TRUCK MOUNTED PNEUMATIC BRAKE CONTROL SYSTEM

Abstract: A railway car has a brake control equipment group on each truck for governing the brakes thereof including sim­ plified light weight triple valve and reservoir equipment (100) and a modulation equipment group (300) is disposed be­ tween trucks of the car providing normal per car require­ ments for modulating pressure in the brake pipe that would normally be provided by a conventional ABD valve required for each truck equipment group.

Description: The present invention relates generally to pneumatic rail brake systems, and more particularly relates to the main control valve of such a system. In the prior U.S. Patent No. 3,160,446, a braking system is disclosed having a brake pipe, an auxiliary reservoir, an emergency reservoir, and a brake cylinder. The braking system having a control valve device having service and emergency portions wherein the service portion has a triple valve for governing pressurisation of a brake cylinder at times by pressure in the auxiliary and emergency reservoirs in response to change in pressure signals communicated through the brake pipe, the braking system having an inshot valve for delivering fluid to the brake cylinder at a high rate initially for a service application and delivering fluid to the brake cylinder at a slower rate for final pressurisation during an emergency application, an emergency application requiring actuation of an emergency valve, and a substantially large emergency reservoir because of equalizing the emergency reservoir into the auxiliary reservoir during emergency brake application. An object of the present invention is to provide an improved system for control of a brake cylinder by auxiliary and emergency reservoirs which substantially obviates one or more of the limitations and disadvantages of the described prior art system. Another object of the present invention is to materially reduce the required size of emergency reservoirs by permitting the equalization of the auxiliary and emergency reservoirs only when charging, but not during an emergency brake application. According to the invention there is provided a control valve for a brake system having a brake pipe, brake cylinder, auxiliary reservoir, and emergency reservoir with respective ports (A) as well as an atmosphere port, characterized by the fact that it comprises fluid pressure sensing means connected to the brake pipe port (A) for sensing service brake application signals, brake release signals and emergency signals in the brake pipe, first valve means (G) connected to said sensing means for interconnecting the brake cylinder port and the auxiliary reservoir port for a service brake application signal sensed by the sensing means, and for interconnecting the brake cylinder port and atmosphere port for a brake release signal sensed by the sensing means, said first valve means (G) and a second valve means being operable for an emergency brake application sensed by the sensing means to sequentially interconnect the brake cylinder port and auxiliary reservoir port while isolating the brake cylinder port from the emergency reservoir port, and subsequently interconnecting the brake cylinder port and the emergency reservoir port while isolating the auxiliary reservoir port from the emergency reservoir port. An embodiment of the inventive control valve device is further characterized by the fact that the second valve is axially operated when brake cylinder pressure becomes substantially equal to service brake pressure of 50 lbs. during an emergency brake application to isolate the auxiliary reservoir port from the brake cylinder port and to connect the emergency reservoir port to the brake cylinder port. An embodiment of the inventive control valve device is further characterized by the fact that a small initial axial movement of the second valve opens a passage to cause fast operation of the second valve to a full emergency position to charge the brake cylinder to a conventional 60 lb. pressure. This invention makes possible the mounting of the auxiliary and emergency reservoirs along with a triple valve, on a car truck because of being able to materially reduce the size of the emergency reservoir by not equalizing its pressure into the auxiliary reservoir during emergency brake application. This is also desirable because it reduces the volume of air required to recharge the reservoirs. A triple valve assembly is provided which has reduced auxiliary and emergency reservoirs mounted directly thereon. The 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 emergency 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 cylinders. First 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 reduction in the volume of the emergency reservoir used to accomplish this pressure. In both service and emergency applications, a variable flow rate valve is connected between the supply portion of the 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 the second stage. The triple valve assembly is easily adaptable for receiving a load responsive fixture. This fixture includes a first path for connecting 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 controlled 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. A double acting piston is provided 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 brake release sequence. A modulating valve is also provided independent of the triple valve assemblies, which enhances brake pipe pressure reduction by filling a quick service volume with 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 of 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 differential pressure between the release reservoir and the brake pipe. A quick action chamber is included for providing accelerated response for filling the quick 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. The present invention will be described in conjunction with the accompanying drawings, in which, Figure 1 is a schematic perspective of a train brake system made up of different types of cars. Figures 2 is a perspective view of a truck mounted brake incorporating the valve and reservoir of the present invention. Figure 3 is a perspective view of the modulation valve of the present invention. Figure 4 is a cross-section of the supply valve of the present invention. Figure 5 is a cross-sectional view of the load fixture incorporating the principles of the present invention. Figure 6 is a cross-sectional view of the modulation valve incorporating the principles of the present invention. 