Patent 10213912 was granted and assigned to Makita on February, 2019 by the United States Patent and Trademark Office.
An impact driver includes a motor, a spindle rotated by the motor, a hammer that is movable forward and rearward with respect to the spindle and that has an inner peripheral portion facing the spindle, and an anvil struck in a rotational direction by the hammer. A grease supply path is provided to supply grease to the inner peripheral portion of the hammer.