CA1269126A - Modulating valve for a brake pipe - Google Patents

Abstract

ABSTRACT.

MODULATING VALVE FOR A BRAKE PIPE

A modulating valve in a brake control for a railway car has a sensor connected to a brake pipe port for sensing a service signal, a release signal and an emergency signal pressure and connects to an atmosphere port, a quick service volume, a bulb volume and a release reservoir. The quick service volume is filled from the brake pipe when a service signal is sensed with sequential venting of the bulb volume to atmosphere and refilling of the bulb volume from the brake pipe as a function of the magnitude of the service signal, and feeding fluid to the brake pipe from the release reservoir when a release signal is sensed.

Description

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The present invention relates generally to pneumatic rail brake systems and more specifically to improved components for th.e system.
The prior art brake systems were gener~lly standarized to include an ABD or equivalant braking valve connected by conduits to the brake pipe, auxuliary and emergency reservoirs and brake cylinders. These brake valves would control all the brakes on the trucks of a single car. If more than two trucks were to be controlled by the brake valve, relay valves were included. These systems include a substantial amount of conduits connecting the elements of the brake system on each of the cars. The ABD and - equivalant brake valves include the service application, emer~ency application, release and accelerated release function. With the development of non-conventional car designs, brake systems which are adapations of the preexistlng brake systems were developed.
These and the conventional brake systems include an unnecessary amount of conduits per car and unnecessarily large reservoirs.
Thus, it is an object of the present disclosure to provide a simplified flu~d brake system for rail vehicles.
Another object of the present disclosureis to provide a braking system which reduces the size of the auxiliary and e~ergency reservoirs.
A further object of the-present aiSclosureis to eliminate unnecessary piping and reduce the number of sources o~ fluid leakage.

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1Z69:12~D
Another object is to provide a group of standard parts or modules which can ~e economically applied to any type of freight car without special engineering, including articulated cars having any number of trucks between couplers.
Here described is a triple valve assembly having reduced auxiliary and emergency reservoirs mounted directly thereon. ~he assembly is connected only to the brake pipe and to the brake cylinder of one truck and controls the interconnection between the brake pipe, brake cylinder, auxiliary reservoir and emerqency reservoir to produce charging of the reservoirs, service application and emergency application of the brakes and release of air to the brake cylinder. The unique triple valve, in response to the venting of brake pipe which characterizes,an emergency brake application, provides a sequential application of pressure to the brake cylinder. Fir~t the auxiliary reservoir pressure is equalized with that of the brake cylinder, followed by disconnection of the auxiliary reservoir from an application of the emergency reservoir to the brake cylinder. This sequential operation allows increased brake cylinder pressure while allowing redùction in the volume of the emergency reservoir used to accomplish this pressure.
~ n both service and emergency applications, a variable flow rate valve is co,nnected between the supply portion'of tne triple valve and the brake cylinder to allow a high flow during the initial application of the air to the brake cylinder with a decreased flow rate during t~e second stage.

