reluctor

A reluctor is a component used in engineering, particularly in electric motors and ignition systems. In reluctance motors, it operates on the principle that magnetic forces align iron poles. These motors have rotors with iron poles and stators with coils that are energized sequentially to create rotation. The direction of rotation can be altered by changing the order of coil energization.1

In automotive ignition systems, a reluctor is often part of an electronic system that replaces older breaker points. It's typically a ring mounted on the crankshaft with notches. A magnetic sensor is triggered by these notches as the crankshaft rotates, providing position information to control ignition timing. This system is more reliable and offers better engine control than older mechanical systems. The concept of reluctance itself relates to magnetic circuits, where it's analogous to electrical resistance, representing opposition to magnetic flux.23