A centrifugal governor is a specific type of governor with a feedback system that controls the speed of an engine by regulating the flow of fuel or working fluid, so as to maintain a near-constant speed. It uses the principle of proportional control.
Cut-away drawing of steam engine speed governor. The valve starts fully open at zero speed, but as the balls rotate and rise, the central valve stem is forced downward and closes the valve. The drive shaft whose speed is being sensed is top right
Porter governor on a Corliss steam engine
Boulton & Watt engine of 1788
A governor, or speed limiter or controller, is a device used to measure and regulate the speed of a machine, such as an engine.
Cut-away drawing of steam engine speed governor. The valve starts fully open at zero speed, and is closed as the balls rotate and rise. The speed sensing drive shaft is top right
Porter governor on a Corliss steam engine