US1931149A

US1931149A - Railway braking apparatus

Info

Publication number: US1931149A
Application number: US657204A
Authority: US
Inventors: Jr John W Logan
Original assignee: Union Switch and Signal Inc
Current assignee: Hitachi Rail STS USA Inc
Priority date: 1933-02-17
Filing date: 1933-02-17
Publication date: 1933-10-17
Anticipated expiration: 1950-10-17

Description

Oct. 17, 1933. J. w. LOGAN, JR

RAILWAY BRAKING APPARATUS m Q MW m h 1 u I w s N R W m m HR H U S I |\k/ h Wm H 2 QR M.. Q

Q Y a x m N B RN ENB K EQSEQ RQ @ESSQK W. SQ B gnaw Q m m$5 m h QN NM. m m a m Oct. 17, 1933. J LOGAN, R 1,931,149

11.1mm 1111111111111 APPARATUS Fil'ed Feb. 17. 19:53 2 Sheets-Sheet 2 QRW HIS ATTORNEY Patented Oct. 17, 1933 UNITED STATES RAILWAY BRAKING APPARATUS John W. Logan, Jr., Wilkinsburg, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application February '17, 1933. Serial No. 657,204

27 Claims. (01. 303- 20) My invention relates to railway braking apparatus, and particularly to braking apparatus of the type comprising wheel engaging braking bars located beside a track rail, and movable to- 6 Ward and away from the rail into braking and non-braking positions.

scribed wherein the braking bars are arranged to be moved to their braking positions by means 10 of one or more fluid pressure operated motors and to be restored to their non-braking positions 7 by suitable biasing means such as gravity.

Specifically, my invention relates to means for pressure fluid distribution system such as is dis-- closed and claimed in an'application for Letters Patent of the United States, Serial No. 639,434,, filed by Herbert L. Bone, on Oct. 25, 1932, and one object of my invention is to improve and simpli: I

fy the control means disclosed in the said Bone application. I 1

Other objects of my invention will appear as the description proceeds. h

The control means set forth in my present application are somewhat similar to the controlf means set forth in the copending application for Railway braking apparatus, Serial No. 657,210,

filed by H. L. Bone and myself on thesame day as the present application, and the said copending application contains claims which cover broadly certain features of the invention described in my present application.

I will describe two forms of apparatus em bodying my invention, and will then point out the novel features thereof in claims.

40 In the accompanying drawings, Fig. l is a diagrammatic view illustrating one form ofv ap paratus embodying my invention. Fig. 2 is a similar view illustrating a modified form of the apparatus shown in Fig. 1.

Similar reference characters refer to similar parts in both views.

Referring to the drawings, the reference character 1 designates one track rail of a stretch of railway track, which track rail, as here shown, is secured to a rail support 2 mounted on an adjacent pair of the usual crossties 3, only. one crosstie being visible in the drawings, Associated with the rail 1 is a car retarder. comprising two braking bars A and A located on opposite sides More particularly my invention relates to apparatus of the type de-1 of the rail. Each of these braking bars com prises as usual, a brake beam and a brake shoe 5. v I

The braking bars are arranged to be moved toward and away from the rail 1 by meansof a lever 6 which is pivotally mounted at one end on a pivot pin 8 carried by the rail support},

and a lever 7 which is pivotally mountedintere mediate its ends on the pivot pin 8. The lever 6 is inclined upwardly and extends away'from the rail 1, and is provided in its upper surface with a groove 6 which receives the braking bar A The one end 7 of the lever 7 is likewise inclined upwardly and extends away from the rail lat the opposite side ofthe rail from the lever 6, and the other end 7 of the lever '7 is inclined downwardly and extends away from, therail 1 below the lever 6. The end 7 of the lever 7 is provided in its upper surface with a groove 7 similar to the groove 6 in the lever 6, which. groove receives the braking bar A The parts are so arranged and so proportioned that if, the, outer or free ends of the levers S and 7 are movedapart, the braking bars will be moved toward the rail 1 into, their effective or braking positions. When the braking bars occupy their brakingpositionsthe brake shoes 5 will engage the opposite side faces of a car wheel traversing rail 1, and will retard the speed of the car. The,

center. of gravity of the lever' 6 and braking bar A is considerably to the right of the pivot pin 8 so that this lever will normally tend to rotate in aclockwise direction about the pivot pin. Similarly, the center of gravity of the lever 7 and braking bar A is to the left of theivot pin 8, so that this lever will normally tend to rotate ih a counterclockwise direction about the pivot pin 8. It will be. apparent, therefore, that when no force is applied to. the, free ends of thelevers 6 and 7 to move them apart, the free ends of the levers will move toward each other, thereby moving the braking; bars ,to their ineifectiveor non-braking positions in whichthey are illustrated in the drawings.

The levers 6 and '7 areIarranged toibe moved apart to move the braking bars to their braking positions by means of a fluid pressure motor M comprising a cylinder 9 containing a reciprocable piston 10 attached to a piston rod 11. The cylinder 9 is pivotally connected with thefreeend of the lever 6 bymeans of .t'runnions 12 formed on the side of the cylinder and "extending through. bifurcations 13 formed on the lever 6;while the piston rod 11 is connected at its free end with the free end 7 of the lever 7 by means of an adjustable eyebolt l4 and pivot pin 15. Fluid pressure may be admitted to the cylinder 9 between the upper end of the cylinder and the piston 10 through an opening 16 which is thread ed to receive a pipe 17. When fluid pressure is admitted to the cylinder 9 through the opening 16 and pipe 17, the cylinder 9 will be forced upwardly and the piston 10 downwardly, thereby separating the levers 6 and '7, and hence moving the braking bars toward their efiective or braking positions. It will be obvious that when the braking bars are moved to their braking positions, they will exert a braking force whichis proportional to the pressure of the fluid supplied to the cylinder 9. a

It should be pointed out that while I have shown only one operating unit for the braking bars A and A in the drawings, in, actual practice these braking bars will be provided with a plurality of other similar units, disposed at spaced intervals along the bars, substantially as.

shown in an application for Letters Patent of the United States Serial No. 516,883, filed by Herbert L. Bone, on February 19, 1931, for Railway braking apparatus. out, that as a general rule, the car retarder will consist not only of braking bars associated with one track rail'of a stretch of railway track, as shown in the drawings, but also of other similar braking bars associated with the, opposite track rail as well, the length of the braking bars associated with both tracks rails being deter-' minedbythe speed and the weight of'the cars to be retarded, the lengths of the cars, the number of wheels on the cars, etc.

