Patent ID: 7537540
Filing Date: 2009-05-26
Classification: B23B,B25B,F16H

Abstract:
1. An electric motor-driven screw driving or drilling tool device having a housing and a drive shaft disposed within the housing, the device comprising: a planetary gear disposed within the housing, said planetary gear having a ring gear and planet wheels disposed within and cooperating with said ring gear, said planet wheels being driven to roll about said ring gear, said planet wheels having axles driving the drive shaft; locking bodies cooperating with an outer periphery of said ring gear to lock said ring gear relative to said housing, said locking bodies structured for outward displacement in a radial direction when a switch-off torque has been exceeded for thereby allowing said ring gear to rotate relative to the housing, wherein the drive shaft is no longer driven; leaf springs extending in a peripheral direction of said ring gear to pretension said locking bodies in a radially inward direction; and means for adjusting a lever arm length of said leaf springs in a peripheral direction to generate differing bending forces acting on a respective locking body for torque adjustment.