Anactuatoris a component of a machine that is responsible for moving and controlling a mechanism or system, for example by opening avalve. In simple terms, it is a "mover".
An actuator requires a control signal and a source of energy. The control signal is relatively low energy and may be electric voltage or current, pneumatic or hydraulic pressure, or even human power. Its main energy source may be anelectric current,hydraulic fluidpressure, orpneumaticpressure. When it receives a control signal, an actuator responds by converting the signal's energy into mechanical motion.