A process cartridge detachably mountable to a main assembly of an electrophotographic
image forming apparatus. The apparatus includes a motor, a driving rotatable member
for transmitting a rotational driving force having a twisted hole formed at a central
portion and having a non-circular cross-section with corner portions, and a transfer
roller. The process cartridge includes an electrophotographic photosensitive drum,
process components, a twisted projection of non-circular cross-section provided
at a longitudinal end of the drum that is engageable with the twisted hole at three
positions to receive the driving force from the main assembly, and a gear for transmitting
the driving force received by the twisted projection to the transfer roller when
the process cartridge is mounted to the main assembly.
