In automatic control, a regulator is a device which has the function of maintaining a designated characteristic.
It performs the activity of managing or maintaining a range of values in a machine.
The measurable property of a device is managed closely by specified conditions or an advance set value; or it can be a variable according to a predetermined arrangement scheme.
Regulators can be designed to control anything from gases or fluids, to light or electricity.
Speed can be regulated by electronic, mechanical, or electro-mechanical means.