in the H-i and H-2 valves? A. Yes. Q. How may the K-i triple valve be distinguished from the K-2 ? A. The K-I has two holes in the reservoir flange, while the K-2 has three. FULL RELEASE AND CHARGING POSITION. Q. Explain the flow of air through the triple valve, in full release and charging position. A. Air entering from the brake pipe flows through the cylinder cap and port to a chamber on the face of the triple piston; thence through the feed port to the slide valve chamber (which is always in free communication with the auxiliary reservoir). At the same time brake pipe air which has raised the check valve and filled that chamber, flows through the port in the body and valve seat and a port in the slide valve to the slide valve cham- ber until the auxiliary reservoir is charged equal to the brake pipe pressure. Brake cylinder air is now free to pass to the atmosphere. Q. What is the object of having two passages through which the auxiliary reservoir is charged ? A. As the K-2 triple valve is used with an auxiliary reservoir of suitable size for a lo-inch cylinder, it is so large that to charge it in proper time through a single 236 MODERN AIR BRAKE PRACTICE feed port "i" would require such port to be of consider- able size, which would permit of an appreciable amount of auxiliary air feeding back into the brake pipe when a brake pipe reduction was made. For this reason the feed port '*k" is made the same size in the K-i and K-2 triple valves. Q. With the feed port the same size in both the K-i and K-2 valves, why will the reservoirs charge uniformly when the valves are in retarded release position? A. When the valves are in retarded release position the auxiliary side of the piston comes in contact with the end of the slide valve bushing, making an airtight seal, except at one point where a small feed groove is cut in the piston to allow air to pass by the end of the slide valve bushing into the chamber and auxiliary reservoir. The size of this groove controls the charging of the auxiliary reservoirs when the valves are in retarded re- lease position. The feed groove in the piston of the K-2 valve is larger than in the K-i ; therefore both sizes of auxiliary reservoirs are charged in approximately the same time. Q. Is there any other difference between the K-i and K-2 valves? A. No ; in all other respects both valves are the same (except in size of parts and ports), therefore it will only be necessary in the following to consider the K-2 triple valve. Q. With the triple valve in full release position, and the brake pipe and auxiliary reservoir pressure equal what must be done to cause the valve to move to appli- cation position and apply the brake? A. The air pressure on the brake pipe side of the triple EXAMINATION QUESTIONS AND ANSWERS 237 piston must be reduced below that on the auxihary reser- voir side. Q. About how much lower must the brake pipe pres- sure be than the auxiliary reservoir pressure to cause the triple valve to move to application position? A. About two pounds, or just enough to overcome the friction of the slide valve on its seat, and the piston packing ring in its cylinder. QUICK SERVICE POSITION. Q. Explain the action of the triple valve as it moves from release position to quick service position. A. As the brake pipe pressure is reduced below auxil- iary reservoir pressure the triple piston moves to the right until the spider on the end of the piston stem en- gages the slide valve, this movement permitting the pis- ton to close the feed groove and move the graduating valve until it opens the service port in the top of the slide valve, and its cavity connects the two ports in the top of the slide valve ; the piston continues its movement carrying the slide valve until it is arrested by the gradu- ating stem, which is held in place by the compression of graduating spring. Two ports in the seat are in register with the ports in the slide valve. In this position of the valve auxiliary reservoir air flows through a port in the slide valve and the port in the seat to the brake cylinder. Q. In quick service position service port ''Z" in the slide valve is not in full register with brake cylinder port "r"; explain the reason for this. A. The opening as shown is sufficient to permit the air in the auxiliary reservoir to reduce by flowing to the brake cylinder as fast as the pressure is reducing in the brake pipe when the train is of considerable length. 238 .MODERN AIR BRAKE PRACTICE However, if the brake pipe is reduced more rapidly than that of the auxihary reservoir, as may be the case on short trains or trains having heavy brake pipe leakage, the auxiliary reservoir pressure would become sufficiently above that in the brake pipe as to cause the triple piston to slightly compress the graduating spring and move the slide valve to full service position. FULL SERVICE POSITION. J Q. Explain what takes place when the valve moves from quick service position to full service position. A. As the triple piston moves to the right, slightly compressing the graduating spring, it moves the slide valve until the quick service ports in the slide valve and the ports in the seat are no longer in communication, and the auxiliary service port in the slide valve is brought in full register with the brake cylinder port in the seat, permitting the auxiliary reservoir air to flow to the brake cylinder at the same rate that the brake pipe pressure is being reduced. Q. Does not air flow through the quick service ports when the valve is in full service position? A. No. As it requires a prompt fall in brake pipe pressure to cause the valve to move to full service posi- tion, the local brake pipe reduction obtained by the quick service ports is unnecessary, therefore this feature is automatically cut out. Q. Will the air that flows through the quick service ports to the chamber above the emergency piston develop sufficient pressure to force the piston down and cause the triple valve to operate in quick action ? A. No. The emergency piston is sufficiently loose in its cylinder to permit the air that flows through the EXAMINATION QUESTIONS AND ANSWERS 239 small quick service ports to pass readily around the pis- ton to the chamber and to the brake cylinder. Q. With the triple valve in quick service or full serv- ice position, how much air will flow from the auxiliary reservoir to the brake cylinder? A. That depends on the amount of reduction made in the brake pipe. When the discharge of air from the brake pipe ceases, the auxiliary reservoir pressure will continue to fall until the pressure on the auxiliary side of the triple valve piston is slightly below the pressure remaining on the brake pipe side, when the piston will move to the left, causing the graduating valve to close the auxiliary service port and quick service port in the slide valve. Q. As the triple piston moves to the left causing the graduating valve to close the service ports, why does it not move the slide valve to release position? A. The friction of the piston and graduating valve is much less than that of the slide valve, therefore the dif- ference in pressure that will move the piston and grad- uating valve will not move the slide valve, and the move- ment of the piston is arrested when the collar on its stem comes in contact with the slide valve. LAP POSITION. Q. What is meant by lap position ? A. It is a position of the valve where all ports are lapped ; that is, closed. Q. Is there any difference between quick service lap and full service lap positions? A. Yes. In quick service lap position the quick serv- ice ports in the slide valve are still in register with the quick service ports in the seat, whereas in full service 240 MODERN AIR BRAKE PRACTICE lap these ports are not in register. As the sHde valve does not move, when the triple goes to lap position, it will remain in full service position, but with the graduat- ing valve moved back so as to blank the ports in slide valve. Q. If a further brake pipe reduction is made, what action will be obtained from the triple valve? A. It will move to the position it was in before it moved to *'lap." Q. What is the total number of pounds reduction in brake pipe pressure required to fully apply the brake? A. Twenty pounds with proper brake cylinder piston travel (eight inches). Q. Why will a reduction of twenty pounds in brake pipe pressure fully apply the brake ? A. Auxiliary reservoirs are so proportioned to the sizes of the brake cylinders that, with an initial pressure of seventy pounds in the brake pipe and auxiliary reser- voirs, the pressure in the latter will equalize into brake cylinders at fifty pounds. Q. What will be the effect if a reduction of more than twenty pounds is made in the brake pipe ? A. It will be a waste of brake pipe air. The triple piston will move the graduating stem, compress its spring and carry the slide valve to emergency position, but no greater brake cylinder pressure will be obtained as the auxiliary reservoir and brake cylinder pressures are al- ready equalized. Q. With the triple valve in application or lap position, what must be done to cause it to move to release posi- tion? A. The brake pipe pressure must be raised sufficiently to overcome the friction of the piston slide valve. EXAMINATION QUESTIONS AND ANSWERS 241 Q. Explain the action of the triple valve when the brake pipe pressure acting on the piston is great enough to overcome the friction of piston and slide valve. A. The piston will move to the left carrying with it the slide valve until the end of the piston and stem and slide valve comes in contact with the retarding stem which will arrest their movement and stop them in full release and charging position. The flow of air through the triple valve in this position has been explained here- tofore. RETARDED RELEASE POSITION. Q. What must be done to cause the triple valve to move to retarded release position? A. The air pressure on the brake pipe side of the pis- ton must be raised above the pressure on the auxiliary reservoir side of the piston at least three pounds more than that required to overcome the friction of the piston and slide valve. This higher brake pipe pressure will then be sufficient to move the retarding stem and com- press its spring until the piston comes in contact with the end of the slide valve bushing. Q. Explain the flow of air through the triple valve in retarded release and charging position. A. Brake pipe air, which is always present in the chamber on the right of the triple piston, flows through the feed groove in the bushing over the top of piston and through a small groove cut in the piston seal (at the point in contact with the slide valve bush), to slide valve cham- ber and the auxiliary reservoir. The exhaust cavity in the slide valve now being in register with the brake cylinder port, its tail port in register with the exhaust port; brake cylinder air will flow through port, cavity 242 MODERN AIR BRAKE PRACTICE *.U^ "1 and restricted passage to the tail port, thence through the exhaust port to the atmosphere. Q. Is the feed groove in the seal of the piston the same size as the feed groove in the bushing? A. No. This groove is smaller in order that the charging of the auxiliary reservoir will be slower when the triple valve is in retarded release position, than when in full release position. EMERGENCY POSITION. Q. What must be done to cause the triple valve to operate in quick action? A. AVhen the brake pipe pressure on the right of the piston is reduced quickly, and considerably below the auxiliary reservoir pressure on the left, the piston moves quickly to the right, forcing back the graduating stem and compressing its spring, until the pjston seats firmly against the cylinder cap gasket. As the slide valve moves with the piston, it opens the cylinder port in the slide valve seat and allows air from the auxiliary reservoir to flow to the top of the emergency piston, forcing it down- ward and opening the emergency valve. The pressure being thereby instantly reduced, allows brake pipe air to raise the check valve and flow rapidly through to the brake cylinder until brake cylinder and brake pipe pres- sures nearly equalize, when the check valve is forced to its seat by its spring, preventing the brake cylinder air from flowing back into the brake pipe. At the same time the emergency port in the slide valve, being in register with the brake cylinder port, permits auxiliary reservoir air to flow to the brake cylinder, but the size of these ports is such that comparatively little air gets through them before the brake pipe has stopped venting into th^ EXAMINATION QUESTIONS AND ANSWERS 243 brake cylinder. The emergency valve being held open by the emergency piston, will return to its seat when the auxiliary and brake cylinder pressures have nearly equalized due to the pressure of the check valve spring under the emergency valve. Q. What pressure will the auxiliary reservoir and brake cylinder equalize at with an emergency applica- tion? A. With an initial pressure of seventy pounds in the brake pipe and auxiliary reservoir, the auxiliary reser- voir and brake cylinder will equalize at approximately sixty pounds. Q. If one triple valve operates in quick action, does the reduction it makes in brake pipe pressure apply other brakes in quick action? A. Yes. Each valve causes the next to apply, thus giving a quick and full application of all the brakes throughout the train. Q. How long a time does it require to apply the brakes in quick action throughout a fifty-car train? A. About three seconds. Q. Is the release after an emergency application ac- complished the same as after a service application? A. Yes. But it requires a longer time owing to the higher brake cylinder and auxiliary reservoir pressure and the lower brake pipe pressure. Q. What is the object of having the triple valve piston make a joint on the cylinder cap gasket when in emer- gency position? A. To prevent auxiliary reservoir air from leaking into the brake pipe past the piston. Q. Is the graduating spring of the same strength as the retarding spring? 244 MODERN AIR BRAKE PRACTICE A. No. The retarding spring is heavier and stronger than the graduating spring. MANIPULATION. Q. Are any special instructions required by engineers regarding the handling of trains partially or wholly equipped with the K triple valve? A. No; the automatic brake valve should be handled as good practice requires with the H triple valve. Q. What important detail should be observed when making the terminal tests ? A. The results should be carefully checked by noting how the brakes hold in the first running application, and the engineer should be governed accordingly in subse- quent applications. Q. What rule should be observed relative to release? A. Before attempting to release, have ample excess pressure for the length of the train, and in releasing leave the automatic brake valve handle in release position until the rear brakes have had time to release. AUTOMATIC SLACK ADJUSTER. Q. What is the function of the automatic slack ad- juster? A. It maintains a constant predetermined piston travel, and thus insures that each car performs its share of the work. Q. Why is it necessary to take up the slack in the brake rigging? A. On account of the wear of the brake shoes. Q. Suppose two freight cars, with 8-inch brake cylin- EXAMINATION QUESTIONS AND ANSWERS 245 ders and the same levers, be taken with 5 and 9 inches piston travel respectively. Charge them to 70 pounds pressure and then make a 7-pound train pipe reduction. How would the piston pressures of the two brake cylin- ders compare? A. The piston with 5 inches travel would have about 1,150 pounds total pressure, nearly half of a full serv- ice application, while the piston with 9 inches travel would have a total pressure of only about 400 pounds — a little more than one- third of the other. Q. With two cars braking with these different f 01 ces, due to unequal piston travel, what would be the piston pressures if a second or further 7-pound train pipe re- duction were made? A. The one with 5 inches travel would be fully ap- plied, at about 2,600 pounds, and the one with 9 inches travel would be about three-fifths set, at about 1,500 pounds. Q. Suppose a further reduction of 7 pounds, 21 in all, be made? A. This last reduction would be wasted on the brake with 5 inches piston travel, as it was already fully ap- plied, and the one with 9 inches piston travel would now be about as heavily applied as we could get it ; but the total pressure in the cylinder of the latter would be only about 2,300 pounds, or approximately 90 per cent, of the other car. Q. Then the car with 9 inches piston travel would have a much inferior brake, due to the simple fact that it has a too long piston travel ? A. Yes ; it is only 90 per cent, as efficient on the third 7-pound train pipe reduction as the other one, only 60 246 MODERN AIR BRAKE PRACTICE per cent, on the second 7 pounds, and only 30 per cent, as efficient on the first 7-pound reduction. Q. How does the automatic adjuster do its work? A. It adjusts the piston at its proper running or work- ing travel, regardless of the lost travel, or whether the car be high-leveraged or low-leveraged. Thus, if all cars in a train were equipped with automatic slack adjusters, the travel of all pistons would be uniform when brakes were set to slow down or stop the train. The same brake cylinder pressure would be had on all the cars at each reduction. CONDUCTOR S VALVE. Q. What is the conductor's valve and what is it for? A. It is simply an additional stop cock connected with the train pipe, and by opening it the conductor can apply the brakes in case of emergency. Q. How is it connected? A. A branch pipe connecting with the train pipe passes up through the body of the coach, usually in the toilet room, and on this branch pipe is placed the stop cock, or valve. Q. How should the conductor's valve be handled? A. If it is desired to make a gradual stop the valve should be opened gradually, but for a quick stop it must be opened quickly and left open until the train is stopped. TYPE L TRIPLE VALVE. Q. What is the Schedule LN Equipment? A. It is an improved brake for high speed passenger service. EXAMINATION QUESTIONS AND ANSWERS 247 Q. In what respect does it differ from the old standard high speed brake equipment? A. It has additional features necessary for the proper braking of modern trains. Q. What features has the LN Equipment that were not obtained with the old standard high speed brake equipment ? A. Quick recharge of the auxiliary reservoir, quick service application, graduated release and high emergency brake cylinder pressure. Q. In a general way how does this schedule differ from the old high speed brake schedule? A. It has a new type of triple valve and an additional reservoir. Q. What is the designation of the triple valve? A. Type L. Q. Is a high speed reducing valve used with the LN schedule ? A. No ; a safety valve, which is a part of the L triple valve, takes the place of the high speed reducing valve. Q. Does the type L, triple valve operate in harmony with the older standard types of passenger triple valve? A. Yes ; it has all the features of the old types of triple valves in addition to the new features. Q. Are all of the improved features, such as quick re- charge, quick service application, graduated release and high emergency brake cylinder pressure, obtained from the triple valve alone? A. No; they are obtained through the combination of the improved triple valve and the additional reservoir. Q. What is this reservoir called? A. Supplementary reservoir. 248 MODERN AIR BRAKE PRACTICE Q. What is the size of the supplementary reservoir as compared with the auxiliary reservoir? A. It is approximately two and one-half times the size of the auxiliary reservoir. Q. Is the supplementary reservoir volume always con- fined to one reservoir? A. No ; where space under the car does not permit of using one large reservoir, two supplementary reservoirs having an equivalent capacity are sometimes used. Q. In addition to the improved operating feature of the L triple valve, has any other improvement been made ? A. Yes ; this valve is of the pipeless type, which per- mits it to be applied or removed from the brake cylinder head without disturbing any of the pipe joints. Q. What improved features are derived by the use of the LN schedule? A. (a) A moderate brake cylinder pressure obtained from light brake pipe reductions. (b) Heavy service reductions can be made quickly without liability of obtaining quick action. (c) The air pressure can be graduated into or out of the brake cylinder. (d) The auxiliary reservoir re-charges quickly so as to permit of a prompt response to success- ive applications. (e) A high brake cylinder pressure can be obtained quickly from an emergency application. Q. Name the different parts of the complete LN brake schedule. A. Type L triple valve with safety valve; type N brake cylinder with pressure head arranged for all pipe connections ; auxiliary reservoir and its drain cock ; sup- EXAMINATION QUESTIONS AND ANSWERS 249 plementary reservoir and its drain cock ; branch-pipe cut- out cock ; conductor's valve ; angle cocks ; air hose and brake pipe fixtures ordinarily found on a car ; also the automatic slack adjuster. Q. What is the purpose of the cut-out cock? A. It is furnished with this schedule in order that the supplementary reservoir can be cut out during the transi- tion period. Q. How many sizes of L triple valves are there? A. Three; designated as follows: L-i, L-2, and L-3. O. What sizes of brake cylinders are these valves adapted for? A. L-i is for 8-in. and lo-in. brake cylinders ; L-2 for i2-in. and 14-in. ; and L-3 for i6-in. and i8-in. brake cylinders. FULL RELEASE AND CHARGING POSITION. Q. Explain the flow of air through the triple valve in full release and charging position. A. Air from the brake pipe enters the triple valve and flows through into the chamber on the face of the triple valve piston ; thence through feed groove to chamber R and the auxiliary reservoir. Brake pipe air also raises the check valve and flows through ports into the aux- iliary reservoir. A port in the slide valve is now in reg- ister with the supplementary reservoir into which air also passes. In this way both auxiliary and supplemen- tary reservoirs are charged at the same time with the same pressure. At the same time air from the brake cylinder entering the triple flows through a port in the body, and valve seat, to a port in the slide valve, thence through a cavity in the graduating valve to another port in the slide valve, and thence to the atmosphere. 250 MODERN AIR BRAKE PRACTICE QUICK SERVICE POSITION. Q. Explain the operation and flow of air through the triple valve in qiuck service position. flj A. With the air pressure equal in the brake pipe, aux- iliary reservoir and supplementary reservoir, a service reduction in the brake pipe reduces the pressure on the face of triple valve piston below that in the auxiliary reservoir on the opposite side of the piston. The higher auxiliary reservoir pressure, therefore, forces the piston to the left, which carries with it the graduating valve. This movement of the piston closes the feed port in the bushing and permits the graduating valve to close the ports on the upper side of the slide valve, which closes the communication between the brake pipe and the aux- iliary reservoir and supplementary reservoir; also clos- ing the exhaust passage from the brake cylinder to the atmosphere. This same movement opens another port in slide valve and connects two ports through the small cavity in graduating valve. At this time the spider or lugs on the end of the piston stem engage the end of the slide valve, which is carried to the left with the graduat- ing valve until the piston comes in contact with gradu- ating sleeve, which causes it to stop in quick service po- sition. Q. What particular benefit is obtained by the flow of air from the brake pipe to the brake cylinder through the quick service ports just mentioned? A. The brake pipe air assists in moving the brake cylinder piston beyond the leakage groove, and at the same time the local reduction made in brake pipe pres- sure by the triple valve results in the service reduction EXAMINATION QUESTIONS AND ANSWERS 251 being quickly and uniformly transmitted from car to car throughout the train. Q. Is the amount of air vented from the brake pipe to the brake cylinder through the quick service ports very great ? A. No. Q. Why? A. First — because the quick service ports and passages are small, and second — as the piston and slide valve move toward full service position, the quick service port is re- stricted and is completely closed just before the service port in the slide valve is fully opened. Q. What governs the amount of opening, and time that the quick service port remains open ? A. The rate of reduction in brake pipe pressure as compared with that of the auxiliary reservoir. Q. If the brake pipe pressure is reduced quickly, as would be the case with a short train, what will be the result ? A. The higher auxiliary reservoir pressure will move the piston and slide valve promptly to full service posi- tion, thereby automatically cutting out the quick service feature when it is not needed. Q. What will result from a slow brake pipe reduction as with long trains? A. A slow brake pipe reduction will cause a partial opening of the service port sufficient to reduce the aux- iliary reservoir pressure as quickly as the brake pipe pressure is being reduced ; therefore, with this port only partly open, a balance of pressure is maintained on the two sides of the triple valve piston. Q. With the triple valve in quick service position and air flowing from the brake pipe and auxiliary reservoir to 252 MODERN AIR BRAKE PRACTICE the brake cylinder, why does not the valve remain in this position until the brake is fully applied? A. The triple valve will remain in quick service posi- tion as long as air is being discharged from the brake pipe at the brake valve; when the reduction is stopped, the triple valve will move to quick service lap position, due to the fact that the service port in the slide valve is larger than the quick service port. Q. With the triple valve in quick service lap position, what action will take place if a further reduction is made in brake pipe pressure? A. If the brake pipe pressure is reduced slowly, the triple valve piston will again move to the left, carrying with it the graduating valve and opening the service port, and the quick service ports as before mentioned. Q. Will the air obtained from the brake pipe through the quick service ports cause a considerably higher brake cylinder pressure when the brake is fully applied? A. No ; the gain in cylinder pressure is approximately one pound above that which would be obtiained without the use of the quick service feature. FULL SERVICE POSITION. Q. What causes the triple valve to move to full serv- ice position? A. When the pressure in the brake pipe is being re- duced rather promptly, as would be the case with a short train or a train having considerable brake pipe leakage, the triple valve piston will move to the left, coming in contact with the graduating sleeve, moving it slightly and compressing the graduating spring. By this move- ment the service port in the slide valve is brought in full register with the brake cylinder port in the seat, permit- EXAMINATION QUESTIONS AND ANSWERS 253 ting auxiliary reservoir pressure to flow to the brake cylinder at the same rate at which the brake pipe pres- sure is being reduced. Q. If the brake pipe reduction is less rapid than is re- quired to fully open the port, what takes place? A. This port is only partially opened, but sufficient to preserve a balance between the pressures on the two sides of the triple valve piston. Q. How much air will leave the auxiliary reservoir and flow to the brake cylinder when the triple valve moves to full service position? A. Approximately the same reduction in pressure as was made in the brake pipe. Q. Is not the safety valve connected with the brake cylinder in all positions of the triple valve? A. No; it is connected in all, except emergency posi- tion, as will be explained later. Q. What pressure is the safety valve set for? A. Sixty-two pounds. Q. As this valve is connected to the brake cylinder during service operation of the triple valve, does it not answer the same purpose as the high speed reducing valve ? A. Yes; it limits the maximum pressure that can be obtained in the brake cylinder from service applications to an amount not liable to cause wheels to slide. Q. When the triple valve is in quick service or full service positions, does not air from the supplementary reservoir flow to the brake cylinder in addition to the auxiliary reservoir air? A. No. Q. Why? A. The supplementary reservoir is cut off when the ^4 MODERN AIR BRAKE PRACTICE triple valve is in quick service, full service or lap posi tions ; therefore, this reservoir pressure will be retained. LAP POSITION. Q. What will cause the triple valve to move from service position to lap position? A. After sufficient brake pipe reduction has been made to produce the desired application, and the brake valve handle is placed in lap position, a further escape of air from the brake pipe is prevented. When the flow of air from the auxiliary reservoir to the brake cylinder has reduced the pressure on the auxiliary side of the piston slightly below that remaining on the brake pipe side, the greater pressure on the brake pipe side, assisted by the graduating spring, will move the piston and graduating valve to service lap position. Q. As the triple valve piston and graduating valve move from service position to service lap position, what prevents the piston from continuing its movement to release position? A. As the triple valve piston and graduating valve move to service lap position, the shoulder on the stem of the piston comes in contact with the end of the slide valve. The slightly higher pressure acting on the brake pipe side of the piston, which was sufficient to move it and the graduating valve, is not sufficient to overcome the added resistance of the slide valve and the parts re- main in the position shown. Q. With the triple valve in service lap position, are there any ports or passages open? A. No ; except that the safety valve is still in register with the brake cylinder. EXAMINATION QUESTIONS AND ANSWERS 255 Q. Is there any difference between quick service lap and full service lap? A. Yes. The position of the slide valve is not the same as in quick service position. Q. A'fter the triple valve has moved to lap position, following a service reduction, what parts move on a further brake pipe reduction? A. The piston and graduating valve when the brake pipe pressure is reduced at approximately the same rate as the first reduction. Q. With the triple valve in service lap position, what must be done to cause the valve to move to release posi- tion? A. The pressure in the brake pipe must be raised higher than the pressure in the auxiliary reservoir. Q. How can the brake pipe pressure be made greater than the auxiliary reservoir pressure? A. By placing the engineer's brake valve in running or release position, and permitting air to flow from the main reservoir to the brake pipe, or by opening the drain cock on the auxiliary reservoir. RELEASE POSITION. Q. Explain the action of the triple valve and the flow of air through it when moved from service lap position to release position. A. When the brake pipe pressure is raised above that in the auxiliary reservoir, the triple valve piston will move to the right, carrying with it the slide valve and graduating valve to full release and charging position. In this position the air in the brake cylinder is exhausted through the slide valve, graduating valve and passage to the atmosphere. At the same time the auxiliary reser- 256 MODERN AIR BRAKE PRACTICE voir is being re-charged from the brake pipe through the feed groove and ports, as previously described. The air in the supplementary reservoir which remained at its initial pressure when the triple valve moved to service position will now flow into the auxiliary reservoir and help re-charge it, resulting in a quick re-charge. Q. What is the benefit of having the auxiliary reser- voir quickly re-charged? A. It insures an immediate response of the triple valve to a brake pipe reduction, should it be necessary to make a second brake application. Q. What must be done to insure that the triple valve will move to full release position and remain there, ex- hausting all air from the brake cylinder ? A. The brake pipe pressure must be fully restored and the auxiliary reservoir, and supplementary reservoir will be fully re-charged. Q. What will be the result if only sufficient air is ad- mitted to the brake pipe, to move the triple valve to re- lease position, and the brake valve handle is then moved to lap position? A. The flow of air from the supplementary reservoir to the auxiliary reservoir continuing after the rise in brake pipe pressure has ceased, will raise the pressure on the auxiliary reservoir side of the triple valve piston slightly above that on the brake pipe side, which will cause the piston and graduating valve to move to gradu- ated release lap position. Q. What ports are closed when the piston and gradu- ating valve move to graduated release lap position? A. The graduating valve closes the exhaust port thus preventing further flow of air from the brake cylinder to the atmosphere. EXAMINATION QUESTIONS AND ANSWERS 257 Q. How much air will be retained in the brake cylin- der when the triple valve moves to graduated release lap position ? A. This will depend upon the original amount of air pressure in the brake cylinder ; also the amount that was permitted to escape when the triple valve was in release position. Q. When the triple valve moves to graduated release lap, does the slide valve move? A. No ; only the triple valve piston and graduating valve. Q. With the triple valve in graduated release lap, what must be done to cause it to move to release posi- tion? A. The brake pipe pressure must again be raised above that in the auxiliary reservoir, as previously de- scribed. Q. Can more than one graduation of the triple valve be had? A. Yes ; the brake cylinder pressure can be reduced by a series of steps or graduations until the brake pipe pressure has been fully restored and the exhaust of air from the brake cylinder completed. Q. What governs the amount of reduction in brake cylinder pressure during graduations? A. The amount of air pressure which has been restored in the brake pipe. Q. Is the re-charge of the auxiliary reservoir in- fluenced by the rise in brake pipe pressure? A. Yes ; the re-charge of the auxiliary reservoir is in proportion to the rise in brake pipe pressure. 