Patent ID: 7306049

Claim:
A hammer drill having: a motor with a drive shaft; a housing accommodating the motor therein; and a mode change mechanism comprising: a first gear with a first claw portion and engaged with the drive shaft for transmitting rotation of the drive shaft; a second gear having a second claw portion and engaged with the drive shaft for transmitting rotation of the drive shaft; a first drive sleeve having a third claw portion enageable with the first claw portion of the first gear for transmitting rotation of the drive shaft when the third claw portion of the first drive sleeve is engaged with the first claw portion of the first gear; a reciprocating drive shaft driven in response to the rotation of the first drive sleeve; a hammer mechanism responsive to the rotation of the reciprocating drive shaft for generating a reciprocating striking force; a second drive sleeve having a fourth claw portion enageable with the second claw portion of the second gear for transmitting rotation of the drive shaft when the fourth claw portion of the second sleeve is engaged with the second claw portion of the second gear; a rotary drive shaft driven in response to the rotation of the second drive sleeve; a rotary mechanism responsive to rotation of the rotary drive shaft for transmitting a rotational force to a main spindle; and a switching mechanism for selectively engaging or disengaging the third claw portion of the first drive sleeve with or from the first claw portion of the first gear and also selectively engaging or disengaging the fourth claw portion of the second drive sleeve with or from the second claw portion of the second gear, characterised in that the switching mechanism comprises a seesaw lever pivotally connected to the housing, the seesaw lever being pivotable about a pivot axis substantially perpendicular to the reciprocating drive shaft and the rotary drive shaft, the seesaw lever having a first engaging portion and a second engaging portion disposed on opposite sides of the pivot axis, wherein the first engaging portion is adapted to engage the first drive sleeve such that the seesaw lever is pivotable to disengage the third claw portion of the first drive sleeve from the first claw portion of the first gear and the second engaging portion is adapted to engage the second drive sleeve such that the seesaw lever is pivotable to disengage the fourth claw portion of the second drive sleeve from the second claw portion of the second gear.