| 摘要 |
PROBLEM TO BE SOLVED: To replace a hydraulic fluid with a simple structure at a low cost by providing a drain oil pipe connected with one end to the tank side discharge port of a circulation pipe provided between a pressure oil feed pump driving a hydraulic jack and an oil tank, and providing a drain oil tank storing the hydraulic fluid discharged from the drain oil pipe. SOLUTION: A hydraulic fluid is stored in an oil tank 1, and a reflux pipe 8 is provided between a control valve 5 and an oil tank 1. As the oil temperature is lowered, a warming-up operation is conducted to return the control oil sucked by a pump 3 from a pipe 2 into the oil tank 1 via a pipe 4, the control valve 5 and the reflux pipe 8, and the oil temperature is increased. A hydraulic fluid replacing device is provided with a drain oil pipe 10 connected with one end to the discharge port 8a of the reflux pipe 8 and a drain oil tank 11 arranged at the other end of the drain oil pipe 10. When the hydraulic fluid is to be replaced, a warming-up operation is conducted, the hydraulic fluid discharged from the discharge port 8a is stored in the drain oil tank 11 via the drain oil pipe 10, and the hydraulic fluid in the oil tank 1 is discharged.
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