| 摘要 |
PROBLEM TO BE SOLVED: To provide a piston 3 structure of a pneumatic screw tightening tool capable of reducing the rotating resistance of a screwdriver bit 6 at the time of tightening. SOLUTION: The screw driver bit 6 drivingly rotated by an air motor is slidably disposed in a housing, a piston 3 slidably stored in a cylinder 2 arranged along the longitudinal direction of the screwdriver bit 6 is disposed opposedly with the upper end of the screwdriver bit 6, and a sliding resistance reducing means such as steel balls 21 is provided between the upper end surface of the screwdriver bit 6 and the lower end surface of the piston 3.
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