Power tool

A reciprocating power tool comprising:

• a tool bit for performing a predetermined operation on a workpiece by reciprocating,
• a driving motor that drives the tool bit and
• a power transmitting mechanism that converts a rotating output of the driving motor into linear motion in the axial direction of the tool bit,
• the power transmitting mechanism comprising:
• an internal gear having external teeth on its outer peripheral surface, the internal gear being rotatably supported and adapted to receive the rotating output of the driving motor all the time,
• a planetary gear that is driven by the rotating output of the driving motor and revolves around the center of the internal gear,
• a power transmitting part eccentrically disposed on the planetary gear,
• a rotation preventing mechanism that normally prevents rotation of the internal gear by locking a gear that engages with the external teeth of the internal gear, the rotation preventing mechanism being adapted to allow rotation of the internal gear in relation to a load applied to the tool bit and to allow the internal gear to rotate by a predetermined degree and in a predetermined direction, whereby the relative position of the power transmitting part is changed with respect to a point of proximity of the planetary gear to the internal gear, so that a linear stroke of the power transmitting part in the axial direction of the tool bit is changed and
• an internal gear rotation lock that prevents the internal gear from rotating in a direction opposite to said predetermined direction.

A reciprocating power tool comprising:

• a tool bit that performs a predetermined operation on a workpiece by reciprocating,
• a driving motor that drives the tool bit and
• a power transmitting mechanism that converts a rotating output of the driving motor into linear motion in the axial direction of the tool bit,
• the power transmitting mechanism comprising:
• an internal gear having external teeth on its outer peripheral surface, the internal gear being rotatably supported and adapted to receive the rotating output of the driving motor all the time,
• a planetary gear that is driven by the rotating output of the driving motor and revolves around the center of the internal gear,
• a power transmitting part that is eccentrically disposed on the planetary gear,
• a rotation preventing mechanism that normally prevents rotation of the internal gear by locking a gear that engages with the external teeth of the internal gear, the rotation preventing mechanism being adapted to allow rotation of the internal gear according to a load applied to the tool bit and to allow the internal gear to rotate by a predetermined degree and in a predetermined direction, whereby the relative position of the power transmitting part is changed with respect to a point of proximity of the planetary gear to the internal gear, so that a linear stroke of the power transmitting part in the axial direction of the tool bit is changed and
• a one-way clutch that prevents the internal gear from rotating in a direction opposite to said predetermined direction.