The motor M is controlled by three magnet valves designated by the reference characters V V and V respectively, and each comprising a:

valve stem 18 biased to an upper position by means of a spring 19, andprovided with a winding '20 and an armature 21. When valve V isenergized, as shown in thedrawings, valve stem 18 of this valve moves downwardly against the biasexerted by the associated spring 19,-'and under these conditions, a pipe 22 which communicates with the pipe 1'7 is connected with atmosphere through a port 23, thus connecting the upper end of cylinder 9 with atmosphere. When valve V is deenergized, however, valve stem 18 of this valve is moved upwardly 1by-the associated spring 19, and pipe 22 is then disconnected from port 23 so that the upper end of cy1inder 9 is then disconnected from atmosphere. When valve V is energized, valve stem 18 of this valve moves downwardly and pipe 22 is then connected with a pipe 24 forming part of a low pressure distribution system. This low pressure distribution system is constantly supplied with fluid pressure, usually air, from a relatively low pressure source not shown in the drawings, and it follows that when valve V is energized, the upper end of cylinder 9 is supplied with fluid pressure from the low pressure system. When valve V is deenergized,:however,pipe 22 is disconnected from pipe 24, and is connected with a pipe 25 which leads to the valve V When valve V is energized, valve stem 18 of this valve moves downwardly and connects pipe 25 with a pipe 26' forming part of ahigh'pressure' distribution system, which latter system is constantly supplied with fluid pressure, usually air, from a relatively high pressure source. It will be seen, therefore, that when valve V is energized, if valve V isv then deenergized, the upper end of cylinder 9 will be supplied with fluid pressure from the high pressure system. When valve V is deenergized, however, valve stem 18 of this It should also be pointed pressure system, and will close its contact 28- when the pressure of the fluid in the upperend' sure, but for purposes of illustration, I will assume that this pressure is maintained at approximately pounds per square inch. Likewise, the pressure of-the fluid in the high pressure system may be maintained at any desired pressure, butfo'r purposes of illustration, I will assume that this pres-.

sure is maintained at approximately 100 pounds per square inch.

The valves V are controlled in part by two pressure responsive devices P2040 and P each comprising a Bourdon' tube 27 connected to the pipe 17, and hence subjected to the pressure of the fluid in the upper end of cylinder 9 of motor M. a

Each Bourdon tube 2'! controls two contacts 28- 28 and 28-28 The pressure responsive devices P and P are so constructed that theywilloperate successively as the pressure in the upper end of cylinder 9 increases. For example, for all pressures below 20 pounds persquare inch, contact 28-28 of each of these devices is closed.

If the pressure exceeds 20 pounds per square inch, however, contact 2828 of pressure responsive device P opens, and if the pressure exceeds 30 pounds per square inch, contact 23- 28 of device P closes. In similar manner, the pressure responsive device F is adjusted to open its contact 2$--28 at 70 pounds per square inch, and toclose contact 28--2 8 at SDpounds per square inch. Of course, thesespeciflc pressures are not essential, but are only mentioned for purposes of explanation.

The valves V are also controlled by means of two relays B and C of the ordinary quick-acting type, which relays, in turn, are controlled by a pressure responsive device P spects to the previously described pressure responsive devices P2040 and P with the exception that this device is so adjusted that it will open its contact 28---28 when the pressure of the fluid in the upper end of cylinder 9 of motor M increasestoa pressure which is a predetermined amount below the pressure of' the fluidin the low of cylinder 9 of motor M increases to a pressure which is a predetermined amount above the pre sure of the fluid'inthelow pressure system. For a example, for purposes of illustration I will assume that the device I is so adjusted that it will open'its contact 28--2 8 when the pressure'of the fluid in the upper end of cylinder 9 of motor M increases to 40 pounds per square inch, and will close its conta'ct 28-28 when the pressure in the 1 upper end of the cylinder 9 of motor M increases to 60 pounds per square inch.

The control of the relays B and C by the pressure responsive device 1 is such that when contact 28-28 of this device is closed,a circuit 4 will be completed for relay B, andwhen contact 28-28 of this pressure responsive device is closed, a circuit will be completed for relay .0. The circuit for relay B passes from one'terminal of a suitable source of current, here shown as a 3.

battery D, through wires 30, 31,, 32'and 33, a line wire 34, the winding of relay B, wire 35, contact 2828 of pressure responsive device P wires 36, 3'7 and 38, and line wire 39 back to battery D.

The circuit for relay C passes from battery D,

V 'This latter; pressure responsive device is similar in all

rethrough wires

30, 31, 32 and 33, line wire 34, the winding of relay C, wire 40, contact 28--28 or pressure responsive device P wires 36, 3'7 and 38, and line wire 39 back to battery D. It will be apparent, therefore, that when the pressure of the fluid in motor M is below 40 pounds per square inch, relay B will be energized, andthat when the pressure of the fluid in motor M is above pounds per square inch, relay C will be energized, but that when the pressure of the fluid in motor M is between 40 and 60 pounds per square inch, the relays B and C will both be deenergized.

The Valves V are further controlled by means of a manually operable lever L which as here shown, is capable of assuming five positions, indicated by dotted lines in the drawings and designated by the reference characters p to 0 inclusive. The lever L controls a plurality of contacts each designated by the reference character 29 with a distinguishing exponent corresponding to the position of the lever in which the associated contact is closed. For example, contact 29 is closed in the 50 position of the lever, contact 29 in the 12 position or" the lever, etc.

Lever L will usually be located at a point remote from the braking apparatus, as in the control cabin of a classification yard car retarder system, and will be connected with the braking apparatus by means of line wires extending from "the control cabin to the braking apparatus.

tery D through

wires

30, 81, 32 and 33, contact 29 of lever L, line wire 41,

wires

42 and 43, back contact 4444 of relay C, wire 45, winding 20 of valve V wires 37 and 38, and line wire 39 back to battery D. Valve V is therefore energized, so that the upper end of motor M is vented to atmosphere. The valves V and V are both deenergized, and the supply of fluid to motor M from both the high and low pressure systems is accordingly cut off. Since the supply of fluid to motor M is cut off and the motor is vented to atmosphere, the braking bars, are held bygravity in their non-braking positions, in which positions they are shown in the drawings. Furthermore, since the supply of fluid to motor M iscut on, and the motor is vented I make a comparatively light brake application.

To do this, he will move lever L from its p to its p position. This movement of the lever will interrupt the circuit which was previously closed for valve V and will complete a circuit for valve V which latter circuit passes from battery D through

wires

30, 31, 32 and 45, contact 29 of lever L, line wire 46, contact 2 828 of pressure responsive device P wire 47, front contact 4848"- of relay B, wires 49 and 50, wind-- ing 20 of valve V wire 38, and line wire 39 back to battery D. Valve V will therefore become deenergized and valve V will become energized. The deenergization of valve V will disconnect mator M from atmosphere, while the energizae tion of valve V will admit fluid to the motor from the pipe 24, thus causing the brakin bars to move to their efiective or braking positions. When the pressure of the fluid in motor M increases to 20 pounds per square inch, contact 28--28 of pressure responsive device P will open and will deenergize valve V thus cutting off any further supply of' fluid to motor M as long asthe pressure of the fluid in the motor remains above 20 pounds per square inch. 1 If the pressure'of the fluid in motor M now increases to 30 pounds per square inch for any reason,- a circuit will become completed for valve V and valve V will become energized and will exhaust fluid from motor M. The circuit which will become completed for-valve V under these conditions passes from battery D through

wires

30, 31, 32 and 45, contact 29 of lever L, line wire 46,, contact 2828 of pressure responsive device P 9,

wires

42 and 43, back contact 44-44 of relay C, wire 45, winding 20 of valve V wires 37 and 38, and line wire 39 back to battery D. Valve V willremain energized under these conditions, and willcontinue to vent fluid from motor M until the pressureof the .fluid again decreases sufiiciently to permit contact 2828 of pressure responsive device P to open and deenergize valve V parent, therefore, that when lever L occupies its 10 position, the braking bars will be heldin their braking positions by a pressure of between 20 and 30 pounds per square inch. It will also be It will be ap-;

apparent thatthe fluid which is supplied to 1 motor M to move the braking bars to their brakingpositions is supplied entirely from the low pressure system.

