Patent ID: 7588094
Filing Date: 2009-09-15
Classification: B25B

Abstract:
1. A power hand tool comprising: a housing; an electric motor mounted in said housing for providing a rotary motion; a transmission gear set having an output shaft and mounted in said housing and connected with said electric motor for decelerating the rotary motion of said electric motor down to a predetermined speed and then outputting it via said output shaft; a torsion control device having a base, a rotary disk, and a first rotary knob, said base being connected with said transmission gear set and located in said housing, said rotary disk being mounted to said base, said rotary disk being rotatable on a rotary center of said output shaft, said rotary disk being axially movable along said output shaft for adjusting the maximum torsion output of said output shaft, said first rotary knob being mounted to said housing for rotation on the rotary center of said output shaft and connected with said rotary disk for driving rotation of said rotary disk while being turned, said first rotary knob further having an internal periphery and a plurality of dents formed on the internal periphery thereof; an impact device having a switch and a second rotary knob, said switch being mounted in said housing for reciprocating rotation on the rotary center of said output shaft, whereby one of the reciprocating rotation can switch on or off an impact motion formed from said output shaft, said second rotary knob being mounted to said housing for rotation on the rotary center of said output shaft and being connected with said switch for driving rotation of said switch while being turned, said second rotary knob further having an internal periphery and a plurality of second dents formed on the internal periphery thereof; and a locating device having a holder and a locating member, said holder being fixed to said base of said torsion control device, said locating member having two separate base portions and two resilient portions parallel located between said two base portions, each of said resilient portions having a convexity, said base portions of said locating member being mounted to said holder, said two resilient portions facing internal peripheries of said first and second rotary knobs respectively, said convexities of said resilient portions being engaged with said first dents or said second dents, whereby while said first rotary knob or said second rotary knob is turned, said convexities of said resilient portions are engaged with the associated said first dents or said second dents.