Hydraulic control valves

Claim 1

A hydraulic control valve assembly, comprising: a. a main body member having a first feed connector for communication with an actuator, and a second feed connector for communication with a main control valve, b. a spool slidable longitudinally with respect to said second feed connector, c. a chamber bounded on one side by the spool, cooperative sliding surfaces of the spool and body member extending on opposed sides of said chamber, d. said first and second feed connectors communicating internally of the body member via at least one orifice flow means whose effective flow area is governed by movement of said spool in response to variation of a pilot pressure in said chamber, e. said spool being movably between a fully closed and a fully open position with respect to the orifice flow means such that the rate of increase in effective flow area increases with increased movement of the spool towards the fully opened position, and f. biasing means for urging said spool into the closed position, a portion of increased diameter being provided at one end of the spool, said portion defining an annular chamber extending around the spool within the main body of the valve and a pilot feed connector being provided in the main body member communicating with said annular chamber.