A flywheel is a heavy, metal disc or wheel with teeth located at the rear of a crankshaft and used to deliver engine momentum and prevent engine idling. The flywheel controls each power surge released by the crankshaft as the engine’s cylinder fires up and then must resist the tendency of the engine from speeding up at the beginning of the power stroke and then slowing down near the end of it.
Operationally, the flywheel is comparable to a mechanical battery by which the primary function of the flywheel is to take stored mechanical energy and turn it into kinetic energy. An electrical input brings a rotor up to speed by using a built in motor. The same motor then reciprocates the electrical energy by operating as a generator.