What is an Actuator?

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  • Originally Written By: Malcolm Tatum
  • Revised By: A. Joseph
  • Edited By: Lucy Oppenheimer
  • Last Modified Date: 07 February 2020
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An actuator is something that converts energy into motion. It also can be used to apply a force. An actuator typically is a mechanical device that takes energy — usually energy that is created by air, electricity or liquid — and converts it into some kind of motion. That motion can be in virtually any form, such as blocking, clamping or ejecting. Actuators typically are used in manufacturing or industrial applications and might be used in devices such as motors, pumps, switches and valves.

Energy Sources

Perhaps the most common type of actuator is powered by air and is called a pneumatic cylinder or air cylinder. This type of actuator is an airtight cylinder, typically made from metal, that uses the stored energy of compressed air to move a piston when the air is released or uncompressed. These actuators are most commonly used in manufacturing and assembly processes. Grippers, which are used in robotics, use actuators that are driven by compressed air to work much like human fingers.

An actuator also can be powered by electricity or hydraulics. Much like there are air cylinders, there also are electric cylinders and hydraulic cylinders in which the cylinder converts electricity or hydraulics into motion. Hydraulic cylinders, which use liquids, are often found in certain types of vehicles.


Many actuators have more than one type of power source. Solenoid valves, for example, can be powered by both air and electricity. Alternatively, a solenoid can be powered by both hydraulics and electricity.

Types of Motion

Actuators can create a linear motion, rotary motion or oscillatory motion. That is, they can create motion in one direction, in a circular motion or in opposite directions at regular intervals. Hydraulic and air cylinders can be classified as single-acting cylinders, meaning that the energy source causes movement in one direction and a spring is used for the other direction. Alternatively, these cylinders can be double-acting cylinders, meaning that the energy is used in two directions.

Muscles as Actuators

Although actuators typically are discussed in terms of mechanical implements, muscles are sometimes given as an example of actuators. Energy is converted by the muscle into motion. For example, the calories that are in food that a person consumes represent energy that can be used by his or her muscles — which act as actuators — to create motion, such as running, kicking a ball or dancing.


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Post 11

The article is informative and provides very useful information regarding actuator. Since an actuator is used to convert energy into motion and create linear motion, rotary motion, or oscillatory motion, the application of an actuator carries various dimensions and applications. Thanks for providing all the information in one place.

Post 10

is a motor an actuator or is it activated by an actuator like a relay?

Post 6

the most common type of actuator used by most people is a linear actuator, weather its electric, pneumatic etc.

Post 5

seems quite a good site from the outside.

have to check whether detailed info is available regarding a particular topic.

Post 4

Thanks a lot.

Post 2

Instructions on a can of Green Gas tell me to attach an actuator before using. Where will I find one of these?

Post 1

Another, less common, source of energy for actuators: heat. There are thermal actuators and solar actuators.

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