Power driven screwdriver

A power driven screwdriver comprising:

• a spindle rotatably supported by a housing and movable relative to said housing in an axial direction between a first position and a second position;
• said spindle having a first central axis and including a forward end for mounting a driver bit thereon, and said spindle being normally kept at said first portion and being movable to said second position when an axial force is applied to said spindle through said driver bit:
• a drive member disposed rearwardly of said spindle on the same axis as said first central axis of said spindle and rotatably driven by a drive source;
• a clutch mechanism provided between said spindle and said drive member and including a protrusion formed on one of said spindle and said drive member and a recess formed on the other of said spindle and said drive member for engagement with said protrusion;
• said protrusion including a conical outer surface having a diameter decreasing toward said protrusion, and said recess including a conical inner surface corresponding substantially to said conical outer surface and having a diameter increasing toward said recess;
• said conical outer surface having a second central axis displaced from said first central axis of said spindle or said drive member by a first distance, and said conical inner surface having a third central axis displaced from said first central axis by a second distance;
• and
• said protrusion and said recess being kept in disengagement from each other so as to interrupt transmission of rotation from said drive member to said spindle when said spindle is positioned at said first position, said protrusion and said recess being brought in engagement with each other through contact between said conical outer surface and said conical inner surface when said spindle is positioned at said second position.