Patent ID: 7410007

Claim:
An impact rotary tool, comprising: (a) a gearbox connected to a motor and a drive shaft; (b) an impact mechanism including a hammer block connected to the drive shaft and an anvil disposed concentrically with the drive shaft and configured to be selectively engaged by the hammer block, (c) a mode selector moveable between a first orientation where the hammer block is movable parallel to a longitudinal axis of the drive shaft against the biasing force of a spring to cause reciprocating engagement with the anvil and to cause the anvil to rotate and a second orientation where the hammer block substantially constantly engages the anvil causing the anvil to rotate, and; (d) a switching mechanism including a stopper that is movable along the outer surface of the drive shaft with motion of the mode selector, and the stopper is connected to a first pin that moves along a first slot in the drive shaft, wherein when the mode selector is in the first orientation, the stopper does not engage the hammer block and when the mode selector is in the second orientation the stopper engages the hammer block to maintain substantially constant contact between the hammer block and the anvil.