Cartridge and electrophotographic image forming apparatus

1. An electrophotographic image forming apparatus comprising:

a rotatable driving coupling member including a driving force transmitting portion for transmitting a driving force and a driving side abutment portion;

a cartridge dismountable in a dismounting direction substantially perpendicular to a rotational axis of said driving coupling member, said cartridge including:

a casing,

a photosensitive drum rotatably supported in said casing,

a rotatable driven coupling member including a plurality of projections that extend from a surface of said driven coupling member that is perpendicular to a rotational axis of said driven coupling member, with said plurality of projections being driving force receiving portions for receiving the driving force to rotate said photosensitive drum, said driven coupling member including a driven side abutment portion to be abutted by said driving side abutment portion, and said driven coupling member being translatable in a predetermined direction that is substantially parallel with a rotational axis of said photosensitive drum,

wherein at least one of said driving side abutment portion and said driven side abutment portion is inclined so that said driven coupling member is retractable away from said driving coupling member in the predetermined direction by a force received by said driven side abutment portion from said driving side abutment portion when said cartridge is dismounted from a main assembly in the dismounting direction, and

wherein a distance between the rotational axis of said driven coupling member and said driven side abutment portion is not more than a distance between the rotational axis of said driven coupling member and said driving force receiving portions.