US1698007A

US1698007A - Fluid-pressure brake

Info

Publication number: US1698007A
Application number: US228204A
Authority: US
Inventors: Thomas H Thomas; Claude A Nelson
Original assignee: Westinghouse Air Brake Co
Current assignee: Westinghouse Air Brake Co
Priority date: 1927-10-24
Filing date: 1927-10-24
Publication date: 1929-01-08
Anticipated expiration: 1946-01-08

Description

Jan. 8, 1929. I 1,698,007

'r. H. THOMAS ET AL- FLUID PRES SURE BRAKE Filed 001;. 24, 1927 [Va-I EQUAL.

RES.

TIMING RES.

/ 5;; RED.

RES.

76 INVENTORS 2 'I'HOMASJj H MAS CLAUDE A NELSON BYWMrW 'ATTOR EY N .2 EQUAL.

HES.

Patented Jan. 8, 1929.

stares COMPANY, or win MERDING, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

FLUID-PRESSURE BRAKE.

Application filed October 24, 192?; Serial No. 228,204.

This invention relates to automatic train control apparatus and in particular to the type having automatic means for effecting a split or two stage reduction in brake pipe pressure.

In applying the brakes on a train, the usual practice of an. engineman is to first eiiect a light application of the brakes and then after the elapse of a time interval sulficient to gently gather the slack in a train, a second and heavier application of the brakes is made in order to apply the desired.

stopping force to the cars in the train The principal object of our invention is to provide an improved automatic split or two stage reduction apparatus having means whereby a time interval will elapse between the start of the first reduction and the start of the second reduction.

In the accompanying drawing, the single figure is a diagrammatic view of a fluid pressure automatic train control apparatus embodying-our invention. 7

As shown in the drawing, the train control apparatus may comprise an automatic brake valve device 1, a magnet valve device 2, two feed valve devices 3 and 4, and-a split or two stage reduction valve device.

The automatic brake valve device is of the usual type employed with automatic train control apparatus and comprises a casing having a chamber 5 containing a. rotary valve 6 adapted to beoperated by a handle 7 and also having the usual equalizing piston mechanism, which-comprises an equalizing piston 8 forming, at one side, a chamber 9 and forming at the opposite side a: chamber 10 connected to the usual brake pipe 11 through passage 12, said equalizing piston being adapted to operate a brake pipe discharge valve 67. Associated with the brake valve device is a brake pipe cut-oil valve mechanism, which com-prises a cut-oii valve 13 contained in a chamber 14 and adapted in one position to seal on a seat ring 15. Said cut-oft valve is connected to a piston 16 contained in aochamber 17 and is adapted to be operated by said piston. A spring 18 THOMAS H. THOMAS, 0F EDGEWQOD, AND CLAUDE A. NELSON, OF WILMERDING, PENN?w SYLVANIA, ASSIGNORS TO THE WESTINGHOUSE AIR BRAKE downward movement of the piston 16.

Preferably associated with the brake valve 7 device is a brake applicationvalve portion, which comprises an application piston 19 contained in a chamber 20 and a slide valve 21 contained in a chamber 22 and adapted to be operated by said piston. Outwardmovement of the application piston 19 is opposed by the pressure of a spring 23 contained'in the chamber 20. i

The magnet valve device2 comprises a magnet adapted to operate a valve 24 containedin a chamber 25, said valve being opposed inseating by the pressureof a spring 28. When the magnet is deenergized, as in territory governed by unfavorable track conditions, the spring 28 unseats the valve 24, so as to connectthe application piston chamber 20' to the atmosphere by way of passage and pipe 26' and the atmospheric exhaust passage 27. :Upon energization of the magnet, as in territory where the track conditions are favorable, the valve 24 is seated so as to cut off communication between the application piston chamber and the atmosphere.

The split or two stage reduction valve de- I vice comprises a repeater valve portion 29, a hold back valve portion 30, an equalizing valve portion 31 and a maintaining valve portion 32. V V

The repeater valve portion 29 comprises a piston 33 contained in a chamber 34- and a slide valve 35 contained in a chamber 36 and adapted to be operated by said piston, which piston is opposed in outward movement byv the pressure of a spring 37 con- 1 tained in the piston chamber 34.

The hold back valve portion 30 comprises a piston 38 contained in a chamber 39 and a slide valve a0 contained in a chamber-41 and adapted to be operated by said piston, which piston is opposed in outward movement by the pressure-of a spring 42-contained in the piston chamber 39. p

The equalizing valve portion Sloomprises a diaphragm 43 open atone side to a chamvalve chamber 45.

valve 50 is contained in a chamber ber 44 and having at the opposite side a Secured to said diaphragm is an upwardly extending stem 46, having two flanges adapted to engage and operate a slide valve 47.

