detent

A detent is a mechanical feature that holds or indexes a moving part at discrete positions. It typically uses a spring-loaded element, such as a ball, roller, or pin, that engages a matching recess, notch, or cam surface. When alignment occurs, the detent provides resistance to movement and often a tactile feedback or “click” indicating a set position. Detents can be employed in rotary, linear, or combined motion and may serve to locate controls, retain doors, or regulate travel.

Common implementations include ball detents, where a hardened ball is pressed into a groove by a spring; pin detents, which use a spring-loaded pin engaging holes or notches; roller detents, using a rolling element; and cam detents, where a shaped cam and follower create discrete positions. Indexing detents are designed to hold a dial, knob, or lever at preset angles. Detent mechanisms appear in gear selectors, hand wheels, camera lens focus and zoom rings, furniture and equipment locks, and a wide range of consumer and industrial devices.

Operation and design considerations center on selecting detent force to balance ease of movement with retention and wear life. Material choice, surface finish, and tight tolerances influence engagement quality and longevity. Wear, contamination, or debris can degrade performance or cause false positions. Some detents rely on friction for a soft hold, while others deliver positive, repeatable indexing with defined engagement forces.