| 摘要 |
PURPOSE:To facilitate switching of solenoid valves by performing manual switching of the solenoid valves and switching the solenoid valves from automatic operation to manual operation through mounting and demounting operation of a connector. CONSTITUTION:In a tractor provided with a front wheel steering system A and a rear wheel steering system B having respective hydraulic cylinders 18 and 19, the front wheel steering system A is controlled by means of a two- position four-port type solenoid valve 25 and the rear wheel steering system B by means of a three-position four-port type solenoid valve 28. By switching the oil passages of the solenoid valves 25 and 28 to each other, switching of front wheel and rear wheel steering modes and front and rear wheels iso-phase and opposite phase steering modes to each other is practicable. In this case, the solenoid valves 25 and 28 are switched to each other by manual operation in addition to automatic control by a microcomputer. Switching of the solenoid valves from automatic operation to manual operation is effected through mounting and demounting operation of a connector located between the power source part of a main machine and the source feeding part of a microcomputer. |
