| 摘要 |
PROBLEM TO BE SOLVED: To prevent the generation of damage of a piston rod and a packing due to the dust by providing a cylinder part with a bellows fixed between a tip of the piston rod and a front cover and having a hole so as to supply the gas into the bellows. SOLUTION: When a main switching valve 30 and a switching valve 20 are switched to the forward moving mode, the compressed air is supplied to a primary chamber 10 of a cylinder 1 so as to move a cylinder rod 7 forward. Air of a secondary chamber 11 is pressurized by the forward movement of a piston 6, and flows into a bellows 14 with great force through a secondary port 13, a switching valve 20, a pipeline 21 and a port 25 for bellows. As a result, since the volume of the bellows 14 is quickly increased and the air from the secondary chamber 11 is supplied into the bellows 14 in the pressurized condition, the inside of the bellows 14 is enlarged while maintaining the positive pressure. A part of the air is jetted outside from a hole 16, but the outside air does not flow into the bellows 14. Furthermore, since the air of the secondary chamber 11 is the clean air from a pump, adhesion of the dust to the piston rod 7 can be prevented.
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