Hydraulic valve

摘要

592,949. Fluid - actuated valves. PAGE, H, E. Nov. 9, 1944, No. 22100. Convention date, Oct. 30, 1943. [Class 135] A hydraulic valve, for use particularly in hydraulic jacks, comprises a body. 5 having a fluid inlet port 10 leading from a pumping cylinder 8 to an inlet chamber 27, a pressure chamber 42 in communication with a work cylinder 9 via the port 11, a check valve 55 in the pressure chamber seating towards the inlet, an assembly of elements in the pressure chamber including the spring-loaded hollow main plunger 40 and the spring-loaded auxiliary plunger 50 exerting resilient seating pressure on the check valve and means, e.g. the shoulder 40a on the main plunger, responsive to pressure in the pressure chamber for reducing the seating pressure exerted on the check valve. If the piston 16 is fixed, downward movement of the piston 15 will trap fluid in the inlet chamber and force the body 5 downward, the partial vacuum created in the cylinder 9 being relieved by fluid from the reservoir R entering via the port, 12 and the poppet 65, so that the body 5 quickly contacts the work and encounters sufficient resistance to movement to cause the opening of the check valve. If the pressure inthe cylinder 9 becomes too high, the poppet 75 is unseated and the fluid is released via the ports 80, 12, to the reservoir. For effecting a slow release of pressure in the cylinder 9, the check valve 55 is unseated by the cam 90 and the port-obstructing member 32a, the fluid escaping via the poppet 30 and the passages 28 to the reservoir.