258 MODERN AIR BRAKE PRACTICE EMERGENCY POSITION. . Q. With the triple valve in release position, and the auxiliary reservoir and supplementary reservoir charged, what must be done to cause the valve to move to emer- gency position? A. The brake pipe pressure must be reduced quickly or more rapidly than the auxiliary reservoir pressure can flow through the service ports of the triple valve, which will result in the piston being forced quickly to the left, its full stroke, moving with it graduating sleeve, and com- pressing graduating spring. Q. Explain the flow of air through the triple valve when in emergency position. A. Air from the auxiliary reservoir enters the brake cylinder through a port in the slide valve and passage. Another port in the slide valve seat is uncovered by the end of the slide valve, admitting air from the auxiliary reservoir, through this port to the top of the emergency piston, forcing it down, which unseats the rubber-seated emergency valve. This permits brake pipe air to lift the check valve and flow through to the brake cylinder. At the same time a port in the slide valve registers with an- other port in the seat, thus allowing air from behind the by-pass piston to flow to the brake cylinder, in which there is no pressure at this instant. The by-pass piston and valve are forced to the left by auxiliary reservoir pressure acting on the right side of the piston. Air in the supplementary reservoir then flows past the by-pass valve into the passage leading to the auxiliary reservoir, thereby increasing the volume of air available three and one-half times the size of the volume used in service applications. Air from the supplementary reservoir con- tinues to flow to the auxiliary reservoir until the pres- EXAMINATION QUESTIONS AND ANSWERS 259 sure in the latter reservoir, and the pressure in the brake cyHnder nearly equals the pressure remaining in the supplementary reservoir, when the by-pass valve returns to its seat, and closes communication between the two reservoirs. Q. What pressure will thus be obtained in the brake cylinder ? A Pressure in the brake cylinder will rise to within a few pounds of the maximum brake pipe pressure. Q. With the brake fully applied in emergency posi- tion will not the air in the brake cylinder reduce through the safety valve? A. No ; for the reason that there is no communication between the brake cylinder and the safety valve during an emergency application. SAFETY VALVE FOR L TRIPLE. Q. What is the function of the safety valve ? A. To prevent abnormal brake cylinder pressure dur- ing service applications of the brake. Q. When is the safety valve in connection with the brake cylinder? A. At all times, except when the triple valve is in emergency position. Q. How many adjustments has the safety valve? A. Two; maximum and minimum. Q. Explain the action of the safety valve. A. As air from the safety valve port in the triple valve enters the chamber below the safety valve, and its pres- sure becomes sufficient to overcome the tension of the valve spring the valve is moved upward closing the up- per ends of the ports in the valve bushing, and opening the chamber to the atmosphere through ports in the body, 260 MODERN AIR BRAKE PRACTICE thereby permitting the surplus air to escape. As the air pressure under the valve decreases, the tension of the spring forces the valve downward which action restricts the opening through the ports leading to the atmosphere, and also opens the ports through the bushing thus per- mitting air to enter the spring chamber above the valve, and this pressure added to the tension of the spring forces the valve to its seat quickly. As the chamber above the valve is open to the atmosphere at all times through small ports in the body, the air which has en- tered will escape after the valve is again seated. This action causes the valve to open, and close quickly with a pop action. Q. What is, the function of the exhaust regulating ring? A. To regulate the size of opening through the ports in the valve body. Q. Why is such regulation necessary? A. To control the range between opening and clos- ing of the safety valve. Q. What is the purpose of the lock ring? A. To hold the exhaust regulating ring securely in its proper position. Q. How is the safety valve adjusted? A. By means of the regulating nut on top of the spring. Q. How is this nut secured in place? A. By the cap nut. Q. What pressure should this safety valve be adjusted to open at? A. Sixty-two pounds. Q. At what pressure should it close? A. Fifty-eight pounds. EXAMINATION QUESTIONS AND ANSWERS 261 Q. How is the range between opening and closing regulated ? A. By screwing the regulating ring up or down until the exhaust ports have the proper area of opening to cause the valve to close at fifty-eight pounds. TRIPLE VALVE DISORDERS AND REMEDIES THEREFOR. Q. How often should a triple valve be cleaned? A. Once in three months. Q. What kind of lubricant should be used? A. A special lubricant made for the purpose. Q. What method should be pursued in the cleaning and repair of triple valves? A. They should be removed from the cars, and the work done in the shop. Q. Before applying a triple valve to a brake cylinder what should be done? A. The piping should be thoroughly hammered and blown out in order to remove all scale and foreign mat- ter. Q. In applying a triple valve to a brake cylinder, should the gasket be placed on the brake cylinder head or on the face of the triple valve ? A. On the face of the triple valve in all cases. Q. Should the safety valve be cleaned and tested when the triple valve is cleaned and tested? A. Yes; and the safety valve strainer should also be cleaned. O. Should the operating parts of the safety valve be lubricated ? A. No. Q. What is the most prolific cause of disorders in a triple valve? 262 MODERN AIR BRAKE PRACTICE -^-ja A. Dirt or foreign matter getting into the triple valve or the valve becoming dry. Q. What will cause a blow from the exhaust port of the triple valve? A. A leaky slide valve, leaky graduating valve, leaky emergency valve, leaky check valve case gasket or a leaky triple valve body gasket. Q. What air is escaping to the atmosphere when a blow exists at the triple valve exhaust port? A. Brake pipe or auxiliary reservoir air, depending on what particular part of the valve is leaking. Q. Name the different parts that would cause a leak from the auxiliary reservoir. A. The slide valve, graduating valve, or body gasket. Q. What parts, if defective, would cause a brake pipe leak? A. The emergency valve rubber seat or the check valve case gasket. Q. How can the source of leakage in triple valves be determined without removing the valve from the car ? A. By cutting out the brake. If the brake applies and the blow stops, it indicates a leak from the brake pipe. If the blow continues and the brake does not apply, it indicates a leak from the auxiliary reservoir. Q. Will a leak from the brake pipe to the atmosphere through the triple valve when in release position cause a blow when the brake is applied? A. No; with the brake applied, the exhaust port is closed. Q. If a blow at the triple valve exhaust port is due to an auxiliary reservoir leak, will the blow continue after the brake is applied? A. That depends on what part of the triple valve is EXAMINATION QUESTIONS AND ANSWERS 263 defective. A leaky slide valve will usually cause a blow when the slide valve is in either release or application position. This might also be true of the graduating valve, while a leaky body gasket will only cause a blow when the triple valve is in release position. Q. What is the effect of a leak by the emergency valve or check valve case gasket ? A. It is a waste of brake pipe air when the brake is not applied. When the brake is applied it causes the brake cylinder pressure to build up or equalize with the brake pipe pressure, which, with light application, may result in giving greater braking power than is desired. Q. What is the effect of a leak from the auxiliary res- ervoir ? A. It is a waste of air and tends to release the brake after it has been applied. Q. Why will not a leaky body gasket cause a blow from the exhaust port when the triple valve is in appli- cation position? A. In this position the exhaust port is closed. Such air as may leak by the gasket will flow to the brake cylinder. Q. What is wrong with a triple valve if a buzzing or humming sound is heard within the valve after the aux- iliary reservoir is charged? A. This is due either to a leaky emergency valve or leakage from the auxiliary or supplementary reservoirs. Q. What is the usual effect if the triple valve becomes dry and gummy? A. It tends to destroy the sensitiveness of the valve to graduated applications and release. Q. What is the cause of a triple valve operating in quick action during service brake applications? 264 MODERN AIR BRAKE PRACTICE A. The triple valve may be dry or gummy, or the brake pipe pressure reduces through a leakage at too rapid a rate. Q. Would a weak or broken graduating spring cause a triple valve to operate in undesired quick action? A. It may and may not, depending entirely on the con- dition of the triple valve and the rate of brake pipe re- duction. Q. What is the effect if the triple valve piston packing ring is not a good fit in its cylinder ? A. It will allow air from the brake pipe to pass by the piston into the auxiliary reservoir and may cause the brake to fail to release. Q. What is the effect if the triple valve piston does not make a good joint against the cylinder cap gasket when in emergency position? A. In order for the piston to reach the gasket it is necessary to have the brake pipe pressure below that in the auxiliary reservoir; therefore, if a good joint is not made, auxiliary reservoir air can leak by the piston into the brake pipe. Q. What will result from check valve leakage with the brake applied? A. It will permit the brake cylinder and auxiliary res- ervoir air to leak back into the brake pipe whenever the brake pipe pressure is reduced below an equalized pres- sure in the brake cylinder and auxiliary reservoir, re- gardless of whether the brake has been applied in serv- ice or emergency. Q. Is check valve leakage as detrimental with the L triple valves in emergency applications as with the older types of triple valves? A. No ; owing to the great volume of air in the com- EXAMINATION QUESTIONS AND ANSWERS 265 billed reservoirs, it would take considerable time and leakage to make any material reduction in the reservoir pressure. Q. What would be the effect of a leak by the by-pass valve ? A. It would permit supplementary reservoir air to flow to the auxiliary reservoir during service applications and might result in a heavier brake application than was de- sired during light applications. Q. How can the by-pass valve be tested for leakage? A. With the brake pipe, auxiliary reservoir and sup- plementary reservoir charged to 70 pounds, the brake pipe pressure should be reduced 20 pounds, which will cause equalization between the auxiliary reservoir and brake cylinder at about 50 pounds. Brake cylinder pres- sure should then be noted and, if it increases, the in- crease is due to leakage by the by-pass valve into the aux- iliary reservoir and brake cylinder. Q. When quick action triple valves have a continu- ous blow from the exhaust port, how can it sometimes be stopped ? A. By jarring the triple valve slightly near the emer- gency valve. Should this not stop the blow, apply the brake in quick action by parting the hose and opening the angle cock quickly, then release the brake and re- peat the operation if necessary. This may dislodge the dirt and allow the emergency valve to seat properly. Q. Should neither of these remedies prove effective, what should be done? A. The brake should be cut out and the auxiliary res- ervoir and supplementary reservoir drain cocks opened and left in that position. 266 MODERN AIR BRAKE PRACTICE Q. If the triple valve fails to graduate the release of the brake, what is the cause? A. A dry or gummy valve or leakage from the sup- plementary reservoir. OPERATING THE LN EQUIPMENT. Q. Are any special instructions required for handling a train in which are a few cars equipped with LN equip- ment and the remainder old style brake equipment? A. No; the brakes should be handled in the ordinary way. Q. During a service application, will the blow from the brake valve exhaust be as long if a number of LN equipments are in the train? A. No ; it will be shorter from the fact that a portion of the brake pipe air is flowing to the brake cylinders through the quick service ports of the L triple valves. Q. What is the total number of pounds reduction in brake pipe pressure required to fully apply the brake when 70 pounds brake pipe, auxiliary and supplemen- tary reservoir pressure is carried? A. About 20 pounds with proper brake cylinder piston travel (8 inches). Q. Why will a reduction of 20 pounds in brake pipe pressure fully apply the brakes? A. Auxiliary reservoirs are so proportioned to the sizes of the brake cylinders that with an initial pressure of 70 pounds in the brake pipe, and reservoirs, the pres- sure in the auxiliary reservoir will equalize into the brake cylinder at about 50 pounds. Q. What will be the effect if a reduction of more than 20 pounds is made in the brake pipe? A. It will be a waste of air. The triple valve piston EXAMINATION QUESTIONS AND ANSWERS 267 will move the graduating stem sleeve compressing the graduating spring and carry the slide valve to emergency position, but no greater brake cylinder pressure will be obtained, as the auxiliary reservoir and brake cylinder pressures are already equalized. Q. When the triple valve moves to emergency position from an over brake pipe service reduction, does not the supplementary reservoir air flow to the auxiliary reser- voir? A. No; as the by-pass valve does not operate in this case. Q. Is it more difficult to release a brake after the brake pipe pressure has been reduced below equalization than would be the case if the brake pipe and auxiliary reser- voir pressures were equal? A. Yes ; as it will be necessary to raise the brake pipe pressure up to that in the auxiliary reservoir in addi- tion to the added amount required to overcome the fric- tion of the triple valve piston and slide valve. Q. Is it more difficult to release the brake after an emergency application than after a service application? A. Yes ; with a full service application about 50 pounds would remain in the auxiliary reservoir, which would have to be overcome when moving the triple valve to re- lease position; whereas, after an emergency application, the auxiliary reservoir pressure, being considerably higher, would necessarily require a much higher brake pipe pressure to move the triple valve to release position. Q. Can the release of air from the brake cylinder be graduated after an emergency application? A. No. Q. Why? 268 MODERN AIR BRAKE PRACTICE A. Because the auxiliary reservoir and supplementary reservoir pressures are equal. Q. If one triple valve operates in quick action, does the reduction it makes in brake pipe pressure apply other brakes in quick action? A. Yes ; each valve causes the next to apply, thus giv- ing a quick and full application of all the brakes through- out the train. Q. If either 90 or no pounds brake pipe and auxiliary reservoir pressure is carried, how much of a reduction in brake pipe pressure is required to raise the brake cylin- der pressure up to the adjustment of the safety valve? A. About 25 pounds. Q. Will any greater brake cylinder pressure be ob- tained with a 20-pound brake pipe reduction from no pounds initial pressure than would be the case with 70 pounds brake pipe pressure? A. No ; approximately the same brake cylinder pres- sure would be had. Q. What is the proper method of stopping a train fully equipped with LN brake equipment? A. When the speed of the train is high, a 20 to 25 pound brake pipe reduction should be made, which will develop maximum service brake cylinder pressure and, as the speed of the train reduces, the brake cylinder pres- sure should be graduated off by movements of the brake valve handle from lap to running position and back to lap ; thereby reducing the brake cylinder pressure as the speed of the train is being reduced, the effort being to have nearly all brake cylinder pressure discharged at the moment the train comes to rest. Q. Can the brake be re-applied promptly after a re- lease ? EXAMINATION QUESTIONS AND ANSWERS 269 A. Yes ; owing to the quick re-charge feature, a prompt response will be had to any brake pipe reduction. O. If the brake pipe, auxiliary reservoir and supple- mentary reservoirs are over-charged, how can the pres- sure be reduced to normal? A. By making three or four full service applications and releases of the brake, or by bleeding with the auxil- iary and supplementary reservoir drain cocks. Q. If the brake is applied with a service application^ can it be bled off by reducing the air pressure in the supplementary reservoir ? A. Yes ; by reducing the supplementary reservoir pres- sure sufficiently below that in the auxiliary reservoir to permit the by-pass valve to unseat. The auxiliary reser- voir air will then flow into the supplementary reservoir and reduce to an amount sufficient to cause the brake pipe pressure to move the triple valve to release position. Q. Should the supplementary reservoir drain cock be used in bleeding off brakes ? A. This may be done, but it is more desirable to do so with the drain cock in the auxiliary reservoir. O. In bleeding off a brake with the drain cock in the auxiliary reservoir, if the same is closed at the instant the triple valve moves to release position, what might be expected ? A. The triple valve may graduate and only exhaust a portion of the air from the brake cylinder, due to the air from the supplementary reservoir flowing into the aux- iliary reservoir when the triple valve is in release posi- tion, causing it to move to graduated release lap position. Q. What must be done to insure that the triple valve will remain in release position when bleeding off the brake ? 270 MODERN AIR BRAKE PRACTICE ■ A. The auxiliary reservoir pressure should be reduced a considerable amount, and it should be observed that the piston returns into the brake cylinder. Q. Can a brake be bled off by opening the drain cocks in the auxiliary or supplementary reservoirs when the brake pipe is empty? A. As a general rule it cannot, the triple valve being in emergency position. When the auxiliary reservoir pressure is reduced sufficiently to permit the graduating spring to move the triple valve piston and slide valve to emergency lap position, communication is closed between the brake cylinder and the auxiliary reservoir, and such air as is then in the brake cylinder would remain, unless the graduating yalve lifted from its seat, which is rarely the case. Q. When cars are to be set out in a yard, what is the proper manner for releasing the brake? A. The drain cock in the auxiliary reservoir should be opened while there is air remaining in the brake pipe. Q. If, when releasing the brake, air exhausts from the triple valve until the brake cylinder is empty, but the brake piston fails to return to release position, what does it indicate?? A. That the triple valve moved to release position properly, but the brake piston or the rods and levers are bound in some manner. Q. Is a retaining valve necessary on a car equipped with the LN equipment ? A. Not when all cars in the train are equipped with LN equipment, but during the transition period when both LN and old-style equipment are in the train the graduated release feature is not used and retaining valves ^re required. E, T. BRAKE EQUIPMENT 271 THE WESTINGHOUSE E. T. LOCOMOTIVE BRAKE EQUIPMENT— FOR INDEPEND- ENT CONTROL OF ENGINE AND TRAIN BRAKES. The great disadvantage of the old style combined auto- matic and straight air brake valve is that it cannot be used to independently release an automatic application of the engine brakes, because the double check valve pre- vents it, nor can it be used to retain an automatic appli- cation at anything less than what the straight air re- ducing valve is set, and another serious objection to it is the fact that in automatic applications engine and tender brakes are not operated as a unit, which they should be. To meet and overcome these objections it was necessary to produce a new type of engine equipment, and the Westinghouse E. T. is one of several new types of engine equipments designed for this purposee. The object of the E. T. equipment is to provide a means whereby an engineer can operate the locomotive and train brakes independently or together, as conditions may require. The letters E. T. signify Engine and Tender, and while this equipment was first introduced in 1905, it has, how- ever, just recently been brought to its present state of development. During the experimental period of this equipment there have been six styles of it produced, but the No. 5 and No. 6 are the only styles that need to be explained, as the others are now obsolete and are not being made. Aside from the pump, main reservoir and brake cylin- 272 MODERN AIR BRAKE PRACTICE ders, the essential parts of the E. T. equipment consist of two brake valves and a distributing valve, two reduc- ing valves and a duplex pump governor. One brake valve is known as the "Automatic" and the other as the "Independent." The automatic is used in applying and releasing the train and engine brakes together, and also to hold the engine while releasing the train brakes, and the independent valve is used to operate the engine brakes seperately from the train brakes, but in all cases the action of the engine brakes is dependent upon the operation of the distributing valve, the parts of which are practically the same as two triple valves. For in- stance, if it is desired to make an independent application of the engine brakes, it is necessary to pass the air from the main reservoir by way of the independent brake valve to a chamber in the distributing valve known as the application cylinder in order to cause the mechanism in the distributing valve to admit main reservoir pressure into the brake cylinders on the engine and tender ; conse- quently if the distributing valve is inoperative, an inde- pendent or automatic application of the engine brakes cannot be made. Under certain conditions the automatic side of the distributing valve can be cut out, and still allow the independent portion to be operative, but if the distributing valve itself has to be cut out, there can be no action whatever of the engine brakes. In operation the important advantages of the E. T. equipment are that the locomotive brakes may be used with, or independent of the train brakes, and this without regard to the position of the locomotive in the train. The brake cylinder pres- sure on the engine can be automatically maintained by the distributing valve regardless of ordinary brake cylin- der leakage and of variation in piston travel, if the pipe E. T. BRAKE EQUIPMENT 273 connections between the brake valves and the distribut- ing valve are perfectly tight. The engine brakes can be graduated off with either brake valve, and independently graduated on with the independent brake valve; hence, in all kinds of service the train may be handled without shock or danger of parting, and in passenger service smooth, accurate stops can be made with much greater ease than was hereto- fore possible with the old style Westinghouse equipment. MANIPULATION. The following instructions are general, and must nec- essarily be supplemented to a limited extent to fully meet the varying local conditions on different railways. The instructions for manipulating the ET equipment are practically the same as those given for the com- bined automatic and straight air brake ; therefore, no radical departure from present methods of brake manip- ulation is required to get the desired results. The necessary instructions are briefly as follows : When not in use, carry the handles of both brake valves in running position. To apply the brakes in service, move the handle of the automatic brake valve to the service position, mak- ing the required brake pipe reduction, then back to lap position which is the one for holding all the brakes applied. To make a smooth and accurate two-application pas- senger stop, make the first application sufficiently heavy to bring the speed of train down to about 15 miles per hour at a convenient distance from the stopping point, then release as explained in the following paragraph and k 274 MODERN AIR BRAKE PRACTICE re-apply as required to make the desired stop, the final release being made as explained below. Releasing Brakes. — With the changes in operating con- ditions, and in train and locomotive equipments during the past few years it has become possible to obtain still better results in general train handling if the method of operating the brakes is also slightly changed to conform with the progress which has been made in other direc- tions. This is especially true with regard to releasing brakes, and the general instructions which follow are intended to apply particularly to trains having modern equipment, that is, large compressor capacity, large main reservoir volume, high excess pressure and operating under present day average conditions. They are not in- tended to apply rigidly to all individual cases or con- ditions, specific instructions usually being issued by each road to cover its own recommended practice. Passenger Service. In making the first release of a two-application stop the brake valve handle should be moved to release position and then quickly back to run- ning position, where it should be allowed to remain for an instant (ist, to permit the pressure in the equalizing reservoir and brake pipe to equalize and 2nd, to release part of the driver brake cylinder pressure), then moved to lap position and from there to service position as re- quired. In passenger service the time the handle is in ^ release position should be only momentary but the time in running position should be governed by the conditions existing for each particular case, such as the length of train, kind of reduction made, time available, and so on. In making the final release of a two-application stop, with short trains, release shortly before coming to a standstill by moving the handle to release position and i E. T. BRAKE EQUIPMENT 275 immediately back to running position, and leave it there. With long trains, the brakes should, as a rule, be held applied until the train stops. The release after a one-application stop should be made in the same manner as the final release of a two- application stop. Freight Service. Under present conditions it is, as a rule, safest to come to a stop before releasing the brakes on a freight train, especially a long one, rather than attempt to release at low speed. However, if conditions (for example, a short train, or a train equipped with Type K triple valves), permit of the release while in mo- tion, the brake valve handle should be moved to release position and held there long enough to move as many of the triple valves to release position as possible without unduly overcharging the head end of the train (the time in release position should be governed by the length of train, amount of reduction made, etc.) then returned to running position to release the locomotive brakes and complete the re-charging of the auxiliary reservoirs. A few seconds after such a release, particularly on long trains, it is necessary to again move the handle to release position and quickly back to running position to ''kick off" any brakes at the head end of the train that may have re-applied due to their auxiliary reservoirs having been slightly overcharged. Holding Locomotive Brakes Applied. If, when re- leasing as explained above, it is desired to hold the loco- motive brakes applied after the other brakes release, move the handle from release back to holding instead of running position, then releasing the locomotive brakes fully by moving the handle to running position and leav- ing it there, or graduating them off, as circumstances re- 276 MODERN AIR BRAKE PRACTICE ^^^ quire, by short, successive movements between holdii^^ and running positions. A little experience with the ET equipment will enable the engineer to make smooth and accurate stops with much greater ease than was hereto- fore possible. To apply the brakes in emergency, move the handle of the automatic brake valve quickly to emergency posi- tion and leave it there until the train stops and the danger is past. When using the independent brake only, the handle of the automatic brake valve should be carried in run- ning position. The independent application may be re- leased by moving the independent brake valve handle to running position. Release position is for use only when the automatic brake valve handle is not in running posi- tion. While handling long trains of cars, in road or switch- ing service, the independent brake should be operated with care, to prevent damage to cars and lading, caused by running the slack in or out too hard. In cases of emergency arising while the independent brake is ap- plied, apply the automatic brake instantly. The safety valve will restrict the brake cylinder pressure to the proper maximum. The brakes on the locomotive and on the train may be alternated in heavy grade service where conditions (such as short, steep grades or where grade is heavy and straight for short distance) require, to prevent overheat- ing of driving wheel tires and to assist the pressure re- taining valves in holding the train while the auxiliary reservoirs are being recharged. This is done by keeping the locomotive brakes released by use of the independent brake valve when the train brakes are applied, and ap- £. T. BRAKE EQUIPMENT 277 plying the locomotive brakes just before the train brakes are released, and then releasing the locomotive brakes after the train brakes are re-applied. Care and judgment should always be exercised in the use of driver brakes on grades to prevent overheating of tires. When all brakes are applied automatically, to gradu- ate off or entirely release the locomotive brakes only, use release position of the independent brake valve. The red hand of gauge No. 2 (Fig. 79) will show at all times the pressure in the locomotive brake cylinders, and this hand should be watched in brake manipulation. Release position of the independent brake valve will release the locomotive brakes under any and all con- ditions. The train brakes should invariably be released before detaching the locomotive, holding with hand brakes where necessary. This is especially important on a grade, as there is otherwise no assurance that the car, cars or train so detached will not start when the air brakes leak off, as they may in a short time where there is consider- able leakage. The automatic brakes should never be used to hold a locomotive or a train while standing even where the locomotive is not detached, for longer than ten minutes, and not for such a time if the grade is very steep or the condition of the brakes is not good. The safest method is to hold with hand brakes only and keep the auxiliary reservoirs fully charged, so as to guard against a start from brakes leaking off, and to be ready to obtain any part of full braking power immediately on starting. The independent brake is a very important safety feature in this connection, as it will hold a locomotive 278 MODERN AIR BRAKE PRACTICE with a leaky throttle, or quite a heavy train on a fairly steep grade if, as the automatic brakes are released, the slack is prevented from running in or out ( depending on the tendency of the grade), and giving the locomotive a start. To illustrate : — the best method to make a stop on a descending grade is to apply the independent brake heavily as the stop is being completed, thus bunching the train solidly; then, when stopped, place and leave the handle of the independent brake valve in application posi- tion; then release the automatic brakes and keep them charged. Should the independent brakes be unable to prevent the train from starting, the automatic brakes will become sufficiently recharged to make an immediate stop; in such an event enough hand brakes should at once be applied as are necessary to assist the independent brake to hold the train. Many runaways and some se- rious wrecks have resulted through failure to comply with the foregoing instructions. When leaving the engine, while doing work about it, or when it is standing at a coal chute or water plug, al- ways leave the independent brake valve handle in appli- cation position. In case the automatic brakes are applied by a bursted hose, a break-in-two or the use of a conductor's valve, place the handle of the automatic brake valve in emer- gency position. Where there are two or more locomotives in a train, the instructions already given remain unchanged so far as the leading locomotive, or the locomotive from which the brakes are being operated, is concerned. On all other locomotives in the train, however, the double-heading cock under the automatic brake valve must be closed and E. T. BRAKE EQUIPMENT 279 the automatic and independent brake valve handles car- ried in running position. Before leaving the round house, the engineer should try the brakes with both brake valves and see that no serious leaks exist. The pipes between the distributing valve and the brake valves should be absolutely tight. 