GB618543A - Improvements relating to relay valves applicable to compressed air braking apparatusfor railway vehicles - Google Patents

Abstract

618,543. Fluid-actuated valves. WESTING- HOUSE BRAKE & SIGNAL CO., Ltd., SIMMONS, A. W., and KERSHAW, J. W. G. Sept. 10, 1946, No. 27168. [Class 135] [Also in Group XXXIV] In compressed air braking apparatus for railway vehicles comprising a relay valve in which an inlet and exhaust valve assembly for the brake cylinder is operated by the thrust of three movable abutments, one subjected to a pressure dependent upon the setting of a driver's brake valve, a second subjected to a pressure dependent upon the speed or load of the vehicle, and the third subjected to the pressure in the brake cylinder,- the thrust of the second abutment is transmitted to the valve assembly through an adjustable mechanism. As shown, the relay valve has a port 18 communicating with the brake cylinder and connected, through an inlet valve member 14, with a supply connection 17. An exhaust port 7, controlled by a valve member 12, movable with valve member 14, is formed in 'the upper end 4 of a hollow piston whose interior connects, through ports 9, 11, with the atmosphere. The lower end 5 of the piston is subjected to the pressure from the driver's brake valve, and a further controlling pressure, e.g., a pressure derived from that supplied to the relay valve through the driver's valve, but modified in accordance with conditions such as speed or load of the vehicle, is applied, through a port 21, to a piston 20 connected through levers 25, pivoted at 26, and thrust pins 23 to a flange or lugs 22 on the hollow piston. Rollers 24 on the levers engage the thrust pins and rollers 27 coact with the piston 20. To vary the controlling effect of the pressure acting on the piston 20, the spindles of the rollers 27 may be inserted in different holes in the levers.