GB230414A - Improvements relating to fluid pressure braking apparatus - Google Patents

Abstract

230,414. Westinghouse Brake & Saxby Signal Co., Ltd., (Assignees of Thomas, T. H.). March 10, 1924, [Convention date]. Fluid - pressure.- The control of the feed valve used for charging the train pipe is effected by the pressure conditions at a point remote from the point in the train pipe at which fluid is supplied thereto through the feed valve, whereby the regulating-diaphragm of the latter is subject more nearly to the actual train pipe pressure, so that the charging ports of the feed valve may be made larger than usual. In the form shown, the diaphragm 13 of the feed valve is subject through a pipe and passage 17 to the pressure in the train pipe 3 at the driver's valve, when the latter is in charging position, through a cavity 21 in the rotary valve 6. If this pressure is less than that corresponding to the setting of a spring 14, the diaphragm is depressed to open a valve 15, whereby a chamber 9 above a piston 10 is vented to the pipes 17, 3. The piston is therefore raised by main reservoir pressure supplied by a pipe 22 to a chamber 11, and the supply pipe and passage 18 is fed through ports 19 in a slide valve 12. Pressure fluid is thus supplied to the chamber 5 of the driver's valve, and thence through a port 20 to the train pipe 3 until the pressure in the chamber 16 raises the diaphragm to allow the valve 15 to close. The pressures on the two sides of the piston 9 then equalize through a passage 23 and a restricted port 24, so that the piston and slide valve are moved to their lower position by a spring 25, and the supply to the train pipe is cut off. The control and supply pipes 17, 18 are permanently connected through a restricted port 26, so that in the event of leakage from the pipe 18 and chamber 5 when the driver's valve is not in charging position, the fall of pressure is communicated through the pipe 17 to the chamber 16, whereby the valve 15 is opened to restore the pressure in the pipe 18 and chamber 5. The possibility of the valve 6 being lifted off its seat by the pressure in the train pipe in the event of leakage from the chamber 5 is thus obviated. The stem 27 of the piston 10 may be provided with a cylindrical portion 28 at its lower end which is guided in a bushing 29.