280 MODERN AIR BRAKE PRACTICE PARTS OF THE EQUIPMENT. 1. The Air Compressor to compress the air. 2. The Main Reservoirs^ in which to store and cool the air and collect water and dirt. 3. A Duplex Pump Governor to control the pump when the pressures for which it is regulated are obtained. 4. A Distributing Valve^ and small double chamber reservoir to which it is attached, placed on the locomo- tive to perform the functions of triple valves, auxiliary reservoirs, double check valves, high-speed reducing- valves, etc. 5. Two Brake Valves, the Automatic to operate the locomotive and train brakes, and the Independent to operate the locomotive brakes only. 6. A Feed Valve to regulate the brake pipe pressure. M 7. A Reducing Valve to reduce the pressure for the 1 independent brake valve and for the air-signal system when used. 8. Two Duplex Air Gauges ; one, to indicate equal izing reservoir and main reservoir pressures ; the other, to indicate brake pipe and locomotive brake cylinder pressures. 9. Driver^ Tender, and Truck Brake Cylinders, CuT-OuT Cocks, Air Strainers, Hose Couplings, Fit- ; TINGS, etc., incidental to the piping, for purposes readily understood. 1 E. T. BRAKE EQUIPMENT 281 NAMES OF PIPING. Discharge Pipe: Connects the Air Compressor to the first Main Reservoir. Connecting Pipe: Connects the two Main Reser- voirs. Main Reservoir Pipe: Connects the second main reservoir to the Automatic Brake Valve, Distributing Valve, Feed Valve, Reducing Valve, and Pump Gov- ernor. Feed Valve Pipe: Connects the Feed Valve to the Automatic Brake Valve. Excess Pressure Pipe: Connects the Feed Valve Pipe to the upper connection of the Excess Pressure Head of the Pump Governor. Excess Pressure Operating Pipe: Connects the Automatic Brake Valve to the lower connection of the Excess Pressure Head of the Pump Governor. Reducing Valve Pipe : Connects the Reducing Valve to the Independent Brake Valve, and to the Signal System, when used. Brake Pipe: Connects the Automatic Brake Valve with the Distributing Valve and all Triple Valves on the cars in the train. Brake Cylinder Pipe: Connects the Distributing Valve with the Driver, Tender and Truck Brake Cylinders. Application Cylinder Pipe: Connects the Applica- 282 MODERN AIR BRAKE PRACTICE tion Cylinder of the Distributing Valve to the Independ- ent and Automatic Brake Valves. Distributing Valve Release Pipe: Connects the Application Cylinder exhaust port of the Distributing Valve to the Automatic Brake Valve through the Inde- pendent Brake Valve, I E. T. BRAKE EQUIPMENT 283 bo 284 MODERN AIR BRAKE PRACTICE ARRANGEMENT OF APPARATUS. Fig. 58 is a diagram giving the designations of ap- paratus and piping. Referring to Fig. 58, air compressed by the pump passes as usual to the main reservoirs and the main- reservoir pipe. The main-reservoir cut-out cock is to cut off and vent the air from the main-reservoir pipe, when removing any of the apparatus except the governor. The end tov^ard the main reservoir is tapped for a con- nection to the Pump Governor. Before this cock is closed the double-heading cock should be closed, and the brake- valve handle placed in release position. This is to pre- vent the slide valve of the feed valve, and the rotary valve of the brake valve, being lifted from their seats. Beyond the main-reservoir cut-out cock, the reservoir pipe has four branches, one of which runs to the auto- matic brake valve, one to the feed valve, one to the re- ducing valve, and one to the distributing valve. As a result, the automatic brake valve receives air from the main reservoir in two ways, one direct and the other through the Feed Valve. The Feed- Valve Pipe from the feed valve to the auto- matic brake valve has a branch to the top or spring-box of the low-pressure head of the duplex governor. The third branch of the main reservoir pipe connects with the reducing valve. Air at the pressure for which this valve is set (45 pounds) is supplied to the independ- ent brake valve through the reducing-valve pipe. When the air signal system is installed, it is connected to the reducing valve pipe, in which case the reducing valve takes the place of the signal-reducing valve formerly em- ployed. In the branch pipe supplying the air signal NO. 6 E. T. EQUIPMENT 285 286 MODERN AIR BRAKE PRACTICE system are placed a combined strainer and check-valve, and a choke fitting. The strainer prevents any dirt from reaching the check valve and choke fitting. The check valve prevents air from flov^ing back from the signal pipe when the independent brake is applied. The choke fitting prevents the reducing valve from raising the sig- nal-pipe pressure so quickly as to destroy the operation of the signal. The distributing valve has five pipe connections, made through the end of the double-chamber reservoir, three on the left and two on the right. Of the three on the left, the upper is the supply from the main reservoir, the intermediate is the application cylinder pipe, leading to the independent, and automatic brake valves, and the lower is the distributing valve release pipe leading through the independent brake valve, (when the handle is in running position) to the automatic brake valve. Of the two on the right, the lower is the brake pipe branch connection and the upper is the brake cylinder pipe, branching to all brake cylinders on the engine and tender. In this pipe are placed cocks for cutting out the brake cylinders when necessary, and in the engine truck, and tender brake cylinder cut-out cocks, are placed choke fittings to prevent serious loss of main reservoir air, and the release of the other locomotive brakes during a stop, in case of a burst brake cylinder hose. The two duplex air gauges are connected as follows. Gauge No. i, red hand, to main reservoir pipe under the automatic brake valve, black hand to gauge pipe tee of the automatic brake valve. Gauge No. 2, red hand to the brake cylinder pipe, black hand to the brake pipe below the double-heading cock. The amount of reduction made during an auto- NO. 6 E. T. EQUIPMENT 287 matic application is indicated by the black hand of gauge No. i. The black hand of gauge No. 2 is to show the brake pipe pressure when the engine is second in double-header, or a helper. The automatic brake-valve connections other than those already mentioned are^ the brake pipe, the main reservoir, the equalizing reservoir and the lower connection to the low-pressure head of the pump governor. PRINCIPLES OF OPERATION. Before taking up the description of each part of this equipment, the fact should be emphasized that the princi- ples governing the operation of it are just the same as those of previous equipments. The difference consists in the means for supplying the air pressure to the brake cylinders. Instead of a triple valve and auxiliary reser- voir for each of the engine and tender equipments, the distributing valve is made to supply all brake cylinders. The distributing valve consists of two portions called the "equalizing portion^' and "application portion." It is connected to a "double-chamber reservoir," the two chambers of which are called respectively the "pressure chamber" and the "application chamber." The latter is ordinarily connected to the application portion of the distributing valve in such a way as to enlarge the vol- ume of that part of it called the "application cylinder'' Fig. 59. The connections between these parts as well as tlieir operation, may be compared with that of a miniature brake set — the equalizing portion represent- ing the triple valve ; the pressure chamber, the auxiliary reservoir; and the application portion always having 288 MODERN AIR BRAKE PRACTICE TO MAIN RESERVOIR. APPLICATION- CYLINOCR. TO INDEPENDENT ANO AUTOMATIC BRAKE VALVES. TO INDEPENDENT BRAKE VALVE. APPLICATION CHAMBER. PRESSURE CHAMBER. Fig. 59 — Diagrammatic View of the Essential Parts of the Dis- tributing Valve, and Double-Chamber Reservoir. NO. 6 E. T. EQUIPMENT 289 practically the same pressure in its cylinder as that in the brake cylinders. This is shown by the diagrammatic illustration in Fig. 59. For convenience, compactness and security they are combined in one device as shown in Figs. 60, 61 and 62. The equalizing portion and pressure chamber are used in automatic applications only ; reductions of brake-pipe pressure cause the equalizing valve to connect the pressure chamber to the application cylinder, allowing air to flow from the former to the lat- ter. The upper slide valve connected to the piston rod of the application portion, admits air to the brake cylinders and is called the "application valve," while the lower one releases the air from the brake cylinders and is called the "exhaust valve.^' As the air admitted to the brake cylinders comes directly from the main reservoirs, the supply is practically unlimited. Any pressure in the ap- plication cylinder will force the application piston to close the exhaust valve, open the application valve and admit air from the main-reservoirs to the locomotive brake cylinders until their pressure equals that in the applica- tion cylinder; also any variation of application-cylinder pressure will be exactly duplicated in the locomotive brake cylinders, and the resulting pressure maintained regardless of any brake-cylinder leakage. The whole operation of this locomotive brake, therefore, consists in admitting and releasing air pressure into or out of the application cylinder; in independent applications, directly through the independent brake valve ; in automatic ap- plications, by means of the equalizing portion and the air pressure stored in the pressure chamber. The well-known principle embodied in the quick-action triple valve, by which it gives a high braking power in emergency applications, and a sufficiently lower one in 290 MODERN AIR BRAKE PRACTICE Fig. 60 — No. 6 Distributing Valve and Double Chamber Reservoir. CONNECTIONS : MR — Main-Reservoir Pipe ; 4 — Distributing- Valve Release Pipe ; 2 — Application-Cylinder Pipe; CYLS — Brake-Cylinder Pipe; BP— Brake Pipe, I NO. 6 E. T. EQUIPMENT 291 full service applications, to provide a desired protection against wheel sliding, is embodied in the No. 6 dis- tributing valve. This is accomplished by cutting off the application chamber from the application cylinder in all emergency applications. In such applications, the pres- sure chamber as to fill the small volume of the applica- tion cylinder only, thus giving a high equalization, and a correspondingly high brake-cylinder pressure. In serv- ice applications, it must fill the same volume combined with that of the application chamber, thus giving a lower equalization and correspondingly lower brake-cylinder pressure. The following description gives the operation in detail : THE NO. 6 DISTRIBUTING VALVE. This valve is the important feature of the E.-T. equip- ment. Fig. 60 shows photographic views of the valve and its double-chamber reservoir. The pipe connections, as previously referred to, are plainly shown. Fig. 61 shows the two chambers of the reservoir. The safety valve, 34, is an essential part of the distributing valve, and is described later on. Referring to Figs. 61 and 62^ the names of parts of this apparatus are as follows : 2, Body ; 3, Application- Valve Cover; 4, Cover Screw; 5, Application Valve; 6, Application-Valve Spring; 7, Application-Cylinder Cover; 8, Cylinder-Cover Bolt and Nut; 9, Cylinder- Cover Gasket; 10, Application Piston; 11, Piston Fol- lower; 12, Packing-Leather Expander; 13, Packing Leather; 14, Application-Piston Nut; 15, Application- Piston Packing Ring; 16, Exhaust Valve; 17, Exhaust- Valve Spring; 18, Application- Valve Pin; 19, Applica- m MODERN AIR BRAKE PRACTICE NO. 6 E. T. EQUIPMENT 293 tion-Piston Graduating Stem; 20, Application-Piston Graduating Spring; 21, Graduating- Stem Nut; 22, Up- per Cap Nut; 23, Equalizing-Cylinder Cap; 24, Cylin- der-Cap Bolt and Nut; 25, Cylinder-Cap Gasket; 26, Equalizing Piston ; 27, Equalizing- Piston Packing Ring ; 28. Graduating Valve; 29, Graduating- Valve Spring; 31, Fig. 62 — No. 6 Distributing Valve. Cross-Sectional View. CONNECTIONS : MR — Main-Reservoir Pipe ; IV — Distributing- Valve-Release Pipe ; II- Application-Cylinder Pipe; CYLS — Brake-Cylinder Pipe; BP- Brake Pipe. 294 MODERN AIR BRAKE PRACTICE Equalizing Valve; 32, Equalizing- Valve Spring; 33, Lower Cap Nut; 34, Safety Valve; 35, Double-Chamber Reservoir; 36, Reservoir Stud and Nut; 37, Reservoir Drain Plug ; 38, Distributing- Valve Drain Cock ; 39, Ap- plication-Valve-Cover Gasket; 40, Application-Piston Cotter; 41, Distributing- Valve Gasket (not shown) ; 42, Oil Plug ; 43, Safety- Valve Air Strainer ; 44, Equalizing- Piston Graduating Sleeve; 45, Equalizing-Piston Grad- uating-Spring Nut; 46, Equalizing-Piston Graduating Spring. To simplify the tracing of the ports and connections, the various positions of this valve are illustrated in nine diagrammatic views ; that is, the valve is distorted to show the parts differently than actually constructed with the object of explaining the operation clearly instead of showing exactly how they are designed. The chambers of the reservoir are for convenience indicated at the bot- tom as a portion of the valve itself. In Fig. 62 equal- izing piston 26, graduating valve 28, and equalizing slide valve 31, are shown as actually constructed. But as there are ports in the valves which cannot thus be clearly indicated, the diagrammatic illustrations show each slide valve considerably elongated so as to make all the ports appear in one plane, with similar treatment of the equal- izing valve seat. Fig. 63 shows the correct location of these ports. Referring to Fig. 64 it will be seen that main-reservoir pressure is always present in the chamber surrounding application valve 5 by its connection through passage a, a, to the main-reservoir pipe. Chamber h to the right of application piston 10 is always in free communication with the brake cylinders, through passage c and the brake-cylinder pipe. Application cylinder g at the left NO. 6 E. T. EQUIPMENT 295 .../ PLAN OF GRADUATING VALVE. FACE OF SLIDE VALVE. — hi Zl' c::<:;:-:j ■"9-'>-ti p- PLAN OF SLIDE VALVE. (Looking through the top, the dotted lines indicate the cavities in the bottom face of slide valve.) 0-- A-0 0^ '^V>V!:'^Vn'^'^'^^'^^'^^'^ ^^^^^^^^^^^^■^^^^^^^^ I PLAN OF SLIDE VALVE SEAT. Fig. 63 — Graduating Valve, Equalizing Valve, and Equalizing- Valve Seat of No. 6 Distributing Valve. 296 MODERN ATR BRAKE PRACTICE of application piston lo is connected by passage h with the equalizing-valve seat, and to the brake valve through the application-cylinder pipe. AUTOMATIC OPERATION OF THE DISTRIBUTING VALVE. Charging. Referring to Fig. 64, which shows the movable parts of the valve in the release position, it will be seen that as chamber p is connected to the brake pipe, brake-pipe air flows through the feed groove v around the top of piston 26 into the chamber above equalizing valve 31, and through port to the pressure chamber, until the pressures on both sides of the piston are equal. Service. When a service application is made with the automatic brake valve, the brake-pipe pressure in cham- ber p is reduced, causing a difference in pressure on the two sides of this piston, which results in the piston mov- ing toward the right. The first movement of the piston closes the feed groove, and at the same time moves the graduating valve until it uncovers the upper end of port z in the equalizing valve 31. As the piston continues its movement, the shoulder on the end of its stem en- gages the equalizing valve which is then also moved to the right until the piston strikes equalizing-piston gradu- ating sleeve 44, graduating spring 46 preventing further movement ; port .z in the equalizing valve then registers with port h in the seat^ and cavity n in the equalizing valve connects ports h and w in the seat. As the equal- izing-valve chamber is always in communication with the pressure chamber, air can now flow from the latter to both the application cylinder and application chamber. This pressure forces application piston 10 to the right, NO. 6 E. T. EOUIPMEXT 297 MR .' Fig. 64 — No. 6 Distributing Valve Release Position, Automatic or Independent. CONNECTIONS : MR — Main-Reservoir Pipe ; IV — Distributing- Valve Release Pipe ; II — Application-Cylinder Pipe ; CYLS — Brake-Cylinder Pipe ; BP — Brake Pipe, 2-98 MODERN AIR BRAKE PRACTICE MR Fig. 65 — No, 6 Distributing Valve Automatic Service Position. as shown in Fig. 65, causing exhaust valve 16 to close exhaust ports e and d, and to compress application-piston graduating spring 20; also causing appliaction valve 5, by its connection with the piston stem through pin 18, NO. 6 E. T. EQUIPMENT 29^ to open its port and allow air from the main-reservoirs to flow into chambers b, b, and through passage c to the brake cylinders. During the movement just described, cavity t in the graduating valve connects ports r and ^ in the equalizing valve, and by the same movement ports r and ^ are brought into register with ports h and / in the seat, thus establishing a communication from the application cylin- der to the safety-valve, which being set at 68 pounds, three pounds above the maximum obtained in an emer- gency application from 70-pounds brake-pipe pressure, limits the brake-cylinder pressure to this amount. The amount of pressure resulting in the application cylinder for a certain brake-pipe service reduction, de- pends on the comparative volumes of the pressure cham- ber, application cylinder and its chamber. These vol- umes are such that with 70 pounds in the pressure cham- ber and nothing in the application cylinder and chamber, if they are allowed to remain connected by the ports in the equalizing valve, they will equalize at about 50 pounds. Service Lap. When the brake-pipe reduction is not sufficient to cause a full service application, the conditions described above continue until the pressure in the pres- sure chamber is reduced enough below that in the brake pipe to cause piston 26 to force graduating valve 28 to the left until stopped by the shoulder on the piston stem striking the right-hand end of equalizing valve 31, the position indicated in Fig. 66 and known as Service Lap. In this position, graduating valve 28 has closed port ^ so that no more air can flow from the pressure chamber to the application cylinder and chamber. It also has closed port s, cutting off communication to the safety valve, so that any possible leak in the latter can- 300 MODERN AIR BRAKE PRACTICE MR j Fig. 66 — No. 6 Distributing Valve Service Lap Position. not reduce' the application-cylinder pressure, and thus similarly affect the pressure in the brake cylinders. The flow of air past application valve 5 to the brake cylinders ? continues until their pressure slightly exceeds that in the application cylinder when the higher pressure and appli- NO. 6 E. T. EQUIPMENT 301 cation-piston graduating spring together force piston lo to the left to the position shown in Fig. 66, thereby closing port b. Further movement is prevented by the resistance of exhaust valve i6, and the application-piston graduating spring having expanded to its normal posi- tion. The brake-cylinder pressure is then practically the same as that in the application cylinder and chamber. Application piston lo has application-cylinder pressure on one side and brake-cylinder pressure on the other. When either pressure varies, the piston will move toward the lower. If that in chamber h is reduced, by brake- cylinder leakage, the pressure maintained in the applica- tion cylinder will force piston lo to the right, opening application valve 5 and again admitting air from the main reservoirs to the brake cylinders until the pressure m chamber h is again slightly above that in the application cylinder when the piston again moves back to lap position. In this way the brake-cylinder pressure is maintained equal with that in the application cylinder. This is the pressure-maintaining feature, and consequently the pres- sure maintaining feature depends entirely upon keeping all connections to the application chamber absolutely air tight. Automatic Release. When the automatic brake valve is placed in release position, and the brake-pipe pressure in chamber p is thereby increased above that in the pressure chamber, equalizing piston 26 moves to the left, carrying with it equalizing valve 31 and graduating valve 28. The feed groove v now being open permits the pressure in the pressure chamber to feed up until it is equal with that in the brake-pipe. This action does not release the locomotive brakes because it does not dis- charge application-cylinder pressure. The release pipe 302 MODERN AIR BRAKE PRACTICE is closed by the rotary valve of the automatic brake valve, and the application-cylinder pipe is closed by the rotary valves of both brake valves. To release the loco- motive brakes, the automatic brake valve must be moved to running position. The release pipe is then connected • by the rotary valve to the atmosphere, and as exhaust cavity k in the equalizing valve 31 connects ports i, w and h in the valve seat, application-cylinder and cham- ber pressure will escape. As this pressure reduces, the brake-cylinder pressure will force application piston 10 to the left until exhaust valve 16 uncovers exhaust ports d and e, allowing brake-cylinder pressure to escape (Fig. 64), or in case of graduated release, to reduce in like amount to the reduction in the application-cylinder pressure. Emergency. When a sudden and heavy brake-pipe reduction is made, as in an emergency application, the air in the piston chamber forces equalizing piston 26 to the right with sufficient force to compress equalizing- piston graduating spring 46, so that the piston moves until it strikes against the leather gasket beneath cap 23 as shown in Fig. 6y. This movement causes equahzing valve 31 to uncover port h in the bush without opening port w, making a direct opening from the pressure cham- ber to the application cylinder only, so that they quickly become equalized. This cylinder volume, being small, and connected with that of the pressure chamber at 70- pounds pressure, equalizes at about 65 pounds. Also in this position of the automatic b)rake valve, a small port in the rotary valve allows air from the main-reservoirs to feed into the application-cylinder pipe, and thus to the application cylinder. The application cylinder is now connected to the safety valve through port h in the seat, NO. 6 E. T. EQUIPMENT 303 MR Fig. 67 — No. 6 Distributing Valve Emergency Position. cavity q and port r in the equalizing valve, and port z in the seat. Cavity q and port r in the equaHzing valve are connected by the small port, the size of which permits the air in the application cylinder to escape through the safety valve at the same rate that the air from the main- 304 MODERN AIR BRAKE PRACTICE reservoir, feeding through the rotary valve of the auto- matic brake valve, can supply it, preventing the pressure from rising above the adjustment of the safety valve. In High-Speed Brake Service, the feed valve is regu- lated for iio-pounds brake-pipe pressure instead of 70, and main-reservoir pressure is 130 or 140 pounds. Under these conditions an emergency application raises the ap- plication-cylinder pressure to about 93 pounds, but the passage between cavity q and port r is so small that the flow of application-cylinder pressure to the safety valve is just enough greater than the supply through the brake valve, to decrease that pressure in practically the same time and manner as is done by the high-speed reducing valve, until it is approximately 75 pounds. The reason why the pressure in the application cylinder, pressure chamber and brake cylinders does not fall to 68 pounds, to which pressure the safety-valve is adjusted, is because the inflow of air through the brake valve with the high main-reservoir pressure used in high-speed service is equal, at 75 pounds, to the outflow through the small opening in the safety valve. This is done to get a shorter stop in emergency. The application portion of the dis- tributing valve operates similarly, but more quickly than in service application. Emergency Lap. The movable parts of the valve remain in the position shown in Fig. 67 until the brake- cylinder pressure slightly exceeds the application-cylin- der pressure, when the application piston and application valve move back to the position known as Emergency Lap as shown in Fig. 68. The release after an emergency is brought about by the same manipulation of the automatic brake valve as that following service application, but the effect on the NO. 6 E. T. EOUIPMEXT 305 MR \ Fig. 68 — No. 6 Distributing Valve Emergency Lap Positi distributing valve is somewhat different. When the equalizing piston, valve, and graduating valve are forced to the release position by the increased brake-pipe pres- sure in chamber />, the application chamber, with no pressure in, is connected to the application cylinder, with 306 MODERN AIR BRAKE PRACTICE the emergency pressure in, through port w, cavity k, and port h. The pressure in the application cyHnder at once expands into the application chamber until these pres- sures are ' equal, which results in the release of brake- cylinder pressure until it is slightly less than that in application cylinder and chamber. Consequently, in re- leasing after an emergency, the brake-cylinder pressure will automatically reduce to about 15 pounds, which will remain until the automatic-brake-valve handle is moved to running position. If the brakes are applied by a conductor's valve, a burst hose, or parting of train, the movement of equalizing valve 31 breaks the connection between ports h and i through cavity k, so that the brakes will apply and re- main applied until the brake-pipe pressure is restored. The handle of the automatic brake valve should be moved to lap position to prevent a loss of main-reservoir pres- sure. With the No. 5 equipment it is necessary to lap one of the brake valves in order to allow the engine brakes to apply when a conductor's valve is opened. Independent Application. When the handle of the Independent Brake Valve is moved to either application position, air from the main reservoir, limited by the reduc- ing valve to a maximum of 45 pounds, is allowed to flow to the. application cylinder, forcing application piston 10 to the right as shown in Fig. 69. This movement causes application valve 5 to open its port and allow air from the main-reservoirs to flow into chambers h, b and through passage c to the brake cylinders, as in an auto- matic application, until the pressure slightly exceeds that in the application-cylinder. The application-piston grad- uating spring and higher pressure then force application piston 10 to the left until application valve 5 closes its NO. 6 E. T, EQUIPMENT 307 MR Fig. 69 — No. 6 Distributing Valve Independent Application Position. port. Further movement is prevented by the resistance of exhaust valve 16, and the application-piston graduat- ing spring having expanded to its normal position. This [: position, shown in Fig. 70 is known as Independent Lap. 308 MODERN AIR BRAKE PRACTICE MR Fig. 70 — No. 6 Distributing Valve Independent Lap Position It will be seen that whatever pressure exists in the ap- plication cylinder will be maintained in the brake cylinders by the "pressure maintaining" feature already de- scribed. NO. 6 E. T. EQUIPMENT 309 Independent Release. When the handle of the inde- pendent brake valve is moved to release position, a direct opening is made from the application cylinder to the at- mosphere. As the application-cylinder pressure escapes, brake-cylinder pressure in chamber b moves application piston lo to the left, causing exhaust valve i6 to open exhaust ports e and d as shown in Fig. 64 thereby al- lowing brake-cylinder pressure to discharge to the at- mosphere. If the independent brake valve is returned to lap be- fore all of the application-cylinder pressure has escaped, the application piston 10 will return to independent lap position as soon as the brake-cylinder pressure is reduced a little below that remaining in the application cylinder, thus closing exhaust ports e and d, and holding the re- maining pressure in the brake cylinders. In this wav the independent release may be graduated as desired. This equipment has all the flexibility and ease of manipulation possessed by the combined automatic and straight air equipment^ with much less apparatus and complication, besides the other important features of pressure maintaining, equal pressures in all brake cylin- ders, and the fact that it is ahvays possible to release the locomotive brakes with the independent-brake valve, even when automatically applied. In connection with this last mentioned feature, Fig. 71 shows the position the dis- tributing-valve parts will assume, if the locomotive brakes are released by the independent brake valve after an automatic application has been made. This results in the application portion going to release position without changing the conditions in either the pressure-chamber or brake pipe; consequently, the equaHzing portion does not move until release is made by the automatic brake valve. 