Fluid brake control system

Abstract

A fluid brake control system is disclosed having an improved quick service and accelerated release control device having valves operable when rendered effective to locally reduce the brake pipe pressure to accelerate a brake application signal through a train and at other times to apply fluid to the brake pipe for accelerating the release of brakes of a train. The control device comprises a housing containing a fluid pressure differential operated abutment subject to actuation from a normal position by differences in pressure between respective brake pipe and reference fluid pressure chambers on opposite sides of the abutment. Two quick service valves of the ball poppet type are provided on one side of the abutment that are spring biased in the direction of the abutment against their valve seats to normally closed positions and have operating push rods longitudinally disposed between the associated ball poppet valves and one side of the abutment. A ball poppet valve on the other side of the abutment is also normally closed and is opened by movement of the abutment in the other direction for delivering fluid from an emergency reservoir to the brake pipe for providing accelerated release.

What is claimed is: 
     
       1. A fluid brake control system for a train of cars including a car having a brake control pipe, a reference fluid reservoir subject to charge periodically from the brake pipe and an improved quick service control device comprising: a. a housing containing a fluid pressure differential operated abutment subject to actuation from a normal position by differences in pressure between respective brake pipe and reference fluid pressure chambers acting on opposite sides of the abutment,   b. two poppet type valve means on the brake pipe pressure chamber side of the abutment for selectively venting the chambers, each of the valve means being spring biased in the direction of the abutment to a normally closed position and the valve means having respective operating push rods longitudinally disposed between the associated valve means and the abutment, and   c. the poppet valve means being responsive to movement of the abutment in one direction to vent first the brake pipe fluid pressure chamber and thereafter the reference fluid pressure chamber to alternately reverse the differential in fluid pressure acting on the opposite sides of the abutment to thereby reciprocate the abutment cyclically,   d. whereby the poppet valve means are opened and closed in turn so as to intermittently reduce the pressure in the brake pipe as long as the brake pipe pressure is being reduced independent of action of the poppet valve means.   
     
     
       2. A fluid brake control system according to claim 1 wherein the operating push rods are laterally spaced and a bridge in the brake pipe chamber is disposed across ends of the push rods respectively between the rods and the abutment, bearing on the abutment at an intermediate point, for permitting sequential operation of the push rods upon actuation of the abutment in accordance with an imbalance of moments of force of opposite sides of the intermediate point. 
     
     
       3. A fluid brake control system according to claim 2 wherein the intermediate point in the bridge is at a mid-point between the push rods and different opening times of the valve means in response to movements of the abutment is accomplished by an imbalance in valve biasing spring pressures. 
     
     
       4. A fluid brake control system according to claim 3 wherein the valve means for permitting flow of fluid from the brake pipe pressure chamber opens prior to the opening of the valve means for permitting flow of fluid from the reference chamber. 
     
     
       5. A fluid brake control system according to claim 1 wherein means is provided for restricting the rate of fluid flow from the brake pipe chamber, more than the rate of fluid flow from the reference chamber. 
     
     
       6. A fluid brake controls system according to claim 5 wherein means is provided for connecting the brake pipe to the brake pipe chamber through a choke of a size selected in accordance with a desired frequency of cyclically reducing pressure in the brake pipe. 
     
     
       7. A fluid brake control system according to claim 6 wherein a bridge is disposed across ends of the push rods respectively between the push rods and the abutment, bearing on the abutment at an intermediate point in the bridge for permitting sequential operation of the push rods longitudinally upon actuation of the abutment in accordance with an imbalance of moments of force on opposite sides of the intermediate point. 
     
     
       8. A fluid brake control system according to claim 7 wherein the intermediate point in the bridge is at a mid-point between the push rods and different relative opening times of the valve means is obtained upon movement of the abutment by an imbalance in valve biasing spring pressures. 
     
     
       9. A fluid brake control system according to claim 1 wherein the control device comprises an accelerated release poppet type valve means on the reference chamber side of the abutment spring biased in the direction of the abutment to a normally closed position and having a push rod longitudinally disposed btween the associated valve and the abutment, the accelerated release poppet valve means being opened by movement of the abutment in the other direction from its normal position and including means when open for permitting fluid to flow from a fluid reservoir to the brake pipe for providing accelerated release of brakes of the other cars of the train. 
     
     
       10. A fluid brake control system according to claim 9 wherein additional spring biasing means is provided for selectively additionally spring biasing the abutment against movement in said other direction from its normal position dependent upon pressure of fluid in the reference chambers, whereby the additional spring biasing means must be overcome to move the abutment sufficiently to open the accelerated release valve provided pressure in the chambers has been materially depleted as is the condition subsequent to an emergency brake application. 
     
