GB267224A - Improvements relating to fluid pressure braking apparatus - Google Patents

Abstract

267,224. Winter, H. J., Simmons, A. W., and Westinghouse Brake &. Saxby Signal Co., Ltd. Dec. 10" 1925. Fluid-pressure.-In order that a reduced braking pressure may be obtained on an empty or lightly loaded vehicle as compared with that on a loaded vehicle, a valve is provided adapted to cut off the supply of air to the brake cylinder when the pressure therein is a predetermined amount less than that in the auxiliary reservoir, the valve being by-passed under loaded conditions. The effective capacity of the brake cylinder may also be increased in unloaded conditions so that a relatively lower braking pressure is obtained with a given fall in train-pipe pressure. The triple valve 3 is provided with a valve 8 controlled by a piston 11 subject on its under side to the pressure in the auxiliary reservoir 1 by way of the passage 22 whereby normally the valve is held open against the pressure of a spring 13. A cock 6 is provided which in the position shown connects a passage 5 to the valve 8 by the passage 7 and also connects a chamber 23 to the brake cylinder 2 by a passage 24. Thus when the triple valve moves to application position air from the reservoir 1 is supplied to the brake cylinder and to the chamber 23 by the passages 5, 7 past the valve 8 and passage 9. When the brake cylinder pressure acting on the upper and larger area of the piston 11, together with the spring 13 is sufficient to overcome the auxiliary reservoir pressure acting below the piston, the valve 8 closes. In order to restrict the flow of air to the brake cylinder when a predetermined pressure has been reached therein, there may also be provided a valve 25 controlling an additional passage to the brake cylinder, and adapted to close when the brake cylinder pressure acting on a piston 28 overcomes a spring 22. For a loaded vehicle the cock 6 is turned to the position in which the passage 24 therein connects the passages 5, 9<1> thus cutting out the valve 8 and the chamber 23 which in this position of the cock is connected to atmosphere. The relative capacity of the passages 7. 24 in the cock 6 may be such that either the rate of filling of the brake cylinder or the time interval required to obtain the final pressure therein may be the same under light and load conditions.