NUT-DRIVER Russian patent published in 1994 - IPC

FIELD: power tools. SUBSTANCE: nut-driver is placed on the nut of threaded joint which was slightly screwed beforehand and electric drive is started. Rotation is transmitted through first and second stages of planetary reduction gear, splined shaft, drive and drive clutch members and carrier to the spindle provided with head which performs accelerated screwing of the nut. As resistance in the thread increases, current relay disconnects the electric drive and feeds voltage to the electromagnet coil; as a result, ring armature moves towards the carrier and jaws of drive member of inner clutch are thrown into engagement with jaws of driven clutch, thus engaging the third stage of the planetary reduction gear. Then electric motor is switched on again and spindle starts rotating at lesser angular velocity tightening the threaded joint at higher torque. EFFECT: enhanced efficiency and ease in operation. 4 dwg