GB1012414A - Fluid pressure braking systems - Google Patents

Abstract

1,012,414. Fluid pressure braking systems. WESTINGHOUSE BRAKE & SIGNAL CO. Ltd. Sept. 15, 1964 [Oct. 3, 1963], No. 38996/63. Heading F2F. A fluid - pressure braking system includes a manually operated release valve which is connected at 9 to the brake pipe and at 7 to a control reservoir and has first means comprising opposed springs 4, 12 which together urge the valve 3 away from its seat 2, second means comprising the piston 10 subjected to brake pipe pressure and effective when that pressure is at its normal, charged, value to overcome the first means and a third means comprising a handle 17 manually operable to move the valve from the seat irrespective of the effectiveness or otherwise of the first and second means. When the braking system is empty valve 3 is open and on charging air flows therethrough from the pipe to the control reservoir until at the fully charged pressure the piston 10 moves down to overcome spring 10 and allow spring 4 to close the valve. Further charging of the control reservoir continues through an alternative path (not shown) in the system. Equalisation of the pressures in reservoir and brake pipe can be achieved by operation of handle 17 to re-open the valve. To release the brakes of the vehicle after it has been separated from the train, the brake pipe pressure being zero, the handle 17 is operated to lift the valve and release the reservoir pressure through the brake pipe, the valve then being kept open independently of handle position by spring 12. The choke 8 prevents a rush of air from forcing down piston 10 to allow the valve to close. In a modification the cylinder 10 is replaced by a diaphragm disposed above the valve and connected by a second passage to a pressure corresponding to the brake pipe pressure.