" lZ69~Z~i The triple valve assembly is easily adaptable for receiving a load responsive fixture. This fixture includes a first path for connectirlg the supply to the brake cylinder and to a volume reservoir and providing a predetermined portion of supply pressure to the brake cylinder. A second path contrvlled by the load is connected in parallel with the first path, and bypasses the proportioning path and cuts off the volume reservoir for a loaded sensed condition. ~ double acting piston is providea to simultaneously open the bypass and close the dummy reservoir or connect the dummy reservoir and close the bypass. The bypass is also responsive to a brake released signal to bypass the proportioning device during a ~rake release sequence.
A modulating valve is also provided independent of the triple valve assemblies, which enhances brake pipe pressure reduction by filiing a quick service volume wit-l fluid from the brake pipe for a service signal, and sequentially venting a bulb volume to the atmosphere and refills the bulb volume from the brake pipe as a function of the magnitude of the service signal. The modulating valve also charges the brake pipe with previously stored fluid so as to enhance the rise of brake pipe pressure, hence release o' - the brakes from a release reservoir in response to a release ' signal. The filling of the quick service volume occurs at a rate - controlled as a function of the diffential pressure between the release reservoir and the brake pipe. A quick action chamber is included for providing accelerated response for filling the quick 1~6~126 service volume and venting the bulb volume. The quick action chamber is vented after the accelerated initiation and has no effect during further brake pipe pressure reduction activity.
More particularly, in accordance with the invention there is provided, a modulating valve to be connected to a brake pipe comprising:
brake pipe and atmosphere ports;
a quick service volume;
a bulb volume;
a release reservoir;
sensing means connected to said brake pipe port for sensing a service signal, release signal and an emergency signal pressures on said brake pipe port; and valve means connected to said brake pipe port, atmosphere port, said quick service volume, bulb volume, said release reservoir and said sensing means for (a) filling said quick service volume with fluid from said brake pipe port for a service signal sensed by said sensing means;
(b) sequentially venting said bulb volume to said atmosphere port and refilling said bulb volume from said brake pipe port as a function of the magnitude of the service signal sensed by said sensing means;
(c) charging said brake pipe port with fluid from said release reservoir for a release signal sensed by said sensing means.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the invention will now be described with reference to the accompanying drawings wherein;
Figure 1 is a schematic perspective of a train brake system made up of different types of cars.
Figure 2 is a perspective view of a truck mounted brake incorporating a valve and reservoir.
Figure 3 is a perspective view of a modulation valve.
Figure 4 is a cross-section of a suppl~ valve.
Figure 5 is a cross-sectional view of a load fixture.
Figure 6 is a cross-sectional view of the modulation valve.

~2~126 DETAILED DESCRIPTION OF THE DRAWINGS
A train 10 as illustrated in Figure 1 includes a plurality of cars 12, 14, 16 and 18 of different styles for purpose of illustration. Car 12 is a two-axle car, cars 14 and 16 are - 5a -` 12691~6 articulated cars sharing a common axle and car 18 is a conventional car having two axles per truck. A brake pipe 20 extends throughout the train 10. Each of the cars include a brake system which for car 12 is a cingle axle brake 22 and for cars 14, 16 and 18 are double axle brake systems 24. Included at each brake system are a truck 22 and 24 is a novel triple valve 100, Also spread throughout the train at approximately 75 foot intervals are modulation valve systems 300. Thus, it can be seen that a braking vaive is included at each truck irrespective of the truck and car design.
The twin axle brake 24, as shown in Figure 2, consists of a pair of brake beams 30, 32 and a single actuator 34 equipped with double-acting slack adjuster 36 and cable 38 operated parking brake, The a~ctuatar 34 is supported by, and lies along side, beam 30 and operates to spread a palr of bell cranks 40, whose ends are attacned so as to drive the opposite brake beam 32 against its wheels, The pivot points of the bell cranks 40 in the master bea~
30 react the equal and opposite force generated by this action which pushes the master beam up against its wheels.
The 17~ total available stroke of the actuator is sufficient to permit tbe beams to mount 2-1/2~ brake shoes and to operate without adjustment through the life of these shoes and through a full cycle of wheel wear.-lZ6~126 The combined reservoir and triple valve 100, as shown inFigure 2, is designed to be mounted to the truck bolster and connected with armored hoses 42 and 44 to both the brake actuator and the brake pipe respectively. The triple valve is comprisea of three die castings and includes: a simple triple valve to produce service brake cylinder pressure, an emergency equalizing valve to provide high brake cylinder pressure in emergency, and an inshot valve to produce rapid filling of the actuator followed by a controlled brake cylinder pressure rise, which should be particularly important in an emergency brake application.
In connection with the triple valve portion, it should be noted that no release insuring quick service or emergency brake pipe related functions are included. When brake pipe pressure reduces to zero, the triple valve reacts by raising the brake cylinder pressure approximately 15~ higher than the value attained at full service equalization. This will be described in detail below with respect to Figure 4.
To provide cars having high gross-to-tare weight ratios with a more even braking ratio over the entire load range, the triple valve lOO brake equipment includes an optional empty load fixture 200, as snown in Figure 2. Because of the location of the basic triple valve portion of the truck bolster, the empty load fixture can be added by simply replacing a blanking plate with the additional portion as shown -in the figure. The empty load portion has a load arm 202, which can be connected to, or rest upon, the 1265~126 truck frame spring basket so as to detect empt~ or loaded condition by the height of the bolster relative to this basket.
Since this dimension is unaffected by centerplate or side bearing wear or truck swiveling, it provides a reliabli.e, repeatable measure of spring deflection and, therefore, c.~r load.
In operation, the empty load fixtures operalte on the proportioning principle, except that the dummy reservoir is on the high pressure rather than the low pressure side of the proportioning valve, resulting in its volume h~ing to be only 69 cu. in., which volume is easily enclosed in th~ empty load portion itself.
The brake pipe modulation group 300, in Fi~re 3, consists of an E-l modulation valve 302 and KM-2 vent valve 304 mounted to the ends of a 10 x 20 release reservoir 3060 The ~nctions of this valve are to provide all of the brake pipe st~lizing and accelerating features of both the service and oemergency portions of the present ABDW control valve. In particu.~r, the following are carried out:
a) The quick service function detects bra~e pipe pressure eeductions beyQnd a fixed amount and opens bra~e pipe to a quick service volume so as to produce rapid serial t~ansmission of .' service application and assure a minimum brake ,pipe reduction.
~ ) An accelerated application valve provi.~es continuous quick service activity for brake pipe.reduction at a service rate beyond quick service.

