| 摘要 |
PURPOSE:To improve safety in a device hydraulically steering right and left rear wheels by discriminating failing based on signals from three sensors for main pressure, operating condition of a control valve, and rear wheel steering angle, and stopping control of rear wheel steering. CONSTITUTION:A rear steering device B is provided with a hydraulic cylinder 30 to steer right and left rear wheels 2R, 2L by displacement of relay rods 13 in the axiall direction, and right and left steering hydraulic chambers 34,33 partitioned with the piston 32 are communicated to a control valve 36. A control valve sensor 56 to detect operating condition of the control valve 36 based on the stroke of the spool 36a of the control valve 36, a rear wheel steering angle sensor 58 to detect rear wheel steering angle based on displacement of the relay rods 13 in the axial direction, and a pressure sensor 44 to detect main hydraulic pressure, are provided, and these output signals arc input to a control unit 15. From these outputs failing in the hydraulic system is discriminated early and surely, control of rear wheel steering is stopped at discriminating trouble, and the relay rods 13 are returned to neutral position by energizating force of a centering spring 61. |