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 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 single axle brake 22 and for cars 14, 16 and 18 are double axle brake systems 24. Included at each truck 22 and 24 is a triple valve 100 incorporating the principles of the invention. Also spread throughout the train at approximately 23 m (75 feet) intervals are modulation valve systems 300. Thus, it can be seen that a braking valve 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 actuator 34 is supported by, and lies along side, beam 30 and operates to spread a pair of bell cranks 40, whose ends are attached so as to drive the opposite brake beam 32 against its wheels. The pivot points of the bell cranks 40 in the master beam 30 react to the equal and opposite force generated by this action which pushes the master beam up against its wheels. The 432 mm (17") total available stroke of the actuator is sufficient to permit the beams to mount 61 mm (2-½") brake shoes and to operate without adjustment through the life of these shoes and through a full cycle of wheel wear. The combined reservoir and triple valve 100, as shown in Figure 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 comprised 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 100 brake equipment includes an optional empty load fixture 200, as shown 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 truck frame spring basket so as to detect empty 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 reliable, repeatable measure of spring deflection and, therefore, car load. In operation, the empty load fixtures operate 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 having to be only 1,13 liter (69 cu. in.), which volume is easily enclosed in the empty load portion itself. The brake pipe modulation group 300, in Figure 3, consists of an E-1 modulation valve 302 and KM-2 vent valve 304 mounted to the ends of a 10 x 20 release reservoir 306. The functions of this valve are to provide all of the brake pipe stabilizing and accelerating features of both the service and emergency portions of the present ABDW control valve. In particular, the following are carried out: a) The quick service function detects brake pipe pressure reductions beyond a fixed amount and opens brake pipe to a quick service volume so as to produce rapid serial transmission of service application and assure a minimum brake pipe reduction. b) An accelerated application valve provides continuous quick service activity for brake pipe reduction at a service rate beyond quick service. c) An accelerated release valve provides a dumpback to brake pipe of the 26 liter (1600 cu. in.) release volume, any time brake pipe pressure rises more than a fixed amount, whether as a result of service or emergency release. There is no accelerated release after emergency because the 5,2 liter (318 cu. in.) of air stored in the two actuators on a typical car would provide a negligible improvement in brake pipe release when compared With the 1256 20,6 liter (cu. in.) available on a 10 x 12 cylinder at 203 mm (8") piston travel. d) Rapid transmission of emergency brake application from any cause is propagated solely by the KM-2 vent valve portion. TRIPLE VALVE 100 The triple valve 100 as illustrated in Figure 4 includes three devices: the "A" triple valve 102, the "B" emergency equalizing valve 104 and a brake cylinder inshot valve 106. Positions of the triple valve are release and charging, service, service lap and emergency. During both service and emergency brake application, there is both a first and second stage of brake cylinder pressure development controlled by the inshot valve 106. In emergency, a third stage of development increased brake cylinder pressure by approximately 15% above full service. Operation of the equipment for each of the above positions is as detailed below. CHARGING 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 112 to equalizing reset piston, Chamber C, and through Passage 113 to the underside of the emergency reservoir charging check 122. Air flowing through this check 122 and Passage 114 charges the 2,4 liter (150 cu. in.) emergency reservoir and flows by Passage 114a to the emergency equalizing valve spool 123 where it is blocked. Note that when the triple valve piston 124 moves downward, Pilot Pin 125 raises the auxiliary reservoir charging check 126 from its seat, permitting brake pipe air to flow from Chamber A through the open charging check 126 and the hollow stem of the triple valve piston 124 into Chamber B, below the triple piston 124, from whence it flows through Passage 116 into Chamber E to the lower face of the emergency equalizing valve piston 132 holding this valve in its upper position. From Chamber E, air flows through Passage 115 to the emergency equalizing valve spool 123 and simultaneously through Passage 115b to the 10,6 liter (650 cu. in.) auxiliary reservoir. With both reservoirs charged, pressure across the triple valve piston 124 will equalize; and it will move upward allowing the charging check 126 to close cutting off communication between the brake pipe and auxiliary reservoir. This is the release lap position of the triple valve 102. Note that with the emergency equalising valve 104 