GB1081997A - Improvements in and relating to valves for fluid pressure systems - Google Patents

Abstract

1,081,997. Valves; fluid-pressure brakes. AUTOMOTIVE PRODUCTS CO. Ltd. Sept. 24, 1964 [Oct. 11, 1963], No. 40140/63. Headings F2F and F2V. In a valve supplying a fluid pressure-operated brake, the inlet and outlet pressures are equal until the outlet pressure reaches a first predetermined value, whereafter further increase of the inlet pressure causes the outlet pressure to rise at a reduced rate until, when the inlet pressure reaches a second predetermined level, the supply to the brake is cut off. In the embodiment shown, fluid initially flows from a master cylinder to an inlet 17 and thence via a first port 14, the interior of two axially slidable concentric pistons 6, 7, a second port 20 in piston 6 and radial ports 21 to outlets 23 connected to the wheel cylinders. When the outlet pressure reaches a predetermined value it causes the inner piston 6 to move to the left against the action of a spring 12, thereby allowing a ball 24 to close port 20, the ball having been held away from the port by a projection 27 on a plug 9 screwed into the end of piston 7. If the inlet pressure is now increased, the ball 24 will open and close the port to raise the outlet pressure in proportion to the ratio of areas A 1 and A 2 . On reaching another predetermined value the inlet pressure moves piston 7 to the right against the action of a spring 10, thereby allowing a ball 18 to close port 14, the ball having been held away from the port by a projection 13 integral with piston 7.