| 摘要 |
PROBLEM TO BE SOLVED: To secure the supply oil pressure of a cavitation prevention circuit in a device for damping inertia force generated by a fluctuation frame. SOLUTION: A pump 42 supplied to a control valve 40 is provided through a first supply line 44 in a hydraulic device. Fluid from the control valve is guided to a hydraulic cylinder through a working line 46, and fluid discharged from the hydraulic cylinder is guided to a discharge line 50 having a back pressure check valve 52 set at a first pressure level through the control valve. Pressure relief valves 56, 58 attached mutually in parallel and cavitation prevention valves 60, 62 are provided on the hydraulic cylinder. In order to keep the discharge line in a filling state, a second supply line 70 extends between a first supply line and the discharge line. A pressure reducing valve 72 set at a second pressure level lower than the first level of the back pressure check valve is provided on the second supply line.
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