USRE15841E - Elec xx - Google Patents

Description

T. H. THOMAS ELBCTROPNEUMATIC BRAKE M 13, 1924. Y Re. 15,841

-0r:l.g1na1 Filed April 2. 1920 :s Sheets-sheaf] omnuna REL H01. 0

INVENTOR THOMAS H.THOMAS BY 446/ ATTORN EY May 1924. Re. 15,841

T. H. T -|oMAs zwc'rnorummnc BRAKE Original Filed 1mm 2, 1920 a Shasta-Sheet 2 .INVENTOR v THOMAS H. HoMAs ATTORNEY Reissued May 13, 1924.

UNITED STATES I Re. 15,841 PATENT OFFICE.

THOMAS H; THOMAS, 015 EDGEWOOD, PENNSYLVANIA, ASSIGNOR TO THE WESTING- HOUSE AIR BRAKE COMPANY, OF WILMERDING, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

ELECTROPNEUMATIG BRAKE.

Original No. 1,440,421, dated January 2, 1923, Serial No. 376,667, filed April 2, 1920. Application'for reissue filed February 3, 1923. Serial No. 616,803.

To all whom it may concern:

Be it known that I, THOMAS H. THOMAS, a citizen of the United States, residing at Edgewood in the county of Allegheny and State of Fennsylvania, have invented new and useful Improvements in Electropneumatic Brakes, of which the following is a specification.

This invention relates to electro-pneulnatic brakes, and more particularly to a brake equipment for electrically controlling the brakes on the cars of a train.

The principal object of my invention is to provide an improved electro-pneumatic brake equipment in which a reduced number of electric train wires and brake control ma nets are emplo ed.

ther objects an advantages will appear in the following more detailed description of the invention.

In the accompanyin drawings; Fig. 1 is a diagrammatic view 0 an electro-pneumatic brake equipment for a locomotive or head car and other cars of a train, with my invention applied thereto; Figs. 2 to 4 inclusive,

sectional views of the brake switch drum,

showing the electric train line connections in the respective positions indicated on the drawings; Fig. 5 a wiring diagram, including a development of the electric brake drum; Fig. 6 a sectional diagrammatic view of a car electro-pneumatic brake equipment embodying my invention; and Figs. 7 to 9 inclusive, sectional views of the electric portion of the mechanism shown in Fig. 6, in the respective positions of release,service, and emergency.

As shown in Fig. 1 of the drawings, an electric generator 1 is provided on the 1000- motive and a brake switch comprising a contact drum 2 adapted to be operated by a stem 3 which is preferably connected to the usual brake valve device, so that the movement of v the brake valve for controlling the brakes pneumatically also moves the brake drum for controlling the brakes electrically.

On each car of the train, there is provided electro-lnagnets A and B for controlling a valve mechanism by which the brakes may be applied and released.

One terminal of the magnet A is connected through a cut-out switch 4 to an electric train wire 5 and one terminal of magnet B is connected to an electric train wire 6, the

other terminal of said magnets being connected to a return train wire 7 While the car electro-pneumatic brake equipment is designed to operate in connection withvarious forms of brake controlling valve devices, I have shown one application in Fig. 6 of the drawings in which the electro-pneumatic apparatus is applied in connection with a standard quick action triple valve device 8.

Said triple valve device may comprise the usual casing, having a piston chamber 9 connected tothe brake pipe 10 and containing piston 11 and a valve chamber 12, connected to an auxiliary reservoir 13 and containing a main slide valve 14 and a graduating slide valve 15 adapted to be operated by piston 11.

The quick action portion of the triple valve device may comprise the usual piston 16 for operating a train pipe vent valve 17.

The magnet A is adapted to operate valves 18 and 19 and the magnet B valves 20 and 21. Associated with the magnet bracket 22 is a selector valve device 23 having a piston chamber 24 connected to a passage 25, leading through a cut-out cap 26 and controlled by valve 20, and containing apiston 27 and having a valve chamber 28, connected to a passage 29 and containing a slide valve 30, adapted to be operated by piston 27.

Also associated with the magnet bracket 22 is a short circuiting switch device 31 having a piston 32 for operating a switch contact 33, adapted when closed to connect the electric train wires 5, 6, and 7.

In operation, the fluid pressure brake system is charged in the usual manner and fluid from the brake pipe 10 flows to piston chamber 9 of the triple valve device 8 and thence through feed groove 34 to valve chamber 12 and the auxiliary reservoir 13.

