| 摘要 |
PROBLEM TO BE SOLVED: To efficiently cool a hydraulic fluid even by use of a cooling device with a small capacity by providing an accumulator for accumulating pressure oil exceeding the capacity of the cooling device on an inlet oil path of the cooling device. SOLUTION: A cooling device 14 for cooling a hydraulic fluid is disposed in a return oil path extending from a control valve 12 to an oil tank 11, and the capacity of the cooling device 14 is set smaller than the maximum discharge flow of a hydraulic cylinder S. An accumulator 17 for accumulating pressure oil is provided in an oil path extending from the control valve 12 to the cooling device 14, whereby when the discharge flow from the hydraulic cylinder S exceeds the capacity of the cooling device 14, the surplus can be accumulated in the accumulator 17. Therefore, the hydraulic fluid is discharged to pass through the cooling device 14 after the discharge flow of the hydraulic cylinder S is decreased, so that it can be efficiently cooled. Thus, it will be sufficient to provide the cooling device 14 with a small capacity, which contributes to lowering of noise and compactness of the device.
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