Patent ID: 8286525

Claim:
A gear comprising: a single gear shaft; and a gear wheel made of a resin material, the gear wheel being fixed to an outer peripheral surface of the single gear shaft by molding, wherein: a plurality of serration groups in which valley and peak portions engraved in parallel in the axial direction repeat in a circumferential direction, are formed integrally to an outer peripheral surface of the gear shaft at a portion to which the molded gear wheel is fixed to prevent the gear wheel from being rotatable relative to the gear shaft in the circumferential direction, the plurality of serration groups are formed adjacent to one another in the axial direction at the outer peripheral surface of the gear shaft to which the gear wheel is fixed, the adjacent serration groups are arranged offset with one, another in the circumferential direction such that peak portions of one serration group are next to valley portions of another serration group in the axial direction, stepped end faces are formed at an edge surface of the adjacent serration groups based on a difference between inner diameters of the peak portions of one serration group and the valley portions of the another serration group, and the stepped end faces function to prevent the molded gear wheel from coming off from the gear shaft.