What is the primary purpose of a flywheel in an engine?

The primary purpose of a flywheel in an engine is to keep the crankshaft rotating smoothly by smoothing out power pulses.

In an internal combustion engine, the power generated during the combustion process is not consistent and can be pulsating as each cylinder fires. This can lead to vibrations and irregular motion of the crankshaft. The flywheel, which is a heavy, rotating disk, serves to store rotational energy and provides a stabilizing effect. As the engine fires in cycles, the flywheel stores energy during the high power strokes and releases it during low power strokes. This action helps to maintain a more constant speed of the crankshaft, allowing for smoother operation of the engine overall.

Additionally, while flywheels do provide a degree of energy storage, their primary function is to stabilize the engine’s rotation rather than to directly store energy for use in combustion or to improve fuel efficiency. Therefore, the choice that accurately reflects the flywheel’s fundamental role within an engine is the one that highlights its ability to smooth out the power delivery.