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c) An accelerated release valve provides <a dumpback to brake pipe of the 1600 cu. in. release volume, any t~me brake p-pe pressure rises more than a fixed amount, whet~er as a result of service or emergency release. There is no accelerated release after emergency because the 318 cu. in. of air stored in the two actuators on a typical car would provide a ne~ligible improvement in brake pipe release when compared with the ~256 cu. in.
available on a 10 x 12 cylinder at 8~ piston travel.
d) Rapid transmission of emergency brake application from any cause is propagated solely by the KM-2 vent v~ve portion.

The triple valve 100 as illustrated in Fi~re 4 includes three devices: the rA~ triple valve 102, the ~B~ e~ergency equalizing valve 104 and 2 brake cylinder inshot valve 1~l6.
Positions of the triple valve are release ~nd charging, service, service lap and emergency. During ~h service and emergency brake application, there is both a ~rst and second stage of brake cylinder pressure development c~ntrolled by the inshot valve lQ6. In emergency, a third staqe of development increased brake cylinder pressure by approximæ~tely 15% above full service.
Operation of the equipment foz each of the above positions is as detailed below.

lZ69126 In the release and charging position, brake pipe air from the brake pipe enters triple valve 102, through passage 14 to Chamber A, moving the valve stem 121 downward and flows through Passage 11.2 to equalizing reset piston, Chamber C, a~d *hrough Passage 113 to the underside of the emergency reservoir ch~ging check 122.
Air flowing through this check 122 and Passage 114 charges the 150 cu. in. emergency reservoir and.flows by Passa~e 114a to the emergency equalizing valve spool 123 where it ts blocked. Note than when the triple valve piston 124 moves do~ward, Pilot Pin 125 raises the auxiliary reservoir charging che~k 126 from its seat, permitting brake pipe air to flow from C~mber A through the open charging check 126 and the hollow stem of ~he triple valve piston 124 into Chamoer B, below the triple piston 1~4, from whence it flows through Passage 116 into Chamb.e~ E to the lower face of the emergency equalizing valve piston ~32 holding this valve in its upper position. From chamber ~, alr flows through Passage 115 to the emergency equalizing valve. sæool 123 and simultaneously through Passage 115b to the 650- ~. in. auxiliary reservoir.
With.both reservoirs charged, pressure acr~ss the triple valve piston 124 will equalize; and it will move upw.a~d allowing the charging check 126 to close cutting off commun~ation between the brake pipe and auxiliary reservoir. This is t~e release lap ~
position of the triple valve 102.