in its upper position, air from Passage 115 passes upward through the hollow 123a of stem 123 of this valve through Passage 117 to Chamber G of the closed brake cylinder supply valve of the triple valve 102. SERVICE APPLICATION During a service application of brakes, brake pipe pressure reduction in Chamber A will cause the triple valve stem 121 to move upward, unseating the supply valve 127 from its outer seat and connecting auxiliary reservoir pressure from Chamber G past the supply valve seat to Passage 118, through which it flows to the top of the open inshot valve check 128, through this valve to Chamber H, thence, through Passage 119 and the empty load blanking plate 129 to brake cylinder. Brake cylinder air is also fed back through Passage 119a to Chamber F above the emergency equalizing valve 104. As brake cylinder pressure continues to build up during a second stage of a service or emergency application, it passes through Chamber H of the open inshot valve check 128. When sufficient air has flowed into the brake cylinder to raise its pressure to approximately 1 bar (15 psi), the diaphragm piston 130 of Chamber H moves down allowing the inshot valve check 128 to close. Further build up of brake cylinder pressure is under the control of Choke Z. Thus, inshot valve 106 is a variable flow rate valve allowing high flow during the initial stage of brake pressure build-up and a low flow rate in the latter stages. As air flows from the auxiliary reservoir to the brake cylinder, the pressure in Chamber B, 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 reduction of pressure in the auxiliary reservoir and Chamber B, placing the valve 127 in service lap position. RELEASE AFTER SERVICE With the supply valve 127 initially in the service lap position, any increase in brake pipe pressure will cause the pressure in Chamber A to rise above Chamber B, which 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, through Passage 118a and 118 past the open supply valve inner seat, thence, through the hollow 131 of stem 121 of the triple valve 102 to atmosphere. Simultaneously with the above, brake cylinder feedback pressure in Chamber F will reduce through Passage 119a 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. 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 pilot 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 pressure exists in the brake pipe than in auxiliary reservoir will the triple valve stem 121 be forced downward sufficiently to open the charging valve 126. A modification to the triple valve could be made in which further travel of the triple valve downward would lead to a retarded recharge position on cars near the head of the train. However, the 10,6 liter (650 cu. in.) auxiliary reservoir takes so little charging air that this may not be necessary. EMERGENCY APPLICATION In an emergency brake application, brake pipe pressure is suddenly reduced to zero. Triple valve 102 action is identical with that described above under service brake application, and a 15 lb. inshot of air to the brake cylinder will be made prior to closing of the inshot valve check 128, as in service. From the point of closing of the inshot valve check 128 until brake cylinder pressure rises to within 2 psi of auxiliary 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 in the emergency application, pressure in Chamber C beneath the emergency equalizing valve return piston 133 is also reduced to zero, allowing the spring in Chamber D of this diaphragm piston 133 to move it down so that it no longer holds up the emergency equalizing valve stem 123. The emergency equalizing valve 123 will, however, be held up by the differential of auxiliary reservoir in Chamber E over brake cylinder pressure in Chamber F. When brake cylinder pressure in Chamber F rises to within 0,14 bar (2 psi) of auxiliary reservoir pressure in Chamber E, the emergency equalizing valve stem 123 will begin to move downward under the influence of emergency spring 134 in Chamber J. Chamber J is connected to atmosphere through Choke Y and the small hole 135 through the center of the equalizing valve stem 123 to Chamber K beneath the spool 127, opening 137, and Chamber D above the emergency equalizing valve return piston 133. When the emergency equalizing valve stem 123 begins to move downward, supply valve air in Passage 117 flows upward through Passage 117a; and at the first motion of the emergency equalizing spool 123 downward, Passage 117a is connected to Chamber J past the upper land of the emergency equalizing valve spool 123, causing auxiliary reservoir pressure present in Passage 117 to vent into Chamber J where it acts on the top of the emergency equalizing valve stem 123 urging it rapidly downward. Since Choke Y is much smaller than the passage 117a admitting this air to Chamber J, pressure developing in Chamber J assures full motion of the emergency equalizing spool 123 downward until its motion is stopped by the rubber seat 136 at the bottom of Chamber K. When the emergency equalizing valve rests on this seat 136, communication through Choke Y to atmosphere through openings 137 is blocked and brake cylinder pressure is maintained in Chamber F, where along with Spring 134, it continues to hold the emergency equalizing valve 123 downward against its lower seat 136. Motion of the emergency equalizing valve stem 123 to its lower seat cuts off communication via Passage 115 of auxiliary reservoir to brake cylinder and the hollow 123a of the emergency equalizing valve stem 123. In its lower position, this hollow stem 123a of 123 is connected to the emergency reservoir providing passage of air to the brake cylinder from the emergency reservoir. Thus, using emergency reservoir air only to increase brake cylinder pressure and not wasting it by needlessly increasing auxiliary reservoir pressure as in earlier components with the emergency equalizing valve