| 摘要 |
Backwards counters (11,12) are preset with upper and lower limits of the angle through which screws are to be driven, the counters being loaded when a certain value of torque is reached, at which time counting down begins with each increment of rotary angle. When the operation is completed in the usual way after reaching a limit value of torque, the increasing interval between count pulses is detected by a delay circuit (7) and counting is stopped. A logic circuit (15) shows whether the screw connection is satisfactory or whether it is underdriven or overdriven.
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