GB1097398A - Fluid-operated braking systems - Google Patents

Abstract

1,097,398. Fluid-operated braking systems. WESTINGHOUSE BRAKE & SIGNAL CO. Aug. 5, 1966 [Sept. 3, 1965; Dec. 8, 1965]. Nos. 37672/65 and 51993/65. Heading F2F. A fluid-operated braking system comprises a brake actuator 1, fluid-operated locking means 31 for locking the brake actuator in its " brakes applied " condition, a first valve 12 for controlling the supply of operating fluid to the actuator 1 and a second valve 13 for controlling the supply of operating fluid to the locking means 31. The valves 12, 13 are operated by a valve actuating member 14 which can be moved in two connected slots 22, 23. Movement of the member 14 along the slot 22 operates only valve 12 to allow pressurized fluid to enter a chamber 4 of the actuator 1 to apply the brakes. The valve 12 is self-lapping and the pressure of the fluid supplied thereby from a reservoir 15 increases as the slot 22 is traversed by the member 14. Before the maximum possible pressure position of the member 14 is reached, the member is depressed vertically into the slot 23 whence the valve 13 is operated to vent the locking means 31 through a valve 25 to actuate the locking means 31. Further travel of the member 14 along slot 23 returns the valve 12 to its inoperative state. Normal actuation of the brakes is effected by the depression of a pedal of a foot valve 7, pressurized fluid passing to a further chamber 5 of the actuator 1. The chamber 5 is bounded by two diaphragms 2, 3. Fluid pressure supplied by the foot valve 7 to the chamber 5 is also supplied to the valve 25, the valve 25 being actuated to cut-off communication between the valve 13 and the locking means 31 at a predetermined supply pressure such that the pressurized fluid passes to the locking means to keep the locking means in its inoperative state. The predetermined pressure is set by the spring loading the valve member in the valve 25 (Fig. 2, not shown). A reservoir 60 is provided in the circuit of the locking means. In a modification (Fig. 3, not shown), pressurized fluid is supplied to the locking means from the valve 13 through a quick-release valve, pressurized fluid from the foot valve 7 being supplied to the valve 13 through a valve (Fig. 4, not shown), to prevent the valve 13 venting the locking means on operation of the valve 13 when the foot valve 7 is actuated. In this case, fluid pressure from the valve 14 operates a relay valve to allow fluid to be supplied from a reservoir to the chamber 4 of the actuator.