Improved clutch mechanism for use in rotary tools with screw and drilling

A clutch mechanism 17 includes a ring gear 10, and a plurality of cylindrical pins 26 which are urged by a coil spring 25 via a flat disc 24 rearwardly against a front end surface of the internal gear 10 degrees. On the front end face of the internal gear are provided a plurality of cam projections 28 which correspond in number and position with the pins 26th Each cylindrical pin 26 has at its rear end surface a circumferentially chamfered edge 27 and each cam projection 28 has a pair of guide inclined surfaces 29 with the same inclination as the tapered edge 27 of the pin 26th