I will next assume that the operator wishes to cause the braking bars to exert a somewhat higher, braking force. lever L to its p position. In this position of the lever, all of the previously described circuits for the valves V and V will be interrupted, and another circuit will be completed for valve V, which latter circuit passes from battery D through wire 30, contact 29 of lever L, line wire 51, wires 49 and 50, winding 20 of valve V wire 38, and line wire 39 back to battery D. Valve V will therefore now become energized and since the circuit over which it becomes energized is controlled solely by contact 29 of lever L, this valve will subsequently remain energized as long as lever L remains in its p position, so that fluid will now be supplied to motor M from the low pressure source until the pressure of the fluid in the motorbuilds up to that of the low pressure source. parent, therefore, that when lever L occupies its p position, the braking bars will be held in their braking positions by fluid at the full pressure of the low pressure source, which pressure it will be remembered is approximately 50 pounds per square inch. It will be noted that since the mately 50 pounds per square inch, .contact 28-28 of pressure responsive device P will-- become opened, thusdeenergizing relay B. The

deenergization of relay B under these conditions,

however, will have no efiect upon theremainder of the apparatus. I

I will now assume that lever L occupies its 12 position and that the operator in orderto cause the braking bars to exert a still higher-braking force moves lever L to its 17 position. Under these conditions, valve V will become energized over a circuit which passes from battery D It will be ap-,

pressure of the fluid in motor M is now approxi-f through wires 30, 31,32and 45, contact 29 of lever L, linewire 52 contact 28-28 of pressure responsive device P t wires 53 and 47, back contact 48-48 of relay B, wire 54, winding 20 of valve V and line wire 39 back to battery D. The energization of valve V will admit fluid to motor M from pipe 26 until the pressure of the fluid in the motor builds up to 70 pounds per square inch, at which time contact 2828 of pressure responsive device P will open, and will de-energize valve V As soon as-the pressure ofthe fluid in motor M has increased to 60 pounds per square inch, contact 28-28 of pressure responsive device F will become closed, which will cause relay C to become energized. The energization of relay C under these conditions, however, will have no effect on the apparatus unless the pressure in motor M now increases to pounds per square inch, whereupon the resultant closing of contact 2828 of pressure responsive device P will complete another circult for valve V and current will then flow from battery D through

wires

30, 31, 32 and 45, contact 29 of lever L, line wire 52, contact 282.8 of pressure responsive device P wire 43, front contact 44-44 of relay C, wire 50, winding 20 of valve V ,-wire 38, and linewire 39 back to battery D. When this latter circuit for valve V be comes closed, valve V will become energized and will connect the motor M with the pipe 24, and

since the pressure of the fluid in the motor will then be above that of the fluid in the pipe 24,

fluid will be vented from the motor into the pipe,

from battery D through

wires

30, 31, 32 and 45,

contact 29 of lever L, line wire 52, contact 28 28-- of pressure responsive device P wires 53 and 47, front contact 48-48 of relay B, wires 49 and 50, winding 29 of valve V wire 38, and line wire 39 back to battery D. Valve V will thereforebecome energized and will admit fluid pressure to motor M in the manner previously described. When the pressure of the fluid in motor M increases ,to 40 pounds per square inch, contact 2828 -of pressure responsive device P4P50 will open and will deenergize relay B, thus causing relay B to open its front contact iii--43 and to close its back contact 4843 lhe opening of front contact 4848 of relay B will interrupt the circuit just traced for valve V while the closing of back contact 48-48 of relay B will complete the previously described circuit for valve V includ-'- ing this contact. Valve V will therefore now become deenergized and valve V will become energized. When valve V becomes energized, the

apparatus will subsequently function in the same manner as it did after this valve became'ener- I gized when lever L was moved to its 11* position from its p position. It will be apparent, therefore, that when lever L is moved directly from its 39 to its 30 position,'valve V will first'become energized and will admit fluid pressure from the.

low pressure system to motor M until the pressure in the motor increases to 40 pounds I per square inch, after which valve V will become deenergized and valve V will become energized. When valve V becomes energized any further fluid which is supplied to motor M will of course be supplied from the high pressure distribution system.

I will next assume that lever L is in its p position andthat the operator desires to cause the braking bars to exert their maximum braking force. He will therefore move lever L to its p position. Under these conditions, relay 3 will be deenergized when thelever reaches its 10 position and the movement of lever L to its p position will therefore complete a circuit for valve V which passes from battery D through wires 30 and 31,

contact 29 of lever L, line wire 55, back contact 48-4=8 of relay B, wire 54, winding 20 of valve V and line wire 39 back to battery D. Valve V will therefore become energized and will subse quently remain energized, thus permitting the I will now assume that lever L occupies its p position so that the braking are exerting their maximum braking force, and that the operator wishes to by the brakingbars to that corresponding to the pos'itionoi lo or. The operator will the: fore move the lever to its p position. This mo ment of the lever t the circuit which was previously closed 3. ve V and this valve will therefore become d oil the supply of fluid p ssure to motor M from the high pressure source. rmore, since relay 0 is initially energized under these (:01 ditions, this movement of lever L will complete the previously described circuit for valve ii in cluding contact 28-28 of pressure responsive device P and front contact l s- 14 or" re and valve V will thereiorebecome deen the braking force exerted energized, thus cutting and will connect motor M with pipe and -ence will de'energize relay C, and the deenergizatioh of this relay, in turn, will interrupt the circuit which was previously closed for valve V at front 00' tact 44-44 of this relay and will also comp the previously traced circuit for valve V including contact 28-28 of pressure responsiveda' vice 1 and back contact ls-il of relay C. Valve V will therefore become deenergized and valve V will become energized. The deenergiza tion of valve V will prevent fu'l exhaust of fluid pressure from motor lvfI into the low pressure system, while the energizationof valve V will vent fluid from the motor to atmosphere. When the pressure or the fluid motor decreases to 40 pounds per square. inch, contact 28-28 of pressure responsive device P will become closed and will energize relay B. After relay B becomes energized, the apparatus will then function in the same manner as it did whenthe lever L was moved from its 32 to its p position.

