| 摘要 |
PROBLEM TO BE SOLVED: To automatically and stably switch a breaking pressure in response to a load. SOLUTION: If a load is positive, pressure oil which is pressurized by a port (a) of a hydraulic motor 2 flows into a port (b), thereby a pressure of the port a being increased. As a result, selector valve 4A having a large hysteresis is switched, a pilot check valve 3B1 0f a breaking pressure circuit 3B at the port (b) side is applied a pressure so as to reduce a passage resistance at the port (b) side, and a pressure at the port a side is set appropriately according to a load. If a load is negative, a pressure of the port (a) is decreased. As a result, the selector valve 4A is kept in a neutral condition and the pilot check valve 3B1 is kept closed, resulting that a meter-out control is provided by throttle valve 3B2. In either case, the selector valves 4A, 4B having a large hysteresis can stabilize the operation in a broader pressure range.
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