Abstract: A cut-off valve for power steering systems, especially for automobiles, includes a source of a pressure and a container, and is used for limiting a pressure in at least one pressure chamber. The cut-off valve also includes a closing body, which may be adjusted against the force of a spring and a fixed throttling point, which is located in a connecting line between the pressure chamber that is subjected to a first pressure and a pressure chamber that is subjected to a second pressure. The cross-section of the throttling point may be regulated without being disassembled from the outside. By altering the cross-section of the throttle point, it is possible to reduce the width of the tolerance zone or the width of the hysteresis of the valve characteristics to approximately half of the original size.

Abstract: A centering device for steering valves contains a torsion bar (1) that is clamped between a drive part (2) and a power take-off part (3). Because torsion bar (1) does not permit any exact central positioning, a radial borehole (6) of a valve bushing (3A) connected with the power take-off part (3) is provided. A pin (7) which includes a ball-shaped end engages an oblique surface groove (8) and the pin (7) is loaded by a ring-shaped spring (11). Spring (11) sits in a ring groove (10) and includes a flattened section (12). In the area of the flattened section (12), pin (7) engages a recess (13) of spring (11). The mutually rotatable structural parts can be set exactly in the neutral position by this centering device.

Abstract: An auxiliary power steering unit, especially for motor vehicles, contains a control valve (1) made as a rotary slide valve for controlling a pressure medium conveyed by a servopump (3) out of a tank (4) to and from the pressure chambers of a servomotor (2). Control valve (1) reveals two feedback chambers (10, 11) that are connected via one, each, fixed throttle (12, 13) and a common throttle (14) to a pressure line (15) of the servopump (3). The feedback pressure that takes effect in the feedback chambers (10, 11) can be limited to a maximum value by a cutoff valve (18). The cutoff valve (18) is made as pressure balance whose response pressure can be adjusted from the outside without dismantling.