Developing cartridge including first arm pivotally movable along with pivotal movement of cam and along with rotation of first shaft

A developing cartridge comprising:

• a developing roller rotatable about a developing roller-axis extending in a first direction;
• a casing configured to accommodate developing agent therein, the casing having an outer surface positioned at one end portion in the first direction of the casing;
• a first shaft positioned at the outer surface of the casing and rotatable about a rotational axis extending in the first direction, the first shaft having an outer periphery;
• a first arm extending radially outward from the outer periphery of the first shaft, the first arm being pivotally movable about the rotational axis along with rotation of the first shaft;
• and
• a cam extending radially outward from the outer periphery of the first shaft in a direction different from a direction in which the first arm extends, the cam being pivotally movable about the rotational axis along with the rotation of the first shaft, the cam having:
• one end connected to the first shaft;
• another end positioned farther from the rotational axis than the one end is farther from the rotational axis;
• and
• a pressure contact surface inclined so as to approach the outer surface of the casing as extending from the one end toward the another end,
• wherein, when a pressing force is applied to the pressure contact surface, the first arm pivotally moves from a first position to a second position along with pivotal movement of the cam and along with the rotation of the first shaft.