GB521980A - Improvements in hydraulic receivers more particularly for hydraulically actuated brakes - Google Patents

Abstract

521,980. Hydraulic motors. GRATZMULLER, J. L., and IGNACE, L. R. Nov. 30, 1938. No. 34866. Convention date, Dec. 2, 1937. [Class 69 (ii)] [Also in Groups XXXIV and XXVI] A hydraulic receiver, e.g., for actuating brakes, comprises small and large pistons 14 and 4 adapted to operate in succession, the small piston 14 being connected with the part to be actuated and mounted in a bore 13 in the large piston 4 which works in a cylinder 2 and is subject to the return action of resilient means such of a spring 7. Communication between the cylinder 2 and bore 13 is controlled by a check valve 9 initially unseated by engagement with the end of cylinder 2. Fluid is forced into the cylinder 2 and exerts a pressure on both pistons, but initially the pressure is insufficient to overcome the spring 7 so that at first 'the small piston 14 only is displaced. When the resistance to movement of piston 14 increases, as when the slack in the brake mechanism is taken up, the fluid pressure increases until it is sufficent to overcome spring 7. The large piston 4 then commences to move outwards, the check valve 9 immediately closing so that the two pistons move in unison to apply an increased force. In a modification a rubber or other elastic liner interconnects the large piston and cylinder 2. The return spring 7 is then omitted.