Difference between flywheel and governor

Governor and flywheel both of them are used for almost the same purpose, but the main difference between them is the point of impact or area of impact. Flywheel regulates the variation of speed at crankshaft while governer controls the variation of speed caused by load variation. Well, both are used to stabilize speed during fluctuation, so the difference between them is their working. Let us have a deep insight into the difference between those two terms. 

What is flywheel?

A heavy rotating wheel in a machine that increases the machine's momentum and thus provides greater stability or power reserve.

What is the governor?

A governer is also a mechanical speed control device that controls the mean speed of the engine when there are variations in load.

The main difference between them : 

The flywheel is always under operation when the engine is running and operations are continuous, whereas operation is intermittent in case of governer, which means it only operates when the engine does not run at its mean speed.  

Some more difference between them is following below. 
  • Governor maintains the speed of the engine as per load if the load on the engine decreases governor increases the supply of fuel and vice-versa while flywheel stores the energy when the supply of energy is more than the requirement and it releases the energy when a requirement is more than the supply.
  • Governor is an inter cycle device while the flywheel is an intracycle device.
  • Due to external means, the governor controls the speed variations while the flywheel is controlled by internal means.
  • Governor is mandatory for devices where constant speed is desired like generator while the flywheel is mandatory for the machines like a bike for the start of the operation.
  • Governor controls constant mean speed while flywheel controls the variation of speed per each cycle of an engine.
  • The operation of a flywheel is continuous while that of a governor is more or less intermittent.
  • The kind of energy stored in a flywheel is kinetic energy all kinetic energy convertible into work without friction while governor mechanism involves frictional losses.
  • The flywheel may not be used if the cyclic fluctuations of energy output are small or negligible while the governor is essential for all types of engines to adjust the fuel supply as per the demand.
  • The flywheel relatively heavy mechanical device with large moment of inertia whereas a governor is a light mechanical device with a small moment of inertia.