     
       11. A fluid brake control system according to claim 10 wherein the additional biasing means comprises a piston that is spring biased in the direction of the abutment but restricted from contacting the abutment when the abutment is moved in said one direction from its normal position. 
     
     
       12. A fluid brake control system according to claim 11 wherein the piston is restricted from contacting the abutment at times of release of a service brake application by fluid pressure in the reference chamber. 
     
     
       13. A fluid brake control system according to claim 11 wherein the piston is disposed in a bore of the housing and is restricted in its movement toward the abutment by a snap ring in the bore. 
     
     
       14. A fluid brake control system according to claim 13 wherein the push rod associated with the accelerated release valve means passes coaxially through the piston and is slidably operable therein for permitting actuation of the accelerated release valve means to its open position in response to movement of the abutment in said other direction irrespective of movement of the piston. 
     
     
       15. A fluid brake control system for a train of cars including a car having a brake control pipe, a .Iadd.reference .Iaddend.fluid .[.reservoir.]. .Iadd.pressure chamber .Iaddend.subject to charge periodically from the brake pipe.Iadd., an emergency fluid reservoir, .Iaddend.and an improved quick service and accelerated release control device comprising; a. a housing containing a fluid pressure differential operated abutment subject to actuation from a normal position by differences in fluid pressure between respective brake pipe and reference fluid pressure chambers acting on opposite sides of the abutment,   b. poppet valve means on each side of the abutment spring biased in the direction of the abutment to a closed position and having an operating push rod longitudinally disposed between the associated valve means and the abutment,   c. first poppet valve means on one side of the abutment being opened by movement of the abutment in one direction from its normal position and including means for permitting fluid to flow from the brake pipe to provide local quick service reduction in brake pipe pressure, and   d. the poppet valve means on the other side of the abutment being opened by movement of the abutment in the opposite direction from its normal position and including means to permit fluid to be released from the .Iadd.emergency .Iaddend.reservoir to the brake pipe for providing accelerated release of brakes of other cars in the train.   
     
     
       16. A fluid brake control system according to claim 15 wherein the improved quick service and accelerated release control device comprises a second poppet valve means on said one side of the abutment spring biased in the direction of the abutment to a closed position and having an operating push rod longitudinally disposed between said second valve means and the abutment and operable to an open position by movement of the abutment in said one direction, the second poppet valve means being effective when opened to permit fluid to be vented from the reference chamber. 
     
     
       17. A fluid brake control system according to claim 16 wherein the first poppet valve means on said one side of the abutment is operable when opened to release fluid at a restricted rate from the brake pipe through the brake pipe chamber. 
     
     
       18. A fluid brake control system according to claim 17 wherein sequencing means is provided for opening said first poppet valve means on said one side of the abutment prior to the opening of said second poppet valve means. 
     
     
       19. A fluid brake control system according to claim 18 wherein the sequencing means comprises a bridge disposed across ends of the push rods associated with said first valve means and said second valve means and having an intermediate point adapted to be actuated by the abutment for permitting the order of operation of the valve means to their open positions to be determined by the relative spring biasing pressures of these valve means. 
     
     
       20. A fluid brake control system according to claim 19 wherein the spring bias of said second valve means is greater than the spring bias of said first valve means for releasing fluid from the brake pipe prior to releasing fluid from the reference chamber upon actuation of the abutment in said one direction relative to its normal position. 
     
     
       21. A fluid brake control system according to claim 15 wherein the poppet valve means on said other side of the abutment comprises additional spring biasing means independent of the valve means for additionally spring biasing the abutment toward its normal position when there has been an emergency brake application and the fluid pressure in the chambers is materially reduced. 
     
     
       22. A fluid brake control system according to claim 21 wherein the additional biasing means comprises a piston that is spring biased toward the abutment and is normally displaced from the abutment by fluid pressure in the reference chamber. 
     
