Improvements relating to compressed fluid braking apparatus

910,610. Fluid-pressure brakes. WESTINGHOUSE BRAKE & SIGNAL CO. Ltd. Jan. 11, 1961 [Jan.11, 1960], No. 906/60. Class 103 (1). In a compressed fluid brake system operated by pressure difference between the brake pipe and the control reservoir, a relief valve, responsive to a predetermined pressure difference greater than occurs during normal braking, dissipates pressure in the control reservoir. With the brake pipe 17, the control reservoir pipe 16 and auxiliary reservoir pipe 25 at normal fully-charged pressure, the brake cylinder is vented from pipe 21 through the centre of a valve 13 to an exhaust passage 20. A reduction of brake pipe pressure 17 in chamber 15 above a diaphragm 11 causes the valve 13 to rise, lifting a disc closure member 24 from a seating 23 to admit auxiliary reservoir pressure to the brake cylinder pipe 21, and seal off the exhaust passage in the valve 13. Brake pressure build-up in a chamber 19 above a diaphragm 12 depresses the valve 13 to open the central exhaust passage and produce a lap condition. A check valve 29 is interposed between the brake pipe 17 and control reservoir 16 and is loaded by a spring 30 to open only when the pressure difference between the brake pipe and reservoir is greater than the pressure difference used for normal braking. By this means some dissipation of the reservoir pressure, to accommodate the characteristics of different control values, can be made by exhausting the brake pipe through an emergency application.