A centrifugal governor is a specific type of governor that controls the speed of an engine by regulating the amount of fuel (or working fluid) admitted, so as to maintain a near-constant speed, irrespective of the load or fuel-supply conditions. It uses the principle of proportional control.

It is most obviously seen on steam engines, where it regulates the admission of steam into the cylinder(s). It is also found on internal combustion engines and variously fueled turbines, and in some modern striking clocks.

en.wikipedia.org/wiki/Flyball_governor