I will next assume that lever L occupies its 10 position so that the braking bars are exerting their maximum braking force and that the operator,'wishing to restore the braking bars to their ineffective or non-braking positions, moves lever L to its p position Under these conditions,

valve V will become deenergized and Valve V will initially become energized over. a: circuit which passes from battery D' through wires 30, 3 1, 32' and 33, contact 29 01? lever L, line wiref41,

wires

42 and 43, front contact 44 44 of relay C,

wire 50, winding of valve V wire 38, and line l wire'39 back to battery D.' Theenergization of valve V will connect motor M with pipe 24 of the low pressure distribution systemfandsince the pressure of the fluid in motor M willthen be above that in pipe 24, fluid will be vented from the motor into pipe 24i When the pressuIe of f the fluid in the motor decreases to'60 pounds per square inch, contact 2828 of pressure responsive deviceP will open and will deenergize relay C, thereby deenergizing valve V The deenergization of relay C will also complete the previously described circuit for valve V includ ing contact 29 'of lever L and 1 back contact di l-+44 of relay. C, sothat valve .V will now become energized and will exhaust fluidfrom motor M to atmosphere. When the pressure of the fluid in motor M decreasesto 40 pounds per square inch, contact 23--28 of pressure responsive device P will become closed and will energize relay.B. The energization of relay B under these conditions, however, will have no eflect on the remainder of the braking apparatus.

operation of the apparatus for only a few of the possible movements of lever L, the operation of the apparatus for the remainder of the movements of the lever is similar-tothat already described, and it is believed that this operation will be understood from an inspection of the drawings and from the foregoing description without further detailed explanation.

Referring 'now to Fig. 2, as here shown, the

relays B and C instead of being locatedat-the retarder as shown in Fig. l,-are located'at the control point, and rectifiers have been provided to decrease the number of line wiresrequired between the control point and the braking apparatus. Furthermore, lever L'has' been provided -with two additional contacts 292* and 29 the contact 29 being closed in the p and p positions of the lever as well as in any position of the lever intermediate thesetwo positions; and the contact 29 beingclosed' in the'p and 11 positions -ofthe'lever; and in any position of the lever intermediate these two positions. a The remainder of the apparatus here shown is simito that shown in Fig. 1

With the apparatus constructed as here'shown, when the pressure of the fluid in motor M is below 40pounds per square inch, so that contact i another circuit for valve-V Thislatter circuit 2828 of pressure responsive device? 2 is closed, relay B will become energized over a ,circuit which passes from a battery E, through wires 56 and 57,winding of relay B an asymmetric unit 58 in its low resistance direction, .lin'e wire 59, contact 28 28 of pressure respon-. 'sive device P wire 60, line wire 62; and wire 63 back to battery E. Furthermore, with'the apparatus constructed ashere shown, when the pressure of the fluid ,in cylinder 9 in'motor M is above 60 pounds, sothat contact 2828 of pressure responsive device P is closed, relay C will'then become energized over 'a-circuit-which passes from batteryD through wires '65 and 66, line wire 67, contact 28-28 ofpressure-respon sivedevice P ,;line wire 59,, n asymmetric *unit .69. in its low resistance direction; winding of-relayC, and wires-57 and 561' backto battery D; When the pressure of the 'fluidin motor Mis between 40 and 60 pounds per-square inch,

however, the circuits just; traced forthe relays "B and .C will both be open, and, these relays .will of course be-deenergized. I

The: operation of the apparatus shown inIFig; 2,;as .a Whole, is as fo11ows:.;.When :1ever;,Loc cupies its p or fofi position; as showninflthe drawings, ,relay B is energized and relay C,is

deenergized. Valve N is energized over a staircuit which passesfrom battery B through wires 65and '66, contact 29 of lever L; wires {70, :71

and 72,? an as'ymmetric-pnit 73 in its lower resistance direction,,-back contact v48 :48 of rezlay C, 1 line wire {74, an asymmetric'unit ,75' in its low resistance direction, winding 20 of 1 valve 1V lwire 76,-.line-wire '77, and wire 56-back to battery -D. The valves V and V3 are both deenergized. Since valve V isienergized, cylinder of fluid to cylinder 9 of motor M from both the high and low pressure systems is, cutofi; The braking bars are, therefore held in their "brak- '9'of motor1M is vented toatmosphere, and since C .valves' V and 'V are deenergized, the supply,

ing positions by gravity: "Furthermore, since cylinder-9 of motor M is .Lventedfto atmosphere,

and the :supply of fluid "from, both the high and low pressure systemsto they-cylinder is out on,

the contact 28---28 of eachi of the, pressure rea sponsiverdevicesl P isclosed and theficontact I28-28 ofleach of these pressure responsive devices is open. 1 i Y Y --Assuming now that lever L1 is ;moved from its 1 or oil positiontolits p?position,-.valve V willubecome deenergizedmand valve will be-v come energized,fthe circuit for valve, V? under these conditions passing from battery Egthrough wire 56, line wire i'l'l, swirey'l6, winding- 20 ,;of

valve W, line wire .78., wire '79,v contact; 29 of directiongwires '72, ,71 ,and-85,;contact 29 of leverL, line wire 82, contact 28'--28**[ 0i5 pressure responsive "device P 9- line wire 62:, and

no I,

118 IN I 'lever L, wire 80, front conta'ct'44,44% of relay B, an asymmetric unit 81' inyits :low resistance wire 63 back to battery :'I'he deenergization sure source, thus. causing,thebraking-bars @120 of valve :v disconnects the'cylinder 9 of motor from atmosphere, while the ,energization ofvalve v connectsithec'motornwith theglowzpres- "13o be movedto their br aking positions/ When' the pressure of the fluid in:cylinder 9gincreasesto 20 pounds per squareinch', contact;28, 28'i of pressure responsive device will open, and

will "deenergize valve V and if the pressure of the fluid in'motorfM increases to30' pounds; per

square inch, contact 28 28 of --"pressure,.resp0n sive device ,P will close and willzcomplete for: valve g V maybe, traced from battery D through wires 65 and 66, line-wire 67, wire 83, contact 28 28 of pressure-responsive device 12 line wire 82, contact 29 otlever L, wires.

