| 摘要 |
PURPOSE:To provide a driving unit for a hydraulic motor for travelling and driving car, which can prevent cavitation in stopping the car by providing a switching valve adapted to let both supply and discharge paths communicate with each other when the pressure in either of paired supply and discharge paths is negative. CONSTITUTION:In the case where a direction changing valve 11 is located at a position A, and the discharged oil of a hydraulic pump 7 is supplied through a counterbalance valve 13 changed to a position D to a hydraulic motor 5 to drive a car, when the direction changing valve 11 is operated to the neutral position C in such a manner as to stop the hydraulic motor 5, the valve 13 is returned to the neutral position F, with fluid pressure frake force gradually applied to the hydraulic motor 5. At that time, the large inertia force of a high-speed driven car is applied to the hydraulic motor 5, so that the hydraulic motor 5 acts as a pump, and the pressure of the supply and discharge path 1 becomes negative. Accordingly, the pressure in a pilot path 81 is also lowered, and a switching valve 59 is changed to an opening position, which results in that a pair of second paths 17, 19 communicate with each other. |