     
       23. A fluid brake control system for a train of cars including a car having a brake control pipe, a .Iadd.reference .Iaddend.fluid reservoir subject to charge periodically from the brake pipe.Iadd., an emergency fluid reservoir, .Iaddend.and an improved accelerated release control device comprising: a. a housing containing a fluid pressure differential operated abutment subject to actuation from a normal position by differences in pressure between respective brake pipe and reference fluid pressure chambers acting on opposite sides of the abutment,   b. poppet type valve means on the reference chamber side of the abutment spring biased in the direction of the abutment to a normally closed position, the valve means having an operating push rod longitudinally disposed between the poppet type valve means and the abutment for opening the valve means in accordance with movement of the abutment in one direction from its normal position,   c. fluid supply means responsive to the opening of the valve means for permitting fluid to flow from the emergency reservoir to the brake pipe, and   d. additional spring biasing means including a piston having an axial bore for free passage of the push rod for applying additional spring bias against movement of the abutment in said one direction from its normal position only when fluid pressure is materially reduced in the reference chamber.   
     
     
       24. A fluid brake control system according to claim 23 wherein the piston is disposed in a bore in the housing, is spring biased in the direction of the abutment and biased in the opposite direction by fluid pressure in the reference chamber. 
     
     
       25. A fluid brake control system according to claim 24 wherein means is provided for mechanically limiting movement of the piston in the direction of the abutment to prevent the additional spring biasing means from causing movement of the abutment in an opposite direction from its normal position. 
     
     
       26. A fluid brake control system according to claim 25 wherein the mechanical means is a snap ring stop inserted in the bore in the housing between the piston and the abutment. .Iadd. 27. Quick service brake control apparatus for a railway vehicle having a brake control pipe, a reference fluid reservoir subject to charge from the brake pipe and an improved quick service control device comprising: a. a housing containing a fluid pressure differential operated abutment subject to actuation by differences in pressure between respective brake pipe and reference fluid pressure chambers acting on opposite sides of the abutment,   b. first and second valve means each of the poppet type and both disposed on the same side of said abutment and having relatively movable seat and closure elements at least one of which is operatively connected to said abutment,   c. said first poppet valve means being operable by movement of said abutment in response to a decrease in brake pipe pressure relative to reference fluid pressure of a first predetermined amount to reduce said brake pipe presure further relative to said reference fluid pressure,   d. said second poppet valve means being operated by movement of said abutment in response to a decrease in brake pipe pressure relative to reference fluid pressure of a second predetermined amount which is greater than said first predetermined amount to reduce said reference fluid pressure relative to said brake pipe pressure,   e. whereby a decrease in brake pipe pressure indicative of a brake application causes the pressure in said brake pipe and reference fluid pressure chambers to be vented alternately to reverse alternately the pressure differential on opposite sides of said abutment thereby to reciprocate the abutment cyclically and intermittently reduce the pressure in the brake pipe as long as the brake pipe pressure is being reduced   
     
     
        independently of actuation of said valve means. .Iaddend..Iadd. 28.  Fluid brake control apparatus for a railway car having a brake control pipe, a reference fluid reservoir charged from the brake pipe, an emergency fluid reservoir, and an improved quick service and accelerated release control device comprising: a. a housing having a fluid pressure differential operated abutment subject to actuation by difference in pressure between respective brake pipe and reference fluid pressures acting on opposite sides of said abutment,   b. at least one valve means disposed on each side of the abutment, each said valve means being of the poppet type and having relatively movable seat and closure elements at least one of which is operatively connected to the abutment,   said poppet valve means on one side of said abutment being operated by movement of the abutment in response to a decrease in brake pipe pressure relative to reference fluid reservoir pressure to permit fluid to flow from the brake pipe to provide local quick service reduction in brake pipe pressure,   d. said poppet valve means on the other side of said abutment being operated by movement of the abutment in response to an increase in brake pipe pressure relative to reference fluid pressure to permit fluid to flow from the emergency reservoir to the brake pipe to provide accelerated release of brakes of other cars in the train. .Iaddend..Iadd. 29. Fluid brake control apparatus for a railway car having a brake control pipe, a reference fluid reservoir which is at times charged from the brake pipe, an emergency fluid reservoir, and an accelerated release control device comprising:   a. a housing having a fluid pressure differential operated abutment subject to actuation by differences in pressure between respective brake pipe and reference fluid pressure chambers acting on opposite sides of said abutment,   b. valve means of the poppet type having relatively movable seat and closure elements at least one of which is operatively connected to said abutment,   c. fluid supply means responsive to the opening of said valve means by movement of said abutment in response to an increase in brake pipe pressure to permit fluid to flow from said emergency reservoir to the brake pipe,   d. and further means being rendered active in response to the attainment of a predetermined low pressure in said reference fluid reservoir which is indicative of an emergency brake application to apply an additional force to said abutment which resists opening of said valve means in response to an increase in brake pipe pressure of a magnitude less than a predetermined amount. .Iaddend.