| 摘要 |
PROBLEM TO BE SOLVED: To provide a control valve for a closed circuit capable of restraining sudden generation of high brake pressure when rotating a hydraulic motor by external force. SOLUTION: This control valve includes a directional control valve 22 and check valves 6A and 6B arranged between a traveling motor 2 and a variable displacement hydraulic pump 1 connected to the closed circuit via a pair of main pipelines. The check valves 6A and 6B allow a flow of pressure oil to the traveling motor 2 from the hydraulic pump 1. The directional control valve 22 has a driving position (a) for conducting the main pipeline side including, for example, a motor pipeline 11B where the hydraulic pump 1 performs the pump action, the traveling motor 2 performs the motor action and is the outlet side of the traveling motor 2 and a neutral position (b) held when pressure of the pair of pipelines is the almost same pressure. This directional control valve 22 has a passage 26B for conducting the main pipeline side including, for example, the motor pipeline 11B being the outlet side of the traveling motor 2 among the pair of main pipelines and an orifice 24B formed in this passage 26B.
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