310 MODERN AIR BRAKE PRACTICE MR Fig. 71 — No. 6 Distributing Valve Release Position. When Locomotive Brake is released by Independent Brake Valve after an Automatic Application. An independent release of locomotive brakes may also be made in the same manner, after an emergency appli- cation made by the automatic brake valve. However, ow- NO. 6 E. T. EQUIPMENT 311 ing to the fact that, in this position, the automatic brake valve will be supplying the application cylinder through the maintaining port in the rotary valve (see Fig. 67), the handle of the independent brake valve must be held in release position to prevent the locomotive brakes from reapplying, so long as the handle of the automatic brake valve remains in emergency position. The equalizing portion of the distributing valve will remain in the posi- tion shown in Figs. 67 and 68, while the application portion will assume the position shown in Fig. 71. Double Heading. When there are two or more loco- motives in a train, the handles of both brake valves on each locomotive should be carried in running position. The release pipe from the distributing valve on the helper engines is then open to the atmosphere at the automatic brake valve, and the operation of the distribut- ing valve is the same as that described during automatic- brake applications. In double heading, therefore, the application and the release of the distributing valve on each helper locomotive is similar to that of the triple valves on the train. But in case an engineer on a helper finds it necessary to apply or to release his brakes inde- pendently of the train, he can do so by using the inde- pendent brake valve, without moving the handle of the automatic valve. Port u drains the application cylinder of any moisture precipitated from the air in chambers b ; such moisture passes to the lower part of the distributing valve through port m, where it may be drawn off by drain cock 38. To remove piston 10 and slide valve 16, it is absolutely necessary to first remove cover 3, application valve 5 and valve pin 18. 312 MODERN AIR BRAKE PRACTICE THE QUICK-ACTION CYLINDER CAP. The equalizing portion of the distributing valve, as already described, corresponds to the plain triple valve of the old standard locomotive brake equipments. There are, however, conditions under which it is advisable to 1 I Fig. 72 — The Quick-Action Cylinder Cap for No. 6 Distributing Valve. have it correspond to a quick-action triple; that is, — vent brake-pipe air into the brake cylinder in an emer- gency application. To obtain this, the cylinder cap 23, Fig. 62, is replaced by the ''Quick-Action Cylinder Cap," illustrated in Fig. 72. NO. 6 E. T. EQUIPMENT 813 In an emergency application, as equalizing piston 26 moves to the right and seals against the gasket (Fig. 73), the knob on the piston strikes the graduating stem Fig- IZ — Emergency Position of No. 6 Distributing Valve with Quick-Action Cap. 59, causing it to compress equalizing-piston graduating spring 46, and move slide valve 48 to the right, opening port y. Brake-pipe pressure in chamber p, flows to cham- k 314 MODERN AIR BRAKE PRACTICE ber X, pushes down check valve 53, and passes to the brake cylinder through port m in the cap and distribut- ing-valve body. When the brake cylinders and brake pipe equalize, check valve 53 is forced to its seat by spring 54, thus preventing air in the brake-cylinders from flowing back into the brake pipe. When a release of the brakes occurs and piston 26 is moved back to its normal position (Fig. 64), spring 46 forces graduating stem 59 and slide-valve 48 back to the position shown in Fig. 72. In all other respects, the operation of a distributing valve having this cap is exactly as described before. E-6 SAFETY VALVE. Fig. 74 is a sectional view of the safety valve which is an essential part of the distributing valve. It is un- like the ordinary safety valve, as its construction is such as to cause it to close quickly with a *'pop" action, insur- ing its seating firmly. It is sensitive in operation and responds to slight differences of pressure. The names of the parts are 2, Body; 3, Cap Nut; 4, Valve; 5, Valve Stem; 6, Adjusting Spring; 7, Adjust- ing Nut. Valve 4 is held to its seat by the compression of spring 6 between the stem and adjusting nut 7. When the pressure below valve 4 is greater than the force exerted by the spring, it rises, and as a larger area is then ex- posed, its movement upward is very quick, being guided by the brass bush in the body 2. Two ports are drilled in this bush upward to the spring chamber ; and two out- ward through the body to the atmosphere, although only one of each of these is shown in the cut. As the valve NO. 6 E. T. EQUIPMENT 315 Fig. 74— E-6 Safety Valve moves upward, its lift is determined by the stem 5 strik- ing cap nut 3. It closes the two vertical ports in the bush connecting the valve and spring chambers, and opens the 316 MODERN AIR BRAKE PRACTICE lower ports to the atmosphere. As the air pressure below valve 4 decreases, and the compression of the spring forces the stem and valve downward, the valve restricts the lower ports to the atmosphere and opens those be- tween the valve and spring chambers. The discharge air pressure then has access to the spring chamber. This chamber is always connected to the atmosphere by two small holes through the body, 2 ; the air from the valve chamber enters more rapidly than it can escape through these holes, causing pressure to accumulate above the valve- and assist the spring to close it with the "pop^' action before mentioned. The safety valve is adjusted by removing cap nut 3, and screwing up or down on adjusting nut 7. After the proper adjustment is made, cap nut 3 must be replaced and securely tightened, and the valve operated a few times. Particular attention must be given to see that the holes in the valve body are always open, and that they are not changed in size, especially the two upper holes. This safety valve should be adjusted for 68 pounds. The safety valve, as are all adjustable devices, is more easily and accurately adjusted when done on a shop test- ing rack. THE H.-6 AUTOMATIC BRAKE VALVE. This Brake Valve, although modelled to a considerable extent upon the principles of previous valves, is neces- sarily different in detail, since it not only performs all the functions of such types but also those absolutely necessary to obtain all the desirable operating features of the No. 6 Distributing Valve. NO. 6 E. T. EQUIPMENT 317 Figure 75 is taken from a photograph of this brake valve, while Figs. 76 and y^j show two views, the first one being a plan view with section through the rotary-valve chamber, the rotary valve being removed; the other one a vertical section. In these views the pipe connections are indicated. C^ f Fig- 75 — H-6 Automatic Brake Valve. Figure 78 shows two views of this valve similar to those of Figs. 76 and "jj, with the addition of a plan or top view of the rotary valve. The six positions of the brake-valve handle are, beginning at the extreme left. Re- lease, Running, Holding, Lap, Service, and Emergency. 318 MODERN AIR BRAKE PRACTICE The names of the parts are as follows : 2, Bottom Case 3, Rotary-Valve Seat; 4, Top Case; 5, Pipe Bracket 6, Rotary Valve ; 7, Rotary- Valve Key ; 8, Key Washer 9, Handle; 10, Handle-Latch Spring; 11, Handle Latch 12, Handle-Latch Screw; 13, Handle Nut; 14, Handle Lock Nut; 15, EquaHzing Piston; 16, Equalizing-Piston Fig. 76 — H-6 Brake Valve Rotary Valve Seat. Packing Ring; 17, Valve-'Seat Upper Gasket; 18, Valve- Seat Lower Gasket; 19, Pipe Bracket Gasket; 20, Small Union Nut; 21, Brake- Valve Tee; 22, Small Union Swivel ; 23, Large Union Nut ; 24, Large Union Swivel ; 25, Bracket Stud; 26, Bracket-Stud Nut; 2"], Bolt and Nut; 28, Cap Screw; 29, Oil Plug; 30, Rotary Valve Spring; 31, Service Exhaust Fitting. NO. 6 E. T. EQUIPMENT 319 Referring to the rotary valve, a, j and ^ are ports extending directly through it, the latter connecting with a groove in the face ; / and k are cavities in the valve face ; o is the exhaust cavity ; ;i; is a port in the face of the valve connecting by a cored passage with o; h is a Fig- 77— H-6 Automatic Brake Valve. CONNECTIONS : FV — Feed- Valve Pipe ; MR — Main Reservoir Pipe ; GO — To Governor ; III — Distributing- Valve-Release Pipe ; EX — Emergency Exhaust ; II — Application of Cylinder Pipe ; BP — Brake Pipe ; GA — No. 1 Du- plex Air Gauge ; ER — Equalizing Reservoir ; BP Ex. — Service Ex- haust. port extending from the face over cavity k and connect- ing with exhaust cavity o; n is a groove in the face hav- ing a small port which connects through a cavity in the valve with cavity k. Referring to the ports in the rotary- 320 MODERN AIR BRAKE PRACTICE . . FECO VALVE KPIPETAP^' \ MAIN />r set fU/f C9IMUZIN6 nCtCRIfOi\ Fig. 7&— The H-6 Automatic Brake Valve. Cross Section, NO. 6 E. T. EQUIPMENT 32J valve seat, d leads to the feed-valve pipe; b and c lead to the brake pipe; g leads to chamber D, ex is the ex- haust opening leading out at the back of the valve ; e is the preliminary exhaust port leading to chamber D ; r is the warning port leading to the exhaust; p is the port leading to the pump governor; / leads to the distribut- ing-valve release pipe; ii leads to the application-cyhn- der pipe. In describing the operation of the brake valve, it will be more readily understood if the positions are taken up in the order in which they are most generally used, rather than their regular order as mentioned previously. Charging and Release Position. The purpose of this position is to provide a large and direct passage from the main reservoir to the brake pipe, to permit a rapid flow of air into the latter to (a) charge the train brake system; (b) quickly release and recharge the brakes; but (c) not release locomotive brakes, if they are applied. Air at main-reservoir pressure flows through port a in the rotary valve and port b in the valve seat to the brake pipe. At the same time, port ; in the rotary valve registers with equalizing port g in the valve seat, per- mitting main-reservoir pressure to enter chamber D above the equalizing piston. If the handle were allowed to remain in this position, the brake system would be charged to main-reservoir pressure. To avoid this, the handle must be moved to Running or Holding position. To prevent the engineer from forgetting this, a small port discharges feed-valve pipe air to the atmosphere in release position. Cavity / in the rotary valve connects port d with warning port r in the seat and allows a small quantity of air to escape 322 MODERN AIR BRAKE PRACTICE into the exhaust cavity ex, which makes sufficient noise to attract the engineer's attention to the position in which the valve handle is star.Jing. The small groove in the face of the rotary valve which connects with port s, ex- tends to port p in the valve seat, allowing main-reservoir pressure to flow to the excess-pressure head of the pump governor. Large Duplex Aii (No. 1) Gauge. Small Duplex Air Gauge. (No. 2) Fig. 79. Running Position. This is the proper position of the handle (a) when the brakes are charged and ready for use; (b) when the brakes are not being operated; and (c) to release the locomotive brakes. In this posiv tion, cavity /, in the rotary valve connects ports b and (/ in the valve seat, affording a large direct passage from the feed-valve pipe to the brake pipe, so that the latter will charge up as rapidly as the feed valve can supply the air, but cannot attain a pressure above that for which the feed valve is adjusted. Cavity k in the rotary valve connects^ ports c and g in the valve seat, so that chamber D <;nd the equalizing reservoir charge uniformly with NO. 6 E. T. EQUIPMENT 323 the brake pipe, keeping the pressure on the two sides of the equalizing piston equal. Port ^ in the rotary valve registers with port p in the valve seat, permitting the main-reservoir pressure, which is present at all times above the rotary valve, to pass to the excess-pressure head of the pump governor. Port h in the rotary valve registers with port / in the seat, connecting the distribut- ing-valve-release pipe through the exhaust cavity ex with the atmosphere. If the brake valve is in running position when un- charged cars are cut in, or if, after a heavy brake applica- tion and release, the handle of the automatic brake valve is returned to running position too soon, the governor wdll stop the pump until the difference between the hands on gauge No. i is less than 20 pounds. The pump stop- ping from this cause, calls the engineer's attention to the seriously wrong operation on his part, as running position results in delay in charging, and is liable to cause some brakes tO' stick. Release position should be used until all brakes are released and nearly charged. Service Position. This position gives a gradual re- duction of brake-pipe pressure to cause a service appli- cation. Port h in the rotary valve registers wdth port e in the valve seat, allowing air from chamber D and the equalizing reservoir to escape to the atmosphere through cavities in the rotary valve and ex in the valve seat. Port e is restricted so as to make the pressure in the equalizing reservoir and chamber D fall gradually. As all other ports are closed, the fall of pressure in chamber D allow^s the brake-pipe pressure under the equalizing piston to raise it, and unseat its valve, allow- ing brake-pipe air to flow to the atmosphere gradually through the opening marked BP Ex. When the pres- 824 MODERN AIR BRAKE PRACTICE sure in chamber D is reduced the desired amount, the handle is moved to lap position, thus stopping any fur- ther reduction in that chamber. Air will continue to dis- charge from the brake-pipe until its pressure has fallen to an amount a trifle less than that retained in chamber D, permitting the pressure in this chamber to force the piston downward gradually and stop the discharge of brake-pipe air. It will be seen, therefore, that the amount of reduction in the equalizing reservoir determines that in the brake pipe, regardless of the length of the train. The gradual reduction of brake-pipe pressure is to prevent quick action, and the gradual stopping of this discharge is to prevent the premature release of head brakes. Lap Position. This position is used (a), while hold- ing the brakes applied after a service application until it is desired either to make a further brake-pipe reduc- tion, or to release them; and (b) to prevent loss of main- reservoir pressure in the event of a burst hose, a break- in-two, or the opening of the conductor's valve. All ports are closed. Release Position. This position, which is used for releasing the train brakes after an application, without relasing the locomotive brakes, has already been de- scribed under Charging and Release. The air flowing from the main-reservoir-pipe connection through port a in the rotary valve and port h in the valve seat to the brake pipe, raises the pressure in the latter, thereby caus- ing the triple valves and equalizing portion of the dis- tributing valve to go to release position, which releases the train brakes and recharges the auxiliary reservoirs and the pressure chamber in the distributing valve. When the brake-pipe pressure has been increased sufficiently to NO. 6 E. T. EQUIPMENT ' 325 cause this, the handle of the brake valve should be moved to either Running or Holding position ; the former when it is desired to release locomotive brakes, and the latter when they are to be still held applied. Holding Position. This position is so named because the locomotive brakes are held applied while the train brakes recharge to feed-valve pressure. AH ports regis- ter as in running position, except port /, which is closed. Therefore, the only difference between Running and Holding Positions is that in the former the locomotive brakes are released, while in the latter they are held applied. Emergency Position. This position is used when the most prompt and heavy application of the brakes is required. Port x in the rotary valve registers with port c in the valve seat, making a large and direct communi- cation between the brake pipe and atmosphere through cavity o in the rotary valve and ex in the valve seat. This direct passage makes a sudden and heavy discharge of brake-pipe pressure, causing the triple valves and dis- tributing valve to go to the emergency position and give maximum braking power in the shortest possible time. In this position, main-reservoir air flows to the appli- cation cylinder through port /, which registers with a groove in the seat connecting with cavity k; thence through ports n in the valve and u in the seat to the ap- plication-cylinder pipe, thereby maintaining application- cyhnder pressure as already described. The oil plug 29 is placed in the top case 4, at a point to fix the level of an oil bath in which the rotary valve operates. The position of this oil hole is such that it is impossible to pour oil into the valves in excess of the amount required. This arrangement furnishes thorough 326 MODERN AIR BRAKE PRACTICE lubrication. Valve oil should be used. Leather washer 8 prevents air in the rotary-valve chamber from leaking Fig. 80— H-6 Automatic Brake Valve Removed from its Pipe Bracket. past the rotary-valve key to the atmosphere. Spring 30 keeps the rotary valve key firmly pressed against w^asher 8 when no main-reservoir pressure is present. The | NO. 6 E. T. EQUIPMENT 327 handle 9 contains latch 11, which fits into notches in the quadrant of the top case, so located as to indicate the dif- ferent positions of the brake-valve handle. Handle-latch spring 10 forces the latch against the quadrant with suf--- ficient pressure to indicate each position. To remove the brake valve, close the cocks and take off nuts 27. (See Fig. 80.) To take the valve proper apart, remove cap screws 28. The brake valve should be located so that the engineer can operate it conveniently from his usual position, while looking forward or back out of the side cab window. Fig. 81 — S-6 Independent Brake Valve Complete. THE S-6 INDEPENDENT BRAKE VALVE. Figures 81 and 82 illustrate this valve, which is of the rotary type. Fig. 83 shows a vertical section through the center of the valve, and a horizontal section through the valve body, with the rotary valve removed. 328 MODERN AIR BRAKE PRACTICE showing the rotary valve seat. Fig. 84 shows this varve similarly to Fig. 83, with the addition of a top view of the rotary valve. In these views, the pipe con- nections and positions of the handle are indicated. Re- ferring to Fig. 84, the names of parts are as follows : 2, Pipe Bracket ; 3, Rotary- Valve Seat ; 4, Valve Body ; 5, Return-Spring Casing ; 6, Return Spring ; 7, Cover ; 8, Casing Screw; 9, Rotary Valve; 10, Rotary- Valve Key; 11, Rotary- Valve Spring; 12, Key Washer; 13, Fig. 82 — S-6 Independent Brake Valve Removed from Pipe Bracket. Upper Clutch; 14, Handle Nut; 15, Handle; 16, Latch Spring; 17, Latch Screw; 18, Latch; 19, Cover Screw; 20, Oil Plug; 21, Bolt and Nut; 22, Bracket Stud; 23, Bracket-Stud Nut; 24, Upper Gasket; 25, Lower Gas- ket; 26, Lower Clutch; 2J, Return-Spring Stop; 28, Cap Screw. Port h in the seat leads to the Reducing Valve pipe. Port a leads to that portion of the Distributing- Valve NO. 6 E. T. EQUIPMENT 329 C'fr/cy ./^ Fig. 83 — The S-6 Independent Brake Valve. CONNECTIONS : RV — Reducing- Valve Pipe ; EX — Exhaust ; IV — Distributing- Valve Re- lease Pipe to the Distributing Valve ; III — Distributing- Valve Release Pipe to the Automatic Brake Valve ; II — Application- Cylinder Pipe. 330 MODERN AIR BRAKE PRACTICE Release Pipe which connects to the distributing valve at IV (Fig. 64). Port c leads to the other portion of the release pipe which connects to the automatic-brake valve at III (Fig. 78). Port d leads to the applica- tion-cylinder pipe which connects to the distributing valve at II (Fig. 64). Port h in the center, is the exhaust port leading directly down to the atmosphere. Port k is the warning port, connecting with the atmosphere. Exhaust cavity g in the rotary valve is always in com- munication at one end with exhaust port h. Groove e in the face of the valve communicates at one end with a port through the valve. This groove is always in com- munication with a groove in the seat connecting with supply port h, and through the opening just mentioned air is admitted to the chamber above the rotary valve, thus keeping it to its seat. Port m connects by a small hole with groove ^ ; / is a groove in the face of the rotary valve; / consists of ports in top and face of valve con- nected by a passage. Running Position. This is the position that the in« dependent brake valve should be carried in at all times when the independent brake is not in use. Groove / in the rotary valve connects ports a and c in the valve seat, thus establishing communication between the applica- tion cylinder of the distributing valve and port / of the automatic brake valve (Fig. y6), so that the distribut- ing valve can be released by the latter. It will also be noted that if the automatic brake valve is in running position, and the independent brakes are being operated, they can be released by simply returning the independent valve to running position, as the application-cylinder pressure can then escape through the release pipe and automatic brake valve. NO. 6 E. T. EQUIPMENT 331 RV? <•> cut-out cock and after the air pressure has escaped, remove the oil plug in the valve body and fill the oil hole with valve oil. Q. After filling the oil hole and before replacing the oil plug, what should be done ? A. The handle should be moved a few times between release and emergency positions to permit the oil to work in between the rotary valve and its seat. The oil hole should then be refilled and the oil plug replaced. Q. How should the rotary valve key and gasket be lubricated ? A. Remove the cap nut from the rotary valve key and fill the oil hole. Q. Before replacing the cap nut, what should be done ? A. Push down on the key and rotate the handle a few 442 MODERN AIR BRAKE PRACTICE times between release and emergency positions ; then re- fill the oil hole and replace the cap nut. Q. If the handle latch becomes dry, what should be done ? A. Lubricate the sides of the latch and the notches on the quadrant. Q. If, with the handle in release, running, holding or lap positions, there is a leak at the brake pipe service exhaust, what does it indicate ? A. That the equalizing piston valve is unseated, prob- ably due to foreign matter. Q. How can this leak usually be stopped ? A. By closing the double-heading cut-out cock under the brake valve, making a heavy service application and returning the brake valve handle to release position. This will cause a heavy blow at the service exhaust fitting and usually remove the foreign matter and allow the valve to seat. Q. With the handle of the automatic brake valve in service application position, brake pipe pressure seventy pounds, how long should it take to reduce the equalizing reservoir pressure twenty pounds ? A. From six to seven seconds. Q. From a brake pipe pressure of no pounds, how long should it take ? A. From five to six seconds. Q. In case the equalizing reservoir pressure reduces considerably faster than the time given, what is the prob- able cause? A. Either an enlarged preliminary exhaust port, leak- age past the rotary valve, seat, lower gasket, or in the equalizing reservoir and its connections to the brake valve or gage. EXAMINATION QUESTIONS AND ANSWERS ,443 Q. If the reduction is materially slower than the figures given, what is probably the cause? A. A partial stoppage of the preliminary exhaust port or leakage into the equalizing reservoir. Q. How should test be made for a leaky rotary valve ? A. By placing the brake valve handle in service posi- tion and allowing it to remain there until the brake pipe gage pointer drops to zero ; then close the double-head- ing cock under the brake valve and place the brake valve handle on lap. If a blow starts at the brake pipe ex- haust, it indicates a leak by the rotary valve into the brake pipe; if an increase of pressure is noted on the equalizing reservoir gage it indicates a leak past the rotary valve, or body gasket into the chamber above the equalizing piston and reservoir. Q. During this test, if an increase of brake cylinder pressure results, or the safety valve blows intermittently, what does it indicate. A. A leak by the rotary valve into the application cylinder of the distributing valve. O. With the brake valve handle on lap position after making a service application, if the brake pipe service exhaust continues to blow and the air gage indicates a fall in pressure in both the equalizing reservoir and brake pipe, where should the trouble be looked for? A. In the equalizing reservoir and its connections, both to the brake valve and to the air gage, and also the inner tube of the gage. INDEPENDENT BRAKE VALVE TEST. Q. What are the important things to observe in con- nection with the independent brake valve? A. That no external leakage exists in the brake valve 444 MODERN AIR BRAKE PRACTICE or its pipe connections and that the handle and return spring work freely and properly. Q. What can cause the handle to move hard? A. Lack of lubrication of the rotary valve and seat, rotary valve key and gasket or handle latch, same as with the automatic brake valve. Q. What should be done to make the handle move freely ? A. Follow the same recommendations as prescribed for the automatic brake valve. Q. Should the handle continue to work hard after the parts have been lubricated, where is the trouble? A. Probably something is wrong with the return spring or its housing. Q. How should test for leaky rotary valve be made? A. Make a partial independent application of the brakes, place the handle on lapy and note if brake cylin- der pressure increases gradually to the limit of adjust- ment of the reducing valve. Q. Should the handle fail to automatically return to running position or to slow-application position, what is the probable cause? A. Too much friction of the moving parts or a weak or broken return spring. DISTRIBUTING VALVE TEST. i Q. With the system charged to standard pressure, if i a five-pound service reduction in brake pipe pressure fails to apply the locomotive brake, what is the probable cause? A. Excessive friction in one or more of the operative parts of the distributing valve. EXAMINATION QUESTIONS AND ANSWERS 445 Q. How should the test be made to determine which of the operating parts caused the trouble ? A. By recharging, and then making a slow independ- ent application. If the brake applies properly, the indi- cations are that the trouble is in the equalizing portion of the distributing valve; if it does not, the indications are that it is in the application portion. Q. How frequently should the distributing valve be cleaned and oiled? A. At least every six months. Q. What parts of the distributing valve should be lubricated ? A. All operating parts. Q. H water is found in the distributing valve, what is usually the cause ? A. Improper piping on the locomotive ; not sufficient length of radiating pipe between the compressor and res- ervoirs. Q. How should the equalizing piston, slide valve and graduating valve be removed from the distributing valve r A. Remove the equalizing cylinder cap, and carefully pull out the piston and valves so as not to injure them. Q. How should the application piston, application valve and exhaust valve be removed? A. First take off the application valve cover and remove the valve, then take out the application valve pin, after which the application cylinder cover should be removed and the piston and exhaust valve carefully pulled out. Q. ]\Iust the application valve pin always be removed before attempting to take out the application piston and exhaust valve? A. Yes ; if this is not done, damage will result, as the 446 MODERN AIR BRAKE PRACTICE piston cannot be taken out unless the pin is removed. Q. With the valves removed from the distributing valve, what should be done? A. Air should be blown through the ports and pas- sages to remove any foreign matter. Q. Before assembling the parts, what should be done ? A. All seats and bushings should be thoroughly cleaned and carefully examined to see that no lint is on the seats. Q. What else should be given attention? A. The feed groove in the equalizing piston bushing should be carefully cleaned out. Q. What should be the resulting brake cylinder pres- sure from a ten-pound brake pipe reduction? A. About twenty-five pounds. Q. For each pound reduction of brake pipe pressure, what should be the resulting brake cylinder pressure? A. About two and one-half pounds. Q. If, after a partial service application has been made and the brake valve lapped, the brake cylinder pressure continues to increase, what are the causes? A. The most probable cause is brake pipe leakage. Others may be a leak past the automatic rotary valve, the independent rotary valve, the equalizing valve, or the graduating valve in the distributing valve. Q. What brake pipe pressure should be used when testing the ET Equipment ? A. Seventy pounds. Q. Why? A. With seventy pounds brake pipe pressure the point of equalization is below the adjustment of the safety valve. With no pounds pressure the point of equalization is above the adjustment of the safety valve EXAMINATION QUESTIONS AND ANSWERS 447 and therefore leakage could not be so easily discovered. Q. How is the source of leaks determined? A. By making a partial service application and ob- serve to what figure the brake cylinder pressure rises. If it increases to fifty pounds and remains constant, it indicates brake pipe leakage. Q. If the increase in the brake cylinder pressure is due to a leaky rotary in the automatic brake valve, how may it be detected? A. The brake cylinder pressure will increase up to the limit of adjustment of the safety valve, causing it to blow. O. If brake cylinder pressure increases to forty-five pounds and stops, where may the trouble be looked for? A. In the independent brake valve, due to a leaky rotary. Q. With the safety valve removed and the brake ap- plied with a partial service application, if a continuous leak exists at the safety valve connection to the distribut- ing valve, what would probably be the cause? A. A leaky graduating or equalizing valve. Q. If the equalizing valve leaks, how can it be de- tected? A. By a steady discharge of air through the exhaust port of the automatic brake valve when the handle of both this brake valve and the independent brake valve is in running position. Q. If, with a service application there is an inter- mittent blow at the brake cylinder exhaust port, what does it indicate? A. A leaky application valve, provided the applica- tion cylinder and the application cylinder pipe is tight Q. What indicates exhaust valve leakage? 