Image forming apparatus

An image forming apparatus comprising:

• a main assembly including an image forming portion configured to form an image with toner, a driving source configured to generate a driving force, and a detecting portion capable of taking a first state and a second state and configured to output a detection signal depending on each of the first state and the second state;
• and
• an exchange unit detachably mountable to the main assembly and including:
• a rotatable member;
• a first rotatable member configured to be rotated by input of the driving force from the driving source thereto;
• a second rotatable member provided coaxially with the first rotatable member and configured to transmit the driving force toward the rotatable member by being rotated through transmission thereto the driving force by the first rotatable member;
• and
• an urging member configured to urge the first rotatable member against the second rotatable member along a rotational axis direction of the first rotatable member,
• wherein the first rotatable member is movable to a first position and a second position different in position thereof relative to the second rotatable member with respect to the rotational axis direction of the first rotatable member in interrelation with a position of the second rotatable member relative to the first rotatable member with respect to a rotational direction of the first rotatable member depending on a magnitude of a rotational load torque of the rotatable member,
• wherein the detecting portion changes in state between the first state and the second state depending on movement of the first rotatable member between the first position and the second position, and
• wherein a detection pattern of a detection signal outputted by the detecting portion in a predetermined period from a start of drive of the driving source in a state in which the exchange unit is mounted to the main assembly is different between a case where the first rotatable member is in the first position and the rotational load torque of the rotatable member is less than a predetermined value when the drive of the driving source is started, a case where the first rotatable member is in the second position and the rotational load torque of the rotatable member is less than the predetermined value when the drive of the driving source is started, and a case where the first rotatable member is in the second position and the rotational load torque of the rotatable member is the predetermined value or more when the drive of the driving source is started.