Control valves for steering clutches and brakes

Claim 1

A controlling device for a hydraulic system for steering, comprising a valve body, first and second parallel valve spools slidably aRranged within said body, first and second pilot valves affixed to said valve body, at least one feeding port, one outlet port and one drain port for each spool formed in the valve body and communicating with each of the first and second spools, first pressure chambers located respectively at the ends of the first spool and second pressure chambers located respectively at the ends of the second spool, an oil feeding restricted orifice and a feeding chamber within each spool connected between the first pressure chambers and between the second pressure chambers, said feeding chambers connected to said feeding ports by a feeding hole in each spool, springs contained in the pressure chambers on at least one end of each spool for continuously urging said spool toward its opposing pressure chamber, each of said chambers containing said spring being selectively connected to exhaust by one of said pilot valves whereby when one said pilot valve is opened, the pressure in the opposing pressure chamber moves the spool and compresses the spring.