448 MODERN AIR BRAKE PRACTICE A. A continuous discharge of air from the exhaust port when the brake is appHed. Q. If after a service application the equaUzing pis- ton, sHde valve and graduating valve move to release position because of graduating valve leakage, will the locomotive release? A. On the engine from which the brakes are being operated the locomotive brake will not release, but on the second engine in double headers or helpers with the brake valves cut out (double-heading cock closed) the locomotive brake will release. Q. Why does not the brake release on the locomotive from which the brakes are being operated? A. Because under these conditions the automatic brake valve is on lap; consequently the air cannot ex- haust from the application chamber. Q. Why will the brake release on the second locomo- tive or helper? A. Because the release pipe is open to the atmosphere. Q. If the brake released after an automatic appHca- tion, when the handle is placed in release or holding po- sition, but remains applied after an independent applica- tion, where would you look for the trouble ? A. It is caused by a leak from the distributing valve release pipe, between the automatic and the independent brake valves. Q. If the brake releases after an independent appli- cation, but remains applied after an automatic applica- tion, what would cause the trouble? A. A leak in the distributing valve release pipe be- tween the distributing valve and the independent brake valve. Q. If the brake releases after either an automatic or I EXAMINATION QUESTIONS AND ANSWERS 449 an independent application, what would cause the trouble ? A. A leak from the application cylinder pipe or past the application cylinder cap gasket. Q. How could a weak or broken application piston graduating spring be detected? A. If this spring becomes weak or broken, the appli- cation portion of the distributing valve would not be as sensitive to graduation. Q. How should test for leakage in the application cylinder pipe be made? A. ^lake a service application of the brake, lap the handle and note if the brake remains applied. If it does not, it indicates that the application cylinder pipe or pos- sibly that the application cylinder cap gasket is leaking. Q. To determine if the release pipe is leaking, how should test be made ? A. Make a service application of the brake with the automatic brake valve. If the brake remains applied with handle in lap position but releases when handle is returned to holding, it indicates release pipe leakage. Q. If the brake cylinder pressure does not remain at that to which it is applied, what is the cause ? A. Leakage from application chamber, application cylinder or their pipe connections. BRAKE CYLINDER LEAKAGE TEST. Q. Can brake cylinder leakage be readily determined with ET Equipment ? A. Yes. Q. How? A. By noting the number of strokes which the com- pressor makes in a given period of time. Then apply 450 MODERN AIR BRAKE PRACTICE T the brake with the independent brake valve and after the compressor has restored the main reservoir pressure again note the number of strokes. The difference in the number of strokes indicates the amount of leakage in the brake cylinders. Q. Is there any other method of determining brake cylinder leakage? A. Yes; apply the brake with the independent brake valve, then close the cut-out cock in the distributing valve supply pipe and observe the brake cylinder gage. The gage will indicate the amount of leakage from the brake cylinders. Q. Can it h^ determined which of the brake cylinders is leaking? A. Yes. Q. How? A. Apply the brake with the independent brake valve and close the cut-out cock in the distributing valve supply pipe, then close the cut-out cocks in the pipes leading to the truck brake cylinder, driver brake cylinder and tender cylinder in order, noting the gage after each cock is closed. SAFETY VALVE TEST. Q. What attention should be given the E-6 Safety Valve? A. It should be noted that the safety valve is screwed properly in place, that the cap nut is screwed down on the regulating nut, making an air tight joint with the body, and that all vent holes and ports are open. Q. If the cap nut is not screwed down properly, what would be the effect ? A, The valve and its stem would have too much lift I EXAMINATION QUESTIONS AND ANSWERS 451 and the leakage of air around the threads of the regulat- ing nut to the atmosphere would interfere with its proper operation. Q. How should the safety valve be tested to deter- mine if it is properly adjusted? A. Make an emergency application of the brake, allowing the handle to remain in emergency position, and note if the proper brake cylinder pressure is obtained. Q. What brake pipe pressure should be used when testing the safety valve? A. no pounds. Q. Within what limits should the safety valve limit the locomotive brake cylinder pressure ? A. Between 68 and 70 pounds. Q. If the safety valve is adjusted at 68 pounds, and the pressure increases above 70 pounds, what would be the cause? A. The holes leading from the spring chamber of the valve are restricted, or the piston valve has worn loose. Q. If the safety valve permits the pressure to reduce considerably below 68 pounds before closing, what would be the trouble? A. The holes leading from the spring chamber of the valve have been enlarged or gum or dirt has made the piston valve too close a fit. Q. Within what limits should the safety valve limit the locomotive brake cylinder pressure for ordinary serv- ice applications (no lbs. brake pressure)? A. Between 65 and 70 pounds. AIR SIGNAL SUPPLY SYSTEM TEST. Q. In testing the air signal, what should first be done ? A. The signal pipe should be charged and all stop 452 MODERN AIR BRAKE PRACTICE cocks, joints and unions carefully examined for leakage^ Q. How can it be determined whether the proper pressure is being carried in the signal line? A. By attaching a test gage to the signal line hose. Q. What would a too high signal pipe pressure indi- cate? A. That the reducing valve was improperly adjusted or was leaking. Q. What effect might this have? A. In combination with a leaky signal line it might cause the signal whistle to blow when an independent application of the brake is made. Q. How can reducing valve leakage be determined? A. By making a signal pipe reduction and noting if the pressure gradually increases after the standard maximum signal pipe pressure has been attained. Q. With a reasonably tight signal pipe, if the whistle blows when an independent application of the brake is made, what would be the cause ? A. A leaky check valve in the combined strainer and check valve. Q. If, in charging up the signal pipe the test gage indicates a too slow increase of pressure, where should the trouble be looked for ? A. Probably an obstruction in the strainer or choke fitting or a loose fitting feed valve piston. Q. If, with the signal system of the locomotive fully charged, the signal whistle blows, what is the probable cause ? A. Leakage in the signal system and a sluggishly operating reducing valve. EXAMINATION QUESTIONS AND ANSWERS 453 Q. What is the high speed brake? A. A more powerful brake, designed to meet the heavy brake work required on high speed passenger trains. Q. Does the adoption of the high speed brake require any great change in the brake apparatus usually found on a locomotive or car? A. No; simply increasing the pressure in the train pipe and auxiliary reservoirs and the use of a high speed reducing valve connected to the brake cylinders, per- forms the conversion. Q. What is the standard hig'h speed brake pressure carried in the train pipe auxiliary reservoirs? A. One hundred and ten pounds. Q. How much shorter distance will the high speed brake stop a train than the old standard 70-pound brake ? A. About 30 per cent., in emergency stops. Q. Is it understood that this brake is primarily an emergency brake? A. Yes ; but it also greatly improves the service brake work. Q. What advantage is this brake in making service stops ? A. It enables two or three full service applications to be made without recharging the train pipe and auxiliary reservoirs, and still have sufficient pressure in the auxil- iary reservoirs for an emergency application if it is desired. Q. What per cent, of brake power is used on passen- ger equipment cars? A. Ninety per cent., figured from a cylinder pressure of 60 pounds. 454 MODERN AIR BRAKE PRACTICE Q. But does not the use of no pounds auxiliary reservoir pressure give more than 60 pounds cylinder pressure? A. Yes ; if applied in emergency, but not during ordi- nary service applications. Q. What pressure will an emergency application de- velop in the brake cylinders? A. About 88 pounds, if the piston travel is adjusted properly. Q. Why will the cylinder pressure not exceed 60 pounds during a service application, if a heavy train pipe reduction is made? A. The high speed reducing valves attached to each brake cylinder are so designed that they will vent brake cylinder pressure to the atmosphere if it exceeds 60 pounds. Q. If the brakes are applied in emergency, which re- sults in giving about 88 pounds cylinder pressure, will this high pressure remain in the brake cylinder until the train is stopped? A. No; the principle of the brake is to give a high cylinder pressure when the speed is high, and to grad- ually reduce the pressure as the speed reduces. Q. Then the braking power is greatest at the begin- ning of the application, or when the speed of the train is high, and lowest when the speed is lowest? A. Yes ; the braking force is variable, being greatest when the train speed is highest, and, reducing gradually, is least when the train speed is lowest. Q. It is well known that to slide a wheel at high speed is next to impossible. Was it with this knowledge in view that the high speed brake was designed? A- Yes; advantage is taken of this fact to apply the EXAMINATION QUESTIONS AND ANSWERS 455 brakes with extraordinary force when the speed is high and the wheels are rapidly revolving, and to have the braking force decrease as the train speed decreases, end- ing with a still powerful, yet safe braking force as the train comes to a standstill. Thus the variable braking force is practically fitted to the variable speed. Q. Why is a variable cylinder pressure desired when stopping a train? A. Because the friction between the brake shoes and wheels varies with the speed, it being low at high speed and high at low speed. Q. Have any tests been made to prove that such is the case? A. Yes ; the Westinghouse-Galton tests, made in England in 1878, were the first along this line, but of later years many tests have been made, all of which proved that the faster the wheel revolved against the brake shoe the less the friction between the two, but as the speed of the wheel decreased, the friction increased. Q. In stopping a wheel from revolving, what two forces are acting against the wheel in opposite directions ? A. The adhesion, or friction, between the wheel and the rail acts upon the wheel in one direction, tending to keep it revolving, while the friction between the brake shoe and the wheel is acting in the opposite direction, tending to stop it from revolving. Q. As has been described, the brake shoe friction varies with the speed. Does not the rail friction, or ad- hesion, also vary with the speed? A. No; tests which have beeen made to determine this prove that it is constant, regardless of the speed. 456 MODERN AIR BRAKE PRACTICE THE AUTOMATIC REDUCING VALVE. Q. What is the purpose of the automatic reducing valve ? A. To so manipulate the brake cylinder pressure that a variable braking power may be had during the period of a train stop. Q. How is this variable pressure regulated? A. The automatic reducing valve is so constructed that when the maximum pressure is held in the brake cylinder, the pressure is slowly vented to the atmos- phere, gradually reducing that pressure faster and faster, until the minimum pressure is reached, at which time the venting is much more rapid than at the begin- ning. Q. What parts compose the automatic high speed re- ducing valve? A. A piston, the top of which is always exposed to any pressure in the brake cylinder, regulating spring under the piston, which is adjusted by regulating nut; a slide valve, which separates the brake cylinder pressure from the atmosphere through the automatic reducing valve. Q. Explain the action of the automatic reducing valve. A. As the brake cylinder pressure is always on top of the piston, there is a tendency for the piston to descend, equal to the pressure exerted thereon. On the under side of the piston is the regulating spring, adjusted by regulating nut, which has an upward pressure of 60 pounds, the standard adjustment pressure. Q. Brake cylinder pressure then has a tendency to force the piston downward against the resistance of the regulating spring? i i EXAMINATION QUESTIONS AND ANSWERS 457 A. Yes ; and when the brake cylinder pressure on the top side of piston is greater than the resistance of regu- lating Spring, the piston will descend, carrying with it the slide valve. Q. In an emergency application of the brake, how does the automatic reducing valve operate? A. The pressure on the upper face of the piston over- comes the tension of the spring, forces the piston to its lowermost limit and draws the slide valve along with it, making a communication between the brake cylinder and the atmosphere through the apex of a triangular shaped port. Q. How does the automatic reducing valve operate in service application of the brake? A. As the auxiliary reservoir air is sent by the triple valve to the brake cylinder and to the upper side of piston, no effect is had on the reducing valve until such time as the brake cylinder pressure reaches a higher point than the adjustment of the regulating spring, then the piston slowly descends until the base of the triangu- lar port b is opposite the exhaust port a, and brake cylinder pressure is quickly vented to the atmosphere. Q. What is the advantage of such an operation after service application of the brake? A. It prevents an over-accumulation of brake cylin- der pressure, which might result in the sliding of wheels. Q. Is the use of the high speed brake confined exclu- sively to through fast express trains? A. No; it has now come into general use on local as well as through trains, and is being made the standard for all passenger equipment trains on the leading rail- way lines. 458 MODERN AIR BRAKE PRACTICE Q. What is the purpose of having two feed valves on this system? A. They are to permit of changing the pressures readily from high speed to the standard pressure with- out the necessity of readjusting the pump governor and feed valve. Q. How is this accomplished? A. Turning the handle of the reversing cock to the left cuts in the 70-pound feed valve ; turning the handle to the right cuts in the iio-pound feed valve. The small ^-inch cock in the governor pipe must also be opened or closed to change the pump governor control. Q. What pressures are the pump governor heads ad- justed for? A. The low pressure head should be set at 90 pounds, and the high pressure head at 130 pounds, slight modi- fications are sometimes made in connection with this pressure to suit the local conditions. Q. Is there more than one way of coupling up the pump governor heads? A. Yes ; the low pressure head is sometimes coupled to the reversing cock, such as it is with "Schedule U." Q. In handling the high speed brake, should it be operated in a similar manner as the old standard 70-pound brake? A. Yes ; the rules covering the handling of the 70-pound pressure brake on passenger trains apply to the high speed brake, they being heavy initial reductions and the two application stop. Q. What style of triple valve is used on tenders with the high speed brake? A. Quick action triple valve. Q. When the engine is equipped with a truck brake, EXAMINATION QUESTIONS AND ANSWERS 459 is a separate reducing valve used with the truck brake cyHnder ? A. No; the apparatus is so arranged that one reduc- ing valve takes care of the driver and truck brake cylinders. Q. In making an application of the brakes when the high speed pressure is used, will a 20-pound reduction give any more braking power than if the same reduction were made with the 70-pound pressure? A. No ; it appears, however, to give a little more, but this is due to the air entering the cylinder a little quicker. Q. If when making a brake test a 20-pound reduction is made, one of the reducers commences to blow, what would this indicate? A. It is either not adjusted properly, or else the car has very short piston travel, the latter being the usual trouble. Q. What would be the per cent, of braking power on a car if an emergency application is made and 88 pounds cylinder pressure is had? A. If the car is braked on a basis of 90 per cent., with 60 pounds cylinder, 88 pounds of cylinder pressure would give about 130 per cent, of braking power to the weight of the car braked. Q. In handling a light engine, should the high speed brake pressure be used? A. No; the reversing cock handle should be turned to the left and the 70-pound pressure used. Q. Why are the recent reducing valves supplied with a long, straight cap nut on the lower end instead of the usual round cap form? A. It was found that in cold weather water would drip to the lower extremity of the cap, hang there in 460 MODERN AIR BRAKE PRACTICE drops and finally freeze, thus stopping up the small port in the cap nut. The straight sided cap nut prevents freezing of the hole in the cap. Q. Why is this hole placed in the cap nut? A. To permit any leakage of brake cylinder pressure past the piston into the spring case to escape. Q. What harm would the accumulation of such leak- age amount to if permitted to accumulate in the spring case ? A. It would add its pressure to that of the regulating spring, thereby tending to force the piston upward, thereby closing ports b and a, too early, and holding too high a pressure in the brake cylinder. Q. Is it important then that the hole in the cap should be kept open? A. Yes; sometimes this becomes stopped up, either carelessly or purposely, and the valve is given the erratic action already described. Q. In high speed brake service is it necessary that greater care should be given the triple valve and other parts ? A. Yes ; the greater pressure on the back of the slide valve of the triple valve in high speed brake service tends to squeeze out the lubrication from between the face and seat of the slide valve, thus rendering those parts dry, and creating greater friction, which prevents as smooth an operation of the slide valve on its seat as would the 70-pound brake. Sometimes more frequent lubricating is necessary on this account. Q. What other difficulties are encountered in the triple valve in high speed brake service? A. That resulting from moisture in the air reaching the triple valve, which assists in washing off the lubri- EXAMINATION QUESTIONS AND ANSWERS 461 cant, and creating a film of ice in cold weather between the slide valve and its seat, thus creating undue friction of the parts which create a tendency for the triple valve to give undesired quick action. Q. Are there any other points to be watched on high speed brake service with respect to undesired quick action ? A. Yes; the equalizing piston of the brake valve should be kept in good condition to operate smoothly, else undesired quick action may be caused. Q. What attention should be given the high speed reducing valves? A. On engines and tenders they should be cleaned and oiled every six months, on cars once a year. Q. What kind of oil should be used in lubricating the reducing valves? A. The same as is used in the triple valves ; a high grade mineral oil. Q, In cleaning the reducing valve is it necessary to relieve the tension on the adjusting spring? A. No; the lower case can be removed and replaced without changing the adjustment mechanism. V- ESTINGHOUSE HIGH PRESSURE CONTROL SYSTEM, ''schedule U." Q. W^hat is the "Schedule U" or "High Pressure Control System?" A. It consists of a duplex device designed to meet the needs of special air brake service, where the pres- sures ordinarily employed may be quickly changed to higher pressures to meet more difficult conditions, such as controlling trains made up of heavily loaded cars. 462 MODERN AIR BRAKE PRACTICE Q. For what class of service is this device particu- larly designed? A. For coal, iron and other mineral carrying roads in mountainous districts, where loads are carried down hill and empties hauled up. The usual pressure may be em- ployed on the light train up the grade where little brak- ing power is demanded or needed, and by merely reversing a cock the apparatus may be changed to give a predetermined higher pressure with which to operate the loaded train down the grade. Q. Briefly describe the ''Schedule U," or "High pressure control system?" A. It is simply a modification of the usual equipment used on an engine with the addition of a duplex pump governor, two feed valves, reversing cock and bracket, and safety valves connected to a driver and tender brake cylinders. Q. Describe the operation of the apparatus. A. The two pump governor heads are adjusted for 90 and no pounds respectively. Likewise, the two feed valve attachments are set for 70 and 90 pounds. To operate the low or ordinary pressure feature, the handle of the reversing cock is turned to the left. This cuts out the no-pound governor and 90-pound feed valve, and renders operative the 90-pound governor and the 70-pound feed valve. Thus the high pressure control parts are cut out and the low pressure cut in. By re- versing the position of the reversing cock handle, the low pressure parts are cut out and the high pressure parts cut in. Q. How are the two feed valves arranged so that they can both be connected to the brake valve? A. They are attached to the reversing cock, which in EXAMINATION QUESTIONS AND ANSWERS 463 turn is connected to the brake valve by pipes and special pipe bracket. However, only one valve has any connec- tion with the brake valve at one time, this depending upon the position of the reversing cock handle. Q. Does turning the reversing cock handle change the pump governor control as well as the feed valve? A. Yes ; this is arranged by having the low pressure head of the governor attached to the low pressure side of the reversing cock. Q. When making the application of the brakes when the 90 pounds train pipe pressure is used, how much of a reduction should be made to fully equalize the power with standard 8-inch piston travel? A. About 2^ pounds. Q. Does a 5, 10 or 15-pound service application with the 90-pound train pipe pressure develop any greater braking power than it would if only 70-pound train pipe pressure is used? A. No ; the brake power will be about the same and no gain had unless the train pipe reductions are contin- ued beyond what would be necessary to fully equalize the 70-pound train pipe pressure. Q. Would not the high pressure permitted by the iio-pound governor and 90-pound feed valve tend to loosen driving wheel tires by excessive heating and slide wheels under a tender partly relieved of its coal and water ? A. No; as safety valves are supplied for the driver and tender brakes to limit the pressures there to 50 pounds. On very long and heavy grades, it is generally desirable to cut out the driver brakes and use the water brake on the engine to assist the tender and train brakes, 464 MODERN AIR BRAKE PRACTICE Q. if the reversing cock should leak, what would happen ? A. A leakage or mingling of pressures would follow and interfere with the proper operation of the device. This part should be looked after with the same care given the other parts in ordinary service. O. Does the use of "Schedule U," or high pressure control apparatus require any change to be made in the car brake equipment? A. No; the standard car brake apparatus is used and operated in the usual manner. Q. If all cars in the train were loaded except two or three, would it be safe to use the high pressure? A. No ; as the wheels on the light cars may slide. It, however, might be advantageous to cut out the brakes on these few cars and use the high pressure on the others. WESTINGHOUSE DUPLEX MAIN RESERVOIR CONTROL. Q. In what respect does this main reservoir control arrangement differ from what is usually found on a locomotive ? A. In the use of a duplex pump governor, in which one head is adjusted for a low pressure, and one for a high pressure as shown, and connected to different parts of the brake valve. Q. What is the object of this arrangement? A. To permit of accumulating a high main reser- voir pressure with which to release the brakes and re- charge the auxiliary reservoirs, and only requiring the pump to operate against this high pressure for the short time the brakes are held applied. EXAMINATION QUESTIONS AND ANSWERS 465 Q. What pressures are the governor heads usually adjusted for? A. The low pressure head for 85 pounds, the high pressure head for no pounds. Q. By what means is the pump control transferred from one head to the other? A. By the movement of the brake valve handle. Q. In what positions of the brake valve does the low pressure head control the pump? A. In running position, or full release. Q. Explain how the pump governor heads are coupled up in this arrangement. A. The high pressure head is coupled to the usual main reservoir connection of the brake valve, while the low pressure head is connected to port A in the brake valve, which leads to the running position port. Q. Explain how the control of the pump can be trans- ferred from one head to the other. A. As the low pressure head is coupled to the run- ning position port f of the brake valve, it is, therefore, subject to main reservoir pressure when the brake valve is in running or release position, which allows the air pressure to pass to the low pressure head, causing the pump to stop when the main reservoir pressure is equal to the adjustment of this head. However, in placing the brake valve in lap, service or emergency positions, the main reservoir pressure, being cut ofif from the feed valve, is also cut off from the low pressure governor head, which permits the pump to run until the pressure in the main reservoir is equal to the adjustment of the high pressure head, which will then stop the pump. Q. In the description of the brake valve it was stated that the running position port f was closed in release 466 MODERN AIR BRAKE PRACTICE position, therefore, how can the air pressure reach the low pressure governor head to cause it to stop the pump ? A. While it is true the running position port f is closed in release position, air pressure reaches the low pressure governor head by passing back from the train pipe through the feed valve attachment. Q. Will the pipe connection and port A be found in all brake valves? A. No; however, all brake valves supplied recently have this connection, but it can be readily placed in any of the standard form of valves. Q. With this duplex governor arrangement is it neces- sary to have one of the governor vent ports plugged? A. Yes ; one of these ports must be closed in all cases where the duplex pump governor is used. THE WESTINGHOUSE COMBINED AUTOMATIC AND STRAIGHT AIR BRAKE. Q. What is the combined automatic and straight air brake ? A. A device by which either the automatic brake, or the straight air brake may be operated on the engine and tender, at the discretion of the engineer, without the operation of one brake being interfered with by the other. Q. Is it necessary to prepare one brake, by cut-out cocks, movement of brake valve handles, or otherwise, to operate either brake? A. No; the arrangement of the parts is such that the engineer may go from one brake to the other brake without any preparatory movement. Q. Each brake then is independent of the other? A. Yes; although they are combined and attached tc EXAMINATION QUESTIONS AND ANSWERS 467 the same common system, still they are entirely inde- pendent of each other in their action. Q. What comprises the combined automatic and straight air brake? A. The addition of a straight air brake valve and a few simple parts, which permit the use of the straight air on the engine and tender, without interfering with the automatic brake apparatus, both brakes being cut in at all times. Q. The combined automatic and straight air brake then is merely the straight air brake apparatus added to the automatic brake which is already on the engine and tender ? A. Yes ; and while they are combined, yet they are strictly separate. Q. Describe the operation of the combined auto- matic and straight air brake. A. Connection with the automatic brake is made by the straight air brake at three points, viz., to the main reservoir, and to the brake cylinder pipes of both driver and tender brakes. Q. From where is the straight air supply taken? A. From the main reservoir pipe to the automatic brake valve, where clean, dry air is insured. Q. Trace the course of the air used to operate the straight air brake. A. The pressure is taken from the main reservoir pipe supplying the automatic brake valve, is passed through a reducing valve which is set at 45 pounds, then through the engineer's straight air valve to the double seated check valve and to the brake cylinders. Q. Describe the release of the straight air brake. A. When the straight air brake valve is placed in re- 468 MODERN AIR BRAKE PRACTICE lease position, a direct opening is made from the cylin- ders, through the double seated check valve to the straight air brake pipe, thence through the engineer's straight air brake valve to the atmosphere. Q. Where is the double seated check valve located? A. One of these valves is inserted on both the engine and tender, in the pipe leading from the triple valve to the brake cylinders, so that in brake operation, either automatic or straight, the pressure will have to pass through the check valve in going to and from the brake cylinders. Q. Name the principal parts of the combined auto- matic and straight air brake. A. Assuming that the automatic parts are already well known, the remaining parts, those of the straight air portion, are the automatic reducing valve, the engi- neer's brake valve, the double seated check valves, the safety valve and the special hose connection. Q. What is the purpose of the special hose connec- tion? A. It is a special single hose which connects the straight air brake pipe between the engine and tender. It is subject to the low pressure only at 45 pounds, and is, therefore, less liable to burst. This low pressure in- sures greater length of life of the hose. Q. Describe the construction of the double seated check valve? A. It consists of a suitable casing holding the piston, which has, at each end, a leather face. These leather faces make an air-tight joint. The piston valve is shorter than the distance between the two seats b and d, and the bush in which it works has two series of ports, c and CI. With the piston valve against seat b, ports c EXAMINATION QUESTIONS AND ANSWERS 469 afford a free passage for the air from the straight air brake valve to the brake cyHnder. The opening leading to the triple valve, which is now in release position, is closed so no straight air leakage can occur. Q. With the straight air brake valve in release posi- tion, where it should be when not in use, assume that an automatic brake application is made. Describe the pas- sage of the air. A. The air from the triple valve, on entering the double seated check valve, will force the piston valve to the right, against seat d, thus preventing any escape of pressure at the straight air brake valve and opening ports CI so the air can flow uninterrupted into the brake cylinder. Q. Should this double seated check valve be located in any particular position? A. Yes ; in a horizontal position, so this piston valve will not be subject to gravity effect, and only be moved by air pressure. Then the mere act of making either an automatic or straight air application will cause the piston valve to automatically move to the proper posi- tion. REDUCING VALVE AND PIPE BRACKET. Q. Describe the location and operation of the reduc- ing valve and its pipe bracket. A. The reducing valve and its pipe bracket are located in the main reservoir pipe, leading to the straight air brake valve. The reducing valve is the well known slide valve feed valve attachment to the brake valve. Q. What is the purpose of the reducing valve? A. To reduce the main reservoir pressure used, to a safe amount. It should be set at 45 pounds, so that no more than that pressure can reach the brake cylinders. k 470 MODERN AIR BRAKE PRACTICE Q. In a straight air application should more than 45 pounds of pressure get to the brake cylinder, where should we look for the trouble ? A. In the slide valve reducing valve. THE SAFETY VALVE. Q. What is the purpose of the safety valve? A. In the event of the reducing valve getting out of order, due to dirt or any foreign substance deranging it, and an over pressure getting to the brake cylinder, the safety valve, being screwed into either the brake cylin- der or the brake cylinder pipe, will blow off the surplus pressure. engineer's straight air brake valve. I Q. Describe the action of the straight air brake valve? P, This valve is practically a three-way cock in its operation, but is, on account of its special construction, much superior to the three-way cock. There is* no fric- tion to it, and opportunity for leakage is reduced to a minimum. The engineer is able to tell by the touch of the valve just how much of an opening is made. It is designed to run for a long time without repairs. Q. How should the straight air brake valve be con- nected up? A. Within convenient reach of the engineer, both in running ahead, and looking back when switching. The letters cast on the body indicate respectively the main reservoir, train pipe and exhaust connections. Q. How many positions has the straight air brake valve ? A. Three; Release, Lap and Application. EXAMINATION QUESTIONS AND ANSWERS 471 Q. Name the essential parts of this valve? A. The handle, the shaft, to which the handle is con- nected, two check valves which are operated by the shaft. Q. What are the functions of the check valves? A. One controls the supply of air from the main reservoir; the other controls the exhaust from the cylinder. WESTINGHOUSE I ^ -INCH PUMP GOVERNOR. Q. What is the object in applying this enlarged type of governor to the system? A. On locomotives where two air compressors are in use it has been found that the standard i-inch governor will not allow sufficient steam to pass to the pump under certain conditions when there is a great demand for air pressure. Q. Describe the arrangement in use with the i-inch governor for two compressors. A. A I-inch governor complete is connected in the steam supply pipe to one compressor, while a i-inch governor steam valve portion only is connected in the branch pipe to the second compressor. Q. Describe the improved system of regulation. A. A i^-inch governor, and 1^4 -inch steam valve re- place the I -inch governor and valve. Q. What advantage is gained by this arrangement? A. It has ample capacity for two 9^ -inch, or two ii-inch compressors. WESTINGHOUSE CENTRIFUGAL DIRT COLLECTOR. Q. Where is this device connected? 