GB429817A - Improvements relating to fluid pressure braking apparatus - Google Patents

Abstract

429,817. Fluid - pressure brakes. WESTINGHOUSE BRAKE & SAXBY SIGNAL CO., Ltd., 82, York Road, King's Cross, London.-(Assignees of Craig, J. F. ; 49, Beverly Road, Upper Monclair, New Jersey, U.S.A.) Nov. 30, 1934, No. 34456. Convention date, Dec. 1, 1933. [Class 103 (i)] A valve device for fluid-pressure brake apparatus comprises two abutments controlling respectively the supply to and release from a brake cylinder of fluid under pressure, each abutment being subject to the opposing actions of the brake cylinder pressure and the pressure of fluid supplied from the drivers brake valve or its equivalent. A pair of independent pistons 19, 20 are slidable in a cylindrical bushing 13. The chamber 25 between the pistons is connected to the drivers valve by passage 26 and the chambers 21, 27 are connected by radial ports 22, 28 to a chamber 17 surrounding the bushing and thence to the brake cylinder by passage 18. The piston 20 carries a supply valve 33 in a chamber 31 connected by passage 32 to the reservoir. Normally, the chamber 25 is connected to atmosphere through the drivers valve, and the pistons are in the position shown with the piston 19 abutting on an extension 37 of the piston 20 so that the chamber 21 and thus the brake cylinder is connected to atmosphere through passage 24. When pressure fluid is admitted to the chamber 25 the piston 19 moves to left to seat a ridge 23 thereon against the casing to close the release passage 24 and the piston 20 unseats the valve 33 and when the pressure in the chamber 27 and brake cylinder is substantially equal to that in the chamber 25 the piston 20 returns to seat the valve. A graduated release of the cylinder pressure may be similarly obtained by partially releasing the pressure in the chamber 25 through the drivers valve, the piston 19 moving to unseat the ridge 23 until the pressure in chamber 21 has fallen substantially to that in the chamber 25. The bushing 13 has an end plate 15 which is clamped between the casing 10 and a cover 11 and upon detaching this the bushing with the pistons may be removed without disturbing the casing and the pipe connections.