Process cartridge, electrophotographic image forming apparatus and electrophotographic photosensitive drum unit

A process cartridge which is detachably mountable to a main assembly of an electrophotographic image forming apparatus including a driving shaft having a rotational force applying portion by moving in a direction substantially perpendicular to an axis of said driving shaft, said process cartridge comprising:

• i) an electrophotographic photosensitive drum rotatable about an axis and having a photosensitive layer at its peripheral surface;
• ii) process means actable on said electrophotographic photosensitive drum;
• iii) a coupling member engageable with said rotational force applying portion to receive a rotational force for rotating said electrophotographic photosensitive drum, said coupling member being capable of taking a rotational force transmitting angular position for transmitting the rotational force for rotating said electrophotographic photosensitive drum to said electrophotographic photosensitive drum, a pre-engagement angular position in which said coupling member is inclined away from the axis of said electrophotographic photosensitive drum from said rotational force transmitting angular position and a disengaging angular position in which said coupling member is inclined away from the axis of said electrophotographic photosensitive drum from said rotational force transmitting angular position;
• and
• iv) a regulating portion for regulating an inclination angle of said coupling member such that downward inclination angle of said coupling member is smaller than an inclination angle of said coupling member when said coupling member is at the pre-engagement angular position,
• wherein in mounting said process cartridge to the main assembly of the apparatus by moving said process cartridge in a direction substantially perpendicular to the axis of said electrophotographic photosensitive drum, said coupling member moves from the pre-engagement angular position to the rotational force transmitting angular position to oppose the driving shaft, and in dismounting said process cartridge from the main assembly of the apparatus by moving said process cartridge in the direction substantially perpendicular to the axis of said electrophotographic photosensitive drum, said coupling member moves from the rotational force transmitting angular position to the disengaging angular position to disengage from the driving shaft.