In the normal running position of the brake valve and brake switch, the magnet A is energized while the magnet B is deenergized. as shown in Fig. 6 of the drawings. Fluid under pressure is supplied from the brake pipe through passage 35 to passage 29, charging the valve chamber 28 of the selector valve device '23.

Fluid also flows from passage 35 through the cap 26 to a passage 36 which leads to the chamber 37 below the magnet valve 19 and also chamber 38 below the magnet valve 21.

With the magnet B deenergized, the valve 90 will be seated and the va1ve-21 opened, so as to permit fluid from the brake pipe to flow from passage 36 and chamber 38, past the valve 21 to passage 25. The fluid pressures on opposite sides of the piston 27 being thus equalized, the spring 39 maintains piston 27 and slide valve 30 in release position, as shown in Fi 6.

In this position, the brake cylinder 40 is connected to the atmosphere through passage 41, passage 42, passage 43, cavity 44 in slide valve 14 of the triple valve device,

passage 45, cavity 46 in slide valve 30, and

exhaust port 47.

Themagnet A being energized in running position, the valve 18 will be seated and the valve 19 will be held open so that fluid under pressure is supplied from the brake pipe through passage 36 and chamber 37, past the valve 19 to passage 48 and thence to an emergency valve chamber 49, the purpose of which will be hereinafter explained.

If it is desired to eflect a service application of the brakes, the combined brake valve and brake switch is turned to service application position, in which the brake pipe pressure is reduced through the brake valve in the usual manner, and the magnet A is deenergized, while the magnet B is energized.

The energization of magnet B causes the valve 21 to be closed and the valve 20 to be opened, so that passage 25 is connected to an atmospheric exhaust port 50. Fluid under pressure is therefore vented from piston chamber 24 of the selector valve device 23 and consequently the piston 27 and slide valve 30 areshifted to the position shown in Fig. 8 of the drawings.

In this position, the brake pipe is vented to the brake cylinder 40 in the following manner; through passage 35 to passage 29 and valve chamber 28 of the selector valve device 23 and thence through passage 51 to emergency chamber 49, through passage 48, past the valve 18 to passage 52, past check valve 53 to passage 54 and through cap 26 and cavity 55 in slide valve 30 to passage 43, which leads to the brake cylinder 40.

The brake pipe pressure is therefore locally reduced on each car of the train as above described, by the operation of the electric portion and is also reduced at the brake valve, so that the triple valve devices on the train are shifted to service application position, in which the usual service port 56 in slide valve 14 registers with brake cylinder port 43 and fluid under pressure is supplied from the valve chamber 12 and the auxiliary reservoir 13 to thebrake cylinder 40 in the usual manner.

The brakes may be released by first moving the brake valve to release position and then to running position. In release position, fluid is supplied from the main reservoir through the brake valve to the brake pipe in the usual manner tosecure a rapid increase in brake pipe pressure throughout 1 the train and thereby efl'ect the movement of the triple valve devices to release position.

In release position, the brake switch operates to energize both the magnets A and B. Since the magnet B remains energized, as in service application position, the piston chamber 24 of the selector valve device 23 is maintained at atmospheric pressure and the piston 27 and slide valve 30 remain. in service position, as shown in Fig. 7 of the drawings.

The venting of fluid from the brake pipe to the brake cylinder is cut ofl however, since the magnet A is energized to close the valve 18 and thus cut ofl communication through which fluid is supplied from the brake pipe to the brake cylinder.

WVhen the brake pipe pressure has been increased in the release position of the brake valve sufliciently to effect the movement of the triple valves to release position, the brake valve may be turned to running position, in which the brake switch operates to energize the magnet A and deenergize the magnet B.

The deenergization of magnet B causes the valve 20 to be closed and the valve 21 opened, so that fluid under pressure is supplied from the brake pipe through passage 36, past valve 21 to passage 25 and piston chamber 24. The piston 27 and slide valve 30 of the selector valve device are then shifted to release position, in which the brake cylinder is connected to the exhaust port 47, as hereinbefore described.

If the brake valve is left in running position the brakes will be fully released, but if it is desired to effect a graduated release of the brakes, the brake valve may be moved from running to release position, after the brake cylinder pressure has been partially reduced, so as to cut off the further exhaust of fluid from the brake cylinder.

