Patent ID: 8657278

Claim:
An image forming apparatus comprising; a first tray configured to accommodate one or more recording sheets to be supplied to an image forming unit; a body frame configured to position an upper part of a first side of the first tray, the body frame including: a drive source; a body-side gear configured to receive a driving force from the drive source; and an expansion member disposed under the body frame and adjacent to the first tray to position a lower part of the first side of the first tray, the expansion member including: a transmission mechanism configured to be engagable with the body-side gear, the transmission mechanism being configured to convey the driving force to an add-on mechanism, wherein the transmission mechanism comprises: a central gear; a swing gear configured to engage with the central gear and rotate while swinging about the central gear; and a shaft portion that passes through the center of rotation of the swing gear, wherein the body frame includes a pair of body frames of which one of the body frames includes the body-side gear, wherein the expansion member includes a pair of expansion members, and wherein the swing gear is swung by restriction of movement of the shaft portion by the pair of body frames when the pair of expansion members are attached to the pair of body frames and a pitch between the swing gear and the body-side gear is adjusted.