The maintaining valve portion 32 comprises a diaphragm 48 open at one side to the diaphragm chamber 44 and having at the opposite side a chamber 49.

51 and has a fluted stem extending through a wall of the casing and into the diaphragm chamber 49, wherein said'stem engages the depending stem of a follower 52, which follower is held in engagement with the. diaphragm 48 by the pressure of a spring 53 on the valve 50.

In operation, fluid under pressure from a main reservoir 54 is supplied through pipes and passages 55 to the'rotary valve chamber 5 of the automatic brake valve device, the application valve chamber 22, the repeater valve chamber 36 and to the two feed valve devices 3 and 4. Fluid under pressure from'the application valve chamber 22 then flows through a port 56 in the applica tion piston 19 to the application piston chamber 20, and from thence through passageand pipe 26 to the magnet valve device 2. If the track conditions are favorable, the magnet of the magnet valve device 2' is energized and the magnet valve 24 seated. The fluid pressure thus equalizes on the opposite sides of the application piston 19, so that the pressure of spring 23 is permitted to shift the application piston 19 and slide valve 21 to the release position, as shown in the drawing.

In the release position of the application slide valve, fluid at main reservoir pressure flows from the application valve chamber 22 to the repeater valve piston chamber 34 by way of port 57 in the application slide '1 valve 21 and passage and pipe 58. The fluid pressure thus becomes substantially equal on the opposite sides of the repeater piston 33, so that the pressure of spring 37 is permitted to shift the repeater piston 33 and slide valve 35 to the release position, as shown in the drawing.

Fluid at the usual reduced pressure employed in the brake pipe is supplied by the feed valvedevice 3 to the seat of the brake valve rotary valve 5 through pipe and passage 94, and with the brake valve in running position, fluid at the reduced pressure flows from passage 94 through cavity 59 in the rotary valve 5 and passage "60 to the cut-off valve chamber 14, andalso from passage 60 through cavity 61 inthe application slide valve 21, and passage 62 to the cut-ofl valve piston chamber 17. The opposing fluid pressures on the cut-off valve piston 16 thus heing'equal, the pressure of spring 18 holds the cut-off valve 13 in its open position, as

A maintaining from the valve chamber 14, through a Chi 1H1 ber 63 formed intermediate the seat ring 15 and piston 16, and through passage 1.2 to he equalizing piston chamber 10 and to the brake pipe 11,thereby charging said chamber and brake pipe.

Fluid at the reducedv the feed valve device 3 also: flows through cavity 59 in the brake valve rotary valve 5 to the equalizing piston chamber 9 by way of passage 64, cavity 65 in the application slide valve 21 and passage 66. The fluid pressures thus become equal on the opposite sides of the equalizing piston 8, so that said piston operates to hold the brake pipe discharge valve 67 seated. Fluid under pressure from passage 66 also flows through a choked passage 68 and passage and pipe 69 to a No, 1 equalizing reservoir 70 and to the diaphragm tn'essuresupplied by chamber 44 of the split reduction device,

thereby charging said reservoir and chamber to substantially the same pressure as in the brake pipe.

The No. 1 equalizing reservoir pressure acting in diaphragm chamber 44 deflects the equalizing diaphragm 43 upwardly, which through passage and pipe 73. When the fluid pressure in the equalizing valve chamber 45 and the No. 2 equalizing reservoir becomes substantially equal to the pressure in diaphragm chamber '44, the balanced fluid pressures acting on the equalizing (Ella.- phragm 43, causes the equalizing slide valve 47 to be shifted downwardly again and the lap the passage 71.

Fluid under pressure from the brake pipe 11 is supplied to the maintaining diaphragm chamber 49 through passage 11, and since when the brake system is charged, the brake pipe pressure is substantially equal to the pressure of. the fluid in the No. 1 equalizing reservoir 70 and the diaphragm chamber 44, the diaphragm 48 is in a balanced condition,

so that the pressure of spring 53 is permitted valve device 4 is also supplied to the hold back valve chamber through pipe and paesage 75. The fluid pressures thus being equal on the opposite sides of the hold back piston, the pressure of spring 42'normally 82 is vented to the atmosphere through a pipe holds the hold back: piston and slide valve 1 in the position, as shown in the drawing;

with the application valve portion in the releaseposition, a first reduction reservoir 78 is vented to the atmosphere through pipe and passage 79, cavity 80 in the application slide valve 21 and through the exhaust passage 81, While a second reduction reservoir and passage 83, cavity 84 in the brake valve rotary valve 6 and the exhaust passage 85.

