Flywheel Vs. Governor: Know The Difference

SHARE

What is a Flywheel?

Flywheel and governor mainly used to control speed changes of an internal combustion engine. The speed changes occur due to the following:

  1. Due to changes of the torque on the crankshaft.
  2. Due to changes on the load on the engine.

Speed fluctuations due to fluctuations of turning moment on the crankshaft during each cycle can be controlled by mounting a suitable flywheel on the crankshaft. Flywheel is a mechanical device that absorbs mechanical energy during the time when the supply of energy is more than the requirement and releases it during the period when requirement of energy is more than the supply.

What is a Governor?

Governor can be described as a mechanical device used to maintain the constant speed of an engine just by controlling the supply of fuel or working fluid of the engine with concurrent variation in load. When the load increases in the engine, the speed of the engine needs to be decrease by decreasing the supply of fuel (working fluid).Conversely, when the load in the engine decrease, the speed of the engine need to be increased by increasing fuel supply (working fluid).

The Difference

Description

A flywheel is a mechanical device specifically designed and attached to the crank shaft so as to control the fluctuations of speed during different rotational operations. On the other hand, a governor is a mechanical device used to govern the speed of machines. It allows the engine to run at the selected speed without any effect of changing the load.

Influence on Speed

Flywheel controls the variation of speed in each cycle of the operating engine. In contrast, governor controls the mean speed only when load varies or when it’s required by controlling the fuel supply to the engine.

Weight

Flywheel is a heavy machine component, though it cannot change the speed of the crankshaft whereas a governor is relatively light machine component used to limit engine speed.

Condition                                                                                   

The flywheel may not be used if the cyclic fluctuations of energy output are small or negligible (insignificant) while governor is essential for all types of engines to adjust the fuel supply as per the demand.

Mandatory

Flywheel is mandatory for the machines like bikes for the start of operation, whereas governor is mandatory for devices where constant speed is desired like in generator.

Moments of Inertia

Flywheel has large moments of inertia because of the heavy mass of the rotating wheel. The wheel is usually made up of high density cast iron. The governor has relatively less moments of inertia when compared to flywheel.

Under Operation

The flywheel is under operation when the engine is running because it is attached to the crankshaft whereas the governor is under operation only when the engine is not running at its mean speed.

Extra Mechanism

 Flywheel does not need any extra mechanism to supply back energy whereas governor needs a piston (plunger) mechanism.

Size

The size of flywheel may differ from one machine type to another whereas governors come in different variety to be used in different prime movers.

Energy Storage

Flywheel is an energy storing device and prevents the changes in energy during each cycle of engine operation. Governor is not an energy storing component.

Connection

Flywheel is connected to the crank shaft and runs it at a constant speed, both the flywheel and crankshaft rotates simultaneously, whereas the governor is not connected to the crankshaft, it can sometimes be electronically operated.

Valves

Flywheel does not have valves attached to it, whereas governor has valves whose opening is controlled by the centrifugal force on the balls attached to it.

Effect of Quality of Fuel

There is effect of quality of fuel on the governor whereas there is no effect of quality of fuel on function of flywheel.

Main function

Flywheel stores the energy during the power stroke when requirement is less and transfer to shaft when it is required during other strokes of engine. Governor on the other hand, works only to keep the mean speed of running machine constant by regulating the fuel supply. When the load increases the fuel supply increases by opening of the throttle. The reverse is also true.

Application                                                                                                      

Flywheel is used in IC engines of automobiles, punching press and rolling mills etc. while governor is used in machines where constant speed need to be maintained such as turbines and generators.

Classification

Governor is mainly classified as per the working principle e.g centrifugal type and inertia type governor, whereas, flywheels are mainly classified as per their size and shape e.g Rim type, Disc type and split flywheel.

The Difference Between Flywheel and Governor in Tabular Form

BASIS OF COMPARISON FLYWHEEL GOVERNOR  
Description A flywheel is a mechanical device specifically designed and attached to the crank shaft so as to control the fluctuations of speed during different rotational operations. A governor is a mechanical device used to govern the speed of machines. It allows the engine to run at the selected speed without any effect of changing the load.  
Influence on Speed Flywheel controls the variation of speed in each cycle of the operating engine. Governor controls the mean speed only when load varies or when it’s required by controlling the fuel supply to the engine.  
Weight Flywheel is a heavy machine component, though it cannot change the speed of the crankshaft. Governor is relatively light machine component used to limit engine speed.
Main Function Flywheel stores the energy during the power stroke when requirement is less and transfer to shaft when it is required during other strokes of engine. Governor on the other hand, works only to keep the mean speed of running machine constant by regulating the fuel supply. When the load increases the fuel supply increases by opening of the throttle. The reverse is also true.
Condition The flywheel may not be used if the cyclic fluctuations of energy output are small or negligible (insignificant). Governor is essential for all types of engines to adjust the fuel supply as per the demand.  
Mandatory Flywheel is mandatory for the machines like bikes for the start of operation. Governor is mandatory for devices where constant speed is desired like in generator.  
Moments of inertia Flywheel has large moments of inertia because of the heavy mass of the rotating wheel. The wheel is usually made up of high density cast iron. The governor has relatively less moments of inertia when compared to flywheel.  
Under Operation The flywheel is under operation when the engine is running because it is attached to the crankshaft. The governor is under operation only when the engine is not running at its mean speed.  
Extra Mechanism Flywheel does not need any extra mechanism to supply back energy. Governor needs a piston (plunger) mechanism.  
Size The size of flywheel may differ from one machine type to another. Governors come in different variety to be used in different prime movers.  
Energy Storage Flywheel is an energy storing device and prevents the changes in energy during each cycle of engine operation. Governor is not an energy storing component.
Connection Flywheel is connected to the crank shaft and runs it at a constant speed, both the flywheel and crankshaft rotates simultaneously. The governor is not connected to the crankshaft; it can sometimes be electronically operated.  
Valves Flywheel does not have valves attached to it. Governor has valves whose opening is controlled by the centrifugal force on the balls attached to it.  
Application Flywheel is used in IC engines of automobiles, punching press and rolling mills etc. Governor is used in machines where constant speed needs to be maintained such as turbines and generators.
Classification Governor is mainly classified as per the working principle e.g centrifugal type and inertia type governor. Flywheels are mainly classified as per their size and shape e.g Rim type, Disc type and split flywheel.