Electromagnetic clutches and brakes are devices that, as their names suggest, couple, release, brake and hold machinery in place using electromagnetic force generated by passing a current through a coil. They are divided into two types by their method of actuation: electromagnetic actuated and spring actuated. Electromagnetic actuated refers to clutches and brakes that are actuated when a current is passed through a coil; spring actuated refers to brakes that are actuated by the force of a spring when current to the coil is shut off, as happen in power outages.