'85, Hand 72, asymmetric unit 73in its low resistance direction, backcontact 48-48? of relay C, line wire .74, asymmetric unit; 75i'in its -65 and 66, line wire 67, wire .83, contact 28.23

of pressureresponsive device P7073), line wire 86,

his moved from its p 'to' its p position, cylinder-,9 of motor M will'be suppliedwith fluid from the lowpressure source as long as the pres. sure of the'fluid in thecylinder is below 20 poundsper square inch, and if the pressure of 'tthe fluid in-the cylinder exceeds 30 pounds per isquare inch,** the fluid in the cylinder will. be 1 vented to atmosphere.

ti'on; valveV will'become energized over a circuit:-which remains continuouslyclosed as long aslever L remains in its 10 position, this circuit passing from battery D through wire 65, contact -29 of -lever L, line wire 78,winding of valve V wire "76, line wirep77, and wire 56 back to battery D Under these conditions, therefore,

a cylinder 9 will be continuously supplied with'fluid from the' low pressure system, sothat the fluid inrthe ==motor willbuild up to :theifullpressure of this: system. As was previously pointed out,

the fluid in the low pressure system is maintained I at a pressure of approximately 50 pounds per square. inch, so that some time after lever L is moved to} its 71. positiortcontact 28'28 "of pressure respcnsive device P will open and will-deen'ergize relay B. The deenergization of this relay, however, will haveno effect on the f apparatus as long: as lever L remains in its p H lposition j Q "If, now, lever L ismoved irom itsp position to its 10 'position,'va1ve V will-become deenergized, and valve V will-become energized, the

' circuit over which-valve V becomes. energized passing from battery E through wire 56, line .wire "77, winding 20 of .valve V an asymmetric unit 84, in its low resistance direction, line wire,

'74, back contact 44-44 of relay B, asymmetric unit 81in its low resistance direction-wires '72, '71 and 85, contact 29 of lever L, line wire'86, contact 28 28 of pressure responsive device P -,"wire 61, line wire 62,iand wire 63 back "tobattery E. As aresult, fluid will now be supplied to cylinder 9 of motor Mirom-the highv pressure- -system. Whenthe pressure of the fluid in motor M'increases to pounds per square inch, contact 2828 of pressure responsive de- 'vice P will become closed and will complete ;the previously described circuit for relay C so that relay 0 will then become energized. The

energization of relay C, however, has nofimmediate effect onithe apparatusflunder-thesecondition'sf When the pressure of the fluid in"mo'- tor M increases to poundspersquare inch, contact 28-'-28f of pressure responsive device P willl-openand will deenergize'valve vWQand if the pressure of the fluid in motor M increases to 8 0 pounds per square inch, 'so that contact 28-28 2of pressure-responsive -device P becomes closed, a' circuit will become completed for valve V which passes from battery D through wires cont'act 29 of lever L, wires 85,-71'and 72, asymfmetric' unit 73 in'its low resistance direction, front'contact:48-48 of relay C, Wire 80, contact 7, 429% oflever- L, wire "79,line wire 78, winding 20 of valve V wire 76, line wire 77; and wire 56" back to" battery D. Valve V will. therefore become energized'landwill connect the cylinder '9 of motor M with the pipe. 24. When the cylinder 9 becomes connected with the :pipe 24 "under these conditions, the pressure of the fluid in the. cylinder willpof course, be, .above; that of the pressure of the, fluid inl'the pipe 24, so

th atifiuid will be vented from the-1. 1 1 0 into 7 If fthe 'ope'ra'tonmoves'lever L to its 12 posi ,the low pressure distribution system, thus .rendering theexhaust fluid from the motor avail able for later use. It'will be apparent, therefore, thatif lever L is movedto, its 11 position directly fromits' 10 position, fluid pressure will: vbe supplied to cylinder 9 of motor M from the low pressure distributionfsystem until the pressureof the' fluid: in, the motor increases, to 40 pounds per square inch after; which fluid will' be sup--' plied to the motorfro'm' the high pressure distribution system. -It will also be apparent that when theglever occupies itspf position, if the pressure of. the fluid in.thewmotorincreases to 80 pounds per square inch, fluid will beyented from the'motor into the low pressure distribution system. V I

I will next assume that the operator, instead of moving lever L from its;p 'position'toits p position, moves the lever directly from its'go or p position to its 13* position. )Under these condi-- tions, when the lever reaches its 10 position, the

pressurelof the fluid in motor M will be below 40 pounds: per square. inch, so that relay B will sun be energized and as a result, a circuit will then bec'ompletedfor valve V which passes from battery E through wire 56, line wire 77,.

wireflfi, winding 20-of'-valve,V ,-lin e wire 78, wire "i9,-contact.29 of lever L, wire 80, front contact 44+44 of relay B,:asymmetric unit 81 in its'low resistance direction, wires '72, 71 and 85, contact 29 of lever L, line wire 86,-contact 28---28= oi pressure responsive device P wire 61, line wire 62, and wire 63 back to battery,E.' Valve V will therefore become energized and. will admit fluid to cylinder '9 of motor from the low-.pressure-source until thepressure, in the motor builds up to 40 pounds per square inch, at

which time contact 28-- 28*? of pressure responsive tion'of relay B'will also complete the previously described circuit for valve. Viincluding 'backcontact 44-44 of relay B,,so that valve V will then 'become energized. When valve V? becomes energized, the'apparatus will subsequently function .in' the same manner as it does after this valve becomesenergized when lever L is moved to its 12 position from its 11 position.

If the operator ,moves lever L froniitsi'gi' posi tion to its 10 position, valve V will become. enerdevice PW-F will open and will deenergizerelay -B, thus deenergizing valve V The deenergiza T giz'ed; and will thereafter remain energizedv by, virtue of a circuit which passesfrom battery E through wire 56, line wire '77, WindingZO of valve V asymmetric unit 84 in its low resistance direction,-line wire: '74, back contact 44-.-44 of, relay B, asymmetric unit 81 in its low resistance direc tion, wire .72, contact 29 of lever L, and wire 63 1 back to batteryE. Under, these conditions, therestopping the levervin its p orp -position, the apparatu's will function in the same manner as was r previously described, when the lever was moved from its p or p position to its ptposition, up to the time when relay B becomes, deenergized,

whereupon the circuit last'traced for valve V will long as the leverremains in its 10 position, in the become completed. When this circuit becomes completed, valve V will, of course; become energized, and will subsequently remain energized as same manner as when the lever wasjrnoved to its position'from its p position. 7 v I v If, when lever L occupies its p position, so that the braking bars are exerting their maximum braking force, the operator wishing to reduce the braking force exerted by the brakingbarsimoves lever L to its p positionfthe circuit'just described for valve V will become interruptedQand valve Y will become energized over a circuit which passes irom battcry D through'wires 65 and 66, line wire 67, wire 83, contact 28-7-28 of pressure responsive device P 9 line wire 82'; contact 29 of lever L,

7

wires

85, 71 and ,72'asymmetric unit 73 in its low resistance direction, front contact nt-=48? of relay C, wire 80, contact 29 of lever L, wire'79, line wire 78, winding 20 of valve V ,wire 76, line wire 77, and wire 56 backto battery. D.' Fluid will therefore now be vented from motor M into the low pressure system in a mariner which will be readily understood from the: foregoing. ",When the pressure of the fluid in motor M'decr'eases to V 60 pounds per square inch, contact 2?'28 of pressure responsive device P will become opened and will deen'ergize relay C. When'this happens, the circuit which was previously closed for valve V 'a't front'contact 48 f18 "0f1 61a y C, will become interrupted, andvalve V will there-, fore become deener'gizedy thus disconnecting cylinder 9 of motorM from' pipe24'and hence from the low pressure distribution system. ,Fur therrnore, when relay C becomes deenergized, "the previously described circuit for valve V including phere until the pressure in the motor decreases to 30 pounds per square inch, at which time contact 28-28 of pressure responsive: device P P? will open and Will de'energize valve V The 'apparatus will then function in the same'rnanner as from its 11 to its p position. L i

