A drum unit detachably mountable to a main assembly of an electrophotographic image forming apparatus includes a photosensitive drum and a coupling member provided on the photosensitive drum. The coupling member includes a driving force receiving portion and a supporting portion movably supporting the driving force receiving portion. The supporting portion includes a first extended portion and a second extended portion which extend at least in an axial direction of the photosensitive drum.

A process cartridge includes a frame having a slit and a recess formed therein at a side of the process cartridge. A photosensitive drum is supported by the frame, with the photosensitive drum being rotatable about an axis thereof, the photosensitive drum including a first end and a second end opposite to the first end. A developing roller is also supported by the frame, the developing roller being rotatable about an axis thereof. A coupling is operatively connected to the photosensitive drum, with the coupling being rotatable about an axis thereof. A helical gear is positioned at the side of the process cartridge, with the helical gear being rotatable about an axis thereof. The helical gear has a plurality of teeth, with at least some of the teeth being exposed teeth that are uncovered by the frame and exposed to outside of the process cartridge.

A process cartridge removably disposed in an imaging device provided with a rotational force output head. The process cartridge (100) includes a cartridge body, a rotation component having a rotation axis L1, and a driving force receiving assembly. The driving force receiving assembly is disposed at an end of the cartridge body, and includes a rotational force receiving member and a position adjusting mechanism. The rotational force receiving member is provided with a rotational force receiving portion, a connection portion, and a rotational force transmitting portion. The position adjusting mechanism enables the rotational force receiving member to rotate in a preset direction.

A control member 76 for controlling transmission and blocking of a rotational force by a clutch is rotatably supported by a supporting member which supports a developing frame. a locking portion provided on the control member 76 rotates between a position retracted from a locked portion of the clutch and a position for engaging with the locked portion.

An example image forming apparatus includes a frame, a first shaft supported by the frame, and a first coupler. The first coupler includes a body coupled to one end of the first shaft and a first protrusion protruding from the body in an axial direction of the first shaft, the first protrusion having a first surface and a second protrusion protruding from the first surface. The second protrusion is to lock with a groove to mount a cartridge on the frame, the first shaft is to provide a rotational force in a first rotational direction to rotate the second protrusion of the first coupler and to insert the second protrusion into the groove to lock with the cartridge, and the first surface of the first protrusion of the first coupler is to contact a second surface to transmit the rotational force to the second coupler in the first rotational direction.

An image forming unit to be attached to an apparatus body of an image forming apparatus includes a first cartridge including a driven portion configured to rotate on a first rotational axis; and a second cartridge configured separable from the first cartridge. The second cartridge includes an input portion configured to receive driving force from the apparatus body; and a drive transmission portion configured to rotate on a second rotational axis and to transmit the driving force to the driven portion.

A driving-force-transmitting mechanism includes a driving-force-transmitting component that transmits a driving force from an apparatus body to an attaching object, the attaching object being attachable to and detachable from the apparatus body; and plural operating components that enables or disables the transmission of the driving force from the apparatus body to the attaching object when the attaching object is attached to or detached from the apparatus body, the operating components operating sequentially with delays in such a manner as to move the driving-force-transmitting component in a direction intersecting attaching and detaching directions in which the attaching object is attached to and detached from the apparatus body.

An image forming apparatus includes image forming stations including respective electrophotographic photosensitive drums; an image transfer belt contactable to the drums; image transfer rollers, contactable to the transfer belt to urge the belt to the drums for transferring the toner images from the drums onto the belt, the rollers being provided with respective rotational shafts about an axis of which the rollers are rotatable; and a slidable member slidable in a direction in which the stations are arranged to retract the rollers away from the corresponding drums, the slidable member being provided with inclined surfaces contactable to the shafts, the inclined surfaces being disposed at such positions that the rollers are retracted from respective drums sequentially with the movement of the slidable member in the direction.

An image forming apparatus includes a cartridge and a main body into which the cartridge is removably installed. The cartridge includes a first unit and a second unit that is movably connected to the first unit. The main body includes a rotating member, a supporting member disposed at a position away from the rotating member, and a swingable member that is pivotally movable about the supporting member and configured to be moved by the rotating member. The swingable member is movable between a first position at which the swingable member is in contact with the second unit and a second position at which the swingable member is retracted from the first position. Installation and removal of the cartridge into and from the main body is enabled in a state where the swingable member is at the first position and is supported by the rotating member.

A developing device may include an auger or an agitator that is capable of supplying toner in a toner accommodation chamber to a developing chamber and is rotatable about an auger axis extending in an axial direction, a transporting gear that is rotatable together with the auger or the agitator, and a moving gear that is in mesh with a coupling gear and is rotatable both counterclockwise and clockwise. The moving gear is movable while being in mesh with the coupling gear between a first position where the moving gear is in mesh with the transporting gear and a second position where the moving gear is out of mesh with the transporting gear. The moving gear moves to the first position when the coupling gear rotates counterclockwise and to the second position when the coupling gear rotates clockwise.