| 摘要 |
Screwdriver operated with compressed air, which stops automatically when a predetermined torque is reached, with a housing, a compressed air motor situated therein, and an output shaft which is connected to the screwdriver bit by a disengageable coupling. A control valve is provided in the housing for controlling the air to the motor. The position of the valve is controlled by a rod which passes through the shaft. A transverse slot is provided in the shaft, which intersects a longitudinal bore drilled therein and in which a pair of balls are held with the aid of a sleeve surrounding the shaft. A return pin engages on the screwdriver bit on the one hand and on the balls on the other hand, in order to displace the latter in the slot in such a direction that the valve opens. When the predetermined torque is reached, the sleeve moves in such a manner that the balls can move apart from one another and at the same time the valve rod can move in such a manner that the valve closes. <IMAGE>
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