| 摘要 |
PURPOSE:To enable a power vehicle having an adjustable front and rear wheel tread to be safely steered even in the case of a narrow tread by slowing the turning speed of steered wheels in the case of a narrow tread, and increasing the turning speed in the case of a wide tread. CONSTITUTION:A selector valve 40 fitted between a valve 35a and a hydraulic pump 30 is normally selected to a left side chamber. The valve 40 is selected to a right side chamber, only when a solenoid D is excited, thereby reducing an amount of hydraulic fluid flowing into the valve 35a. The solenoid D is excited synchronously with a tread change operation for wheels. When a wheel tread is wide, the solenoid D is not excited and the hydraulic fluid flowing into the valve 35a is never throttled. The wheels are, therefore, steered at the standard operation speed. When the tread is narrowed, the selector valve 40 is selected to the right side chamber and the amount of the hydraulic fluid becomes small, thereby delaying the operation speed. As a result, the motion of the wheels is delayed and the direction thereof is not suddenly changed, even when a steering wheel 38 is turned as before. |