If, when lever L occupies its piposition, the operator instead of movin'g the lever-to its p position to decrease the braking force exerted by the brake bars, moves the lever toits p position in order to restore the brakingbarstotheirnon- ,braking positions, valve v will initially become energized over a circuit which passes'irQin bat-- tery Dthrough wires 65 and66, contact 29 of lever L',

wires

70, 71 and '72, asymmetricunit'm in its low resistance direction, front contact 48-48' of relay C, wire 80, contact f29 -of lever L, wire 79, line wire 78, winding 20 of valve V wire 76, line wire 77, and wire 56 back to battery D, The energization of valve V under theseconditions will cause fluidto be vented from cylinder 9 of motor M into thelow pressure distribution system in the manner previously described until the pressure inv the)? cylinder decreases to 60 pounds per square inch at which time theresultant opening of contact 28-28 of pressure responsive device 1 -9 will deenergize relay C, thus de-' energizing valve V The deenergization of relay" C under these conditions will also complete"the 7 previously described circuit for valve V including contact 29%]01? lever Land back contact 4848 of relay C; so that relay'C will then become energized and will vent the remainder of .the-fiuid from cylinder 9 of motor M'to atmosphere. Whenthe pressure of the mud in motor M decreases to 40"pounds per squar einch,'con- V 1 giz'ed'or deenergized. was previously described when lever Dwas moved .said twomagnet valves.

braking bar extending parallel to a track rail a tact 28- 28 of pressure responsive 'd evi'ce 'P m I will close, thus causing'relayB to again become energized, The energization of relay B under these conditions, however, will have no effect on, the'braking apparatus. As the pressure of the" fluid in motor'M continues to decrease, the braking bars will gradually return to their-non-braking positions, and when the braking bars reach their non-braking positions, all parts of the ap paratus will'thenbe restored to the positions in which they are illustrated in the drawings.

It should be pointed out that while in describ-. ing the operation of the apparatus shown 2, I have onlydescribd the operation "which takesplace during a few of the'possible move rr ents of lever L, the operation 0f the apparatus, for the remainder of thesefmove'ments is 'substantially the same as that for thedes'cribed'. movements, and it is believed, therefore, that-this 1,

operation will be readily understood from thees drawings without further description;

Al houghl have'herein shownand described,

onlytwo forms of railway braking apparatus em-- f bodying my invention, it'is understood that various changes and modifications may made therein ivithinthe scope of the appended claims [without departing from my invention.

the spirit and scope of Haing thus described-my invention, what I claim is: v I lrRailway braking apparatus comprising a braking bar extending parallel to, a track ral1,,a fluid pressure motor for. moving said braking bar 7 toward the track railjinto braking positions, a

Ifirst pipeconnected with a source of relatively 1'10 low pressure fluid, a second pipe connected with 1 a source of relatively, high; pressure fluid, a relay,

means for energizing said-relaywh'en and "only.

when the pressure of the fluid insaid motor is l'below a, predetermined pressure, and means for "H5 iadrhitting' fluid to saidxmotor'fromsaidfirst or isaid second pipe according-asjsaidrelay is ener-' 2.,Railwayfbraking apparatus comprising braking bar Xtending paralleltoa track rail,.a 1 fiuidpress'uremotor for moving said brakingbar towardj'thetrackv rail into braking positions, a first pipe connected with aj-source offrelatiively low pressure fluid, a second pipe" connected with N t asource iotrelatively high pressure fluid, a first i 5 "magnet valveefiective when energized for conn'ecting said motor with said first pipe; afsecon'd magnet valve-effective when energized for connecting said {motor with saidsecond pipe, a relay, i f

means for energizing said relay whenfland, only 1 when T the pressure of the fluid in said motor is below a predetermined pressure,and means controlled by said relay for selectively!controlling '3. Railway braking, apparatuscomprising fluid pressure motor for movingsaid braking bar toward the track rail into braking positions, a first i pipe connected with a source of relatively low u-press'ure fluid, a, second pipe-connected withf a 'lay, m'e ans for energiaing said 'relayf whenland,

only when the pressureof the fluidin'saidmotor is 'below' a predetermined pressure,v and means for at times energizingsaid first orsaidsecond 15cmotor with said two pipes.

' selectively connecting said motor with saidtw valve according as said relayis energized or deasource of relatively high pressure fluid,-a first energized,

1 4. Railway braking bar extending parallel to a track rail, a fluid pressure motor formovingsaid braking bar first pipe connected with a source 'of' relatively 7 low pressure :fluid, a second-pipeconnected with a source of relatively high pressure fluid' a relay, means'for energizing said relay when and only when the pressure o the fluid in said motor is below a predetermined pressure, and means controlled by said relay for selectively connecting said 5. Railway braking apparatus comprising a braking bar extending parallel to; a track rail, 2." fluid pressure motor for moving said braking bar toward the track rail into braking positions, a

braking apparatus comprising a;

magnet valve effective when energized for connecting said motor with said firstpipe, a second magnet valve effective when energized for connecting said motor with said second pipe, a relay,

toward the track rail intobrakin'g" positions, a

means for energizing said relay whenand only. whenthe pressure of the'fluid in said motor is belowa predetermined pressure which is some- 7 "what less than the pressure of the fluid in said is energized ordeenergized;

first pipe, and means for at times'energizing said first or said second valve according assaid relay V 10.' Railwaylbraking apparatus comprising: a

, braking bar extending parallel to a track rail, 9,

first pipeconnectedwith a. source of relatively low pressure fluid, asecond pipe connected witha source of relatively high pressure fluid, -,a relay, means for controlling said relay in accordance with the pressure of thefluid in said motonand means controlled by said relay for selectively connecting said motor withsaid two pipes. I

6. Railway braking apparatus}.comprisinga braking bar extendingparaliel to a track rail, a fluid pressure motor for moving said braking bar toward'the trackvrail into braking positions, a

first pipe connected with a'source of relatively low pressure fluid, a second pipe connected with a source of relatively high pressure fluid,'a relay, means for energizing said relay when and-v only when the pressure of. the fluid in said motor is below a predetermined pressure which is so .ewhat lower than the pressure of said low pressure source; and means controlled by said relayfor '7.'Railway braking apparatus comprising a braking bar extending parallelto a track rail, a

, fluid pressure, motor for'moving said braking'bar fluid pressure motor for "moving said braking-r bar toward the track rail into braking positions, a'first pipe connected with a source of relatively low pressure fluid, a se'condpipe connected with a source of 'relativelyhig h pressurevfluid, a first magnet valve effective when energized for con 1 necting said motor with said first pipe, at second magnet valve effective when energized for connecting said motor with said second pipe, and

'means responsive to thepressure of the fluid in I said motor for selectively energizing said two valves.

