Control valves

Claim 1

A pressure compensated directional control valve comprising a directional control valve for selectively operating a fluid motor at controlled speed, said valve having inlet and outlet ports and first and second motor ports for connection to opposite sides of a fluid motor, a longitudinal bore in said control valve, a valve spool movable in said bore, said valve spool being hollow at each end forming spaced chambers selectively communicating through the valve spool walls with the inlet ports, outlet ports and work ports and with a pair of spaced grooves surrounding the valve spool, flexible annular band check means surrounding each groove, a pressure sensing port communicating selectively with each groove in the spool, a pressure compensating valve having an axial bore, an inlet port connected to the inlet port of said control valve, an outlet port connected to the outlet port of said control valve, a pressure sensing port communicating with the pressure sensing port of the directional control valve, a valve member movable in said axial bore, means biasing said valve member to a position normally blocking said outlet from said inlet port, said valve member having opposite surfaces thereon exposed respectively to fluid pressure from said inlet port and to fluid pressure at said pressure sensing port acting with said biasing means, said valve member being movable in response to fluid pressure differential between its inlet port and pressure sensing port through the pressure sensing port of the directional control valve to connect said inlet and outlet ports for bypassing input pressure fluid to thereby regulate the input flow through said directional control valve to one of said work ports.