~26~3~L26 Note that with the emergency equalizing va~w~ 104 in its upper position, air from Passage 115 passes upward thr~ugh the hollow 123a of stem 123 of this valve through Passage 1il7 to Chamber ~ of the closed brake cylinder supply valve of th~ t~iple valve 102.
During a service application of brakes, brake pipe pressure reduction in Chamber A will cause the triple valwe stem 121 to move upward, unseating the supply valve 127 fro~ its outer seat and connecting auxiliary reservoir pressure fro~ Chamber G past the supply valve seat to Passage 118, through ~lch it flows to the top of the open inshot valve check 128, th~gh this valve to Chamber H, thence, through Passage 119 and the e~pty load blanking plate 129 to brake cyiinder.
Brake cylinder air is also fed back throug~ ~assage ll9a to Chamber F above the emergency equalizing valve ~4.
: - As brake cylinder pressure continues to bui~ up during a second stage of a service or emergency applicat~on, it passes through Chamber ~ of the open inshot valve chedk 128. When sufficient air has flowed into the brake cylin~ to raise its pressure to approximately 15 psi, the diaphragm ~iston 130 of Cha~ber H moves down allowing the inshot valve c~eck 128 to close. Further build up of brake cylinder press~re is under the control of Choke Z. Thus, inshot valve 106 is a variable flow rate valve allowing high flow during the initi~l stage of brake pressure build-up and a low flow rate in the la~~ter stages.

"` 1~69126 As air flows from the auxiliary reservoir to the brake cylinder, the pressure in Chamber ~, beneath the triple valve, piston 124 falls until it nearly equals that of Brake Pipe in Chamber A, at which point the valve stem 121 will move downward and allow the supply valve 127 to close on its outer seat. This will prevent the supply of further auxiliary reservoir air to brake cylinder and, hence, terminate the reduc ion of pressure in the auxilia~ry reservoir and Chamber B, placing the valve 127 in service lap position.
With the supply valve 127 initially in the service lap position, any increase in brake pipe pressure ~ill cause thé
pressure in chamber A to rise above Chamber B, ~hich will pull the triple valve stem 121 down away from the supply valve 127, opening the inner seat and permitting brake cylinder air to flow back through the inshot check valve 128, opening it, hence, tnrough Passage 118a and 118 past the open supply valve inner seat, thence, through the hollow 131 of stem 12i of the triple valve 102 to atmosphere. Simultaneously with the above, brake ~ylinder feedback pressure in Chamber F will reduce through Passage ll9a along with brake cylinder.
Note that reduction of brake cylinder pressure in this manner does not upset the balance of brake pipe pressure over auxiliary reservoir, and the triple valve 102 remains in its release position until brake-cylinder pressure reduces to zero.

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Note also that if the brake pipe-pressure is only slightly higher than auxiliary reservoir, the supply valve 127 inner seat will be open; but because of the length of the auxiliary reservoir charging check valve pllot pin 125, the charging check 126 will remain on its seat preventing premature charging of the auxiliary reservoir and, thus, assuring that no air will be trapped in the brake cylinder. Only when a slightly greater pr~ssure exists in the brake pipe than in auxiliary reservoir will the triple valve stem 121 be forced downward sufficiently to open ~he charging valve 126.
A modification to the triple valve could be m~de in which further travel of the triple valve downward woul~ lead to a retarded recharge position on cars near the head ~f the train.
~owever, the 650 cu. in. auxiliary reservoir take~ so little charging air that this may not be necessary.
In an emergency brake applicatlon, brake pipe ~ressure is suddenly reduced to zero. Triple valve 102 acti~ is iden~ical with that descrlbed above under service brake application, and a 15 lb. inshot of air to the brake cylinder will ~e made prior to closing of the inshot valve check 128, as in ser~ice From the point of closing of the inshot valve check 128 u~il brake cylinder pressure rises to within 2 psi of auxil-ary reservoir pressure, brake cylinder pressure development is affected only by the triple valve 102 and inshot valve check 128. Note, however, that when brake pipe pressure is reduced to zero ln the emergency _ 13 -lZ6912~i application, pressure in Chamber C beneath the eme gency equalizing valve return piston 133 is also reduced ~o zero, _ allowing the spring in Chamber D of this diaphragm piston 133 to move it down so that it no longer holds up the eme~gency equalizing valve stem 123. The emergency equalizing valve 123 will, however, be held up by the differential of a~xiliary reservoir in Chamber E over brake cylinder pressure in Chamber F.
When brake cylinder pressure in Chamber F rises to within 2 psi of auxiliary reservoir pressure in Chamber E, ~he emergency equallzing valve stem 123 will begin to move downward under the influence of emergency spring 134 in Chamber J. C~amber J is connected to atmosphere through Choke Y and the sm~ll hole 135 through the center of the equalizing valve stem 12~ to Chamber K
- beneath the spool 127, opening 137, and Chamber ~ aDove the emergency equalizing valve return piston 133. Whe~ the emergency equalizing valve stem 123 begins to move downward, supply valve air in Passage 117 flows upward through Passage l~a; and at the first motion of the emergency equalizing spool 123 downward, Passage 117a is connected to Chamber J past the u~er land of the emergency equalizing valve spool 123, causing auxillary reservoir pressure present in Passage 117 to vent into Cham~er J where it acts on the top of the emergency equalizing valve Sfem 123 urging it rapidly downward. since Choke Y is much smaller than the passage 117a admitting this air to Chamber J, presure developing in Chamber J assures full motion of the emergency e~ualizing spool 123 downward until its motion is stopped by the ru~er seat 136 at the bottom of Chamber K.