Further reductions in brake cylinder pressure may be effected, as will be evident, by

moving the brake valve between running and release position as often as desired.

An emergency application of the brakes may be effected by moving the brakevalve to emergency position in which the brake pipe pressure is suddenly reduced at the brake valve and in which all the electric brake circuits are opened, so that both the magnets A and B are deenergized.

Since the magnet B- is deenergized, the piston 27 of the selector valve device 23 will be maintained in release position, the supply of fluid-under pressure to the piston chamber 24 being maintained past the open valve 21. i

The magnet A being deenergized, the

valve 19 will be closed and the valve 18 o ened, so that fluid under pressure is supp ied from the normally charged emergency chamber 49 to the quick action piston 16, through passage 48, past the valve 18, through passage 52, past check valve 53, through passage 54: and cavity 55 in selector slide valve 30 to passage 57 and thence to the quick action piston 16.

Said piston then operates to open the brake pipe vent valve 17 and vent fluid from the brake pipe to effect a local reduction in brake pipe pressure in the usual manner.

Fluid under pressure is also supplied through assage 57 to the outer seated area of a va ve piston 58, which is thereby opened, so as to permit fluid under pressure to flow throu h a passage 59 to the switch piston 32. aid switch piston then operates the switch bar 33 to bridge the contacts connected to the train wires 5, 6, and 7.

Where an emer ency application of the brakes is initiated y movement of the brake valve to emer ency position, as above described, the bridgin of the contacts by the switch bar 33 will ave no effect, since the train line circuits are all open at the brake valve, but in case an emergency application of the brakes is initiated by a train breakin-two or because of a bursted brake pipe hose, the quick action piston of the triple valve device on the forward portion of the train, ad'acent to the break, will be operated by t e sudden reduction in brake pipe pressure, so that fluid is supplied to the correspondin switch piston 32 by the opening of the va ve piston 58 and under these conditions, the brake valve will probably be in a position other than the emergency position, and therefore a circuit will be closed through one or more of the train wires 5, 6, and 7, so that the bridging of the contacts connected to said train wires by the closure of switch bar 33 will cause a short circuit through the energized train wires and thereby a sudden rush of current through the overload switch device 60 in the current supply lead 61. The overload switch will then be operated in the usual way to open the generator circuit, so that all of the train wires will be deenergized and consequently an emergency application of the brakes will be produced on the cars at the head end of the train to the point where the breakin--two has occurred.

Brake cylinder pressure is supplied to the spring side of the valve piston 58 through passage 62, so that when the brake cylinder pressure plus the pressure of spring I 63 slightly exceeds the auxiliary reservoir pressure acting on the opposite side of the valve piston, said valve piston will be moved to its seat, closing communication from the auxiliary reservoir to its seat, closing commumcation from the auxillary reservoir to the switch piston 32, permittingthe piston 32 to return the switch 33 to its open position, and thus restoring the electric train lines to normal condition, for further electric operation.

The quick action piston 16 being of the usual construction, permits the slow equalization of pressures on its opposite sides, so v that after a predetermined time interval necessary to secure such equalization, the piston 16 will return to its normal position, permitting the vent valve 17 to close, so that the brakes may now be released, if desired.

If the magnet A remains deenergized after an emergency application of the brakes due to a broken train wire or loss of current, any fluid pressure remaining in the chamber 49 will be vented to the brake cylinder by flow around the quick action piston after the triple valve parts have moved torelease position and the pressure in the brake cylinder has been released to the atmosphere.

If a car equipped with the above described apparatus is placed in the train not provided with electric control, the magnets A and B will both be deenergized, so that the valve 19 will be seated, cutting off the supply of fluid from the brake pipe to the emergency chamber 49 while the valve 18 will be opened, and fluid in said chamber will be vented to the chamber above the quick action piston 16.

Since there is no fluid pressure in the chamber 49 under the above conditions, there will be no action of the electric portion and the equipment of the train will act only pneumatically in the usual manner.

If an emergency application of the brakes as effected by operation of the electrically controlled mechanism is due to the breaking of a train wire or the failure of current it will be seen that Since it is necessary to previously energize the magnet A in order to charge the chamber 49 with fluid. under pressure, the electrically controlled mechanism will thereafter be rendered ineffective so long as the train wires remain broken or so long as there is a failure of electric current and under such. circumstances, the brakes may be controlled pneumatically by the operator upon manipulation of the brake valve in the usual manner, without the necessity on the part of the operator to perform any special act and without the electrically controlled mechanism interfering in any manner with the proper functioning of the pneumatic brake control.

