Hydraulically operated lock valve assembly

Claim 1

A lock valve assembly for controlling fluid flow in a hydraulic jack having inlet and outlet means for selectively supplying fluid to either end of the jack cylinder while exhausting fluid from the opposite end comprising: a valve housing; a bore formed in said housing; a first pair of ports in spaced communication with said bore for communicating with a source of pressurized fluid; a second pair of ports communicating with said bore and opposite ends of the jack cylinder; first check valve means disposed in said bore between one of said first ports and one of said second ports; second check valve means disposed in said bore between the other of said first port and the other of said second port; each of said first and second check valve means including a passage communicating between each of said respective first and second ports, a valve seat surrounding said passage, and a valve element engaging said seat normally for blocking fluid flow from said second pair of ports to said first pair of ports; and an actuator piston reciprocally disposed in said bore between said first pair of ports and having a pair of plungers extending axially from opposite ends thereof, said plungers terminating in metering head means operative to engage and unseat either check valve element upon endwise movement of the piston, said metering head means being shaped to provide separate metering portions cooperating with said valve passage for regulating fluid flow through the check valves.