| 摘要 |
A steering system for a construction vehicle operable to control the position of a pair of front wheels and a pair of rear wheels relative to the frame of the vehicle includes a hydraulic fluid circuit for distributing hydraulic fluid. A hydraulic cylinder is connected to each of the wheels for turning same in a desired manner. A steering wheel is interposed in the hydraulic fluid circuit for selectively directing hydraulic fluid to the cylinders for steering said wheels in a desired direction. A mode selector valve is interposed in the fluid flow circuit between the steering wheel and the cylinders for selectively selecting either four-wheel steer, crab steer, or front-wheel steer mode of steering for said vehicle. A control momentarily overrides the mode selector valve to isolate the rear hydraulic cylinders from the front hydraulic cylinders for permitting independent movement of the rear wheels of the vehicle. |
