Patent ID: 7828074

Claim:
A hammer drill comprising: a motor; a spindle rotatingly driven by the motor and holding an output bit; a motion conversion member for converting rotational movement of the motor to reciprocating movement; a striker reciprocatingly driven by the motion conversion member for applying an axial striking force to the output bit; a striking-motion-releasing mechanism for releasing the striking force applying action exercised by the striker; a tightening-torque adjusting clutch for interrupting a transfer of a rotational force to the output bit when a load torque applied to the output bit is larger than a threshold fastening torque; and a clutch handle for adjusting the threshold fastening torque, the clutch handle having a groove, wherein an end of the striking-motion-releasing mechanism is engaged with the groove of the clutch handle so that the striking-motion-releasing mechanism is adapted to move in response to the actuation of the clutch handle so as to convert a releasing operation of the striking force applying action to a non-releasing operation and vice versa.