Abstract: A hydraulic power steering system for non-tracked vehicles, particularly motor vehicles, has a steering adjustment of the steered vehicle wheels which takes place of a hydraulic actuating assembly which can be connected by a change-over valve with one respectively of two or several hydraulic circuits. In normal operation, the circuits operate in parallel and functionally in the same direction so that, in the event of a disturbance, a change-over can take place to another hydraulic circuit without any interruption. For controlling the actuating assembly, each hydraulic circuit comprises a servo valve which is operated as a function of a desired-actual value comparison of the steering angle by a control and automatic control device, which is connected with an actual steering angle value generator operated by the steered vehicle wheels and a desired steering angle value generator controlled by way of the steering handle operated on the driver side.

Abstract: The invention relates to a hydraulically assisted steering system for a motor vehicle. Because there is associated with the hydraulic system an electromechanical valve 12 which, in the open state, hydraulically indirectly or directly connects the working chambers 3 , 4, it is possible to dispense with conventional mechanical pressure limiting valves, secondary suction valves and limit stop valves.

Abstract: A steering valve arrangement of a hydraulic steering system has a rotary valve with a first and a second control part that are rotationally movable relative to one another. By rotational adjustment of the control parts a hydraulic servomotor is controlled which is connected drivewise with the steered wheels of a vehicle. An electric motor is mounted in a fixed location for actuating the rotary valve relative to the first control part and is connected drivewise with the second control part. The driving connection from the electric motor to the second control part is provided indirectly by a step-down transmission, including a small gear fixed to the motor drive shaft and a large gear connection with the second control part. The steering valve and the motor are disposed side by side and parallel to one another in a compact design.