Patent GB-237102-A (GB)
Title: Improvements in or relating to trip valve devices for use with fluid pressure braking apparatus
IPC: B60T7/18
Filed: 1924-07-31
Abstract: 237,102. Winter, H. J., and Westinghouse Brake & Saxby Signal Co., Ltd. July 31, 1924. Fluid-pressure. - A trip valve, adapted when actuated by means on the track, to vent the train pipe to apply the brakes, is reset by means of fluid pressure, either by means under the control of the driver, or automatically, when a predetermined pressure reduction has been effected or after a predetermined time. In the form shown, in Fig. 2, the trip valve 2, controlling communication between the train pipe 3 and the atmosphere at 4 through a second valve 5, is adapted to be reset by the stem 11 of a valve 7, subject to main reservoir pressure in a chamber 8, and to train pipe pressure through a port 3<1> and to the pressure of a control spring 9, when the train pipe pressure has been reduced by a predetermined amount. In order that the descent of the valve 7 may be rapid, a portion only of its upper face is subject to main reservoir pressure when it is closed. After the valve 2 has been reset, the valve 7 is raised to its normal position on restoring the pressure in the train pipe. In the form shown in Figs. 3 and 4, in which the valve 2 is reset after a predetermined time, the train pipe 3 is connected to a timing-reservoir 16 through a check valve 18, a casing 24 between the parts 16, 18 being provided with a pair of valves 25, 26, subject on their outer faces respectively to main reservoir pressure, and to the pressure in the reservoir 16, and having between them a spring 27. When the train pipe and reservoir are charged, the valve 25 is held in the raised position shown, in which it cuts off the main reservoir from the chamber 8 above the valve 7, Fig. 2, through the pipe 17 and connects the latter to atmosphere at 28. When, however, train pipe pressure is reduced by the operation of the valve 2, the pressure in the reservoir 16 falls by escape of air to the train pipe through an adjustable small port 20 in the valve 18, so that after a predetermined time the valve 25 is opened to supply pressure to the chamber 8 to actuate the resetting valve 7, the valve. 26 moving to its seat 29 to prevent leakage therethrough. In a further form shown in Fig. 5, a manually operable valve 30 may, in the position shown, connect the chamber 8 to atmosphere, either past the valve stem 32 or through a small port, and be adapted, when moved to the left, to open a valve 31 to supply air at main reservoir pressure to the chamber 8, a packing 33 then serving to prevent leakage past the stem 32. In further forms, an electromagnetically operated valve may be used, or an additional fluid-pressure line may be provided, the supply to which is controlled by the driver. Isolating cocks may be provided to cut the trip valves out of action, and be adapted, when closed, to open switch contacts included in a circuit leading to a controller for the current driving the vehicle, emergency switch contacts being, however, provided to permit the circuit to be re-established independently of the isolating cock contacts. In addition to the fluid-pressure resetting-means, mechanical resetting-means may be provided.