Fixing device and image forming apparatus

An image forming apparatus comprising:

• a developer image forming unit configured to form a developer image on a sheet;
• a fixing device configured to fix the developer image on the sheet;
• a housing in which the developer image forming unit and the fixing device are housed;
• and
• a main gear provided in the housing to transmit a driving force to the fixing device,
• wherein the fixing device comprises:
• a first fixing member configured to rotate;
• a second fixing member configured to form a nip in combination with the first fixing member;
• a first gear configured to receive the driving force from the main gear;
• a second gear configured to rotate together with the first gear about a center of rotation of the first gear;
• a third gear provided in mesh with the second gear and configured to rotate together with the first fixing member;
• a metal shaft by which the first gear and the second gear are rotatably supported;
• a side frame supporting the first fixing member and the metal shaft;
• and
• a sleeve provided around the metal shaft,
• wherein a material of the second gear and a material of the sleeve have melting points higher than a melting point of a material of the first gear, and
• wherein the first gear is supported via the sleeve by the metal shaft.