What is an Actuator?
An actuator is a device that converts an electrical, hydraulic or pneumatic signal into physical motion. Actuators carry out actions in an automated system, such as opening a valve, moving an arm, rotating a motor or switching a relay.
They are the executing component in an automation or control loop.
⚙️ What does an actuator do?
An actuator:
- Receives a control signal (e.g. from a PLC, HMI or controller)
- Converts it into mechanical motion (linear or rotary)
- Drives a machine, process or component
🧱 Examples of actuators
| Type of actuator | Motion | Example applications |
|---|---|---|
| Electric actuator | Linear/rotary | Opening/closing valves, electric motors |
| Pneumatic actuator | Linear | Pneumatic cylinders in packaging lines |
| Hydraulic actuator | Linear | Heavy machinery, presses, lifting arms |
| Servo actuator | Precision, rotary | Robot arms, CNC machines |
| Solenoid | On/off linear | Door locks, valve operation |
🔄 Sensor vs. Actuator
| Sensor | Actuator |
|---|---|
| Measures the state of the process | Changes the state of the process |
| Provides input to control systems | Carries out output from control systems |
| Example: temperature sensor | Example: heating element |
🔗 Actuator in a control loop
In a closed control loop:
- The Sensor measures the actual value
- The controller compares it with the Setpoint
- The actuator carries out the adjustment (e.g. opening a valve when the temperature is too low)
🏭 Where are actuators used?
- Process industry: operating valves and pumps
- Machine building: linear motion, gripper arms
- Building management: opening ventilation grilles or sun shading
- Automotive: electronic throttle valves, windscreen wipers
- robotics: precise, programmed motion
📌 In summary
An actuator is the “muscle” of an automation system: it carries out physical actions in response to electronic or pneumatic signals.