Abstract: A hydraulic control circuit for a vehicle steering system is provided. The hydraulic control circuit is responsive to the rotational position of a steering wheel and controls the actuation of a steering gear assembly in response thereto. The hydraulic circuit includes a first actuator coupled to the vehicle steering wheel and a second hydraulic actuator coupled to the vehicle steering gear assembly. The first and second hydraulic actuators are coupled together by a pair of fluid conduits. Rotation of the steering wheel selectively causes the first actuator to force hydraulic fluid through one of the plurality of fluid conduits to cause the second hydraulic actuator to produce a corresponding output motion. The corresponding output motion is operable for actuating the steering gear assembly in a predetermined direction. The preferred embodiment includes a control system for improved monitoring and control of the hydraulic circuit, as well as an assist pump and compensation valve for gain control.