To solve a problem that a working machine using environment is polluted when a pressurized fluid is leaked from a gap and the like because the pressurized fluid is used as the hydraulic fluid in a working machine such as a forklift, and that limitation exists when used in a warehouse for foods and the like.
A check valve is provided to be interposed in a flow passage between a cylinder 12 of a valve for the working machine 1 and a check valve 3 lower part chamber communicated to an inflow port PS and a outflow port TI by spool 2 drive, to be opened by pressurized water from the inflow port when the working machine is operated, and to close the passage by a pressure difference between pressure in the check valve lower part chamber lowered by discharge of the pressurized water from the outflow port when a set position of the working machine is held and pressure of the pressurized water in the cylinder. The check valve closes thereby the passage by a face sheet based on the pressure difference, leakage from the gap is substantially eliminated in the valve even when the pressurized water is used as the hydraulic fluid, and the leakage is substantially eliminated to hold the set position and a set attitude accurately, in particular, even in use of the pressurized water when the working machine is held in a fixed position.
FUTAHASHI KENSUKE
SATO AKIRA
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