If a train enters territory governed by unfavorable track conditions, the magnet of the magnet valve device is deenergized and the spring 28 then unseats the magnet valve 24, which permits the fi'u-id pressure to be vented from the application piston chamber to the atmosphere through passage and pipe 26 and the atmospheric exhaust passage 27. The fluid at main reservoir pressure in the application valve chamber 21 then shifts the application piston 19 and slide valve 21 outwardly to application position, in which position the cut-off valve piston chamber 17 is vented to the atmosphere through passage 62, cavity 61 in the application slide valve 21 and the atmospheric passage 86. The opposing pressure of the brake pipe fluid on the cut-ofli valve piston 16, then shifts said piston clownwardly against the pressure of spring 18 and thereby causes the cut-off valve to seal on the seat ring 15 and prevent further flow of fluid under pressure to the brake pipe.

In application positionof the application slide valve, the repeater piston-chamber 34k is, vented to the atmosphere through passage and pipe 58, cavity in the application slide valve and the exhaust passage 81, so that the pressure of the main reservoir fluid in the repeater valve chamber 36 is permitted to shift the repeaterpiston 33 and slide valve 35 outwardly to the application position, in which position the passage 71 leading to the seat of the equalizing slide valve 47 is lapped and the No. 1 equalizing reservoir 70 is connected to the No. 2 equalizing reservoir 72 through pipe and passage 69, cavity 87 in the repeater slide valve 35, passage 88, cavity 89 in the hold back slide valve and passage 73, thereby providing an enlarged volume of equalizing reservoir, for reasons to be hereinafter explained.

' In application position of the application slide valve 21 the supply of fluid pressure from the brake valve device 3- to the N0. 1 equalizing reservoir 70 and to the equalizing piston chamber 9 is cut oil and said reser-. voir and chamber are connected to the first reduction reservoir 78' through passage 69-, pasta ball check valve and at the same time through the choked passage 68, through the passage 66, cavity 65 in the application slide valve 21 and choked passage and pipe 7 9. Fluid pressure from both the No. 1 and causes a: predetermined reduction in pressure in the equalizing reservoirs No. 1 and N o. 2 and in. the pressure acting 1n chamber 9-upon the equalizing piston 8, which piston then operates the brake pipe discharge valve 67 to cause a corresponding reduction in brake pipe pressure, in the Well known manner.

In application position of the repeater slide valve 35, the hold back piston chamber 39. and the timing reservoir 74 are connected to the atmosphere through passage and pipe 77, cavity 7 6 in the repeater slide valve 35 and through a choked atmospheric passage 91, and the pressure of the fluid in said chamber and reservoir thereby reduces at a predetermined rate. When said pressure is thus reduced a predetermined degree, the higher feed valve pressure acting in the 'hold back valve chamber 411 shifts the hold back piston 38 and slide valve 10 downwardly to the second reduction position, in which position the

passages

88 and 73 leading to the No. 1 and'No. 2 equalizing reservoirs, respectively, are disconnected from each other and the second 7 reduction reservoir 82 is connected to the first reduction reservoir 78 through pipe and passage 83, cavity 89 in the hold backslide valve 40 and passage and pipe 79. The pressure of the fluid in the N o. 1 equalizing reservoir 70, the equalizing piston chamber 9 and in the connected first reduction reservoir 78 is thus permitted to further reduce by flow to the second reduction reservoir 82 and thereby cause the equalizing mechanism to again operate and cause a corresponding second reduction in brake; pipe pressure.

In order tolimit the total degree'oi' brake pipe reduction to that necessary to effect a full service application of the brakes, the brake valve handle is turned to lap position, in which position the passage 83' from the second reduction reservoir 82. is lapped, so that the second reduction in the pressure of the fluid in the No. 1 equalizing reservoiris thereby limited to the equalization into the two reduction reservoirs.

n The rate of reduction in brake pipe pressure can not exceed the rate at which the pressure in the equalizingreservoir volume is reduced, since if leakage of fluid under pressure from the brake pipe to the: atmosphere is so severe asto tend to cause the brake pipe pressure to decrease at a rate faster than the equalizing reservoir pressure reduces, the brake pipe pressure acting on the diaphragm 418 of the maintaining portion 32 permits the higher equalizing reservoir pressure in chamber 14 to deflect the diaphragm 48 downwardly and unseat the main taining valve 50, which permits main reservoir fluid toflow from the repeater valve chamber 36 into the brake pipe by way of,

passage 92 and past the unseated valve 50. When the brake pipepressure has been increased a degree substantiallyequal to the of spring 53 seats the maintaining valve 50 and thereby prevents further increase in the brake pipe pressure. 1 i

' With a train operating in territory governed by favorable track conditions, the engineermay manually effect a brake application int-he usual manner, since only the No. 1 equalizing reservoir 70 is connected to the brake valve device, which reservoir corresponds in volume to that employed in the usual locomotive brake equipment.

