GB301358A - Improvements relating to fluid pressure braking apparatus - Google Patents

Abstract

301,358. Winter, H. J., and Westing- house Brake & Saxby Signal Co., Ltd. Aug. 27, 1927. Fluid-pressure.-Application of the vacuum brakes on a locomotive is brought about by the application of the compressed air brakes on the train by means of a control valve comprising a valve 19 adapted to admit air to the vacuum train pipe 7 and controlled by the pressure in the compressed air train pipe acting in a chamber 14 on a piston 18, and the pressure in the vacuum train pipe acting in a chamber 3 on a diaphragm 2 and a substantially constant pressure acting in a chamber 10 on a piston 9. The pistons 9, 18 and the valve 19 are attached to the diaphragm by spindles 9<a>, 21. The constant pressure is supplied to the chamber 10 through a non-return valve 12 and the chamber 14, from a pipe 15 connected to the equalizing reservoir 16 of the compressed air drivers valve. Atmospheric pressure exists in chambers 4, 20. When the pressure in the compressed air train pipe is reduced the pressure in chamber 14 is reduced and the pistons and diaphragms move to the left to open the valve 19 and admit air to the vacuum pipe 7 through the chamber 3 and pipes 5, 24, until the pressure in the chamber 3 is sufficient to move the diaphragm to reclose the valve 19. For every pressure in the compressed air pipe there is thus a corresponding pressure in the vacuum pipe. A modified arrangement is shown in which the constant pressure in the chamber 10 is replaced by a spring acting on the diaphragm 2. The spring and the constant pressure may be used simultaneously. A cock 6 is provided so that the control valve can be cut off from the vacuum pipe 7 when the locomotive is coupled to vehicles having vacuum braking apparatus. When the control valve is connected to the train pipe 7 a small passage 26 in the cock leads to the ejector device 28.