GB668122A - Improvements relating to control valve devices for fluid pressure braking apparatus for railway and like vehicles - Google Patents

Abstract

668,122. Fluid pressure brakes. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd., SIMMONS, A. W., and GNAVI, A. Jan. 25, 1950, No. 1935/50. Class 103 (i). In a control valve for automatic fluid pressure brakes for railway and like vehicles comprising a diaphragm in pile unit 17 having diaphragms 3, 24, 26, 28, separating chambers 2, 4, 25, 27, 31, subject respectively to the pressures in the control reservoir 171, the auxiliary reservoir part 172, atmosphere, brake cylinder and brake pipe, a retarded recharge valve 35, a hand-release valve 74, a quick inshot valve unit 106, a control reservoircharging valve 140, a valve unit 155 controlling the action of the quick service bulb 88, 89 and a passenger freight change-over lock 166, during release of the brakes after a brake application. The decrease in brake cylinder pressure is arranged to control both the recharging of the auxiliary reservoir 172, 175 through the recharge valve 35, and the re-opening of the control reservoir charging valve 138 independently of the increase above a certain value of the brake pipe pressure acting in chamber 31 on the diaphragm pile unit. Since the equilibrium of the diaphragm pile unit 17 is dependent on the upward force due to brake pipe pressure acting in chamber 31 and brake cylinder pressure in chamber 27 (the diaphragm 26 having a larger effective area than the diaphragm 28), acting against the downward force of control reservoir pressure in chamber 2, the atmospheric pressure in chamber 25 being constant, and the auxiliary reservoir pressure acting in chamber 4 having no resultant force, if when the slide valve is in the release position shown the brake pipe pressure is increased sufficiently to overcome spring 22, spring 38 moves the retarded recharge value stem 30 so as to cut-off the connection to the brake pipe through port 35a, so that the pressure in chamber 31 is limited. Since the collar 20 on the slide valve spindle 23 is in abutment with the valve body, the slide valve remains in the release position shown and the recharging of the auxiliary reservoir and control reservoir will be dependent upon a variation of the brake cylinder pressure acting in chamber 27 of the diaphragm pile and chamber 134 of the control reservoir charging unit 140. The invention is also described as applied to a control valve which differs only in that there is no quick service bulb control device 155, this function being performed by the addition of suitable ports and passages in the main and graduating slide valves.