<P> A governor', or speed limiter' or controller, is a device used to measure and regulate the speed of a machine, such as an engine . </P> <P> A classic example is the centrifugal governor, also known as the Watt or fly - ball governor on a reciprocating steam engine, which uses the effect of centrifugal force on rotating weights driven by the machine output shaft to regulate its speed by altering the input flow of steam . </P>

What is the purpose of a governor on an engine