Drive apparatus for a process cartridge of an image-forming apparatus

A buffering device for use with a process cartridge disposed for detachable mounting in an image-forming apparatus. The buffering device is disposed for buffering the longitudinal movement of a photosensitive member relative to the casing of the process cartridge and, also if desired, for buffering the longitudinal movement of the process cartridge casing relative to a reference wall of the image-forming apparatus. The longitudinal movement is in response to rotation of a helical gear mounted on the rotatable photosensitive member by a helical gear on a drive shaft of the image-forming apparatus. The buffering device also is disposed for imparting a reciprocal longitudinal movement to the photosensitive member and the casing.