'11. Railway braking apparatus comprising a braking bar extending parallel to a track rail, a

fluid pressure motor-for moving said braking bar toward the, track rail into braking positions, a

first pipe connected with a source of relatively f low, pressure fluid a second pipe connectedwith a source of relatively'high pressure fluid, afirst ,m'agnet valveeffective'whenenergized for connecting said motorwith' saidfirst pipe, a second magnet valve effective when energized forconnecting said motor with-said second pipe, means 1 effective when and, only whenthe' pressure in said motor is below a predetermined pressure for at times energizing. said first valve, and means effective..when and only when the pressure in said motor is above said predetermined pressure for at other times energizingsaid second valve.

, 12. Railway braking apparatus comprising a 1 braking bar extending. parallel to a track rail, c a .fluidpressure motor for moving said braking bar toward the track rail into brakingpositions,

'a'first pipe connected with a source of relatively when the pressure ofthe fluid in said motor is.

below a predetermined pressure which is somesaid motor with said first or said" second pipe according as said relay is energized or deener- "giz'ed. T

, 8. Railway braking apparatus comprising :a' braking bar extending parallel to a track rail,

' a fluid pressure motor for moving said'br'aking bar toward the track rail into braking positions, a first pipe connected with a source of; relatively low pressure fluid, a second pipe connected with a source of relatively high pressure fluid, a first magnet valve effective when energized. for con-- necting said motor withsaid first pipe, a second low pressure fluid, a-second pipe connected with sure source, and means forat times' connecting I a source of-relatively'high pressure fluid, a first,

magnet valveeffective when energized for connecting said motor with saidfirst pipe,'a second magnet yalve effective wh'enflenergized for connecting said motor with said second pipe, a third magnet valve efiective when energizedfor con- V necting said motorv with atmosphere, means for,

at times energizing said first or said second valve according as the pressure of the fluid in said motor is then below or above a first predetermined pressure, and means for at other times energizing said first or said third valve according as the pressure of the fluid in said motor is then above orbelow a second predetermined'pressure.

magnet valve ,efiective when energized for connecting said motor with said second'pipe, a relay,

- means for controlling said relay in accordance, Y with the pressure of the fluid in said motor, and

-means controlled by said relay for selectively energizing said valves.

9. Railwayv braking apparatus comprising a braking bar extending parallel to a track rail, fluid pressure motor for movingjsaid braking bar toward the track railinto braking positions,

a first pipe connected with a source of relatively low. pressure fluid, a second pipe connected with .13. Railway braking apparatus comprising a braking bar extending parallel to a track rail,

a fluid pressure motor for movingsaid braking bar toward the track rail into braking positions,

afirst pipe connected with asource of relatively low pressure fluid, a second pipe connected with a source of relatively high pre'ssi'ire' fluid, a first magnet valve effective when'energizedffor connecting said motorwith said first'pipe, a second magnet valve effective" when energized for iconnecting said motor with said second pipe, athird magnet valve effective when energized for con- I the pressure of the fluid in said motor is below 7 motor and adjusted to close at a fourth predef a first predetermined pressure which is somewhat lower than the pressure of said low pressure source, a second relay, means forenergizing said second relay whenever the pressure of the fluid in said motor is abovea second predetermined pressure which is somewhat higher than the pressure of said low pressuresource, a manually operable leverprovided with two contacts, a first 'contact responsive to the pressure of the fluid in said motor and adjusted to open at a third predetermined pressure which is higher than said second predetermined pressure, a second contact re's ponsive to the pressure of the fluid in said 'termi'ned pressure which is higher than said third predetermined pressure, a first circuit for said first magnet valve including one of said lever contacts and a front contact of said second 'relaypa first circuit for said third magnet valve including said one lever contact and a back contact of said second relay; a second circuit for said first magnet valve including the other lever contact, said, first pressure'responsive contact, and a front contact of said fir t relay; 'a third circuit for said first magnet valve including said other lever contact, said second pressure responsive contact, and a front contact of said second relay, and a circuit for said second magnet valve including said other lever contact, said first pressure responsive contact, and a back contact of said first relay.

20. Railway braking apparatus comprising a braking bar extending parallel to a track rail, a fluid pressure motor for moving said braking bar toward the track rail into braking positions, a first pipe connected with a source of relatively low pressure fluid, a second pipe connected with a source of relativelyhigh pressure fluid, a first magnet valve eifective when energized for 0on necting said-motor with said first pipe, a second magnet valve effective when'energized for connecting said motor with said second pipe, a third magnet valve effective when energized for connecting said motorv with atmosphere, a relay, means for energizing said relay when the pressure of the fluid in said motor is above a predetermined pressure which'is somewhat higher than the pres-' times energizingsaid second magnet valve, a

manually operable contact, a circuit for said first magnet valve including said manually operable contact and a front contact of said'relay, and a-circuit for said third magnet valve including said'manually operable contact and a back contact of said relay. v

'21. Railwayvbraking apparatus comprising a braking bar extending parallel to a track rail, a fluid pressure motor for moving said braking bar toward the track rail into braking positions, a first pipe connected with a source of relatively low pressure fluid, a second pipe connected with a source of relatively pressure 'fiuid, a first magnet v'alve'e'fiective when energized for connecting said motor with said first pipe, a second magnet valve effective when energized for con necting said motor with said second pipe, a third magnet valve effective when energized for connecting said motor with atmosphere, a first relay, means for energizing said first relay whenever source, a second relay, means for energizing said necting said motor with said second pipe, a third second relay whenever the pressure of the fluid in said motor is above a second predetermined pressure which is somewhat higher than the pressure of sa id'low pressure source, a first contact responsive to thefl'pressure of the fluid in said "'80 motor and adjusted to open at a third predetermined pressure which'is below said first predetermined pressure, a second contact responsive to the pressure of the fluid in said motorand ad"- justed to close at a fourth predetermined pressure which is between said first and third, predetermined pressures, a manually operable contact, means including a back contact of said first relay for at times energizing said second magnet'valve; a first circuit for said first magnet valve including said manually operable contact, said first pressure responsive contact, anda front'contact of said first relay, a secondocircuitfor saidflrst "for said third magnet valve including saidmanually operable contact, said second pressure responsive contact and a back contact of said second relaya 22.Railway braking apparatus comprising a braking bar extending parallel to'a track rail, a fluid pressure motor for moving said braking bar toward the track rail into braking, positions, a first pipe connected' with a source of relatively low' pressure fluid, a second pipe connected with a source of relatively highpres'sure" fluid, a first magnet valve efiective when energized for connecting said motor with said first pipe, a'second magnet valve effective when energized for'conmagnet valve effective when energized for connecting said motor with atmosphere, a first relay, means for energizing said first relay whenever thepressure 'of the fluid in said motor is below a first predetermined pressure which is somewhat lower than the pressure of said low pressure source, a second relay, means for energizing said second relay whenever the pressure of the'fiuid in said motor is above a second predetermined pressure which issomewhat higher than the pre ssure of said lowpressure source, means controlled by a back contact of said first relay for'at times energizing said second magnet valve, means controlledby a front contact of said first relay for at times energizing said first magnet valve, means controlled by a front contact of said second relay for at other times energizing said firstxvalve, means controlled by a back contact of said sec ond relay for at-times energizing said third valve, a manually operable contact, anda circuit for said first valve controlled solely by said manually operable contact. 7 23. Ra lway braking apparatus comprising a braking bar extending parallel to a track rail, 2, fluid pressure motor for moving said braking bar toward the track rail into braking'positions, a first pipe connected with a source of relatively low pressure fluid, asecond pipe connected with a'source of relatively high pressurefiuid, a first 140 magnet valve efiective when energized for connecting said motor with said first pipe, at second magnetvalve effective when energized for con necting said motor with said second pipe, a third magnet valve effective when energized for cone 145 necting said motor with atmosphere, a first relay; means for energizing said first relay whenever the pressure of the fluid in said motor is below a first predetermined pressure which is somewhatlower than the pressure of said low pressure150 Ill) source, a second relay, means for energizing said second relay whenever the pressure of the fluid insaid motor is abovea second predetermined pressure which is somewhat higher than the pressure of said low pressure source, a first contact responsive to the pressure of the fluid in said motor and adjusted to open at a third predetermined pressure which is higher than said second contactof said first relay; a second circuit for said first magnet valve including said manually operable contact, said second pressure responsive contact, and a frontcontact of said second relay; a circuit for said second magnet valve including said manually operable contact, said first pressure'responsive contact, a back contact of said first relay; and means for at times energizing said third magnet valve when and only when said manually operable contact is open.