472 MODERN AIR BRAKE PRACTICE A. In the branch pipe between brake pipe and triple valve. Q. What is its function? A. To collect all dirt and foreign matter in the brake pipe, and prevent its passing into the triple valve. Q. Describe the operation of this dirt collector. A. It is so constructed that, due to the combined action of the centrifugal force, and gravity, the dirt, etc., is automatically eliminated from the air passing through the collector, and is deposited at the bottom of the device. Q. How is the collector cleaned ? A. By removing a small plug at the bottom, and this can be done without breaking any pipe connections whatever. Q. What other advantage attends the use of this device ? A. It operates to materially reduce the work of clean- ing and oiling the brake equipment to which it is attached. WESTIXGHOUSE "PC" EQUIPMENT 473 WESTINGHOUSE ''PC'' PASSENGER BRAKE EQUIPMENT. With the introduction of heavy (125,000 lbs. to 150,000 lbs.) passenger equipment cars in steam road service, the brake force required to control such heavy cars with ap- proximately the same effectiveness as is obtainable with the apparatus used on lighter cars became so great as to exceed the capacity of a single brake cylinder even with the highest brake cylinder pressure and greatest multipli- cation of its power by leverage that could be permitted. The increased speed and weights of trains and the econ- omy of time necessary for the highest operative efficiency under modern severe traffic demands, together with the increase in length of trains and the much greater volume of air which must be handled through the brake pipe, have imposed conditions which the type of brake which was adequate for past conditions has been unable to meet satisfactorily. While a high maximum emergency stopping power is required to insure the safety of passengers and rolling stock, the ordinary service functions and automatic safety and protective features became hardly secondary in im- portance. Briefly stated, the requirements recognized as essential in a satisfactory brake for this modern service are as follows : 1. Automatic in action. 2. Efficiency not materially affected by unequal piston travel or brake cylinder leakage. 3. Certainty and uniformity of service action. 4. Graduated release. 5. Quick recharge and consequent ready response of brakes to any brake pipe reduction made at any time. I 474 MODERN AIR BRAKE PRACTICE o On O k bo II (r C ll\ o ffl* '•5 c o P^ CO Vh (L> 'O § .s ^ >» 1 s. u 1 5^ ,^ ^^ '"" '^-t a ji *3 / (? ] 0) I ^ tk rt BK^ u fflfc^ M '3l 5 a^ V4 (L> 45 jj bo fis > c (U \ >» 1 oj r P-l ' k u ?r g fl4 bo WESTINGHOUSE "pc" EQUIPMENT 475 bo C .s 'o 5 c s 'I CJ bO 476 MODERN AIR BRAKE PRACTICE 6. Maximum possible rate of recharging the brake pipe alone (rate of rise of brake pipe pressure when re- leasing, limited only by length of brake pipe, not by neces- sity for recharging reservoirs as well as brake pipe, before rear brakes in train can be released). 7. Predetermined and fixed flexibility for service operation. 8. Maximum sensitiveness to release, consistent with stability, combined with minimum sensitiveness to the in- evitable fluctuations in brake pipe pressure tending to cause undesired light service applications, brakes creeping on, etc., and yet guard against the attainment of too high a difference of pressure between the brake pipe and pres- sure chamber (auxiliary reservoir). 9. Full emergency pressure obtainable at any time after a service application. 10 Full emergency pressure applied automatically after any predetermined brake pipe reduction has been made after equalization. 11. Emergency braking power approximately 100% greater than the maximum obtainable in service applica- tions. 12. Maximum brake cylinder pressure obtained in the least possible tirfie. 13. Maximum brake cylinder pressure maintained throughout the stop. 14. Brake rigging designed for maximum efficiency. 15. Adaptability to all classes and conditions of ser- vice. That certain of these requirements demanded radical changes in the valve device used on the car is evident if a comparison of the above is made with the functions of previous types of brakes in general service. These con- WESTINGHOUSE "Pc" EQUIPMENT 477 siderations led to the development of the equipment known as the Westinghouse Improved Brake Equipment, Scheduled "PC," employing what is known as a Control Valve in the place of a triple valve. NOVEL FUNCTIONS. 1st. Graduated release and quick recharge, obtained as with previous improved types of triple valves {e. g. Type L). The air supply to assist in recharging and to accomplish the graduations of the release is taken from the emergency reservoir. 2nd. Certainty and uniformity of service action se- cured by insuring that the valve parts move so as to close the feed grooves on the slightest brake pipe reductions, the design of the valves being such as to then require the necessary and proper differential to be built up to move the parts to service position as the brake pipe reduction is continued. 3rd. Quick rise in brake cylinder pressure provided for by insuring a prompt movement of the parts and direct and unrestricted passage from reservoirs to brake cylinders during applications. 4th. Uniformity and maintenance of service brake cylinder pressure during the stop, provided for in the same manner as by the application portion of the distrib- uting valve. 5th. Predetermined limiting of service braking power fixed by the equalization of the pressure and applica- tion chambers of the control valve. This eliminates the safety valve feature of previous equipments and is both positive and uniform. After such equalization has taken place, any further brake pipe reduction causes the moving 478 MODERN AIR BRAKE PRACTICE parts of the valve to travel slightly beyond the service position to the ''over-reduction" position. Air then flows from the pressure chamber to the reduction limit- ing chamber until equalization takes place between these two chambers, if the brake pipe reduction is continued far enough. During this time the application chamber re- mains at the first equalization pressure and the brake cyl- inder pressure is maintained accordingly. The maximum service brake cylinder pressure (ser- vice equalization) is fixed at 86 lbs., instead of at 50 lbs. as with previous equipments. On this account it is possible to use a much lower total leverage ratio (which is necessary if the required efficiency of the foundation brake rigging for the classes of cars considered, is to be maintained). This equalization pressure corresponds to a reduction of 24 lbs. from no lbs. brake pipe pressure, which is the reduction required with high speed brake equipment to give maximum service brake cylinder pres- sure (60 lbs., corresponding to the opening point of the high speed reducing valve). This insures uniformity of service operation of old and new equipments mixed in the same train. 6th. Automatic emergency application on depletion of brake pipe pressure. If the brake pipe reduction is still further continued below the point at which the pres- sure and reduction limiting chambers equalize, the parts move to emergency position and cause both the quick action and emergency portions to operate, starting serial quick action throughout the train and obtaining emer- gency brake cylinder pressure. 7th. Full emergency braking power at any time. As the operation of the emergency and quick action portions just described is dependent only upon the movement of WESTINGHOUSE ''Pc" EQUIPMENT 479 the parts to emergency position and, as this can be caused at any time by making an emergency apphcation with the brake valve, conductor's valve, etc., it follows that full emergency braking power can he obtained at any time, irrespective of a service application previously made. 8th. The service and emergency features being sepOr- rated permits the necessary flexibility for service applica- tions to be obtained without impairing in the slightest the emergency features of the equipment. 9th. A low total leverage ratio, with correspondingly greater overall efficiency, is made possible by the use of two brake cylinders per car, and also higher service equalization pressure. loth. Less sensitiveness to the inevitable fluctuations in brake pipe pressure, which tend to cause undesired light applications of the brake. This insures against brakes creeping on or dragging, burning of brake shoes, delays to the train and so on. nth. Maximum rate of rise of brake pipe pressure possible with given length of brake pipe with consequently greater certainty of brakes releasing when a release is made. With non-graduated release equipments or pre- vious graduated release equipments operating with grad- uated release feature cut-out, the recharging of the brake pipe toward the rear end of a train of any length may become very slow due to the draining away of the air from the forward end of the brake pipe by the large reservoirs with large sized feed grooves which take their entire supply from the brake pipe only. The quick re- charge feature of the 'TC" equipment overcomes this difficulty, with graduated release cut in, by restoring the pressure to the pressure chamber on each car at as rapid a rate as the brake pipe pressure alone can be raised by 480 MODERN AIR BRAKE PRACTICE the flow of air through the brake valve. Consequently up to the point of equalization of the pressure chamber and the emergency reservoir under each car (about 5 lbs. less than normal brake pipe pressure), no air is being drawn from the brake pipe. This insures a prompt and certain release of the brakes, and a rapid recharge and prompt response to successive reductions which may be made, because (i) practically no air is drawn from the brake pipe; (2) pressure chamber and brake pipe recharge at the same rate; and (3) with graduated re- lease cut out, no air is supplied to pressure chamber except from brake pipe. 1 2th. Greatly increased sensitiveness to release, as demanded by the changed conditions already referred to, which tend to produce a very slow rate of rise of brake pipe pressure when releasing and recharging, especially toward the end of a long train of heavy cars having large reservoirs. It then becomes necessary to provide the maximum sensitiveness to an increase in brake pipe pres- sure, in order to insure all valves in the train responding as intended. 13th. The elimination of the graduated release fea- ture is especially provided for in the construction of the valve. During the transition period when graduated re- lease equipment is likely to be handled i^ the same train with cars not equipped with a graduated release brake, especially where long trains are handled and the air sup- plied from the brake pipe likely to be limited in any way from any cause, it is usually best to cut out the graduated release feature until all cars are furnished with this type of brake. All that is required to change the "PC" equip- ment from the graduated to a direct release brake or vice versa, is the loosening of a bolt and turning of the WESTINGHOUSE "pc" EQUIPMENT 481 "Direct and Graduated Release Cap" on the front of the control valve head until the desired position is indi- cated, the bolt being then retightened. (See Figs. 114 and 116.) It should be further stated, that all the functions men- tioned have been so combined that the requirements of interchangeability with existing equipments have been fully satisfied. PARTS OF THE "PC" EQUIPMENT. The following is a list of the parts which make up the equipment with a short description of each : 1. The control valve which corresponds in a general way to the triple valve of the old style passenger equip- ment or more closely to the distributing valve of the "ET" locomotive brake. It operates to control the ad- mission of air to and release of air from the brake cyl- inders. 2. Two brake cylinders (one for service and both for emergency applications) with pistons and rods so con- nected through the brake levers and rods to the brake shoes that when either piston is forced outward by air pressure, this force is transmitted through said rods and levers to the brake shoes and applies them to the wheels. 3. Two supply or storage reservoirs denoted as the service and emergency reservoirs respectively, accord- ing to the brake cylinders to which they are related. 4. A centrifugal dirt collector, connected in the branch pipe between the brake pipe and control valve as near the control valve as circumstances will permit, for the purpose of preventing pipe scale, sand, cinders or for- eign particles of any kind from reaching the control valve. 482 MODERN AIR BRAKE PRACTICE 5. A branch pipe air strainer, inserted in the branch pipe close to the control valve for further protection to this valve. 6. A conductor's valve placed inside each car by means of which the brakes may be applied by the con- ductor in case of accident or emergency. 7. Various cut-out cocks, angle cocks, hose couplings, dummy couplings, etc., the location and uses of which will be readily understood from the isometric views of the equipment, Figs. 11 1 and 112, and the descriptions which follow. 8. While not a fundamental part of the equipment each brake cylinder is usually provided with an Auto- matic Slack Adjuster. This is a simple mechanism by means of which a predetermined piston travel, and con- sequently a uniform cylinder pressure is constantly main- tained, compelling the brakes on each car to do their full share of work, thus securing the highest efficiency and reducing the danger of flat wheels which are likely to accompany a wide range of piston travel. This device establishes the running piston travel ; that is, the piston travel occurring when the brakes are applied while the car is in motion ; and since this is the time during which the brakes perform their work, the running travel is most important. LOCATION, ADJUSTMENT AND OPERATION OF PARTS. The No. 3-E control valve consists of four portions: (i) Equalizing Portion. (2) Application Portion. (3) Emergency Portion. (4) Quick Action Portion. WESTINGHOUSE "Pc" EQUIPMENT 483 These valve portions are supported upon the com- partment reservoir which is bolted to the underframing of the car, all pipe connections being made permanently to this reservoir so that no pipe connections need to be Fig. 113 — No. 3-E Control Valve, Side View. disturbed in the removal or replacement of any one of the operating portions of the control valve. The compartment reservoir is made up of the follow- ing chambers : Pressure Chamber. Application Chamber. Reduction Limiting Chamber. The equalizing portion is similar, in a general way, to the equalizing portion of the distributing valve used with the "ET" equipment, or the plain triple valve of the old style brake. It is the portion which is directly affected by variations in brake pipe pressure and it controls (either directly or indirectly, through the medium of the other portions of the control valve), the desired charging of the 484 MODERN AIR BRAKE PRACTICE reservoirs, the application of the brake, whether in ser vice or emergency, and the release of the brake. The application portion corresponds to the application portion of the distributing valve used with the ''ET" equipment. It controls the flow of air only from service reservoir to service brake cylinder and the release of same, and has nothing to do with the emergency reservoir or the emergency brake cylinder. The emergency portion contains a double piston and slide valve which controls the flow of air from the emer- J Fig. 114 — No. 3-E Control Valve, Front View. gency reservoir to the emergency cylinder, and the release of same to the atmosphere. The quick action portion corresponds in general de- sign and function to the quick action portion of a triple valve. It operates only when an emergency application of the brakes is made, vents brake pipe air to the atmos- phere locally on each car and closes the vent to the at- WESTIXGHOUSE PC EQUIPMENT 485 mosphere automatically after the desired brake pipe re- duction has been made. A full description of the functions and detailed opera- tion of the control valve will be given later. Fig. 113 is a view of the No. 3-E control valve assembled, complete, taken from the side on which the quick action portion is located. Fig. 114 is a photograph of the equalizing portion 'S^^ APPLICATION PORTION COMPAftTMENT RESERVOIR; Fig. 115 — No. 3-E Control Valve, Showing the Different Portions of the Valve. mounted on the triple compartment reservoir, taken from directly in front. The direct and graduated release cap, with its pointer and positions for cutting graduated re- lease in or out, is clearly shown. Fig. 115 is a photograph from the opposite side with the 486 MODERN AIR BRAKE PRACTICE portions separated from each other to show their relative location and method of assembling. Referring to Fig. 117, which shows actual sections through the portions of the control valve and the triple compartment reservoir, the following are the names of the detail parts (the numbers given are reference num- bers only, to assist in identifying the names of the parts. These numbers should not be used in ordering new of repair parts. The proper parts can be furnished only when the order specifies the correct piece number, which is given in the regular part catalog price lists covering this device) : Equalizing Portion : 2, Equalizing Body; 3, Release Piston; 4, Release Slide Valve; 5, Release Slide Valve Spring; 6, Release Graduating Valve ; 7, Release Graduat- ting Valve Spring ; 8, Release Piston Cap Nut ; 9, Release Piston Ring; 10, Release Cylinder Cap; 11, Release Cylinder Cap Gasket; 12, Square Head Cap Screw; 13, Release Piston Graduating Sleeve; 14, Release Piston Graduating Spring; 15, Release Piston Graduating Nut; 16, Check Valve; 17, Check Valve Cap Nut; 18, Direct and Graduated Release Cap ; 19, Stud and Nut for Direct and Graduated Release Cap; 20, Equalizing Piston; 21, Equalizing Piston Ring (Large) ; 22, Equalizing Slide Valve ; 23, Equalizing Slide Valve Spring ; 24, Equalizing Graduating Valve; 25, Equalizing Graduating Valve Spring; 26, Large Equalizing Cylinder Cap; 27, Large Equalizing Cylinder Cap Gasket; 28, Square Head Cap Screw ; 29, Equalizing Piston Stop Sleeve ; 30, Equalizing Piston Stop Spring; 31, Equalizing Graduating Nut; 32, Equalizing Piston Ring (Small); 33, Small Equalizing Cylinder Cap ; 34, Gasket for Small Equalizing Cylinder Cap; 35, Square Head Cap Screw; 36, Cap Nut for Small WESTINGHOUSE "Pc" EQUIPMENT 487 I o U W 1 488 MODERN AIR BRAKE PRACTICE Equalizing Cylinder Cap; 37, Small Equalizing Piston Bush ; 38, Service Reservoir Charging Valve ; 39, Charg- ing Valve Piston Ring ; 40, Charging Valve Piston Ring ; 41, Charging Valve Seat; 42, Charging Valve Washer; 43, Internal Charging Valve Nut ; 44, External Charging )- "\i5HUr;;lffl3ngy PIPE EMtR CYLE;t Fig. ii6a — No. 3-E Control Valve, Outline. I Valve Nut ; 45, Gasket for Direct and Graduated Release Cap. Application Portion : 75, Body ; y6, Piston Stem ; yy, Piston Ring (Small); 78, Piston Head; 79, Piston Seal; 80, Piston Ring (Large) ; 81, Piston Follower; 82, Piston Packing Leather; 83, Piston Packing Leather Ex- pander; 84, Piston Nut; 85, Piston Cotter; 86, Exhaust Valve ; 87, Exhaust Valve Spring ; 88, Application Valve ; 89, Application Valve Spring; 90, Application Piston Bolt; 91, Spring Box; 92, Piston Spring Sleeve; 93, Piston Spring; 94, Graduating Nut; 95, Application WESTINGHOUSE "Pc" EQUIPMENT 489 Valve Cover; 96, Application Valve Cover Gasket; 97, Square Head Screw for Application Valve Cover. Emergency Portion : 107, Body ; 108, Piston com- plete; 109, Piston Ring; no, Slide Valve; in, Slide Valve Spring; 112, Small Cylinder Cap; 113, Large Cylinder Cap; 114, Small Cylinder Cap Gasket; 115, Large Cylin- der Cap Gasket; 116, Piston Spring; 117, Square Head Cap Screw for Small Cylinder Cap; 118, Oval Fillister Head Cap Screw; 119, Emergency Piston Bush. Quick Action Portion: 130, Body; 131, Piston complete; 132, Piston Ring; 133, Quick Action Valve; 134, Quick Action Valve Seat; 135, Quick Action Valve Nut; 136, Quick Action Valve Spring; 137, Quick Action Valve Cap Nut; 138, Quick Action Valve Cover; 139, Quick Action Closing Valve ; 140, Quick Action Closing Valve Spring; 141, Cover Cap Nut; 142, Cover Gasket; 143, Square Head Cap Screw for Cover. Reservoir: 153, Triple-compartment Reservoir; 154, Cap Nut; 155, Stud with Hex. Nut; 156, Stud with Hex. Nut; 157, Emergency Cylinder Gasket; 158, Quick Ac- tion Cylinder Gasket; 159, Large Reservoir Gasket; 160, Equalizing Cylinder Gasket. Figs. 118, 119 and 120 show views of the seats and faces of the equalizing and release slide and graduating valves and of the emergency slide valve. The chambers, etc., to which the ports in the seat^connect are as fol- lows : — Equalizing Slide Valve Seat: i, Emergency Reser- voir Check Valve (under side) ; 2, Brake Pipe; 3, Direct and Graduated Release Cap (open only when cap is adjusted for graduated release) ; 4, Reduction Limiting Chamber Exhaust; 5, Small End (chamber G) of Service Reservoir Charging Valve; 6, Reduction Limit- 490 MODERN AIR BRAKE PRACTICE Ul bo »* CM o j: WESTINGHOUSE ''Pc" EQUIPMENT 491 ing Chamber; 7, Large End (chamber K) of Service Reservoir Charging Valve ; 8, Release Slide \^alve Cham- ber (chamber E) ; 9, ^application Chamber and Front of Application Piston (chamber C) ; 10, Emergency Reser- voir; II, Pressure Chamber; 12, Slotted Port; 27, Small Equalizing Piston (chamber F). Release Slide Valve Seat: 13, Large Emergency Piston (chamber P) ; 14, Small Emergency Piston (cham- ber S) ; 15, Direct and Graduated Release Cap (open only when cap is adjusted for graduated release) ; 16, Fig. 117a — No. 3-E Control Valve, Equalizing Portion. Emergency Piston Exhaust; 17, Direct and Graduated Release Cap (open only when cap is adjusted for direct release) ; 18, Application Chamber Exhaust, also Direct and Graduated Release Cap (the latter open only when cap is adjusted for direct release) ; 19, Application Chamber; 20, Quick Action Closing Valve; 21, Emer- gency Reservoir; 22, Small Equalizing Piston (chamber F). Emergency Slide Valve Seat: 23, Service Brake Cylinder; 24, Back of Application Piston (chamber M) ; 492 MODERN AIR BRAKE PRACTICE FACE VIEW GRADUATING VALVE I ^- LI'V::j_JT X ■r-p' PLAN VIEW D Z UJ O CZ^O o z <) ( o) CID O o o ^ O FACE VIEW EQUALIZING SLIDE VALVE 1 r,i (D <''°^ 1 '^ 1 z ® © © © ^ ■N f 5 « ) 270 EQUALIZING SLIDE VALVE SEAT Fig. ii8 — Equalizing Graduating Valve, Slide Valve and Slide Valve Seat. WESTINGHOUSE PC EQUIPMENT 493 25, Emergency Cylinder Exhaust; 26, Emergency Cylin- der. Fig. 121 shows the flanges of the different portions of the control valve and the seats on which these flanges 08 FACE VIEW RELEASE GRADUATING VALVE a '"< --X-C-- y 2 .^y- iV V '• r- ...u 1 '.i.. d; PLAN VIEW © cz ( 3 00 ( FACE VIEW RELEASE SLIDE VALVE i ® ® ® ® § © ® © ® i ® ® ® RELEASE SLIDE VALVE SEAT Fig. 119 — Release Graduating Valve, Slide Valve and Slide Valve Seat. fit, with all ports marked so as to assist in readily locat- ing to what portions or chambers the openings are con- nected. The diagrammatic drawings, Fig. 122, and those fol- 494 MODERN AIR BRAKE PRACTICE lowing, have been made up to assist in describing the different operations of the various parts of the control valve. They illustrate diagrammatically only those parts of the valve which come into play as the various opera- tions are performed. For the sake of clearness, the actual construction of the parts has been disregarded. All ports and parts of the valve concerned in the performance of the particular function to be described have been shown as if located in the same plane, with the connections in- dicated as clearly as possible and without attempting to follow the actual construction of the valve. Furthermore, it will be noted that all ports and passages which are not operative in the various positions, have been omitted in the corresponding diagrammatic views, so that in considering each successive position of the valve, the functions being performed by the valve will be more easily explained and understood by the reader than if those ports which exist, but which are not operative in the position shown, were allowed to remain. NORMAL POSITION. Before taking up the various positions assumed by the valve, reference should be made to Fig. 122, showing diagrammatically all of the ports and operative parts of the control valve in Normal Position. This is the posi- tion which the various parts of the valve would occupy with all parts properly assembled, but before any air has been admitted to the brake pipe, and is shown here in order to indicate the relation of all the ports and detail parts of the valve which will not be shown complete in any of the succeeding views. All of the chambers, connections and detail parts of WESTINGHOUSE PC EQUIPMENT 495 the valve are clearly indicated so that further explana- tion will be unnecessary. It will be noted that the various chambers, etc., have been designated either by name or by letter, but that the ports have not been designated. In describing the operation of the valve in detail, the por- tions from and to which the air moves in the various positions have been carefully explained but with only such o z LJ 2 V — ' ^ Q. Ul O CD U FACE VIEW SLIDE VALVE QD © 26 SLIDE VALVE SEAT Fig. 120 — Emergency Slide Valve, and Slide Valve Seat. references to the path pursued as will enable its course to be easily followed by reference to the illustrations. It should, therefore, be constantly borne in mind that the descriptive matter is incomplete without constant refer- ence to the diagrammatic illustrations, and that only by a study of both the text and the diagrams can a clear understanding of the manner in which the functions of the control valve are performed, be obtained. It will be noted that in Fig. 122, the direct and gradu- ated release cap is shown in its Graduated Release posi- 496 MODERN AIR BRAKE PRACTICE tion. Just below it is shown the position which the cap occupies when adjusted for direct instead of graduated release. In all the succeeding views, except Fig. 134, the cap is considered to be adjusted for graduated release. Fig. 134 with the accompanying explanation, refers to the operation of the valve with the cap adjusted for direct release. RELEASE AND CHARGING POSITION. Fig. 123 shows diagrammatically only those parts and ports which are operative while the brake is being released and the pressure chamber, and emergency and service reservoirs are being charged. In charging the empty equipment, air from the brake pipe entering the control valve at the point indicated, passes to chambers B and A and forces the equalizing and release pistons of the equalizing portion, with their attached valves, to Release position. Brake pipe air then passes from chamber B, lifting the equalizing check valve, and by way of the equalizing slide valve into chamber D, Air from chamber D then flows through the equalizing graduating and slide valve, (so shown in the diagrammatic drawing for the sake of clearness. In this and a number of instances following, this port in actual valves opens past the end of instead of through the graduating valve), past the emergency reservoir check valve and thence in two directions, ( i ) to chamber R and to the emergency reservoir and (2) through the equaliz- ing slide valve to two different ports connecting (i) to the service reservoir charging valve, thence to the service reservoir and, (2) by way of the direct and graduated release cap and through the release slide valve and past the end of the release graduating valve to chamber E. WESTINGHOUSE "PC" EQUIPMENT 497 498 MODERN AIR BRAKE PRACTICE o J. I— I si ga 553 U iiii is S£ f- WESTINGHOUSE ''Pc" EQUIPMENT 499 Air from the brake pipe and chamber B also flows through feed groove i and charges chamber E. From chamber E, the air flows by way of the equaliz- ing slide valve in two directions, (i) to the pressure chamber direct (which is thus charged to brake pipe pressure) and (2) to chamber K. With substantially the same pressures (brake pipe pressure as explained) in chambers G and K, and a lower pressure (service reservoir pressure) in chamber H, the service reservoir charging valve remains in the position shown in Fig. 123, being held in this position until the recharging is com- pleted, since chamber K is relatively small and the ports leading to it of ample capacity to charge it more quickly than the pressure can be built up in chambers G and H. Referring to Fig. 122, it will be noted that the pressure chamber check valve prevents the air in chamber E from flowing directly to the pressure chamber. Conse- quently this check valve is not shown in Fig. 123. It allows, however, a free passage of air in the opposite direction. That is to say, w^hen charging or recharging, air reaches the pressure chamber only by way of the equalizing slide valve but during an application of the brakes (to be explained later) the pressure chamber and chamber E are to all intents and purposes one and the same and may then be referred to as such. Chamber F at the small end of equalizing piston is connected through the release slide valve to the emer- gency piston exhaust and atmosphere, thus holding the equalizing piston and its valves positively in Release position. Chamber S at the small end of the emergency piston is connected through the release slide valve to the emer- .gency piston exhaust and the atmosphere in Release 500 MODERN AIR BRAKE PRACTICE WESTINGHOUSE "Pc" EQUIPMEiXT 501 position, thus holding the emergency piston and its valve positively in the proper position. The reduction limiting chamber is connected through the equalizing slide valve to the reduction limiting cham- ber exhaust and atmosphere. The application chamber and chamber C are connected through the release slide valve and graduating valve to the application chamber exhaust port leading to the at- mosphere. The service brake cylinder is connected through the exhaust slide valve of the application portion to the serv- ice brake