An actuator is a component designed for moving or controlling and mechanism or system. The actuator requires a control signal and an energy source. When the actuator receives the right command, the actuator converts the energy into mechanical motion.
Most industrial actuators are pneumatic, driving linear or rotary motion with pressurized air. They are primarily used for motor control because they provide quick-response start and stop actions. Pneumatic actuators are differentiated by stroke length, torque, and max psi. More generally, actuators are classified by force, speed, and operating conditions.
Other types of actuators are hydraulic, electric, thermal, magnetic, or mechanical. Furthermore, certain actuators are designed to perform specific tasks. Damping actuators are useful in HVAC applications, used to actuator exhaust or fire/smoke dampers. Valve actuators are designed specifically to open and close valves.