Gear and an electric actuator provided therewith

A gear formed of sintered alloy comprising:

• spur teeth formed on a circumference of the gear;
• a central hole on the center of the gear;
• a boss formed around and adjacent the central hole;
• a peripheral portion is formed radially inward of and adjacent the teeth so that a step portion, projecting directly from the peripheral portion, is formed adjacent the teeth between the teeth and the peripheral portion, a thickness of a region between the boss and the peripheral portion being thinner than that of the boss;
• and
• the peripheral portion is formed on at least one side of the gear and has an axially larger thickness than the region between the boss and peripheral portion, the axial thickness of the peripheral portion and that of the boss of the gear are substantially same, and side faces of the peripheral portion and the boss of at least one side of the gear are substantially axially flush with each other;
• a clearance amount (δ) between the tooth and the peripheral portion of the gear is limited within a range of 0.1˜0.5 mm.