Claims
- 1. A graduated release valve for a rail vehicle having a pneumatic control valve, a brake pipe, at least one reservoir charged from said brake pipe, and a brake cylinder, said graduated release valve comprising:
a. a metering valve controlling the exhaust of pressure from said brake cylinder generally responsive to changes in brake pipe pressure; b. a changeover valve selectively switchable between a direct release position and a graduated release position; c. wherein said metering valve is interposed for controlling the exhaust of pressure from said brake cylinder device in a graduated manner in said graduated release position; and d. wherein said metering valve in said direct release position is isolated from said brake cylinders such that said pneumatic control valve controls the exhaust of pressure from said brake cylinder.
- 2. The graduated release valve of claim 1 further comprising a brake pipe sensor valve communicating with said changeover valve and said brake pipe, said sensor valve controlling said selectively switchable changeover valve between said direct release position and said graduated release position.
- 3. The graduated release valve of claim 2 further comprising said sensor valve responsive to pressure in said brake pipe.
- 4. The graduated release valve of claim 3 wherein said sensor valve is responsive to a first brake pipe pressure to switch said changeover valve to said graduated release position and a second brake pipe pressure to switch said changeover valve to said direct release position.
- 5. The graduated release valve of claim 4 wherein said first brake pipe pressure is greater than the normal freight train brake pipe pressure and said second brake pipe pressure is less than the normal brake pipe pressure for a typical freight train service brake application.
- 6. The graduated release valve of claim 1 wherein said rail vehicle further has a trainlined air pipe having a fluid pressure supply and said changeover valve selectively switching between said direct release and said graduated release positions responsive to pressure in said air pipe.
- 7. The graduated release valve of claim 1 wherein said at least one reservoir further comprises an emergency reservoir and an auxiliary reservoir, and wherein said metering valve exhausts brake cylinder pressure generally as a function of a pressure differential between said brake pipe and said emergency reservoir.
- 8. The graduated release valve of claim 7 wherein said metering valve further comprises a graduating piston having at least brake pipe pressure communicating on a brake pipe side of said graduating piston and at least emergency reservoir pressure communicating on an emergency reservoir side of said graduating piston.
- 9. The graduated release valve of claim 8 further comprising brake cylinder pressure communicating on said brake pipe side of said graduating piston through a brake cylinder exhaust port in said pneumatic control valve.
- 10. The graduated release valve of claim 9 further comprising:
a. a graduating spring acting on said brake pipe side of said graduating piston and each of said emergency reservoir and brake pipe sides of said graduating piston having respective surface areas on which said pressures communicate; b. each force of said respective surface areas and said graduating spring being designed to generally balance such that said graduating piston remains in a closed position where no pressure is exhausted from said brake cylinder device in response to a pressure reduction in said brake pipe; and c. said metering valve portion exhausting brake cylinder pressure in a graduated manner responsive to a pressure increase in said brake pipe.
- 11. The graduated release valve of claim 1 further comprising an auxiliary reservoir charging check valve interposed between said auxiliary reservoir and said brake pipe.
- 12. The graduated release valve of 11 wherein said auxiliary reservoir charging check valve is set to permit said pneumatic control valve to go to a release position at a first increase in brake pipe pressure following a brake application.
- 13. The graduated release valve of claim 12 wherein said auxiliary reservoir charging check valve is set at about 2.5 psi.
- 14. The graduated release valve of claim 11 wherein said auxiliary reservoir charging check valve is set to prevent said pneumatic control valve from going to release by connecting the brake pipe to auxiliary reservoir.
- 15. The graduated release valve of claim 14 wherein said auxiliary reservoir charging check valve is set at about 0.5 psi.
- 16. The graduated release valve of claim 2 wherein said changeover valve comprises a spool valve having a spool member and a changeover spring acting a first end thereof and brake pipe pressure selectively communicated on an opposite end thereof through said brake pipe sensor valve for selectively switching said changeover valve between said graduated and direct release positions.
- 17. The graduated release valve of claim 5 wherein said changeover valve comprises a spool valve having a spool member and a changeover spring acting a first end thereof and air pipe pressure communicating on an opposite end thereof for selectively switching said changeover valve between said graduated and direct release positions.
- 18. The graduated release valve of claim 1 wherein said pneumatic control valve is an ABD-type pneumatic control valve having a pipe bracket, an emergency portion and a service portion and wherein said release graduating valve portion is operatively connected to an interface plate which is connected between said service portion and said pipe bracket.
- 19. The graduated release valve of claim 18 further comprising a brake pipe sensor valve operably connected to said changeover valve portion for controlling the position thereof.
- 20. A graduated release valve for a rail vehicle having a pneumatic control valve, a brake pipe, at least one reservoir charged from said brake pipe, and a brake cylinder device, said release graduating valve comprising a metering valve communicating with said brake cylinder and controlling the exhaust of pressure therefrom responsive generally to increases in brake pipe pressure.
- 21. The graduated release valve of claim 20 further comprising said metering valve communicating with a relatively small volume charged from said at least one reservoir, said volume being communicated with said brake pipe when said pneumatic control valve triggers a service accelerated release.
- 22. The graduated release valve of claim 20 wherein said at least one reservoir further comprises an emergency reservoir portion and an auxiliary reservoir portion, and wherein said metering valve exhausts brake cylinder pressure generally as a function of a pressure differential between said brake pipe and said emergency reservoir.
- 23. The graduated release valve of claim 22 wherein said metering valve further comprises a graduating piston having at least brake pipe pressure communicating on a brake pipe side of said graduating piston and at least emergency reservoir pressure communicating on an emergency reservoir side thereof.
