| 摘要 |
PURPOSE: To prevent cavitation at abnormal rotation time of a hydraulic pump by preventing a pilot operation type main check valve from being forcedly opened by a malfunction of an opening solenoid valve, and preventing inside leakage of the pilot operation type main check valve by an oil temperature rise. CONSTITUTION: A check valve 109 is arranged in a prescribed part between a hydraulic cylinder 104 for raising a car 100 and a hydraulic pump 121 for pumping a hydraulic fluid, and a cylinder pressure detecting means 116 is arranged on upper one side of the check valve 109. A hydraulic pump pressure detecting means 117 is arranged on lower one side of the check valve 109, a closing solenoid valve 111 is arranged on one side of a pipeline connected to the check valve 109, and is constituted so as to apply pilot pressure to an opening solenoid valve 110 only by pressure generated from the hydraulic pump 121. |
