Abstract: A conventional gear mechanism for employment in, e.g., an accumulator driven electric bore machine or electric drill, is provided with an overload coupling provided with a light-weight plastic annular gear and a separate metal cam disk or guard plate which protects the plastic annular gear from the abrasive or damaging forces occurring at the time of the torque limiting produced by the slipping of the torque overload coupling. In the present invention the plastic annular gear and guard plate are formed as a single component, namely, a plastic annular gear with an integral wear resistant cam disk, the annular gear and cam disk formed as unit of an injection molded plastic, wherein the face side of the annular gear is layered with a wear resistant material.

Abstract: The preferably for use in an accumulator driven electric drill or electric screwdriver provided gear comprises an overload coupling for limiting torque for the adaptation to various torque loads. The overload coupling is comprised essentially of an annular gear which is formed of a plastic material and which circumscribes and is associated with a planetary gearing, which has an internal teeth which are in engagement with the planetary gear. A spring element presses against the annular gear, in order to press the annular gear axially against a detente wall, so that the annular gear is frictionally prevented from rotation, until a predetermined torque loading is exceeded and upon exceeding of the predetermined torque loading the annular gear is allowed to rotate. For this there is provided between the plastic annular gear and the spring element a metallic cam disk, which is non-rotatingly secured to the annular gear.