- 24. The graduated release valve of claim 23 further comprising brake cylinder pressure communicating on said brake pipe side of said graduating piston.
- 25. The graduated release valve of claim 24 further comprising a graduating spring acting on said brake pipe side of said graduating piston.
- 26. The graduated release valve of claim 25 further comprising:
a. each of said emergency reservoir side and said brake pipe side of said graduating piston having respective surface areas on which said pressures communicate; b. each of said respective forces of surface areas and said graduating spring being generally balanced such that said graduating piston remains in a closed position where no pressure is exhausted from said brake cylinder device in response to a pressure reduction in said brake pipe; and c. said metering valve portion exhausts brake cylinder pressure in a graduated manner responsive to a pressure increase in said brake pipe.
- 27. A method of controlling braking on a rail vehicle to produce a graduated release of brake pressure, said rail vehicle having a pneumatic control valve, a brake pipe, at least one reservoir normally charged from the brake pipe, and a brake cylinder device, said method comprising:
a. controlling pressurization of said brake cylinder device responsive to reductions in brake pipe pressure using said pneumatic control valve; and b. controlling exhaust of said brake cylinder device responsive to increases in brake pipe pressure by metering said exhaust to produce said graduated release of brake cylinder pressure.
- 28. The method of claim 27 further comprising metering said exhaust generally as a function of a pressure differential between said at least one reservoir and said brake pipe.
- 29. The method of claim 28 wherein said at least one reservoir further comprises an emergency reservoir portion and an auxiliary reservoir portion, and wherein said metering exhausts brake cylinder pressure generally as a function of a pressure differential between said brake pipe and said emergency reservoir.
- 30. A method for controlling braking on a rail vehicle to selectively produce a graduated release of brake pressure, said railcar having a pneumatic control valve, a brake pipe, at least one reservoir normally charged from the brake pipe, and a brake cylinder device, said method comprising:
a. controlling pressurization of said brake cylinder responsive to reductions in brake pipe pressure using said pneumatic control valve; and b. selectively switching between a graduated release mode wherein metering to produce said graduated release of brake cylinder pressure and a direct release mode wherein said pneumatic control valve exhausts brake cylinder pressure in a conventional manner.
- 31. The method of claim 30 further comprising controlling said selectively switching between said direct release and graduated release positions by sensing pressure in said brake pipe.
- 32. The method of claim 30 further comprising controlling said selectively switching between said direct release and graduated release positions responsive to pressure in a trainlined air pipe provided on said rail vehicle.
- 33. The method of claim 30 wherein said graduated release of brake pressure produced by metering comprises exhausting brake pressure generally as a function of a pressure differential between said at least one reservoir and said brake pipe.
- 34. The method of claim 33 wherein said at least one reservoir further comprises an emergency reservoir portion and an auxiliary reservoir portion, and wherein said metering valve portion exhausts brake cylinder pressure generally as a function of a pressure differential between said brake pipe and said emergency reservoir.
- 35. The method of claim 30 further comprising maintaining said pneumatic control valve in an application mode during said increases in brake pipe pressure such that said pneumatic control valve is prevented from moving to a release mode while metering the exhaust of said brake cylinder device to produce said graduated release of brake pressure.
- 36. The method of claim 34 wherein said pneumatic control valve switches to a release mode responsive to a certain pressure differential between said brake pipe and said auxiliary reservoir, said method further comprising:
a. communicating said brake pipe and said auxiliary reservoir through a charging check valve within said metering valve; and b. providing a charging cut off pressure below said certain pressure differential to prevent said pneumatic control valve from switching to said release mode.
- 37. The method of claim 36 further comprising providing a charging cut off pressure greater than said certain pressure differential to permit said pneumatic control valve to switch to said release mode at a first increase in brake pipe pressure after a brake application.
- 38. A graduated release valve for a rail vehicle having a pneumatic control valve, a brake pipe, at least one reservoir charged from said brake pipe, and a brake cylinder, said graduated release valve comprising:
a. a metering valve controlling the exhaust of pressure from said brake cylinder generally responsive to changes in brake pipe pressure; b. a changeover valve selectively switchable between a direct release position and a graduated release position; c. wherein said metering valve is interposed for controlling the exhaust of pressure from said brake cylinder device in a graduated manner in said graduated release position; d. wherein said metering valve in said direct release position is isolated from said brake cylinders such that said pneumatic control valve controls the exhaust of pressure from said brake cylinder; and e. an emergency reservoir charging check valve permitting charging of the emergency reservoir, the pressure in the emergency reservoir is less than the pressure in the brake pipe.
- 39. The graduated release valve of claim 38 further comprising a brake pipe sensor valve communicating with said changeover valve and said brake pipe, said sensor valve controlling said selectively switchable changeover valve between said direct release position and said graduated release position.
- 40. The graduated release valve of claim 38 wherein said rail vehicle further has a trainlined air pipe having a fluid pressure supply and said changeover valve selectively switching between said direct release and said graduated release positions responsive to pressure in said air pipe.
- 41. The graduated release valve of claim 38 wherein said metering valve further comprises a graduating piston having at least brake pipe pressure communicating on a brake pipe side of said graduating piston and at least emergency reservoir pressure communicating on an emergency reservoir side of said graduating piston.
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on provisional patent application Ser. No. 60/214,511, filed Jun. 28, 2000.
Provisional Applications (1)
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Number |
Date |
Country |
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60214511 |
Jun 2000 |
US |