Patent ID: 7841424

Claim:
A power output mechanism for power tools, comprising a main part driving an output shaft, a pressing unit, and an operation member; a switch unit having a tubular portion and a rotation collar mounted to the tubular portion, the tubular portion including a plurality of slots and the rotation collar including a plurality of axial protrusions; an impact unit having an orientation wheel which is movably connected to the output shaft and an operation wheel which is secured to the output shaft, the orientation wheel including a first toothed contact surface and the operation wheel including a second toothed contact surface which is removably engaged with the first toothed contact surface, a ring portion defined on an outer periphery of the orientation wheel; and a plurality of positioning springs located in the slots of the tubular portion and inserted into the rotation collar, the ring portion of the orientation wheel having a corrugated surface defining peaks and valleys, wherein when the rotation collar is rotated to a non-impact position, the positioning springs are located within the rotation collar and do not engage with the valleys so that the orientation wheel is freely rotatable relative to the output shaft, when the rotation collar is rotated to an impact position, the positioning springs are pushed by the rotation collar and engaged with the valleys so that the orientation wheel is restricted to rotate relative to the output shaft, the operation wheel moves periodically toward the orientation wheel so as to output an intermittent impact from the output shaft.