cylinder exhaust port leading to the atmos- phere. The emergency brake cylinder is connected through the emergency slide valve to the emergency cylinder exhaust port leading to the atmosphere. It will be noted that Fig. 122 and some that follow show a small cavity in the release graduating valve. This cavity is connected to the emergency piston exhaust in all positions of the valve, but has no other connection. The purpose of this cavity is merely to insure that, under all conditions, there will be sufficient differential pressure acting on the graduating valve to hold it to its seat. SERVICE APPLICATION. a. Preliminary Service Position. With the equipment fully charged as explained above, the result of a service reduction in brake pipe pressure will be to lower the pressure in chambers A and B below that in chambers D and E, thus creating a differential pressure on the equalizing and release pistons. Since chamber F is open to the atmosphere (see Fig. 123), the 502 MODERN AIR BRAKE PRACTICE o o '> ;-< CO C I Ph bo WESTINGHOUSE "Pc" EQUIPMENT 503 release piston will move on a much less differential than the equalizing piston. There is a small amount of lost motion between the release piston and release graduating valve, and somewhat more between release piston and release slide valve, so that during the first movement of the release piston, the release slide valve still remains in its Release position, thus keeping chamber F open through the emergency piston exhaust port to the atmosphere. The release piston, therefore, is the first to move when a brake pipe reduction is made, and it carries with it the release graduating valve and finally moves the release slide valve to the position shown in Fig, 124, called Pre- liminary Service position. In this position the piston has closed the feed groove i (which is therefore not shown in Fig. 124) and just touches the release graduat- ing piston sleeve. The function of the valve in this position is to close the port leading from the application chamber to the atmos- phere (which is therefore not shown in Fig. 124) to close the port connecting chamber F to the emergency piston exhaust and to open this latter port, connecting chamber E past the end of the release graduating valve and through the release slide valve to chamber F. Pressure chamber air is therefore free to flow past the pressure chamber check valve to chamber F, thus balancing the pressures in chambers F and D on the opposite sides of the small end of the equalizing piston. The other connections shown in Fig. 124, which remain as shown in Fig. 123, continue to perform the same func- tions as explained with reference to Fig. 123 and conse- quently do not need to be again referred to. This position, it should be understood, is assumed only momentarily and should be regarded as the first stage 504 MODERN AIR BRAKE PRACTICE o U w d bO WESTIXGHOUSE ''PC" EQUIPMENT 505 only of the complete movement of the parts from Re- lease and Charging to the Service position of the parts. b. Secondary Service Position. The balancing of the pressures in chambers F and D, as explained, permits the equalizing piston to move in accordance with the difference of pressure already exist- ing between chambers D and A. When the shoulder on the end of the piston stem comes in contact with the equalizing slide valve, as shown in Fig. 125, a connection is momentarily made from the emergency reservoir through the equalizing slide valve and past the end of (although shown as through in the diagrammatic view) the graduating valve to chamber D. The purpose of this connection (which is cut off, it will be observed, as soon as the equalizing piston is moved beyond the equalizing piston stop sleeve) is to prevent a drop in pressure in chamber D which would otherwise take place on account of the movement (displacement) of the equalizing pis- ton. The displacement of the equalizing piston is suffi- ciently great, compared with the volume of chamber D, to require the provision just explained. At the same time, the pressure chamber is connected through the equalizing slide valve and graduating valve to chamber D, thus keeping the pressures in these two cham- bers equal. The other connections remain as explained under the heading "Preliminary Service Position." c. Service Position. The differential between the brake pipe pressure in chamber A and the pressure in chamber D {pressure 506 MODERN AIR BRAKE PRACTICE o O w CO d bo 3| < Q O 4 O ^ « O <£ iiJ £ X O D w <9 a ^ u WW if WESTINGHOUSE *'pc" EQUIPMENT 507 chamber pressure as explained) is sufficient to move the equalizing piston and its valves past the intermediate secondary service position into Service position (Fig. 126) in which the equalizing piston just touches the equal- izing graduating spring sleeve. Chambers F and D are in communication by Vi^ay of a feed port around the small end of the equalizing piston. The pressure chamber is connected to chamber D through two channels, first, by way of the pressure chamber check valve to chamber E and thence past the end of the release graduating valve through the release slide valve to chamber D by way of a port past the end of (show^n as through in cut) the equalizing slide valve, as well as through chamber F, and, second, the pressure chamber is also connected directly to the seat of the equal- izing slide valve and past the end of (shown as through in cut) the slide valve direct to chamber D. From chamber D, air from the pressure chamber can flow past the end of the equalizing graduating valve and through the equalizing slide valve to the application chamber and chamber C on the face of the application piston. The pressure of the compressed air thus admitted to chamber C causes the application piston to move to its Application position, compressing the application piston spring in so doing. In this position the brake cylinder exhaust slide valve closes the brake cylinder exhaust ports (which, there- fore, are not shown in Fig. 126) and the application slide valve. opens the application port, permitting air from the service reservoir (chamber N) to flow to chamber and the service brake cylinder, thus applying the brakes. The air flowing thus to the service brake cylinder also flows 508 MODERN AIR BRAKE PRACTICE m c cS w CO d WESTINGHOUSE "Pc" EQUIPMENT 509 by way of the emergency slide valve to chamber M, in which the pressure is increased equally with that of the serz'ice brake cylinder. The flow of air from the service reservoir to the service cylinder continues, there- fore, until the pressure in the service brake cylinder and in chamber M becomes substantially equal to that in the application chamber on the opposite side of the applica- tion piston. The application piston spring then returns the piston and the application slide valve back to Lap position (see Fig. 127), thus holding the brakes applied with a service brake cylinder pressure substantially equal to that put into the application chamber, as before men- tioned. It will be noted that in Service position, the reduction limiting chamber and emergency brake cylinder still re- main connected to the atmosphere, as explained under the heading "Release Position." d. Service Lap Position. In case that less than a full service reduction is made, that is to say, that the brake pipe pressure is not reduced below the point at which the pressure chamber and appli- cation chamber pressures equalize, the flow of air from the pressure chamber to the application chamber as ex- plained under the heading "Service Position" will finally reduce the pressure in chamber D to slightly below that to which the brake pipe pressure is reduced. The slightly higher brake pipe pressure in chamber A then causes the equalizing piston and graduating valve to return to their Service Lap positions (Fig. 127) and close com- munication from the pressure to the application chamber 510 MODERN AIR BRAKE PRACTICE and holding whatever pressure was built up in chamber C and the application chamber. It will be plain that any decrease in brake cylinder pressure, due to leakage, will now reduce the pressure in chamber M below that which is bottled up in the appli- cation chamber {chamber C). The differential pressure thus established on the application piston will cause it to move again toward its Service position and open the application valve port, as shown in Fig. 128, just enough to supply a sufficient amount of air from the service reservoir to the service brake cylinder to restore the de- pleted brake cylinder pressure to its original amount, fol- lowing which the application valve will be again lapped as already explained. In this way, the brake cylinder pressure will be maintained constant, regardless of leak- age, up to the capacity of the service reservoir. The release piston and graduating valve may, or may not return to their Lap positions at the same time as, and in a manner similar to the movement of, the application piston and valves, but they perform no function in either case. Otherwise the parts remain the same as in Service position. e. Over Reduction Position. If the b-rake pipe reduction is carried below the point at which the pressure and application chambers equalize (86 lbs. when using no lbs. brake pipe pressure and 54 lbs. with 70 lbs. brake pipe pressure), such an over re- duction results in lowering the pressure in chamber A below that in chamber D (pressure chamber pressure). The equalizing piston consequently moves beyond its WESTINGHOUSE "PC" EQUIPMENT 511 c o U W CO 6 i be C 3 u.ki '5 o5 512 MODERN AIR BRAKE PRACTICE Service position (Fig. 126) carrying with it the equaHzing sHde valve and graduating valve to what is called the "Over Reduction Position." (Fig. 128.) The relative resistances of the release and equalizing graduating springs is such that the release piston and its valves still remain as in Service, although for the moment the same differential between pressure chamber and brake pipe pressure is acting upon the release piston as was sufficient to move the equalizing piston and its valves to the Over Reduction position. The result is that air from the pressure chamber, (which is still connected to chamber D in substantially the same manner as explained under "Service Posi- tion") now flows past the end of the equalizing grad- uating valve and through the equalizing slide valve to the reduction limiting chamber instead of to the application chamber as in Service position. The reduction limiting chamber being at atmospheric pressure, permits the pressure in the pressure chamber (and chambers E and D) to drop in accordance with the continued over reduction of brake pipe pressure, to the point of equalization of the reduced pressure cham- ber pressure and the reduction limiting chamber pressure. Otherwise the condition of the pressures in the reser- voirs and brake cylinders controlled by the control valve is unchanged, except that in the movement of the equaliz- ing slide valve to Over Reduction position, a connection is made from the application chamber and chamber C by way of the equalizing slide valve to the top (chamber G) of the service reservoir charging valve, and from cham- ber D (pressure chamber pressure) past the end of the equalizing graduating valve and through slide valve to chamber K. Since the pressure in the pressure chamber WESTINGHOUSE "PC" EQUIPMENT 513 is being reduced, as already explained, while that in the application chamber and service reservoir is equalized, or practically so, at about 86 lbs. pressure, the service reser- voir charging valve is not lifted, but is held down to its seat. With the parts in this position, it will be noted that the service reservoir and the application chamber are sepa- rated only by the ring in the small end of the service reservoir charging valve. If there is any slight leakage which tends to cause a drop in application chamber pres- sure (which is relatively small compared with the service reservoir volume), the air in the service reservoir will gradually find its way around the ring in the small end of the service reservoir charging valve and prevent any material drop in application chamber pressure, thus prac- tically eliminating the possibility of the brakes gradually leaking off, due to application chamber leakage. The application valve port is shown partly open, sup- plying brake cylinder leakage, as already explained. /. Over Reduction Lap Position. Provided the brake pipe reduction is not carried below the equalizing point of the pressure chamber and reduc- tion limiting chamber, a slight reduction of the pressure in the pressure chamber (and chambers D and E) below that held in the brake pipe, resulting from the continued flow of air from the pressure to the reduction limiting chamber, will cause the equalizing piston and graduating valve to be returned to Over Reduction Lap position (Fig. 129). This closes the port from the pressure cham- ber to the reduction limiting chamber and prevents fur- ther flow of air in this direction, but otherwise all parts and pressures are as explained above under heading 514 MODERN AIR BRAKE PRACTICE o hJ c ■*-> o -a o i ho WESTINGHOUSE "Pc" EQUIPMENT 515 "Over Reduction Position," except that the port connect- ing chamber D past the end of the equaHzing graduating valve and through sHde valve to chamber K is blanked by the movement of the equalizing graduating valve. Should the brakes be held applied in Over Reduction Lap position for a sufficient length of time with an ap- plication chamber leakage so great that the air from the service reservoir could not get past the ring in the small end of the service reservoir charging valve fast enough to supply such leakage (in the manner explained in con- nection with Fig. 128), the service reservoir charging valve will finally be lifted, making wide open connection from the service reservoir to the application chamber. From what has been said, it will be plain that if the brake pipe reduction is continued below the point at which the pressure and the reduction limiting chambers equalize, the pressure in the pressure chamber can no longer con- tinue to reduce in accordance with the still falling brake pipe pressure. This results in a differential being estab- lished between the pressure in the pressure chamber (and chambers D and E) and the brake pipe pressure which, when the brake pipe pressure is reduced below 60 lbs. when carrying no lbs. brake pipe pressure, or below 35 lbs. with 70 lbs. brake pipe pressure, is sufficient to cause the release piston to travel to its extreme (emergency) position and produce quick action and an emergency ap- plication of the brakes as will be explained under the heading "Emergency Position." RELEASING. a. Preliminary Release Position. Whether the parts are in Service Lap, or Over Reduc- tion Lap position, after an application has been made, an 516 MODERN AIR BRAKE PRACTICE o U w I CO 6 bo WESTIXGHOUSE "PC" EQUIPMENT 517 increase in brake pipe pressure above that in the pressure chamber (chambers D and E) will cause the equalizing piston and its valves to return to the release positions de- scribed below. The equalizing piston moves before the release pis- ton, the parts being designed to require a somewhat higher differential to move the release piston and its attached valves than is sufficient to move the equalizing piston. In Preliminary Release position (Fig. 130), it will be noted that chamber E behind the release piston, is con- nected by way of the equalizing slide valve and gradu- ating valve to the reduction limiting chamber exhaust. This connection is made but momentarily, in what may be considered the first stage of the movement of the parts to Release position. It plays a very important part, how- ever, in the release operation of the valve, since by thus insuring a momentary but material drop in the pressure in chamber E below that in the brake pipe and in chamber B, the release piston is forced to return positively to its Release position shown in Fig. 131 — Secondary Release position. In Preliminary Release position, the pressure cham- ber is connected, by way of the equalizing slide valve to chamber F. The pressure thus acting in chamber F, in addition to the force of the equalizing stop spring, serves to insure that the equalizing piston and its valves hesi- tate in Preliminary Release position for a sufficient length of time to reduce the pressure in chamber £ (as already explained). It will be observed that the application piston is still in its Lap position, holding the pressure in the service brake cylinder. This continues until the release of air 518 MODERN AIR BRAKE PRACTICE from the application chamber and chamber C, which does not take place until the parts move to the next stage in the release movement, called Secondary Release position, Fig. 131. In the movement of the equalizing slide valve to Pre- liminary Release position, the reduction chamber is con- nected to the reduction chamber exhaust port and the atmosphere and so remains until the parts again move to Over Reduction position or beyond. Although there are other connections made in the Pre- liminary Release position as shown in Fig. 130, they per- form no particular function other than has already been described, and consequently do not need to be again re- ferred to. b. Secondary Release Position. In the movement of the parts to Release position, the next stage, following the Preliminary Release position, is called the Secondary Release position and is shown in Fig. 131. It will be seen from the illustration that the venting of the air from chamber E through the equaliz- ing slide valve and graduating valve to the reduction limiting chamber exhaust has resulted in the relatively higher brake pipe pressure moving the release piston and its valves to their Release positions, although for an in- stant the equalizing piston and its valves still remain as shown in Fig. 130 — Preliminary Release position. With the release piston and its valves in the position shown in Fig. 131, a connection is made from chamber F through the release slide valve to the emergency piston exhaust. At the same time the pressure chamber is con- nected by way of the equalizing slide valve to the same WESTINGHOUSE "Pc" EQUIPMENT 519 1 520 MODERN AIR BRAKE PRACTICE port which connects chamber F to the atmosphere. This tends to maintain the pressure in chamber F temporarily so as to insure the connection from chamber E to the atmspohere being held open, as explained above, until the release piston and its valves are entirely back in their Release positions. In so moving, however, the release slide valve is gradually increasing the size of the opening from chamber F to the atmosphere, until a point is reached where the pressure in chamber F is lowered sufficiently to permit the differential pressure already acting on the equalizing piston to start this piston toward its Release position. The resulting movement of the equalizing slide valve restricts, and finally stops entirely, the flow of air from the pressure chamber to chamber F, the pressure in which is, therefore, rapidly exhausted to the atmosphere through the ports already mentioned, and the equalizing piston and its valves are then held positively in their Re- lease position as shown in Fig. 132. Comparing Fig. 130 and Fig. 131, it wall be noted that the movement of the release piston, slide valve and grad- uating valve from the position shown in Fig. 130 to that shown in Fig. 131, opens communication from chamber E past the end of the release graduating valve, through the release slide valve and direct and graduated release cap, and through the equalizing slide valve to the reduction limiting chamber exhaust and atmosphere. This outlet from chamber E to the atmosphere is simply additional, it will be noted, to that already existing as explained in connection with Fig. 130, and, like it, is but momentary. In the succeeding position (Fig. 132) both these connec- tions from chamber E to the atmosphere are cut off. The movement of the release graduating and slide valves to their Release positions opens the application WESTIXGHOUSE "Pc" EQUIPMENT 521 522 MODERN AIR BRAKE PRACTICE chamber and chamber C by way of the valves mentioned to the application chamber exhaust and atmosphere. The resulting reduction of pressure in chamber C below that exerted by the application piston spring and the air pres- sure in chamber M causes the application piston, with its attached valves, to move back to Release position (Fig. 131), opening the service brake cylinder through the exhaust valve to the service cylinder exhaust and at- mosphere. The release of the brake is, therefore, com- menced as soon as the release piston and its valves are re- turned to their Release positions. While there are other connections shown in Fig 131 be- sides those just explained, they perform no particular function, so far as the momentary position of the parts in Secondary Release position (Fig. 131) is concerned, and will, therefore, not be referred to until all can be ex- plained together under the heading "Graduated Release Position" (Fig. 132). c. Graduated Release Position. As already stated, the movement of the release slide valve to its Release position connects chamber F to the emergency piston exhaust and atmosphere, causing the equalizing piston and its valves to be moved to and held positively in their Release positions, as shown in Fig. 132. It should be clearly understood that a very slight increase in brake pipe pressure (about 1^/2 to 2 lbs.) above that remaining in the pressure chamber, is sufficient to move the parts through the successive mo- mentary positions of Preliminary and Secondary Re- lease as just explained, until they reach their final posi- tions shown in Fig. 132 — Graduated Release position. WESTIXGHOUSE "PC" EQUIPMENT 523 In this position (graduated release being assumed to be cut in), the application chamber and chamber C are open through the release slide valve and graduating valve to the application chamber exhaust and atmosphere. So far as this connection is concerned, the release would be complete, provided the parts did not move, but it will be noted that in this position also the emergency reservoir is connected by way of the equalizing slide valve, and the direct and graduated release cap (which is adjusted to give graduated release) through the release slide valve and past the end of the release graduating valve to cham- ber E. The pressure in the emergency reservoir is sub- stantially that to which it was originally charged, namely, normal brake pipe pressure. The pressure in chamber E, it will be remembered, was reduced equally with the pressure chamber pressure when the brake applica- tion was made. Air from the emergency reservoir, at the higher pressure, will therefore flow into chamber E and, from chamber E, by way of the equalizing slide valve, to the pressure chamber, at the lower pressure, and tend to increase the pressure in chamber E and the pressure chamber at the same time that the brake pipe pressure in chamber B is being increased. If the pres- sure in chamber E rises faster than that in chamber B, the higher pressure which will soon be built up in cham- ber E will tend to move the release piston and graduat- ing valve over toward Graduated Release Lap position (Fig 133) and either partially restrict or wholly stop the flow of air frem the application chamber to the atmos- phere, and from the emergency reservoir to chamber E. If the brake pipe pressure is increased very slowly, the relatively rapid increase of pressure in chamber E may cause the release piston and graduating valve to gradu- 524 MODERN AIR BRAKE PRACTICE o a, a o U w CO d bo C O kl N ^ 11 ill ii WESTINGHOUSE "Pc" EQUIPMENT 525 ate the release as explained in connection with Fig. 133. If the rate of rise of brake pipe pressure is not slow enough to permit this action, the parts will move toward the position shown in Fig. 133 sufficiently to so restrict the flow of air from the emergency reservoir to chamber E, as to adjust the rate of rise of pressure in cham- ber E, to correspond to that of the brake pipe and chamber B, in which case the release of air from the application chamber will be correspondingly prolonged. The escape of air from the application chamber and chamber C to the atmosphere as already explained in connection with Fig. 131, results in the application piston spring and brake cylinder pressure acting in chamber M, moving the application piston with its valve back from their Lap positions, as shown in Fig. 130, to their Re- lease position, as shown in Figs. 131 and 132, in which position, air from the brake cylinder is exhausted to the atmosphere by way of the exhaust valve, and service cylinder exhaust port. Whether the brake cylinder pres- sure is entirely, or only partially released depends upon whether the exhaust of air from the application cham- ber and chamber C is partial, or complete. This has already been referred to and will be further mentioned in connection with Fig. 133. It will be not^ed that in Figs. 130, 131 and 132, the reduction limiting chamber is connected to the reduction limiting chamber exhaust and atmosphere through the equalizing slide valve, and that in Figs. 131 and 132 chamber S is connected through the release slide valve to the emergency piston exhaust and atmosphere, so that the air in these chambers is com- pletely exhausted to the atmosphere when either a grad- uated or direct release is made. Referring to Fig. 132, it will be noted that chamber E 526 MODERN AIR BRAKE PRACTICE is connected to chamber K and that air from the emer- gency reservoir has access to chamber G. These con- nections being opened by the movement of the equaHz- ing slide valve to its Release position, whether or not the service reservoir charging valve will be opened and per- mit the recharging of the service reservoir to begin at once, will depend on the relative pressures in the pres- sure chamber, emergency and service reservoirs. With the ordinary manipulation of the brake, the service reservoir charging valve will remain closed, as shown in Fig. 132, preventing the air from the emergency reservoir reaching the service reservoir and the pressure chamber only will be recharged until its pressure has been increased to within about 5 lbs. of that in the emer- gency reservoir. The other connections which are shown in Fig. 132 have been fully explained in what has preceded and re- quire no further mention at this time, since they are not concerned in the particular function under discussion. As already indicated, if the brake pipe is fully re- charged without a graduation of the release being made, the parts will remain in the positions shown in Fig. 132 and the release will be complete and without graduations. The only change which takes place while such a release is being made is the movement of the service reservoir charging valve from the position shown in Fig. 132 to that shown in Fig. 123, which should properly be re- garded as illustrating the final stage in the recharging of the equipment of which Fig. 132 illustrates the initial stage. That is to say, at first the pressure chamber alone is recharged, and this recharge is accomplished (as has been pointed out) from the emergency reservoir only, without any air being drawn for this purpose from the WESTINGHOUSE "PC" EQUIPMENT 527 brake pipe. The air which is supplied through the brake valve to the brake-pipe is, therefore, given every pos- sible advantage and opportunity to accomplish what is in- tended when the brake valve handle is moved to Release position, namely, to release the brakes by causing an in- crease of pressure sufficient to accomplish this, through- out the entire length of the brake pipe. After the release has been thoroughly established in this manner, the recharging of the reservoirs to their original pressure takes place as explained in connection with Fig. 123. That is to say, when the pressure cham- ber has been recharged to within about 5 lbs. of the pres- sure remaining in the emergency reservoir, the service reservoir charging valve is lifted from its seat, opening the connection from the emergency reservoir to the service reservoir, and as the brake pipe pressure con- tinues to be increased, the service reservoir, emergency reservoir and pressure chamber are finally recharged to full brake pipe pressure by the air coming from the brake pipe, as already explained in conection with Fig. 123. d. Release Lap Position. If, however, the brake pipe pressure is not fully re- stored, a graduation of release being made; that is, if the brake pipe is partially recharged and the brake valve handle then returned to Lap position, the continued flow of air from the emergency reservoir to pressure chamber and chamber E, as previously explained, will tend to in- crease the pressure in the pressure chamber and chamber E above that of chamber B which is now stationary, causing the release piston and graduating valve to move over until the shoulder on the end of the release piston 528 MODERN AIR BRAKE PRACTICE Stem comes in contact with the release sHde valve as shown in Fig. 133. This closes the exhaust from the ap- plication chamber to the atmosphere and prevents further flow of air from the emergency reservoir to the pressure chamber and chamber E. The flow of air from the service brake cylinder to the atmosphere (continuing as explained in connection with Fig. 132), will at once reduce the pressure in chamber M below that now retained in chamber C by the small amount which is sufficient to cause the application piston to move over to the position shown in Fig. 133, in which the exhaust valve is closed, thus preventing further re- lease of air from the service brake cylinder. The other connections remain as already explained. e. Release and Charging Pressure Chamber and Emer- gency and Service Reservoirs. The gradual release of brake cylinder pressure may be continued as explained above (Fig. 133) until the pressures in the emergency reservoir and pressure cham- ber have become equal. On acount of the relatively large volume of the emergency reservoir compared with that of the pressure chamber, this equalization will not take place until the pressure chamber has been recharged to within about 5 lbs. of the brake pipe pressure carried. Beyond this point, whatever small amount of pressure may remain in the service brake cylinder is released en- tirely and the emergency and service reservoirs, as well as the pressure chamber, are recharged from the brake pipe as described in connection with Fig. 133. WESTINGHOUSE ''Pc" EQUIPMENT 529 O bo C^ > u c o U W 6 1 bo 530 ' MODERN AIR BRAKE PRACTICE /. Direct Release and Charging Position. Up to this point, the direct and graduated release cap has been assumed to be in the position for graduated re- lease. Fig. 134 corresponds to Fig. 132, except that the direct and graduated release cap is adjusted for direct release. It will be noted that there is now no connection from the emergency reservoir to the pressure chamber or chamber E, Consequently the pressure chamber is being recharged only by air from the brake pipe going through feed groove i to chamber E, and thence by way of the equalizing slide valve, to the pressure chamber. The pressure in chamber E cannot, therefore, increase above that in chamber B and the release piston, grad- uating valve and slide valve remain in the position shown in Fig. 134. With the direct and graduated release cap adjusted for direct release, it will be noted from Fig. 134 that the ap- plication chamber and chamber C are open through the release slide valve to a part connecting through the direct and graduated release cap to the application chamber exhaust and atmosphere. This affords an outlet from the application chamber to the atmosphere which cannot be closed as long as the release slide valve remains in the position shown, even though the release piston and grad- uating valve, should, from any cause, be moved back so that the release graduating valve would partially or en- tirely restrict the application chamber release port, which is also shown to be open through the release graduating valve in Fig. 134. Moreover, it will be noted that there are two outlets from the application chamber to the atmosphere when the valve is adjusted for direct release as compared with one when graduated release is