Clutch mechanism for use in rotary tools having screw-driving and drill modes

摘要

A clutch mechanism (17) includes an internal gear (10) and a plurality of cylindrical pins (26) pressed rearward against a front end surface of the internal gear (10) by a coil spring (25) via a flat washer (24). Provided on the internal gear's front end surface are a plurality of cam protrusions (28) corresponding in number and position with the pins (26). Each cylindrical pin (26) has at its rear end surface a circumferentially chamfered edge (27) and each cam protrusion (28) has a pair of guide slope surfaces (29) with same inclination as the chamfered edge (27) of the pin (26).