| 摘要 |
This screwdriver is driven pneumatically and has all pneumatic control means. The screw-gripping jaws operable pneumatically are separately controlled from the operation of the screwdriver to grip the screw first loosely as it is fed into place between the jaws, the jaws being thereafter closed for accurate positioning and guiding of the screw while the driving commences, the jaws finally opening wide as the screw is driven home. Pneumatic limit switches or valves control the operation of the screwdriver independently of the control of the screw-holding jaws, and a mechanically operable torque measuring gauge or clutch automatically shuts off pneumatic power to the screwdriver by switch or valve control when the screw is driven home or in the event of a jam due, for example, to cross-threading. There is an adjustability feature adapting the screwdriver to operation on different lengths of screws.
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