in its lower position, emergency reservoir air flows through the hollow 123a of stem 123 of the equalizing valve to Passage 117, thence, past the open supply valve to Passage 118, and through Choke Z of the inshot valve check 128 to the brake cylinder, adding a third or high pressure phase to brake cylinder pressure development. RELEASE AFTER EMERGENCY With the brake applied in emergency, brake cylinder pressure, with an initial 4,8 bar (70 psi) brake pipe, cylinder pressure, with an initial 4,8 bar (70 psi) brake pipe, would be 4,1 bar (60 psi); auxiliary reservoir pressure would be 3,4 bar (50 psi) (lower than brake cylinder because of the emergency equalizing valve). Thus, when brakes are released, the brake pipe need only be restored to something above 3,4 bar (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 of air from the modulating 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 air to flow from brake cylinder to Passage 119 back through the inshot check valve 128, unseating this check 128, through Passages 118a and 118 and past the inner seat of the supply valve 127 to atmosphere 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 being 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 atmosphere 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 1 bar (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 10,6 liter (650 cu. in.) auxiliary reservoir will 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 2,4 liter (150 cu. in.) emergency reservoir will resume when auxiliary reservoir pressure has been restored above 60 psi so that pressure can flow from Passage 2 through Chamber C and the emergency reservoir charging check 122 to recharge this 2,4 liter (150 cu. in.) volume. EMPTY LOAD FIXTURES 200 In the event that an empty load brake system 200 is required, the empty load blanking plate 129 shown in Figure 4 may 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: EMPTY CAR BRAKE APPLICATION When a brake application is made, brake cylinder pressure enters from the triple valve in passage 221 and flows to Chamber A on the left side of the ratio valve. Simultaneously, air flows through Passage 211a to the semi-circular area 208a on top of the change over valve key 208. In the event that the car is light, the load arm 202 will be positioned downward; and brake cylinder air will flow from Passage 211a past the key 208 to Passage 213, thence to Chamber C on the right hand side of the lock over piston 206. Chamber D on the left hand side of lock over piston 206 is vented to atmosphere by area 208b on the change over valve key 208. Moving this piston 206 to the left requires only 0,34 bar (5 psi) or less; and in its left most position, the piston is detented by an annular spring 207 engaging a detent groove 209a. As air pressure continues to rise in the supply pressure in Chamber A on the left hand side of the ratio valve 204 exerts less force on the spool of this valve 204 than does the brake cylinder pressure in Chamber B on its right hand side, forcing the 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 the particular diaphragms used. As supply pressure from the triple valve continues to rise, Chamber A pressure will build up, 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. 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 1,1 liter (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 equal 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 provided 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 214a to the face of bypass check valve 232 but cannot open this valve because of the higher supply pressure behind it from 211c which holds it to its seat. However if the car becomes heavier after an initial light load application and before release, change over key valve 208 will rotate causing lock over piston 206 to move right opening bypass check valve 232 and allow dummy volume cut-off check 230 to close. This allows the brake cylinder pressure at 214 to equalize and reduce with the supply from the triple valve at 211 via the bypass paths. Dummy volume cut-off check 230, responsive to the reduction of pressure in passage 211b, opens to equalize and reduce the pressure in dummy volume 210. EMPTY CAR BRAKE RELEASE 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 Passage 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 cylinder pressure flows from brake cylinder into Passage 214, through Chamber B, Passage 214a, past the bypass check valve 232, unseating it, into Passage 211 to the triple valve and exhaust. Since dummy cut-off check 230 is held open by lock over piston 208(a), the dummy reservoir 210 is also emptied via passage 211b, etc. LOADED CAR BRAKE APPLICATION If the car weighs heavy, the load arm 202 will be moved upward and Passage 211a will be connected through the changeover valve key area 208b to Passage 215. Supply 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 detented by detent spring 207 and groove 209B 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 ratio valve 204 to chamber B and the brake cylinder and, again, forces the ratio valve to the left. However, 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 supplied by the triple valve in the loaded position must be passed to the brake cylinder, the dummy volume cut-off check 230, 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 volume 210. CAR BRAKE RELEASE 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 check 232 off of its seat as it is held open by the lock over piston 206 in any case. E-1 BRAKE PIPE MODULATION VALVE 302 The purpose of the E-1 brake pipe modulating valve 302 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 the E-1 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. INITIAL CHARGING 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 quick action chamber 308, and 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 control check 