Image forming apparatus including particular gear-shaft configuration

An image forming apparatus configured to form an image on a recording material, comprising:

• a driving source including an output shaft that outputs power to be transmitted to a driven member, the output shaft including (i) a large diameter portion having a first outer diameter and (ii) a small diameter portion having a second outer diameter that is smaller than the first outer diameter;
• a first gear including (i) a first portion provided with a first opening having a first diameter and (ii) a second portion provided with a second opening having a second diameter that is smaller than the first diameter, and (iii) gear teeth formed on an outer peripheral surface of the second portion, the first gear being mounted on the output shaft such that the large diameter portion is inserted into the first opening and the small diameter portion is inserted into the second opening;
• and
• a second gear that engages with the gear teeth of the first gear and is driven by the first gear,
• wherein rotation of the first gear with respect to the output shaft is restricted by at least a part of the large diameter portion.