| 摘要 |
PROBLEM TO BE SOLVED: To recycle return pressure oil from a hydraulic motor. SOLUTION: This system is provided with a hydraulic pump 10, an operation valve 13 and a counter balance valve 30. The return pressure oil from a hydraulic motor 17 is streamed out from the operation valve 13 to a recovery circuit 23 and a back pressure valve 25 is provided in this recovery circuit 23. When the counter balance valve 30 is positioned to a first position B and a second position C from a neutral position A, a first selector valve 37 for communicating a first pressure receiving part 32 to a tank and a second selector valve 41 for communicating a second pressure receiving part 33 to the tank are provided. Thereby, when the hydraulic pump 10 is rotated by an outer force and the delivery pressure of the hydraulic pump 10 is dropped, the counter balance valve 30 is not positioned to the neutral position A and a return pressure oil is streamed in the delivery passage 11 of the hydraulic pump 10. |
