Image forming apparatus

An image forming apparatus, comprising:

• a first photosensitive drum;
• a first development roller movable relative to the first photosensitive drum between a contact position in which the first development roller is in contact with the first photosensitive drum and a separate position in which the first development roller is separate from the first photosensitive drum;
• a first separation cam configured to move the first development roller between the contact position and the separate position when receiving a driving force;
• a fixing device comprising a heating portion and a pressure portion, the fixing device being configured to convey a sheet nipped between the heating portion and the pressure portion when receiving a driving force;
• an adjusting cam configured to switch a nip pressure to be produced by the heating portion and the pressure portion between a first nip pressure and a second nip pressure higher than the first nip pressure when receiving a driving force;
• a main motor;
• a separation gear train configured to transmit a driving force of the main motor to the first separation cam;
• a fixing gear train configured to transmit the driving force of the main motor received from the separation gear train to the fixing device;
• and
• an adjusting gear train configured to transmit the driving force of the main motor received from the separation gear train to the adjusting cam.