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When the emergency equalizing valve rests on this seat 136, communication through Choke Y to atmosphere through ~penings 137 is blocked and brake cylinder pressure is maintaineæ .in Chamber F, where along with spring 134, it continues to hold t~e emergency equalizing valve 123 downward against its lower seat 136.
Motion of the emergency equalizing valve stem 12~ to its lower seat cuts off communication via Passage 115 of auxi~l~ry reservoir to brake cylinder and the hollow 123a of the emerge~y equalizing valve stem 123. In its lower position, this hollow stem 123a of 123 is connected to the emergency reservoir providi~ passage of air to the brake cylinder from the emergency reserv~i~. Thus, using emergency reservoir air only to increase brake ~yinder pressure and not wasting it by needlessly increasins a-~xiliary reservoir pressure as in earlier components with the ~mergency equalizing valve in its lower position, emergency re~rvoir air flows through the hollow 123a of stem 123 of the e~:~lizing valve to Passage 117, thence, past the open supply valve t~ ~assage 118, and through Choke z of the inshot valve check 128 t~ ~he brake cylinder, addlng a third or high pressure phase to ~rake cylinder pressure development.
With the brake applied in emergency, brake cyli~er pressure, with an initial 70 psi brake pipe, would be 60 psi; auxiliary reservoir pressur~ would be 50 psi (lower than brake cylinder~
because of the emergency equalizing valve). Thus, w~en brakes are released, the brake pipe need only be restored to s~ething above - 15 - .

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50 psi to raise the pressure in Chamber A above the auxiliary reservoir pressure in Chamber B. This reduced brake pipe pressure requirement,..along.with_the,.dumpback o,f,air from the modulatlng valve 300 should overcome the,need for the present accelerated emergency release feature.
, As with service release, when the triple valve piston 124 moves down, it unseats its hollow spool 131 from the inner seat of the supply valve 127, permitting brake cylinder alr to flow from brake cylinder to Passage 119 back through the insho~ check valve 128, unseating this check 128, through Passages 11~ and 118 and past the inner seat of the supp~y valve 127 to atmosDhere through the hollow center 131 of the triple valve piston.
This action reduces brake cylinder pressure at a'rate - independent of inshot choke z. As brake cylinder pressure reduces, so does the pressure in Chamber F above the emergency equalizing valve 132. At the same time this pressure is be~ng reduced, pressure in Chamber C, beneath the emergency equalizing valve return piston 133, is acting to force the emergency equalizing valve 123 upward to its service position_ When the brake cylinder.pressure in chamber F above the emergency equalizing valve piston 132 drops to the point where the combined ' effort of auxiliary reservoir pressure in Chamber E and return piston pressure in Chamber C are sufficient to urge it upward, it will begin to move upward'and will cut off communication through Passage 117a to Chamber J allowing Chamber J pressure to reduce to .

691Z~i atmosphe~e through Choke Y, assuring that once the emergency equalizing valve 123 has started to move upward, this motion will be continued_to its upper most stop and the release position.
Finally, when brake cylinder pressure drops below 15 psi, this pressure acting in Chamber G will no longer be sufficient to keep the inshot valve piston 130 down and will allow this piston 130 to move up, aiding the back flow of air to keeping open the inshot valve check 128 and assuring complete release of brake cylinder air to the atmosphere.
Charging of the 650 cu. in. auxiliary reservo-r ~ill begin when sufficient differential of brake pipe pressure over auxiliary reservoir pressure exists to open the charging check 126 in the triple valve stem, and charging of the 150 cu. in. e~ergency reservoir will resume when auxiliary reservoir pressure has been restored above 60 psi so that pressure can flow from ~assage 2 through Chamber C and the emergency reservoir charging check 122 to recharge this 150 cu. in. volume.

