Patent ID: 8307937

Claim:
An apparatus for use in steering rear wheels of a vehicle which has front wheels which are steered in response to turning of a steering wheel; said apparatus comprising: a pump connected in fluid communication with a reservoir, a hydraulic motor connected with the rear wheels of the vehicle, said hydraulic motor including a first chamber which holds hydraulic fluid and a second chamber which holds hydraulic fluid, each one of said first and second chambers including a hydraulic fluid inlet through which fluid flows into said one of said first and second chambers and a hydraulic fluid outlet through which hydraulic fluid flows from said one of said first and second chambers, an increase in fluid pressure in the first chamber acting to turn the steerable rear wheels of the vehicle in a first direction and an increase in fluid pressure in the second chamber acting to turn the steerable rear wheels of the vehicle in a second direction; a control valve which is connected in fluid communication with said pump and with said inlets to said first and second chambers of said hydraulic motor, said control valve directing fluid to at least one of said first and second chambers to steer the rear wheels of the vehicle in response to turning of the steering wheel, said control valve being free of a return flow of hydraulic fluid from said motor to the reservoir when said control valve directs fluid to the at least one of said first and second chambers; and a conduit which is connected with the hydraulic fluid outlets from the first and second chambers and which conducts a flow of hydraulic fluid from the hydraulic fluid outlets to the reservoir along a flow path which is spaced from said control valve.