| 摘要 |
A speed adjusting apparatus for a pneumatically driven power tool includes a control valve that is adapted to be mounted rotatably within an intake passageway in an outer housing. A connecting rod extends through a pivot hole in a rear cover, and interconnects the valve and a rotary member that is disposed rotatably on the rear cover in such a manner that the valve rotates synchronously with the rotary member. The rotary member can be rotated to align an intake outlet passageway in the valve with a selected one of a forward passageway and a reverse passageway in the rear cover. When the intake outlet passageway is aligned with the forward passageway, a tool head rotates in a direction. When the intake outlet passageway is aligned with the reverse passageway, the tool head rotates in the opposite direction. The tool head rotates at a speed, which depends on the intersecting area between the intake outlet passageway and the selected one of the forward passageway and the reverse passageway that is determined by the rotational angle of the rotary member relative to the rear cover.
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