| 摘要 |
PCT No. PCT/EP94/00499 Sec. 371 Date Aug. 23, 1995 Sec. 102(e) Date Aug. 23, 1995 PCT Filed Feb. 22, 1994 PCT Pub. No. WO94/19226 PCT Pub. Date Sep. 1, 1994In a servo-steering unit provided for motor vehicles, one pinion (2) supported in a steering housing (1) meshes with a rack (6). A steering valve (8) which serves to control the pressurized fluid for the servo-steering unit has two inlet seat valves (10, 11) and two outlet seat valves (12, 13) the closing members of which are movable via actuating tappets depending upon rotation of a steering spindle. The outlet seat valves (12, 13) are open in the neutral position of the steering valve. The inlet seat valves (10, 11) are actuatable in a closing direction by the force of pressure springs and are opened only after closing of the respective outlet seat valve (12, 13). A limiting piston (31) is provided for each side of the steering valve (8). Each limiting piston (31) is actuated on one side by one of the centering springs (30) and by a first pressure prevailing in a working chamber of a servo-motor and on the other side by a limiting force. In the neutral position of the steering valve (8) the limiting force is stronger than the force of the centering spring (30) so that the limiting piston (31) abuts against a stop shoulder in the neutral position of the steering valve (8). An "interception" or "actuating torque limitation" is obtained with such an arrangement.
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