Developing cartridge and process cartridge for stably rotating developing roller

A developing cartridge configured to be insertable into and removable from an image forming device, the developing cartridge comprising:

• a developing roller having a rotational axis, the developing roller including:
• a developing roller main body having a first end and a second end opposite to the first end;
• a first protrusion protruding outwardly from the first end of the developing roller main body along the rotational axis,
• a second protrusion protruding outwardly from the second end of the developing roller main body along the rotational axis, and
• a developing gear,
• wherein the first protrusion has a circular peripheral surface having no stepped circumferential surface;
• and
• wherein the second protrusion includes:
• a small diameter part having a circular peripheral surface having a diameter smaller than a diameter of the first protrusion;
• and
• a gear fixing part disposed between the developing roller main body and the small diameter part along the rotational axis and having a D-cut part, the gear fixing part fixing the developing gear,
• a gear cover covering at least a portion of the developing gear,
• the gear cover having an outwardly protruding insertion part through which the small diameter part of the first protrusion is inserted.

A developing cartridge configured to be insertable into and removable from an image forming device, the developing cartridge comprising:

• a developing roller configured to rotate about a rotational axis based on a driving force received from the image forming device, the developing roller including:
• a developing roller main body having a first end and a second end opposite to the first end;
• a first protrusion protruding outwardly from the first end of the developing roller main body along the rotational axis,
• a second protrusion protruding outwardly from the second end of the developing roller main body along the rotational axis, and
• a developing gear configured to mesh with a transmission gear to receive the driving force from the image forming device,
• wherein the first protrusion has a circular peripheral surface having no stepped circumferential surface;
• and
• wherein the second protrusion includes:
• a small diameter part having a circular peripheral surface having a diameter smaller than a diameter of the first protrusion;
• and
• a gear fixing part disposed between the developing roller main body and the small diameter part along the rotational axis and having a D-cut part, the gear fixing part fixing the developing gear,
• a gear cover covering at least a portion of the developing gear,
• the gear cover having an outwardly protruding insertion part through which the small diameter part of the second protrusion is inserted.

A developing cartridge comprising:

• a developing roller having a rotational axis, the developing roller including:
• a developing roller main body having a first end and a second end opposite to the first end;
• a first protrusion protruding outwardly from the first end of the developing roller main body along the rotational axis,
• a second protrusion protruding outwardly from the second end of the developing roller main body along the rotational axis, and
• a developing gear,
• wherein the first protrusion has a circular peripheral surface having no stepped circumferential surface;
• and
• wherein the second protrusion includes:
• a small diameter part having a circular peripheral surface having a diameter smaller than a diameter of the first protrusion;
• and
• a gear fixing part disposed between the developing roller main body and the small diameter part along the rotational axis, the gear fixing part fixing the developing gear, and
• a gear cover covering at least a portion of the developing gear, the gear cover having an outwardly protruding insertion part through which the small diameter part of the second protrusion is inserted.