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All-wheel steering

  • US 5,092,419 A
  • Filed: 09/29/1989
  • Issued: 03/03/1992
  • Est. Priority Date: 10/01/1988
  • Status: Expired due to Fees
First Claim
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1. All-wheel steering for motor vehicles having front wheel steering actuated by a steering handwheel and motor-driveable rear wheel steering which is actuated by a control means as a function of a vehicle parameter through comparison of set values and actual values of the rear-wheel steering angle, comprising:

  • the front wheel steering is positively coupled to a first double-acting piston-cylinder unit positively coupled to the front wheel steering and having two swept chambers of different effective piston area and a piston which, in a central straight-ahead position of the front wheel steering, connects the two swept chambers of the piston-cylinder unit;

    a self-locking-free motor drive provided in the rear wheel steering and prestressed by a spring arrangement into a straight-ahead position of the rear wheel steering;

    said self-locking-free motor drive being positively coupled to a second double-acting piston-cylinder unit;

    the second double-acting piston-cylinder unit having two swept chambers which have an equal effective piston area ratio with the swept chambers of the first double-acting piston-cylinder unit;

    said two piston-cylinder units fluidly coupled to one another via two connecting hydraulic lines with one line connecting the larger swept chambers of the two piston-cylinder units and the other line connecting the smaller swept chambers;

    a third double-acting piston-cylinder unit having two swept chambers which have an equal effective piston area ratio with the swept chambers of the first and second piston-cylinder units, the larger swept chamber of the third piston-cylinder unit being connectable via a shut-off valve to the line connecting the larger swept chambers of the two other piston-cylinder units and the smaller swept chamber of the third piston cylinder unit being connectable via a further shut-off valve to the other of the two lines connecting the smaller chambers of the two other piston-cylinder units;

    wherein, when the two shut-off valves are closed, front wheel steering and rear wheel steering are hydraulically positively connected by the two lines to produce a deflection in the same direction of front and rear wheels.

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