24. Railway braking apparatus comprising a braking bar extending parallel to a track rail, a fluid pressure motor for moving said braking bar toward the track rail into braking positions, a

first pipe connected with a source of relatively low pressure fluid, a second pipe connected with a source of relatively high pressure fluid, a first magnet valve effective when energized for connecting said motor with said first pipe, a second magnet valve effective when energized for connecting said motor with said second pipe, a third magnet valve effective when energized for con necting said motor with atmosphere, a first relay,

- means for energizing said first relay whenever the pressure of the fluid in said motor is below a first predetermined pressure which is somewhat lower than the pressure of said low pressure source, a

second relay, means for energizing said second relay whenever the pressure of the fluid in said motor is above a second predetermined pressure which is somewhat higher than the pressure of said low pressure source, a manually operable contact, a circuit for said first magnet valve including said manually operable contact and a front contact of said first relay, a circuit for said second magnet valve including said manually operable contact and a back contact of said first relay, and means including a back contact of said second relay and efiective when neither of said circuits is closed for at times energizing said third magnet valve.

25. Railway braking apparatus comprising a braking bar extending parallel to a' track rail, a

:- fluid pressure motor for moving said braking bar toward the track rail into braking positions, a

first pipe connected with a source of relatively low pressure fluid, a second pipe connected with a source of relatively high pressure fluid, a first magnet valve for connecting said motor with said first pipe, a second magnet valve for connecting said motor with said second pipe, a third magnet valve for connecting said motor with atmosphere, a first contact responsive to the pressure of the fluid in said motor and adjusted to open at a 'flrst predetermined pressure which is below the second predetermined pressure which is above all and a second relay,three :wires, a first source of electromotive force connected with a first andja second one of said wires, a second source ofelecr tromotive force connected with said firstwire and the third wire, means including afirst asymmetric unit and-said first pressure responsivecontact for connecting said first relay lwith said first and second wires, means including a second asymmetric unit and saidsecond pressure responsive contact for connecting said second relay with said first and third wires, said two asymmetric units being disposed in ODDQsite directionslwith respect to said first wire, and means controlled by said two relays for selectively controlling said magnet valves. 7 i

26. Railway braking apparatus comprising" a braking bar extendingparallel to a track rail, a

fluid pressure motor for moving said braking bar, toward the track rail into braking positions, a first pipe connected with, a source of relatively 1 low pressure fluid, a second pipeconnected with a source of relatively high pressure fluid, a first magnet valve for connecting said motor with, said first pipe, a second magnet valve for connecting said motor with said'second pipe, a third magnet valve for connecting said motor with atmosphere, a first relay, means for energizing said first relay when the pressure of'the fluid in said motor is below a first predetermined pressure which is lower than the pressure of said low pres, sure source, a second relay, means for energizing said second relay when the pressure of the fluid in said motor is above a second predetermined pressure which is higher than the pressure of ,said' low pressure source, three wires, a first source of electromotive force connected with a first and a second one of said wires, a second source of electromotive force connected with said first wire and the third wire, a lever provided with a plurality of contacts which may be selectively operated by manipulation of said lever, a first. contact responsive to the pressure of the fluid in said. motor and adjusted to become opened at a'predetermined pressure, a second contact responsive to'the pressure of the fluid in said motor and adjusted to become closed at a pressure which is somewhat higher than the pressure at which said first contact becomes opened, four asymmetric units, means including a first contact of said lever, a first one of said asymmetric units, a back contact of said second relay and a second one of said asymmetric units for connecting said third magnet valve with said second and first wires; means including said first contact of said lever, said first asymmetric unit, a front contact of said second relay and a second contact of said lever for connecting said first magnet valve with said second and first wires; means including a front contact of'said first relay, a third one of said asymmetric units, a third contact of said lever, and said first pressure responsive contact for connecting said first magnet valve with said first and said third wires; means including said second pressure responsive contact, said third contact of said lever, said first asymmetric unit, said back contact of said second relay and said second asymmetric unit for connecting said third magnet valve with said second and first line wires; means including said145 second pressure responsive contact, said third contact of said lever, said first asymmetric unit and saidfront contact of said second relay for connecting said first magnet valve with said second and first wires; and means including the 150 first "pipe connected with a source of relatively low pressure fluid, a second pipe connected with a source of relatively high pressure-fluid, a first magnet valve for connecting said motor with said first pipe, a second magnet'valve for connecting said motor with said second pipe, a third magjnet valve for connecting said motor with atmosphere, a first contact responsive to the pressure of the fluid in said motor and adjusted to open at a first predetermined pressure which is below the pressure of the fiuid in said first pipe, a second contact responsive to the pressure of the fiuid in said motor and adjusted to open at a second predetermined pressure which is above the pressure of the fluid in said first pipe, a first and asecond relay, three wires} a firstsource of electromotive force connected with a first and a second one of saidwires, 'a' second source of electromotiveforce connected with said first wire and the third wire, means including a first asymmetric unit and said first pressure responsive contact for connecting said first relay with said first and second wires, means including a second asymmetric unit'and said second pressure responsive contact for connecting'said' second relay with said first and third wires, said two asymmetric units being disposed in opposite directions with I respect to said first wire, means controlled by a front contact of said; first relay for energizing said first magnet valve, means controlled by a back contact of said first relay for energizing'said second magnet valve,'means controlled by a front contact of said second relay for energizing said first magnet valve, and means controlled by a back contact of said-second relay f or energizing said third magnet valve." r Y 'JOI IN W. LOGAN,"J n.-