| 摘要 |
PURPOSE:To aim at improvement in operation reliability, by arranging two spool valves and a stop valve in a hydraulic circuit between a pump and a hydraulic jack and performing the circuit opening/closing according to the change over of the stop valve, thereby increasing and decreasing the ground clearance. CONSTITUTION:In the ground clearance increase, the spool 33 of a stop valve 32 is moved and positioned on the upper side, thereby hydraulic pressure via an oil passage 5a, the oil chamber 8 of a spool valve 6 is led from the oil chamber 34 of the stop valve 32 into a tank 3, and the spool 7 of the first spool valve 6 is raised so as to close an oil hole 11. Therefore, the oil chamber 9 of the spool valve 6 is led into the oil chamber 16 of the second spool valve 14, a spool 15 is pushed down and returned so as to close an oil passage 26, thus a hydraulic circuit being closed. Accordingly, a check valve 22 is opened, and the hydraulic pressure is supplied to a hydraulic jack 21 so that the ground clearance is increased. On the other hand, in the ground clearance decrease, the spool 33 of the stop valve 32 is lowered, and an oil passage 38 and the oil chamber 34 are closed, thereby the circuit being opened. With this arrangement, it is possible to improve reliability in operation. |
