GB310912A - Improvements relating to fluid pressure braking apparatus - Google Patents

Abstract

310,912. Winter, H. J., and Westinghouse Brake & Saxby Signal Co., Ltd. Feb. 2, 1928. Fluid-pressure. - Fluid-pressure braking apparatus of the combined automatic and straight type comprising light and load brake cylinders is provided with a valve device adapted under load conditions, both in automatic and Straight application, to control the supply of fluid under pressure to the brake cylinders so that the stroke of the light cylinder is rapidly effected and substantially completed before fluid is supplied to the load cylinder, and when the brakes are released the venting of fluid from the load cylinder is completed first. In automatic application the fluid supplied from the triple valve 28 moves a check valve 26 in the valve device to close the straight air pipe 29 and passes through ports 31 to a chamber 15 and passages 16, recess 18 in a piston valve 4, passages 21, 22 to the light cylinder 20, also through a restricted passage 24 to this cylinder, and the slack in the brake rigging is taken up and a braking effort applied. When the pressure in the cylinder 20 and chamber 15 has obtained a predetermined value the piston 4 is raised against the pressure of a spring 8 closing the communication of the load cylinder 14 with the atmosphere through a port 6 and supplying it with fluid under pressure by a restricted port 23. Communication between the chamber 15 and the cylinder 20 through the recess 18 is out off by the upward movement of the piston 4, but the supply continues through the port 24. Fluid is released from the brake cylinders through ports 23, 24 and the triple valve until a predetermined reduction in the pressure in the cylinder 14, when the piston 4 returns to the lower position and the cylinder 4 is vented direct to the atmosphere through a port 6 and the cylinder 20 is vented through the recess 18, but not so rapidly as the cylinder 14, so that the venting of this latter is completed first. When straight air is supplied through pipe 30, 29 the check valve 26 is moved to close the pipe 27 from the triple valve and the supply and release of fluid to and from the brake cylinders takes place through the same passages as in the automatic application. The brake cylinder 14 may be rendered inoperative when the vehicle is empty by means of a cock 37 which connects it to the atmosphere.