It will now be seen that the above feature as well as the feature of permitting the operation of the equipment in a train not equipped for electric control is accomplished broadly by providing an electrically controlled means which will operate to efpressure is effected in the el foot an application of the brakes upon deenergization, but only after the previous energization of said means.

A choke 64 in the passage 42 ensures that the brake pipe pressure will not reduce faster than the auxiliary reservoir pressure in an electric service application of the brakes, since the brake pipe pressure as well as fluid from the auxiliary reservoir must flow through. the choke to get to the brake cylinder and this prevents the possibility of the triple valve device shifting to emergency position by the reduction in brake pipe pressure which is efl'ected in an electric service application of the brakes.

In order that the release of the brakes.

flow through the may not be restricted by choke64, the release offluid from the brake cylinder is augmented through a by-pass, containing a cheek valve 65, from the passage 62 to the passage 43.

As hereinbefore described, the apparatus operates both electrically and pneumatically, that is to say, the brake pipe pressure is reduced in electric operation, and the triple valve devices operate by the reduc-' tion in brake pipe pressure to supply fluid to the brake cylinder.

If it is desired to operate electrically only, without having the triple valvedevices function, a plug 66 .in a passage67 leading from the valve chamber'12 to the passage 29 is removed and placed in thethreaded opening 68 in the passage 35, 'so as to close the brake pipe passage 35 and open the auxiliary reservoir passage 67.

With this arrangement, it will be seen that upon operation of the electric portion. fluid under pressure will be taken from the auxiliary reservoir instead of the brake pipe in making an application of thebrakes. In this case the electric positions of the brake valve are separate fromthe pneumatic positions, so that no reduction in brake pipe ectric service position.

While in making an electric serviceapplication of the brakes, the auxiliary reser-- voir pressure tends to be reduced, the pressure in the auxiliary reservoir will be sub: stantiall maintained by flow from the brake pipe through the usual feed groove 34 around the triple valve piston 11.

Having now described my invention, what I claim asnew and desire to secure by Letters Patent, is

1. In an electro-pneumatic brake, the combination with a valve mechanism operated by variations in fluid pressure for controllin the application and release of the braies, of two electro-magnets and double beat valves operated by each magnet for.

controlling the fluid pressure variations.

2. In an electro-pneumatic brake, the combination with a valve mechanism operated by variations in fluid pressure for control lin the application and release of the bra es, of two electro-magnets and two valves operated by each magnet, one adapt ed to seat upon energization and the other upon deenergization of the cooperating magnet for controlling said variations in flu1d pressure.

3. In an electro-pneumatic brake, the combination with two electro-magnets, of means controlled by said magnets for efiecting an application of the brakes upon energization of one magnet, the release of the brakes upon energization of the other magnet, and holding the brakes applied upon energization of both magnets.

4. In an electro-pneumatic brake, the combination withtwo electro-magnets, of means controlled by said magnets for efi'ecting a service application of the brakes upon energization of one magnet, the release of the brakes upon energization of the other magnet, the holding of the brakes applied upon energization of both magnets, and an emergency application of the brakes upon deenergization of both magnets.

' 5. In an electro-pneumatic brake, the combination with two electro-ma ets, of means controlled by said magnets or effecting a service application of the brakes upon energization of one magnet, the release of the brakes upon energization of the other magnet, and an emergency application of the brakes upon deenergization of both magnets.

6. In an electro-pneumatic brake, the combination with a selector valve device, of electrically controlled means for eflecting a service a plication of the brakes with the selector va ve device in one position and an emergency application of the brakes with the selector valve device in another position and electrically controlled means for effecting the operation of said selector valve device.

7. In an electro-pneumatic brake, the combination with a selector valve device having one position in which communication is established for effecting a service application of the brakes and another position in which communication is established for eflecting an emergency application of the brakes, of electrically controlled means for initiating a service or an emergency application of the brakes through saidselector valve device and electrically controlled means for effecting the operation of said selector valve device.

8. In an electro-pneumatic brake, the combination with a selector valve device adapted to control the release of the brakes .and having one position in which communicatlon 1s estabhshed for effecting a service application of the brakes and another position in which communication is established for efl'ecting an emergency application of the brakes, of electrically controlled means for initiating a service or an emergency application of the brakes through said selector valve device and electrically controlled means for effecting the operation of said selector valve device.

