A sector gear is a gear that has teeth along a short section of its circumference. The remaining portion of the gear is smooth without any teeth. Sector gears are used in applications when less than 360 degrees of rotations is required. In the areas where there are no gear teeth, the material can be removed. This can reduce weight and supply clearance. A typical application would be a valve actuator that only requires 90 degrees to open or close. Aircraft radar also would utilize this type of gear as it would only scan forward of the plans. An X-ray machine also uses dual sector gears. Sector gears can be manufactured as spur, helical, bevel, or even worm type gears.
Avon Gear custom manufactures sector gears in a wide range of materials including aluminum, steel and stainless steel.