What's a flywheel?

Flying wheel (flying wheel), a disk-shaped part with a large moment of inertia, its role as an energy storage. For four-stroke engine, every four piston stroke work once, that is, only the work stroke work, while the exhaust, intake and compression of the three strokes to consume power. Therefore, the crankshaft external torque is periodically changing, and the crankshaft speed is not stable. In order to improve this situation, a flywheel is installed at the rear end of the crankshaft.