9. In an electro-pneumatic brake, the combination with a selector valve device having one position for establishing communication for efl'ecting a service application of the brakes and another position for establishing communication for efi'ecting an emer ency application of the brakes, of electrical y controlled means for effecting the operation of said selector valve device.

10. In an electro-pneumatic brake, the combination with two electro-ma ets and means controlled by said magnets or effecting a service application of the brakes, an emergency app ication of the brakes, and the release of the brakes, of a train wire through which each magnet may be energized and a common return for said magnets.

11. In an electro-pneumatic brake, the combination with two electro-ma ets and ing a service a lication of the brakes, an

,. emergency app lcation of the brakes, the

holdin of the brakes applied, and the release 0 the brakes, of a train wirefor each magnet through which current is supplied for energizing the corresponding magnet and a common return wire for both magnets. 12. In an electro-pneumatic brake, the combination with a valve device operated by fluid under pressure for eflecting an emergency a plication of the brakes, of an emergency 0 amber and electrically controlled means adapted upon energization to charge said chamber wit fluid under pressure and upon deenergization to connect said chamber with said valve device. 13. In an electro-pneumatic brake, the combination with a brake pipe and a quick action valve device operated by fluid under pressure for venting fluid from the brake pipe to effect an emergency application of the brakes, of an emergency chamber and electrically controlled means adapted when energized to charge said chamber with fluid under pressure and u on deenergization to vent same to said qulc action valve devlce.

14. In an electropneumatic brake, the combination with a brake pipe, auxiliary reservoir, and brake cylinder, of electrically controlled means for controlling a passage through which fluid is vented from the brake ,pipe to effect an application of the brakes and a passagethrough which fluid from the auxilia reservoir is supplied to efl'ect an application of the brakes and means for. c

osing communication through one passage when the other passage is open.

15. 11 an electro-pneumatic brake, the

combination with a brake pipe, auxiliary reservoir, and brake cylinder, of a valve device operated upon a reduction in brake pipe pressure for supplying fluid from the auxiliary reservoir to the brake cylinder and electrically controlled means for controlling a passage through which fluid is vented from the brake pipe and a passage through which fluid is supplied from the auxiliary reservoir directly to the brake cylinder and means for closing one passage when the other passage is used. I

16. In an electro-pneumatic brake, the combination with a brake pipe, of two electro-magnets, means operated upon deenergization of both magnets for effecting an emergency application of the brakes, a train wire for each magnet throu h which the corresponding magnet is energized, a common return wire, an overload circuit breaker in the electric supply circuit for said train wires, and a switch device operated upon a reduction in brake pipe pressure for establishing a short circuit from the supply train wires to the return wire.

17. In an electro-pneumatic brake, the combination with two train wires, of means operative upon energization of one train wire to effect an application of the brakes, upon energization of the other train wire to effect the release of the brakes, and upon energization of both train wires to hold the brakes applied. I

18. In an electro-pneumatic brake, the combination with twotrain wires, of means operative upon energization of one train wire to effect an application of the brakes, upon energization of the other train wire to efi'ect the release of the brakes, upon en ergization of both train wires to hold the brakes applied, and upon deenergization of both train wires to efl'ect an emergency application of the brakes.

19. In an electro.pneumatic brake, the combination with two brake magnets, of means operative upon energization of one magnet and the deenergization of the other magnet for effecting a service application of the brakes and upon deenergization of both magnets for efliecting an emergency application of the brakes.

20. In an electro-pneumatic brake, the combination with two brake magnets, of means operative upon energization of one magnetand the deenergization of the other magnet for effecting the release of the brakes and upon deenergization of both magnets for effecting an emergency application of the brakes.

21. In an electro-pneumatic brake, the combination with a chamber normally charged with fluid under pressure, of a valve device operated by fluid supplied from said chamber for effecting an ap lication of. the brakes andelectrically controlled means for controlling the supply of fluid from said chamber to said valve device.

