Process cartridge

A cartridge detachably mountable to a main assembly of an image forming apparatus, the cartridge comprising:

• a drum unit including a photosensitive drum;
• a developing unit including:
• a developing roller,
• a driving force receiving portion for receiving a driving force for rotating the developing roller from the main assembly, and
• a development gear fixed at a longitudinal end portion of the developing roller,
• wherein the developing unit is connected to the drum unit so as to move, with respect to the drum unit, between a contact position in which the developing roller contacts the photosensitive drum and a spaced position in which the developing roller is spaced from the photosensitive drum;
• a driving train configured to transmit the driving force received from the driving force receiving portion to the development gear, wherein the driving train includes a first driving portion connected to the driving force receiving portion so as to receive the driving force from the driving force receiving portion, and a second driving portion configured to receive the driving force from the first driving portion and to transmit the driving force toward the development gear, wherein the developing unit includes the first driving portion, and the drum unit includes the second driving portion,
• wherein the first driving portion is movable, with respect to the drum unit, in conjunction with a movement of the developing unit between the contact position and the spaced position such that when the developing unit is in the contact position, the first driving portion and the second driving portion are connected with each other so as to transmit the driving force from the first driving portion to the second driving portion, and such that when the developing unit is in the spaced position, the first driving portion and the second driving portion are not connected with each other to prevent the driving force from being transmitted to the second driving portion from the first driving portion.