cut in. WESTINGHOUSE "Pc" EQUIPMENT 531 This, together with the fact that the direct release port is of greater capacity than the graduated release port, results in a more rapid rate of release being obtained with the direct than with the graduated release adjust- ment of the equipment, as is desirable. As the other con- nections shown in Fig. 134 are the same throughout as ex- plained in connection with Fig. 132, it will be unneces- sary to make further reference to same. EMERGENCY POSITION. a. Quick Action Valve Venting. When the brake pipe pressure is reduced faster than at the predetermined rate for service applications, or if the brake pipe reduction should be continued below the point at which the pressure and reduction limiting cham- bers equalize (as explained above under the heading *'Over Reduction Position") the differential pressure acting on the release and equalizing pistons becomes suf- ficient to move them to their extreme or Emergency positions as shown in Fig. 135. In this position, air from the emergency reservoir flows directly to chamber E and from chamber E to the under side of the quick action closing valve. Chamber T, above the quick action closing valve, is connected to the emergency brake cylinder port, in which there is no pressure, even though a full service application of the brakes may have just preceded the emergency appli- cation. The higher pressure on the under side of the quick action closing valve therefore raises this valve and air flows to chamber W above the quick action piston, forc- ing the latter down and opening the quick action valve 532 MODERN AIR BRAKE PRACTICE < u "B a o o PL. a 4) c o U W I CO bo WESTINGHOUSE "PC" EQUIPMENT 533 against brake pipe pressure in chamber Y. As soon as the quick action valve is unseated in this manner, air from the brake pipe flows past the quick action valve to the quick action exhaust and atmosphere, causing a local venting of brake pipe air and transmitting the quick ap- plication serially throughout the train. Air from the emergency reservoir flowing to chamber E also flows directly to the application chamber and chamber C which forces the application piston and its valve over into their extreme positions, opening the service reservoir through the application slide valve and chamber O to the service brake cylinder, thus permitting the pressures in the service reservoir and service brake cylinder to equalize. At the same time chamber P, above the large emer- gency piston, is connected through the release slide valve to the emergency piston exhaust and atmosphere, per- mitting the emergency reservoir pressure in chamber R to force the emergency piston and its slide valve upward to their Emergency positions. In this position of the emergency parts, the emergency reservoir is connected past the end of the emergency slide valve to the emergency brake cylinder, thus per- mitting the pressures in the emergency reservoir and brake cylinder to equalize. Chamber R is also connected through the emergency slide valve to the service cylinder port which permits equalization of the service and emer- gency reservoirs and brake cylinders. It will be noted that in this position the emergency slide valve opens a port which connects chamber M, be- hind the application piston, through the emergency slide valve to emergency cylinder exhaust. This, in connection with the admission of air from the emergency reservoir 534 MODERN AIR BRAKE PRACTICE to the application chamber and chamber C, as already explained, still further insures a quick and positive movement of the application piston and its valves to Emergency position. In this position the pressure chamber is connected through the equalizing slide valve to chamber D. The pressure chamber is also connected past the pressure chamber check valve to chamber E, and chamber D is connected past the end of the equalizing graduating valve through the equalizing slide valve to the reduction limit- ing chamber. These connections perform no particular function except to insure pressure acting on all slide valves, graduating valves, etc., so as to hold them to their seats as well as to provide for the equalization of all chambers, reservoirs, etc., of the equipment when an emergency application is made. b. Quick Action Valve Closed. The emergency brake cylinder pressure and that in chamber T, above the quick action closing valve, con- tinues to rise and the pressure in the emergency reservoir and in chamber W below the quick action closing valve falls, as explained above, until these pressures become substantially equal. This equalization of the pressures on the opposite sides of the quick action closing valve permits its spring to return the valve to its seat, cutting off further flow of air to chamber W. Chamber W is connected through the leakage hole in the quick action piston to chamber X so that as soon as the quick action closing valve is seated, the pressure in chamber W ex- pands through this leakage hole to chamber X and the atmosphere, through the quick action exhaust opening. WESTINGHOUSE "Pc" EQUIPMENT 535 3 a o a (U bO ! U u pq o m < bfl I WESTINGHOUSE "Pc" EQUIPMENT 541 cylinder air flows through pipe b into slack adjuster cylinder 2 where the small piston 19, Fig. 140, is forced outward, compressing spring 21. Attached to piston stem 23 is a pawl extending into casing 24, which engages ratchet wheel 27, mounted within casing 24 upon screw 4, Fig. 139. When the brake is released and the brake cylinder piston returns to its normal position, the air pressure in cylinder 2 escapes to the atmosphere through pipe b, port a and the non-pressure head of the brake cylinder, thus permitting spring 21 to force the small piston to its normal position. In so doing, the pawl turns the ratchet wheel upon screw 4 and thereby draws lever 5 slightly in the direction of the slack adjuster cylinder, thus shortening the brake cylinder piston travel and forc- ing the brake shoes nearer the wheels. As the pawl is drawn back to its normal position, a lug on the lever side strikes projection a. Fig. 140, on the cylinder, thus rais- ing the outer end of the pawl, disengaging it from the ratchet wheel and permitting the screw to be turned by hand if desired. To apply new shoes, turn casing i to the left, thus moving lever 5 toward the position shown in Fig. 139, until sufficient slack is introduced in the brake rigging. To bring the shoes closer to the wheels and shorten the piston travel, turn casing i to the right. The screw mechanism is so proportioned that the brake shoe wear is compensated for at the rate of about 3V of an inch for each operation of the adjuster, thereby re- moving the danger of unduly taking up false travel which would result in the shoes binding on the wheels. The best results are obtained by the use of copper pipe from the brake cylinder to the adjuster cylinder, since 542 MODERN AIR BRAKE PRACTICE this pipe is more flexible and does not corrode. It should always be firmly secured. Every time the brake cylinder is cleaned and oiled, the slack adjuster should receive the same attention, and. »CLCASeO APPUED Fig. 140 — Automatic Slack Adjuster Cylinder. after each cleaning and oiling, a test of the brakes should also include one of the adjuster. CENTRIFUGAL DIRT COLLECTOR. The centrifugal dirt collector, as illustraed in Fig. 141, is so constructed that, due to the combined action of centrifugal force and gravity, all dirt and foreign ma- terial is automatically eliminated from the air flowing WESTIXGHOUSE PC EQUIPMENT 543 through the collector — as when the brakes are applied or released — zmthout reducing the area of the c^^ening in any way. The efficiency of this method of keeping dirt out of the brake system is remarkable, and the impor- tance of this fact will be appreciated by those who are familiar with the troubles which result from the entrance Fig. 141 — Centrifugal Dirt Collector. of dirt, pipe scale, etc., into the brake system and espe- cially the triple valves. The design of the collector is such that the dirt and foreign matter eliminated falls into the bottom chamber and by means of a plug may be removed at intervals without breaking any pipe connec- tions whatever. conductor's valve. The conductor's valve, Fig. 142, may be located at any convenient point in the car, preferably with a cord at- 544 MODERN AIR BRAKE PRACTICE tached to its handle and running the length of the car; however, one valve may be placed at each end which will obviate the necessity of the cord. When this valve is opened, the air from the brake pipe flows directly through it to the atmosphere, setting the brakes in emer- gency. It should therefore be used only in case of actual danger and should then be opened as wide as possible and left open until the train stops. PIPE FITTINGS. The cut-out cock, Fig. 143, of which there is one i-inch in the branch pipe, should be placed where it can be Fig. 142 — C-s Conductor's Valve. easily reached but protected from accidental closing, The handle should be in such position that, as affected by vibration, it would tend to jar open instead of shut. The self-locking angle cock has been developed to pre- WESTINGHOUSE "PC" EQUIPMENT 545 vent any accidental movement of the handle from either open or closed position by flying missiles, loose brake rods, swinging check chains or other cause. In all de- tails except the handle the self -locking type is the same as the old style angle cock; the upper illustration. Fig. 144, shows the self -locking handle while the lower repre- sents the old form. In the case of angle cocks now in service it is necessary to supply only the improved handle to secure advantages which the self-locking angle cock provides. Hose couplings, Fig. 145, make the brake pipe continu- ous throughout the train. When cars are being separated, as in switching, the hose should be uncoupled by hand, to prevent rupture or damage. Dummy couplings, Fig. 146, are provided at each end of the car to which the hose coupHngs should be attached when not coupled up, to protect against injury to the hose couplings or dirt entering the pipes. GENERAL HINTS. The brake should be handled by the engineers in the same manner as with cars equipped with quick-action triples, the only difference being that an emergency ap- plication will be obtained should a service reduction of the brake pressure be continued below 60 lbs. when carry- ing 1 10 lbs. pressure or below 35 lbs. with 70 lbs. brake pipe pressure. When it is found necessary to cut out the brake, close the cut-out cock in the crossover pipe and bleed both the service and emergency reservoirs. Should it become necessary to bleed the brake when the engine is detached, or air connection is not made, 546 MODERN AIR BRAKE PRACTICE first bleed the brake pipe and then bleed both the service and emergency reservoirs. The two sets of cylinder level's are connected to the same truck pull rods as stated above. Therefore, when a service application of the brake is made, the push rod end of the emergency cylinder lever will move the same distance as the push rod end of the service cylinder lever, but the cross head being slotted, the piston of the emer- gency cylinder will not move. Consequently, the fact that Fig. 143— Cut Out Cock. the emergency cylinder cross head is in release position does not indicate that the .air brakes are released. To determine this, look at the ends of either the service or emergency cylinder levers. Whenever it is necessary to change the adjustment of the automatic slack adjuster, it is imperative that the cross heads of the two adjusters be left at the same distance from their respective brake cylinder heads, in order that the piston travel of the two cylinders in emergency appli- cation will be the same. The various exhaust openings referred to in the fol- lowing are plainly marked on the outline drawings, Figs. 116 and ii6^ The Quick Action Exhaust is the one-inch opening in WESTINGHOUSE "PC' EQUIPMENT 547 the bottom of the control valve reservoir. Should there be a continual blow at this opening, make an emergency application and then release; if the blow continues, re- move the quick action portion and substitute a new or repaired portion, or repair the quick action valve seat which will be found defective. The quick action portion is at the left hand when facing the equalizing portion. Fig. 144 — New and Old Angle Cock Handle. There are three control valve exhaust openings, two on the equalizing portion and one on the side of the control valve reservoir, all tapped for %-inch pipe. Should there be a blow at the Application Chamber Exhaust (^-inch exhaust opening on the side of the con- trol valve reservoir) with the brakes applied or released, it indicates a defective equalizing portion and a new one, or one that has been repaired, should be substituted. Should there be a blow at the Reduction Limiting Chamber Exhaust ( ^-inch exhaust on left side of equal- izing portion) in release or service position it indicates a defective application portion and a new one, or one that has been re], aired, should be substituted. This portion J3 located back of the equalizing portion, inside the reser- 548 MODERN AIR BRAKE PRACTICE voir. If the blow occurs only after 30 lbs. brake pipe reduction, it indicates a defective emergency reservoir check valve (the middle check valve in the equalizing portion) and a new one, or one that has been repaired, Fig. 145 — Hose Coupling. should be substituted. If the blow does not cease, it in- dicates a defective equalizing portion and a new one, or one that has been repaired, should be substituted. Should there be a blow at the Emergency Piston Ex- haust (^-inch exhaust on the right hand side of the equalizing portion) make a 15-lb. brake pipe reduction and lap the brake valve. If the blow ceases, it indicates Fig. 146 — Dummy Coupling. that either the emergency portion or seal on the small end of the equalizing piston is defective and a new portion, as found to be needed, or one that has been repaired, should be substituted. If the blow does not cease, it in- dicates that the equalizing portion is defective and a new one, or one that has been repaired, should be substituted. A hard blow at the Service Brake Cylinder Exhaust WESTINGHOUSE "Pc" EQUIPMENT 549 (tapped for ^-inch pipe and located on the left side of the control valve reservoir) with the brakes applied, in- dicates that the application portion is defective and a new one, or one that has been repaired, should be sub- stituted. This portion is located back of the equalizing portion inside the reservoir. If this blow occurs when the brakes are released it indicates either a defective ap- plication or emergency portion and a new one, or a re- paired portion, as found to be required on investigation, should be substituted. A hard blow at the Emergency Cylinder Exhaust (tapped for ^-inch pipe and located on the bottom of the control valve reservoir) with the brakes either applied or released, indicates a defective emergency portion and a new one, or one that has been repaired, should be substi- tuted. If the trouble described in the five paragraphs immedi- ately preceding is not overcome by the remedies therein suggested, remove the application portion and examine its gasket, as a defect in same way may be the cause of the difficulty. When removing the application, emergency and quick action portions, their respective gaskets should remain on the reservoir. On removing the equalizing portion, its gasket should remain on the application portion, except when the application portion is shipped to and from points where triple valves are cared for. When applying the different portions, the gaskets should be carefully examined, to see that no ports are restricted, and that the gasket is not defective between ports. See also that all nuts are drawn up evenly to pre- vent uneven seating of the parts. On the front and at the center of the equalizing portion 550 MODERN AIR BRAKE PRACTICE is located the direct and graduated release cap (held by a single stud) on which is a pointer. (See Fig. 114.) The position of this pointer indicates whether the valve is ad- justed for direct release or graduated release. This cap should be adjusted for either direct or graduated release according to the instructions issued by the railroad. LUBRICATION OF NO. 3-E CONTROL VALVE. Equalising Portion. All equalizing portions should be lubricated with dry graphite instead of oiling. The following is the method of lubricating the equaliz- ing portion: After the bearing surfaces have been properly rubbed in by a free use of oil, this oil should be wiped off with a soft cloth or some soft material. All oil, gum, or grease should be thoroughly removed from the slide valves and seats. After this has been done, rub a high grade of very fine, dry (not flake) graphite, of the highest obtainable fineness and purity, on to the face of the slide valves, their seats, the face of the graduating valves, their seats, and the upper portion of the bushings where the slide valve springs bear, in order to make as much as possible adhere and fill in the pores of the brass and leave a very thin, light coating of graphite on the seats. When this is completed, the slide valves and their seats must be en- tirely free from oil or grease. Care must be taken when handling the slide valves, after lubricating, that the hands do not come in contact with the lubricated parts, as moist- ure will tend to remove the thin coating of graphite. To apply the graphite, use a stick, suitable for the pur- pose, about 8 inches long, on one end of which a small pad of chamois skin has been glued. Dip the skin covered WESTINGHOUSE **PC" EQUIPMENT 551 end in the dry graphite and rub the latter on the surfaces specified. A few light blows of the stick on the slide valve seats will leave the desired light coating of loose graphite. After the pistons and slide valves have been replaced in the equalizing portion, they should be moved to Release position, and a little good oil or lubricant ap- plied to the circumference of the piston bushings, and the pistons moved back and forth several times to insure proper distribution of this lubricant on the walls of the cylinders. When oiling, as just directed, or in the cases which fol- low, only a thin coating of oil is necessary and care should be taken not to leave any free oil on the parts. Application Portion. The exhaust valve and seat and application valve and seat of the application portion should be cleaned, rubbed in and sparingly lubricated with graphite grease. Before applying the piston to application portion, clean the application cylinder and piston. Lubricate the walls of the cylinder and piston ring, using Emery Brake Cylinder Lubricant. Emergency Portion. After the bearing surfaces have been properly cleaned and rubbed in, and before applying the slide valve to the emergency portion, remove the top cover and take out the loose fitting cylinder bushing. Lubricate the large piston with a few drops of a good grade of triple valve oil and apply the same oil sparingly to the slide valve, then enter the slide valve into the por- tion. Lubricate the slip bushing for the small emergency piston, applying a few drops of triple valve oil to inner circumference. Apply the bushing to the portion and bolt on top cover. Move the slide valve to Release posi- tion and put a few drops of triple valve oil on the walls 552 MODERN AIR BRAKE PRACTICE of the large cylinder bushing. Move the slide valve and piston back and forth several times to insure a proper distribution of the oil. Apply the large cover to the emer- gency portion. Quick Action Portion. No parts of the quick action portion require lubrication but, if desired, the closing valve piston and cylinder bushing may be sparingly lubri- cated with triple valve oil. After lubricating, work the piston a few times, making sure that it moves freely. 1 INDEX A Page Air Brake System o 1-5 Development of 2-5 Essential Parts of 1-2 Air Pump 3-20, 29-52 Eight Inch Pump 5-9 Eleven Inch Pump 13-17 Nine and One-half Inch Pump 9-13 Six Inch Air Pump 5 Tandem Compound Air Pump 17-20 "Trigger" Air Pump 3-5 Air Pump Governors 20-25, Z77~2>7^ Duplex Type 23-25 Enlarged Type (i>4 inch) Z77-Z7^ Single Top Style 20-23 Automatic Oil Cups — Nos. i and 2 25-29 Automatic Slack Adjuster 179-187 Action explained 180-185 Care and Adjustment 186-187 B B-6 Feed Valve 334-340 Bleeding ofif a Brake 269-270 Blow from Exhaust Port 262-265 Brake Cylinder — Leakage Test 449-450 Brake Cylinders — Sizes of 249 11 INDEX Broken Pipes 430-433 By Pass Valve — Leakage 265 C Centrifugal Dirt Collector 37^-379 Combined Automatic and Straight Air Brake . . . 363-374 Description 367 Double Seat Check Valve 364-366 Manipulation 372-374 Straight Air Brake Valve 368-369, 372-373 Combined Strainer and Check Valve 346-347 Conductor's Valve 187 Cross Compound Air Compressor 29-52 Description 31-38 Disorders — Causes and Remedies 48-50 Lubrication — Air Cylinder 45-48 Lubrication — Steam Cylinder 48 Maintenance 50-52 Operation 38-44 Piping 44 Starting and Running 44-45 D D-8 Brake Valve 104-120, 122-123 Dead Engine Fixture 414-416 Development of the Air Brake 2-5, 55-59 Development of the Air Pump 59-6o Disorders and Remedies — Air Pump 95-IOI Pressure Retaining Valve 226-227 Pump Governor 78-80 Distributing Valve Test 444-449 Double Heading 278-279, 311 INDEX 111 E Engineer's Brake Valve 104-120 D-8 Brake Valve 107-1 12 F-6 Brake Valve 112-116 G-6 Brake Valve 1 17-120 Three Way Cock Type 106-107 E. T. Brake Equipment 271-354 Advantages of 272-273 Applying Brakes in Emergency 276-277 Arrangement of Apparatus . . . . 284-287 Duplex Air Gauges 286-287 Double Heading 278-279, 311 Essential Parts of 271-272 Holding Engine Brakes Applied 275-276, 278 Instructions for Handling 273-279 Object of 271 Parts — Name and Function of Each 280 Piping 281-282 Principles of Operation 287-291 Releasing Brakes 274-277 Freight Service 275-276 Passenger Service 274-275 E. T. Brake Equipment — B-6 Feed Valve 334-340 Adjustment of 340 Advantages in use of 334-33^ Description and Action 336-340 Distinguishing Feature of 339 Names of Parts 336 C-6 Reducing Valve 340-341 "Dead Engine" Feature 346-347 . E-6 Safety Valve 314-316 H-6 Automatic Brake Valve 316-327 IV INDEX Charging and Release 321-322 Cleaning and Oiling 325-327 Description 319-321 Emergency Position , 325 Holding Position , 325 Lap Position 324 Location on Engine 327 Names of Parts .318 Release Position 324-325 Running Position . 322-323 Service Position 323-324 E« T. Brake Equipment — No. 6 Distributing Valve 291-31 1 Automatic Operation of 296 Automatic Release 301-302 Charging 296 Emergency 302-304 Emergency Lap 304-306 Independent Application 306-308 Independent Release 309-31 1 Names of Parts 291-294 Service 296-299 Service Lap 299-301 S. F. Type of Pump Governor 342-345 Adjustment of Low Pressure Head 345 Construction and Operation 343*345 Important Features of 342 S-6 Independent Brake Valve. 327-334 Description of 328-330 Lap Position 332 Location of 334 Names of Parts 328 Quick Application 332 INDEX ^ V Release Position 332-334 Runnins: Position 330-331 Slow Appli' ation , 332 F F-6 Brake Valve , 1 12-1 16 Feed Valve Test 438-440 Feed Valves — Purpose of 458 Freight Braking ' 428-430 Friction of Brake Shoes and Wheels 455 Full Service — L Triple 198-199, 252-254 Full Service — K Triple 229, 238-239 Full Release and Charging, L Triple Valve ...... 249-252 Full Release and Charging, K Triple Valve 235-237 G G-6 Brake Valve 1 17-120, 126-130 General Operation No. 6 E. T 419-421 H High Pressure Control — Schedule U 354-361 High Speed Brake 347-354 Automatic Reducing Valve 350-351 Description and Illustration 349-354 Safety Valve for 354 Service Stop 353 I Important Features of K Triple Valve 22y Important Features of L Triple Valve 188, 247-248 Independent Application 306-308 VI . INDEX Independent Release. 309-311, 396 Installation and Maintenance of L Triple Valve. .205-209 K K Type Triple Valve 158-179 Description and Explanation , 162-165 Emergency Position 176-178 Full Release and Charging 165-167 Full Service Position 170-172 K-2 Triple — Parts of 161 Lap Position 172-173 Manipulation 179 Principles Explained 158-161 Quick Service Position 167-170 Retarded Release and Charging Position. . . .173-176 L Triple Valve 188-209 Charging Position 195 Description I93-I95 Emergency Position 202-204 Full Service 198-199 Graduated Release 201-202 Important Features of 188-191 Installation and Maintenance 205-209 Lap Position 199-201 L. N. Equipment Complete 206-207 Operation 195 Parts — Names and Numbers of 191-193 Safety Valve for L Triple .207-209 Service Application 196-199 I INDEX vii M Main Reservoir 52-54 Main Reservoir Control — Duplex 361-363, 377 N No. 6 E. T. Brake Equipment 271-354 No. 6 Distributing Valve 291-31 1, 393-405 Normal, and Retarded Release 230-234 P "PC" Passenger Brake Equipment 473-552 Application Portion 488-491 Automatic Slack Adjuster 539-543 Brake Cylinders 536-537 Conductor's Valve 543-544 Direct Release, and Charging 530-531 Emergency Position 531-536 Emergency Slide Valve Seat 491-494 Equalizing Portion 436-488 General Hints 545-550 Graduated Release Position 522-527 No. 3-E Control Valve — Lubrication 550-552 Normal Position 494-496 Novel Functions of 477-481 Over Reduction 510-515 Parts of 481-486 Pipe Fittings 544-545 Quick Action Valve Closed 534-536 Release and Charging Position 496, 528-530 Release Lap Position 527 Vlll INDEX Release Slide Valve .491 Releasing — Preliminary 515-518 Releasing — Secondary 518-522 Requirements for Modern Service 473-477 Reservoirs • 537-538 Reservoirs — Enameled 539 Service Application — Preliminary. ........ .501-505 Service Application — ^Secondary 505 Service Position 505-509 Service Lap Position 509-510 Plain Triple Valve 210-216 Pressure Retaining Valve » 154-157 Pump Governor — Enlarged Type ', 471 Q Quick Action Triple Valve 143-151 Description 144-145 Emergency Position 149-151 Lap Position 146-148 Names of Parts 144 Positions 145 Release and Charging 145-146 Service Position 146 R Reducing Valve Test 440 Releasing Brakes — No. 6 E. T 2'/4-2y'/ Restricted Exhaust 232 Retarded Release — K Triple Valve 173-176 S Safety Valve Test 450-451 Safety Valve for High Speed Brake 354 INDEX IX Safety Valve for L Triple \^alve 207-209 S. F-4 Pump Governor 342-345 S-6 Independent Brake Valve 327-334 Slide Valve Feed Valve 1 18-120 T Triple Valve 131-151 Action Explained 136-142 Care and Operation 137 Description I33-I34 Manipulation 134-136, 141 Plain Triple — New Style 131-142 Triple Valve, Auxiliary Reservoir and Brake Cyl- inder Combined 152-154 U Uniform Recharge ^3-2-233 Uniform Releace 230 W Whistle Signal System 358, 374-376 INDEX EXAMINATION QUESTIONS AND ANSWERS A Page Air Brake — Development of •-• 55-59 Air Gauges .80-81 Air Pump — Development of 59-6o Air Pump — 8 inch 60-64 Air Pumpi — 8^ inch-cross compound 81-101 Air " Pump — 9^ inch 64-69 Air Pump — 1 1 inch 69-70 Air Pump — Tandem Compound 70-73 Air Pump Governor 73-8o. Disorders and Remedies , 78-80 Automatic Lubrication 76-78 Automatic Slack Adjuster 244-246 C Centrifugal Dirt Collector 471-472 Combined Automatic and Straight Air Brake. . . .466-469 Conductor's Valve 246 Cross Compound Air Compressor „ . . . .81-101 Care and Operation 90-95 Description 81-85 Disorders and Remedies c . . .95-101 Operation — Air Compressor Portion 87-89 Operation — Steam Portion 85-87 INDEX E Engineer's Brake \^alve 121-130 D-8 Brake Valve , 122-123 F-6 Brake Valve 123-126 G-6 Brake Valve 126-130 E. T. No. 6 Brake Equipment 380-453 Advantages and New Features 380-381 Air Gauges 416 Air Signal System 418 B-6 Feed Valve 405-408 Broken Pipes » 430-433 C-6 Reducing Valve 408-409 Cut Out Cocks. , 416-418 Dead Engine Fixtures. . . , 414-416 Essential Parts » 381 Freight Braking. . , 428-430 Functions of the Various Parts. 381-384 General Operation of No. 6 E. T , 419-421 H-6 Automatic Brake Valve. , 384-389 Action Explained 386-389 Pipe Connections 385-386 Positions of Valve 384 Independent Lap , 427 Manipulation — Locomotive and Train Brakes , 422-430 Quick Application 426 Release after Two Application Stop 424 Release after One Application Stop 425 E. T. No. 6 Brake Equipment No. 6 Distributing Valve 393-405 Action explained ^ 393 Automatic Release 399 INDEX Automatic Service . . o 397-399 Description 394-396 Emergency Application 399-400 Independent Release 396-397 Pressures in Brake Cylinder , 400-402 Quick Action Cylinder Cap. . .312-314, 403-405 S-6 Independent Brake Valve 389-393 Pipe Connections 390-391 S F-4 Pump Governor 409-413 Action explained 410-413 Safety Valve .402-403 Special Parts of E. T. No. 6 381 Testing 421-422 Tests Made by Round House Inspector 433-452 Air Signal System Test 451-452 Automatic Brake Valve Test 441-443 Brake Cylinder Leakage Test. .0 449-450 Distributing Valve Test 444-449 Feed Valve Test 438-440 Independent Brake Valve Test 443-444 Pump Governor Test 437-438 Reducing Valve Test 440 Safety Valve Test » 450-451 H High Pressure Control — Schedule U 461-464 High Speed Brake 453-461 Automatic Reducing Valve 456-457 Feed Valves — Purpose of 458 Friction of Brake Shoes and Wheels. . . „ 455 Percent of Brake Power 453-459 Provisions for Cold Weather 459-460 INDEX Quick Action Triple. 458-459 Reducing Valves 461 Standard Pressures for 453-454 K K Triple Valve. 227-244 Emergency Position 242-244 Full Service Position 229, 238-239 Full Release and Charging 235-237 Important Features of 227 K I, and K 2 Valves Compared. 235 Lap Position 239-241 Manipulation 244 Normal and Retarded Release 230234 Quick Service Feature 227-229 Quick Service Position 237-238 Restricted Exhaust 232 Retarded Release 241-242 Uniform Recharge 232-233 Uniform Release 230 L L Triple Valve « 246-260 Brake Cylinders — Sizes of 249 Cut Out Cock — Purpose of 249 Emergency Position 258-259 Full Release and Charging 249-252 Full Service Position 252-254 Improved Features of .247-248 Lap Position 254-255 L. N. Equipment 247, 266-270 Nam^es of Parts 248-249 INDEX Release Position 255-257 Safety Valve for L Triple 259-261 Supplementary Reservoir 247-248 L. N. Equipment — Operation of 266-270 Bleeding off a Brake 269-270 Number of Pounds Reduction required 266-268 Releasing Brake when setting out cars 270 Retaining Valves — When required 270 M Main Reservoir 101-103 Main Reservoir Control 464-466 P Plain Triple Valve 210-216 Emergency Position 214-216 Lap Position 213-214 Release Position 210-21 1 Service Application 211-213 Pressure Retaining Valve. 223-227 Action explained 224-225 Disorders and Remedies 226-22'] Purpose of 223 Three Position Valve 225-226 Pump Governor — Enlarged type 471 Q Quick Action Cylinder Cap 312-314 Quick Action Triple Valve 216-223 Emergency Position 221-223 Lap Position ...» 219-221 INDEX Release and Charging Positions. = 217-218 Service Application Position 218-219 R Reducing Valve, and Pipe Bracket 469-470 S Safety Valve ., 470 Straight Air Brake Valve. . . . , 470-471 T Triple Valve — Disorders 261-265 Brake Pipe Leak 262 Blow from Exhaust Port 262-265 By Pass Valve Leakage 265 Check Valve Leakage with Brake Applied. .264-265 Cleaning and Lubrication 261 Emergency Valve Leak 263 Leak from Auxiliary Reservoir 262-263 Main Cause of Disorders 261-262 I Books That ReallyTeach you the things you want to know, and in a simple, practical way that you can understand Our illustrated catalogue, which will be sent you free upon request, tells all about the Practical Mechanical Books for Home Study that we pablbh. There are popular priced books on the operation of trains and station work, prac- tical mechariical drawing and machine designing, pattem making, electrical railroading, power stations, automobiles, gas engines, electrical wiring, armature and magnet winding, dynamo tending, elementary electricity, wireless telegraphy and telephony, carpentry and architecture, concrete con- struction, plumbing and heat- ing, sign and house painting, amusements, etc., etc. No matter what your ambi- tion or desire for knowledge may^ be, we publish books written by authorities in their different lines that will give you just the training and information that you want and need. Write today for this up-to-date and complete illu8« trated catalogue and popular price list. It is free* FREDERICK J. DRAKE & CO. 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