22. In an electro-pneumatic brake, the combination with a chamber normally charged with fluid under pressure, of a valve 3 for effecting an application of the brakes, of "electrically controlled means operative 'upon deenergizati'on for effecting the operation of said valve device and means for effecting the movement ofsaid valve device to nor mal'position after a predetermined time to permit the release of't'he brakes.

charged with fluid under pressurejand a valve device operated byfluid suppliedffrom said chamber for eflecting an application of the brakes, of electrically controlled -means for controlling the supply of fluidlfrom said! chamber to said'valve device and means for slowly venting. fluid from said chamber to permit a return movement of said valve device and the releaseof the brakes after a predetermined time intervaL,

'25. In an electro-pneumatic brake, the combination with a valve device for effecting an application of 'the'brakes, of electrically controlled means operative upon deenergization' for effecting the operat on of said valve device and means operative to permit the release of the brakes after a predetermined time interval.

26. In an electro-pneumatic 'brake, the combination with a brake cylinder and a fluid pressure operated valve device for controlling the release of fluid under pressure from said brake cylinder, of an additional valve device for controllin the release of fluid from' the brake cylin er through said fluid pressure operated valve device and electrically controlledmeans for effecting the operation of said additional valve device.

27. In an electro-pneumatic brake, the combinationwith a brake cylinder and a valve device for controlling the exhaust of fluid from the brake cylinder and communication through which'fluid underpressure is supplied .to the brake cylinder, 7 of electrically contro11d'meansfor controlling the combination with 1 a p valve 'n 'viee ibrgeeat roning the supply of fluid from 'saidcommunication to the brake cylinder.

28. In an 'el'ectro gneu'matic 'brake, the {rake 'ylinder'and a eirhaust of g auia'na ahe brakecylinfier and oomf muni- -;ca'tion through whighfflnidimdr presaug j re.

combination with a reservoir, and brake cylinder, of electrically controlled means for first supplying fluid 'from -the-brake pipe tothe brake cylinder and' then from the auxiliary reservoir and cembin'ation with n'eans, ofmeans operative u is supplied to the brake cylinder, of.electripressure for e ecting an application of the brakes, and a valve mechanism operated by an increase n fluid pressure for venting fluid from the brake pipe, of a selector valvedevice'having a position for establishing communication through which fluid is supplied to said valve mechanism and a positlon in which communication is established for venting fluid from the brake pipe, and electrically controlled means for controlling the operation of said selector valve device. 24. 'In an electro-pneumatic fbrake, the combination with a chamber normally 30. In an electro-pfieumatic brake, the rake pipe, auxiliary means operated upon a reduction in brake p 1'pe pressure for establishing communication through which, said electrically controlled means supplies fluidfrom the aux- I iliary reservoir to the brake c linder.

131. In an electro-pneumatlc brake, the combination with a valve mechanism operat1ve toeflect an application of the brakes, of electrically controlled means operative upon deenergization for efieeting the operatIOII Of said valve mechanism and means 0 erative upon energization of said electrically controlled means for rendering said electrically controlled means efl'ective upon deenerglzation to cause the operation of said valve mechanism.

32. In an electro-pneumatic brake, the

combination with a valve mechanism operated by fluid under pressure for effecting an application of the brakes, of a chamber and electrically controlled means adapted upon energization to efl'ect the charging of said chamber with fluid under'pressure and upon deenergization to supply fluid from sa d chamber to saidvalve mechanism.

33. In an electro-pneumatic brake, the combmatlon with electrically controlled -means, the operation of which upon deenergization is-adapted to effect an application of the brakes, of means operative upon'energ'ization of said electrically controlled means =for rendering said electricallycontrolledfmeans efl'ective u on. deenergization to cause an apphcationo the brakes.

34. In an electroneumatic "brake, the e ectrically controlled on energization of said electrically contra; dmeahs for rendering said electrically controlled means efiective upon deenergization to cause an application of the brakes.

35. In an electro-pnenmatic brake, the combination with electrically controlled means, of means operative upon energization of said electrically controlled means for rendering said electrically controlled means effective upon deenergization to cause an emergency application of the brakes.

combination with a brake cylinder, of electrically controlled means rendered operative .when ener ized to thereafter effect the sup- I Ill ply of flui under pressure to the brake cylinder upon deenergization of said electrically controlled means.

37. In an electro-pneumatic brake, the combination with electrically controlled means for effecting an application of the brakes, of means controlled by said electrically controlled means for rendering said electrically controlled means operati ve upon deenergization to effect an application of I the brakes at one time and inoperative at 36. In an electro-pneumatic brake, the

another time.

In testimony whereof I have hereunto set my hand.

THOMAS H. THOMAS.

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