PURPOSE: To control a rear wheel to surely return to the neutral position with an auxiliary motor when abnormality occurs, especially, in the main control system.
CONSTITUTION: In a four-wheel steering gear, which steers rear wheels by computing the rear wheel steering angle, based on the detection signal of a sensor for detecting the condition of a vehicle and controlling the revolution of a first electric motor 16, a second electric motor 25 is provided, which is coupled with a rear wheel steering unit if abnormality occurs in this rear-wheel steering control system. This second electric motor 25 is supplied with a drive current through a changeover switch 32. This changeover switch 32 has a rotary plate equipped with a slide contact rotated by the rotary shaft steering the rear wheel and a fixed contact plate, and is so arranged as to stop the second electric motor 25 in neutral position, inverting the polarity of the drive current of the second electric motor 25 at or around an angle a in the vicinity of the neutral position of the rear wheel.
HASEDA TETSUSHI
OGURA HIROSHI
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