| 摘要 |
PROBLEM TO BE SOLVED: To prevent generation of a water hammer by preventing leakage of pressure fluid and avoiding sudden closing of a valve element held in a valve opening state and sudden closing of the valve element in the midway of closing even when cracking and damage are caused in a pressure fluid supply and discharge system between a pressure fluid supply and discharge port and a flow change-over means of the pressure fluid. SOLUTION: A working regulation valve 31 of a cylinder is provided adjacent to a pressure oil supply and discharge port 8A in a first communicating pipe 18 provided along a coupling 14 and the pressure oil supply and discharge port 8A of a hydraulic cylinder 6. Consequently, the working regulation valve 31 of the cylinder is made to open in a state of equilibrium of first pressure of the pressure oil supply and discharge port side 18A and second pressure of a coupling side 18B in the first communicating pipe 18, and the working regulation valve 31 of the cylinder is made to close in the case when the coupling side 18B is broken and differential pressure is generated between the first pressure and the second pressure.
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