In manually making a brake application, the No. 1 equalizing reservoir pressure acting in diaphragm chamber 44: is reduced through the brake valve device in the usual manner and the higherpressure of the No. 2 equalizing reservoir fluid acting in the equalizing valve chamber 45, deflects the diaphragm 43 downwardly, which causes the slide valve 47 to be'shifted so as to connect the No. 2 equalizing reservoir and the equalizing valve chamberet) to the atmosphere through the exhaust passage 93, thereby permitting the No. 2 equalizing reservoir pressure to reduce at the same rate as the No. 1 equalizing reservoir pressure is reduced. This is desirable, for if an automatic brake application is initiated in the manner hereinbefore described, such automatic application may then continue the reduction in equalizing reservoir pressure from the point at which the manual application is stopped. It the No. 2 equalizing reservoir pressure is not reduced with the/No. 1 equalizing reservoir pressure during a manual brake appli cation, then if an automatic brake application should be started, the higher pressure in the No. 2 equalizing reservoir would have to be reduced before any' further reduction in brake pipe pressure could be effected@ As hereinbefore described, the No. 1 and No. 2 equalizing reservoirs are connected together during the first reduction and the No. 2 equalizing reservoir is cut out or inoperative during the second reduction. Since the rate at whichthe pressure of the equalizing reservoir volume is reduced is controlled through the choked portion of passage 79 in the application portion, during both the first and second reductions, the rate at which the pressure in the connected equalizing reservoirs is reduced during the first reduction is slower than the rate at 1 which the pressure in the single No. 1

equalizing reservoir is reduced during the second reduction. The slow rate of initial reduction is adapted to apply the train brakes at such a rate as to provide adequate time for gently gathering the slack between the cars in a train, and after such slack is gathered thenrthe faster rate of reduction which occurs during the second reduction is such as to cause a brake application of the desired force for effectively stopping the train. V r

Vhile one illustrative embodiment of the inventionhas been described in detail, it is not our intention to limit itsscope to that embodiment or otherwise than by thev terms of the appended claims.

Having now described our invention, what we claim as new and desire to secure by Letters Patent, is

1. The combination with a brake pipe, of

means for eifecting a reduction in brake pipe pressure in two stages including two equalizing reservoirs, two reduction reservoirs, means for venting fluid from both equalizing reservoirs to one reduction.reservoir to effect the first reduction in brake pipe pressure, a timing reservoir, and a valve device operated upon a predetermined reduction in pressure in said timing reservoir for connecting one reduction reservoir with the other.

V 2..The combination witha brake pipe,of means for effecting a reduction in brake pipe pressure in two-stages including two equalizing reservoirs, two reduction reservoirs, means for venting fluid from bothequalizing reservoirs to one reduction reservoir to effect the first reduction in brake pipe pressure, a timing reservoir, and a valve device operated upon a predetermined reduction timing reservoir, and a valve device included in said last mentioned means and operated upon a predetermined reduction in pressure in the timing reservoirs. for conto effect the second stage of reduction in brake pipe pressure, a

necting one reduction reservoir with the other.

4. The combination with a brake pipe, of means for eifecting a'reduction in brake pipe pressure in two stages including two equal izing reservoirs, two reduction reservoirs, meansfor venting fluid from both equalizing reservoirs to one of the reduction reservoirs to effect the first stage of reduction in brake pipe pressure and for venting fluid from only one of said equalizing reservoirs to both reduction reservoirs to effect the second stage of reduction in brake pipe pressure, tion is out off and communication is estaba timing reservoir, and a valve device having lished between the'tWo reduction reservoirs.

a position for establishing communication In testimony whereof We have hereunto .10

from one equalizing reservoir to the other set our hands this 21st day of October, 1927. and movable upon a predetermined reduc- I v tion in pressure in the timing reservoir to THOMAS H. THOMAS. another position in Which said communica- CLAUDE A. NELSON.