326 through Passage 316b. Brake pipe air flows through Choke Z into Passage 318 and the underside of the accelerated release check 328, thence past this check 328 into Passage 319 whence it charges the release reservoir and through Passage 319a to Chamber F above the quick service limiting valve piston 330. With the equipment fully charged, pipe pressure may be reduced to initiate 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 pipe pressure drops about 34 mbar (½ psi) and will not move down until the stabilizing spring has been overcome. When this occurs, the accelerated release valve diaphragm piston 320 will move down opening the quick service check valve 338. When the quick service check valve 338 is moved off its seat, brake pipe air will flow to the quick service volume 340; and because of the proximity of 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 open wide, permitting brake pipe pressure to flow from brake pipe through Passage 311, Chamber A, Passage 312, past the open quick 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 car and will terminate when a 0,2 bar (3 psi) differential of release reservoir pressure over brake pipe pressure is established, which differential will move the quick service limiting valve spool 332 down cutting off further communication with brake pipe through the quick service check 338. At this same time, accelerated application pilot valve piston 322 also moves down forcing its check 324 from its seat and permitting quick action chamber 308 air to flow from Passage 317a past the open check valve 324 to atmosphere through Choke U, while subjecting the inner area of the accelerated application valve diaphragm 342 to the pressure backed up by Choke U. If this backed up pressure is sufficient, it will cause the accelerated application diaphragm 342 to move downward from its 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 long as the accelerated application pilot valve 322 is down, permitting quick action chamber 308 air to flow to atmosphere, the accelerated application valve piston 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 which 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 with 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 of events much the same way the accelerated application valve operates on the present ABDW emergency AAV portion. ACCELERATED BRAKE RELEASE Whenever brake 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, aiding in the restoration of brake pipe 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 exhaustion of brake pipe air when the quick service limiting 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-1 brake pipe modulating valve 302 will be returned to its fully charged position. Above this pressure, brake pipe pressure can only be supplied from the locomotive; and when a further 3 psi has been built 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. From the preceding description of the preferred embodiments, it is evident that the objects of the invention 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.

Claims: A control valve for a brake system having a brake pipe, brake cylinder, auxiliary reservoir, and emergency reservoir with respective ports (A, 119a, 115b, 114a) as well as an atmosphere port (131) characterized by the fact that it comprises fluid pressure sensing means (124, 132, 133) connected to the brake pipe port (A) for sensing service brake application signals, brake release signals and emergency signals in the brake pipe (20), first valve means (G) connected to said sensing means for interconnecting the brake cylinder port (119a) and the auxiliary reservoir port (115a) for a service brake application signal sensed by the sensing means, and for interconnecting the brake cylinder port (119a) and atmosphere port (131) for a brake release signal sensed by the sensing means, said first valve means (G) and a second valve means (123) being operable for an emergency brake application sensed by the sensing means to sequentially interconnect the brake cylinder port (119a) and auxiliary reservoir port (115b) while isolating the brake cylinder port (119a) from the emergency reservoir port (114a), and subsequently interconnecting the brake cylinder port (119a) and the emergency reservoir port (114a) while isolating the auxiliary reservoir port (115b) from the emergency reservoir port (114a). A control valve according to claim 1, further characterized by the fact that the second valve means (123) is axially operated when brake cylinder pressure becomes substantially equal to service brake application pressure during an emergency brake application to isolate the auxiliary reservoir port (115b) from the brake cylinder port (119a) and connect the emergency reservoir port (114a) to the brake cylinder port (119a). A control valve according to claim 2, further characterized by the fact that a small movement of the second valve means (123) due to pressure at the brake cylinder port (119a) causes snap action of valve means (123) during an emergency brake application to isolate the auxiliary reservoir port (115b) from the emergency reservoir port (114a) when pressure at the brake cylinder port (119a) is just slightly less than auxiliary port (115b) pressure A control valve according to claim 3, further characterized by the fact that a first check valve (122) is located in a passage (133) between the brake pipe port (A) and the emergency reservoir port (114a) for permitting the charging of the auxiliary and emergency reservoirs, and a second check valve (126) is located in the sensing means for permitting the charging of the auxiliary and emergency reservoirs when brake pipe (20) pressure rises above auxiliary reservoir port (115b) pressure.

Inventors: ENGLE, THOMAS H.
Applicants: GENERAL SIGNAL CORPORATION
Application year: 1986
Main classification: B60T15
IPC codes: B60T13, B60T15, B60T8