Hydrostatic control device, particularly steering device

Claim 1

A hydrostatic steering control device, comprising, a housing have a plurality of ports including inlet and outlet ports and two motor ports connectable to an external servomotor, a metering motor having a casing rotatably mounted in said housing, a rotor mounted in said metering motor casing and being moveable relative thereto to form expansible and collapsible chambers, control shaft means for actuating said rotor, directional valve means for selectively directing pressurized fluid to and draining fluid from said motor ports, said directional valve means having opposite turn functions, said directional valve means having axially abutting planar faces respectively on said housing and said metering motor casing and being operable upon said shaft turning said casing and said rotor in unison, commutating valve means for selectively directing pressurized fluid to and drainage fluid from said motor means to impart directional movement thereto pursuant to the operation of said directional valve means, said commutating valve means being between said metering motor casing and said rotor, resilient means for maintaining said directional valve means in a neutral position in the absence of a turning force on said shaft, passage means cooperable with and connecting said housing ports with said directional valve means and said commutating valve means, said directional valve means being operable for each said turning function to (1) route pressure fluid from said inlet port through one side of said commutating valve means to expanding chambers of said metering motor and pressurized fluid from collapsing chambers of said metering motor to one of said motor ports and (2) route fluid from the other of said motor ports to said outlet port.