| 摘要 |
PROBLEM TO BE SOLVED: To suppress cavitation when a hydraulic motor is stopped. SOLUTION: A counter balance valve 11 comprises first check valves 12 and 13 provided in the middle of main lines 4 and 5, return passages 14 and 15 provided bypassing the first check valves 12 and 13 in the middle of the main lines 4 and 5, a pressure control valve 16 provided in the middle of the return passages 14 and 15, second check valves 21 and 22 located on the downstream side of the pressure control valve 16 and provided in the middle of the return passages 14 and 15, and a communication passage 23 to communicate the return passages 14 and 15 with each other between the pressure control valve 16 and the second check valves 21 and 22. Pressure oil discharged to the main line 5 from a hydraulic motor 3 which is inertially rotated during the stop is fed to a suction side of the hydraulic motor 3 via the return passage 15, the pressure control valve 16, the communication passage 23, the return passage 14, the second check valve 21, the main line 4 and the like, and generation of cavitation can be suppressed thereby. COPYRIGHT: (C)2004,JPO
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