Patent ID: 8548357

Claim:
A drive transmission system comprising: a shaft member including; a shaft outer circumferential sliding section on its outer circumferential surface, and a shaft outer circumferential small diameter section having a smaller diameter than that of the shaft outer circumferential sliding section, said shaft outer circumferential smaller diameter section forming a circular groove storing grease; a drive transmission gear freely rotatably supported by the shaft member therearound, said drive transmission gear being rotated when a rotation driving force is input thereto, said drive transmission gear including, a gear inner circumferential sliding section on its inner circumferential surface, said gear inner circumferential sliding section contacting and sliding on the shaft outer circumferential sliding section of the shaft member when the drive transmission gear rotates, and a gear inner circumferential large diameter section having a large diameter than that of the gear inner circumferential sliding section on its inner circumferential surface; a gear moving device configured to move the drive transmission gear reciprocally along the shaft member in a shaft direction; and a restriction device configured to restrict movement of the drive transmission gear along the shaft member in the shaft direction to enable the gear inner circumferential large diameter section to face the shaft outer circumferential small diameter section substantially continuously.