In the event that an empty load brake system 200 is requried, the empty load blanking plate 129 shown in Figure 4 ~ay be removed and the empty load device 200 shown diagrammatically in Figure 5 is mounted to it with the load arm 202~connected to the car as shown in FigUre 2. This valve contains a simple ratioing valve 204, lock over piston 206, change over valve 208 and dummy volume 210, as shown in FigUre 5, and operates in the following manner:

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When a brake application is made, brake cylinder p~essure enters from the triple valve in Passage 221 and flows. ~o Chamber A
on the left side of the..ratio valve. Simultaneously, air flows through Passage 211a to the semi-circular area on top ~f the change over valve key 208. In the event that the car ~s light, the load arm 202 will be positioned downward; and bra~ cylinder air will flow from Passage 211a past the key 208 to P~ssage 213, thence to ~hamber C on the right hand side of the lock over piston 2Q6. Moving this piston 206 to the left requires onlyt 5 psi or less; and in its left most position, the piston is de~nted by an annular spring engaging a detent groove.
As air pressure continues to rise in the supply pressure in Chamber A on the left hand side of the ratio valve 204 ~xerts less force on the spool of this valve 204 than does the bra~e cylinder pressure in Chamber B on its right hand side, forcinq ~e double piston spool to the left against the ratio valve seat at a ratio of 50, 60 or 70% of input pressure, as determined by t~
particular diaphragms used. As supply pressure from th~ triple valve continues to rise, Chamber A pressure will build ~p, forcing the spool to the right, allowing further passage of air through the hollow spool to Chamber B causing it, again to close, with - Chamber B pressure always at the desired ratio to Chamber A
pressure.

`" ~269126 Air also flows from Chamber A through Passage 211b and the unseated dummy volume cut-off check valve 230 into Passage 212 and the dummy volume 210. since the dummy volume 210 is only 69 cu.
in., this volume will accept the additional air supplied by the triple valve and not needed by the brake cylinder at the lower pressure of the ratio valve 204, thus, bringing about an e~ual reduction in auxiliary reservoir pressure in response to brake pipe pressure reduction whether the car is empty or loaded. Thus, at final equalization in either service or emergency, the output pressure of the triple valve in Passage 211 will be exactly the same, whether the car is loaded or empty. Brake cylinder pressure, however, whether service or emergency, will be 50, 60 or 70~ of that provlded by the triple valve as determined by the ratio of Chamber A area to Chamber B area.
Note that during the above light, car operation, brake cylinder air from Chamber B also flows through 114a to the face of bypass check valve 232 but cannot open th-s valve because of the higher supply pressure behind it, which holds it to its seat.
When brake cylinder pressure is released, air flows from Chamber A out to the triple valve, through the triple valve~ and to atmosphere causing the ratio valve 204 to close more tightly to its seat. However, air from brake cylinder in Passage 214 can flow through Chamber B, through Pas-sage 214a, and will unseat~the bypass check 232 because of its differential over the now reduced supply pressure in Passage 211c. Thus, during release, brake ~Z6~1Zf~
c~linder pressure flows from brake cylinder into Passage 214, through Chamber B, Passage 214a, past the bypass check ~alve 232, unseating it, into Passage 211c, Passage 211b, Chamber A, and out Passage 211 to the triple valve and exhaust.
If the car weighs heavy, the load arm 202 will be moved upward to Position C; and Passage 211a will be connected through the changeover valve key to Passage 215. Brake cylinder air will, thus, enter Chamber D on the left side of the lock over piston 206, forcing it to the right, in which position it will be detected, forcing the bypass check 232 off of its seat and allowing the dummy volume cut-off check 230 to move to its seat.
As air pressure builds up in Passage 211 and Chamber A where, again, it flows through the hollow piston rod of the rat~o valve 204 to Chamber B and the brake cylinder and, again, forces the ratio va]ve to the left. ~owever, with the lock over piston 206 in its right hand position, air can flow from Chamber A through Passages 211b and 211c and past the opened bypass check into Passage 214, Chamber B, and out to the brake cylinder.
Since the dummy volume 212 is not desired cut in, as all air suppiied by the triple valve in the loaded position must be passed to the brake cylinder, the dummy volume cut-off check 23~, which is permitted to move to its seat by the lock over piston 206, will do so and prevent unnecessary loss of-air to the dummy ~olume-210.

