Patent ID: 8620180

Claim:
A process cartridge that is detachably mounted on a main casing of an image-forming device, the main casing being provided with a coupling member providing a driving force, the process cartridge comprising: a photosensitive cartridge that has a photosensitive drum; and a developing cartridge that is detachably mounted on the photosensitive cartridge, the developing cartridge comprising: a developing roller that supplies toner to the photosensitive drum; an input gear that comprises a contact portion configured to be in contact with the coupling member to receive the driving force, an outer circumferential wall, and a gear portion, the outer circumferential wall and the gear portion being configured to rotate about a rotational axis defining an axial direction when the contact portion receives the driving force, the outer circumferential wall having a curved surface whose center of radius of a curvature is coincident with the rotational axis, the outer circumferential wall having a dimension greater than that of the gear portion in a direction perpendicular to the rotational axis of the input gear; a transmission gear that is meshingly engaged with the gear portion to transmit the driving force from the input gear to the developing roller; and a supporting cover that covers the curved surface of the outer circumferential wall to rotatably support the outer circumferential wall.