Freeing mechanism for motorized gear reducer

摘要

A motorized gear reducer wherein a first external gear 41 is mounted on an input rotary shaft 11 coupled to a driving motor 3 and wherein a second external gear 43 is capable of engaging with the first external gear. The front end portion 63 of the first external gear side of the input rotary shaft is unable to make a relative rotation with respect to the input rotary shaft but made movable in the axial direction of the input rotary shaft. The front end portion thereof movably axially engages with the first external gear. The front end portion and the first external gear are allowed to select one of the conditions including making an integral rotation and freely making relative rotations in accordance with the axial movement of the front end portion.