- 2~ -" ~Z69126 When brakes are released after an application with the empty load fixtures in the loaded position, air flow out of the valve is exactly the same as in the empty position with the exceptiOn that brake cylinder pressure does not have to move the bypass ~heck 232 off of its seat as it is held open by the lock over piston 206 in any case.

The purpose of the E-l brake pipe modulating valve 3~2 shown in Figure 3 and diagrammatically in Figure 6, is to provide quick service propagation of an initial service application and to provide a continuous quick service function. A third purpoSe is to control the storage and release back to brake pipe of air in a release volume so as to provide accelerated release of brakes - -after both service and emergency brake applications.
The only connection to tbe E-l brake pipe modulating valve 302 is to the brake pipe and the augmentation of brake pipe pressure change it provides will be comparable to those in the AB, ABD and ABDW type control valves.
When charging this valve 302, air flows initially from brake pipe by passage 311 to the underside of accelerated release valve piston 320, Chamber A, thence through Passage 316 to Chamber C on the underside of accelerated application pilot valve piston 322.
Air from Chamber C flows through Quick Action Chamber Charging Choke Y and Passage 317 to the ~uick action chamber 308, and - ~2691Z~
Passage 317a to the back of-the accelerated application pilot valve check valve 324. Air flowing through Choke Y is at qUiCk action chamber pressure and is communicated via Passage 317b to Chamber D, above the accelerated application pilot valve piston 322 and Chamber B, above the accelerated release valve piSton 320.
Note that brake pipe pressure in Passage 316 also flows through Passage 316a to Choke z and to the face of release reservoir c~ontrol check 326 through Passage 316b. Brake pipe air flows through Choke z into Passage 318 and the underside o~ the accelerated release check 328, thence past this cbeck 328 into Passage 319 whence it charges t~e release reservoir and through Passage 319a to Chamber F above the quick service llmiting ~alve piston 330.
With the equipment fully charged, pipe pressure may be reduced to initate a brake application. When such a reduction is begun simultaneous reduction-of pressure in Chambers A, C and E occurs.
No motion of the quick service limiting valve 332 will occur because it is held up by a 3 psi differential spring 334 in Chamber G. The accelerated release valve piston 320 will initially be resting on the stabilizing spring cage 336, having permitted the accelerated release check 328 to close at the termination of release reservoir 306 charging. The accelerated release valve piston 320-will not move down until the brake plpe pressure drops-about 1/2 psi and will not move down until the stabilizing spring has been overcome. When this occurs, the 126~

accelerated release valve diaphragm piston 320 will move do~n opening the quick service check valve 338. ~hen the quick service check valve 338 is moved off its seat, brake pipe air will ~low to the quick service volume 340; and because of~the proximity ~f the quick service check 338 to Chamber A, this flow will cause a further downward motion of the accelerated release valve piston 320, thus, assuring that the quick service check 338 will o?en wide, permitting brake pipe pressure to flow from brake p-pe through Passage 311, Chamber A, Passage 312, past the open guick service check 338 to the quick service limiting valve spool 332, hence, into the quick service volume 340.
Initial flow of air will be rapid enough to propagate this quick service action to the next ca~ and will terminate when a 3 psi differential of release reservoir pressure over brake p pe pressure is established, which differential will move the quick service limiting valve spool 332 down cutting off further communication with brake p-pe through the quick service check 338.
At this same time, accelerated application p-lot valve piston 322 also moves down forcing its check 324 from its seat and perm tting quick action chamber 308 air to flow from Pass2ge 317a past the open check valve 324 to atmosphere through Choke U, while .' subjecting the inner area of the accelerated application valve d-aphragm 342 to the pressure backed up by Choke V. - - -If this backed up pressure is sufficient, it will cause the accelerated application diaphragm 342 to move downward from its 12691Z~
seat exposing the larger outer area and permitting the upper accelerated application check valve to seat 344, cutting off communication between brake pipe in Passage 312 and the already charged bulb volume 346. As ].ong as the accelerated application pilot valve 322 is down, permitting quick action chamber 3~8 air to flow to atmosphere, the accelerated application valve p ston 342 will be held down by air acting over its full upper diaphragm face, and will drain the bulb volume 346 through Passage 314 and its lower check valve 348. When quick action chamber 308 pressure reduction exceeds that of the brake pipe, the accelerated application pilot valve piston 322 will rise, allowing its check 324 to close and cut off the supply of quick action chamber 308 air to the accelerated application valve piston 342 ~hich will allow its upper chambers to drain through Chokes U and T. This action will allow the accelerated application valve piston 342 to move upward, returning its lower check 348 to its seat to prevent further draining of the bulb volume 346 and reopening its upper check 344, thus, reconnecting the drained bulb volume 346 to brake pipe causing a controlled volume of air to be withdrawn from it, thus, causing a further reduction of brake pipe pressure by allowing Passage 312 to communicate past the upper check 344 to Passage 313 and through Choke V wi~h the now drained bulb volume 346. After quick service activity has terminated, any time brake pipe pressure is reduced, the accelerated application pilot valve piston 324 will, again, move down triggering this sequence o~
events much the same way the accelerated application valve operates on the present A8DW emergency AAV portion.

