Image forming apparatus

An image forming apparatus comprising:

• a main assembly;
• a rotatable unit provided rotatably relative to said main assembly;
• a first drive transmission member, provided in one of said rotatable unit and said main assembly, including a drive transmission portion at an arcuate portion having a center substantially aligned with a rotation center of said rotatable unit;
• a second drive transmission member, provided rotatably in another one of said rotatable unit and said main assembly, engageable with said first drive transmission member in a first rotation region of said rotatable unit;
• a third drive transmission member provided at a position different from a position of said second drive transmission member with respect to a circumferential direction of the arcuate portion of said first drive transmission member, wherein said third drive transmission member is engageable with said first drive transmission member when said rotatable unit is rotated in a second rotation region thereof;
• and
• a damper mechanism for imparting rotational resistance to said second and third drive transmission members when each of said second and third drive transmission members is rotated.