lZ6~1Z6 Whenever ~rake pipe pressure rises above quick action chamber pressure in Chamber B by more than a predetermined amount, accelerated release valve piston 320 will be moved upward and unseat the accelerated release check 328. This action will dump accelerated release volume 306 back to brake pipe, aidins in the restoration of brake plpe pressure by way of Passage 319, past the open accelerated release check 328, Passage 318 and 318a, through the release control check 326 bypassing Choke z, into Passage 316a and 316b, Chamber A, and out Passage 311 to the brake pipe. At the same time, the motion of the accelerated release valve piston 320 upward allows the quick service check 338 to seat, preventing the exhaustior. of brake pipe air when the quick service limlting valve 332 returns to its upper position. As brake pipe pressure recharges and accelerated release reservoir air pressure decreases, the differential of Chamber A over Chamber B in the accelerated release valve will be decreased; and when brake pipe pressure is less than 5 psi, higher than accelerated release check 328 pressure, the accelerated release check 328 spring will return this check valve 328 to its seat and the E-l brake pipe modulating valve 302 will.be returned to its fully charged posltion. Above this pressure, brake pipe pressure can only be supplied from the locomotive; and when a further 3 psi has been bullt up in the brake pipe, its pressure will be higher than accelerated release reservoir pressure and accelerated release reservoir 306 recharge will begin through Choke Z and the accelerated release reservoir charging check 328.

12~91~6 From the preceding description of the preferred embodiments, it is evident that the desired objects are attained in that reduced size reservoirs are mounted directly to the triple valve which are mounted on each truck. The accelerated application and release functions are separate from the triple valve and are distributed throughout the train.
Although the invention has been described and illustrated in detail, it is to be clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation. The spirit and scope of the invention are to be limited only by the terms of the appended claims.

Claims (4)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A modulating valve to be connected to a brake pipe comprising:
brake pipe and atmosphere ports;
a quick service volume;
a bulb volume;
a release reservoir;
sensing means connected to said brake pipe port for sensing a service signal, release signal and an emergency signal pressures on said brake pipe port; and valve means connected to said brake pipe port, atmosphere port, said quick service volume, bulb volume, said release reservoir and said sensing means for (a) filling said quick service volume with fluid from said brake pipe port for a service signal sensed by said sensing means;
(b) sequentially venting said bulb volume to said atmosphere port and refilling said bulb volume from said brake pipe port as a function of the magnitude of the service signal sensed by said sensing means;
(c) charging said brake pipe port with fluid from said release reservoir for a release signal sensed by said sensing means.

2. A modulating valve according to claim 1, including means connected to said valve means, service reservoir, release reservoir and brake pipe port for discontinuing filling of said release reservoir at a preselected differential pressure between said release reservoir and said brake pipe port.

3. A modulating valve according to claim 1, including a quick action chamber means connected to said valve means for providing a fluid pressure to said valve means to accelerate initiation of filling said quick service volume and venting said bulb volume.

4. A modulating valve according to claim 3, including means connected to said sensing means, said quick action chamber means and said atmosphere port for venting said quick action chamber to decrease its effect on said valve means after said accelerated initiation.