What is an Actuator?

An actuator is a type of instrument that is responsible for moving or controlling a mechanism or system. It is operated by a source of energy, It can be controlled mechanically, by  electric current, hydraulic fluid pressure, or pneumatic pressure, and converts that energy into motion.

In my research, I found out that there are 5 types of actuators and these are the following.

Mechanical Actuators

In mechanical actuators normally a rotary motion is converted into linear motion to perform an operation. Such actuator normally involves gears, rails, pulley, chain etc to operate.

Basic example of mechanical actuator is chain block hoisting weight in which mechanical motion of chain over the sprocket is utilized to lift a rated load.


Pneumatic Actuator

Pneumatic energy is most commonly used for actuators used in In this type, compressed air at high pressure is used which converts this energy into either linear or rotary motion.

We can see a lot of this actuators in electronic industries loads are not  high and involves fast movements. The use of this actuators is also important in engine controls and fluid  flow controls.



“Pneumatic cylinder (animation)” by Kamarton – Own work. Licensed under CC BY 3.0 via Commons – https://commons.wikimedia.org/wiki/File:Pneumatic_cylinder_(animation).gif#/media/File:Pneumatic_cylinder_(animation).gif


Hydraulic Actuator

Hydraulic actuators may consists of cylinders or fluid motors that uses hydraulic power to that outputs mechanical motion in terms of linear, rotary or oscillatory motion.


hydraulic suspension


Unlike air, liquid cannot be compressed and hydraulics generates higher energy than any other system. All systems involving high loads are operated by hydraulic actuators in which oil pressure is applied on mechanical actuator.

We can typically find this kind of actuators on heavy equipment facilitating arm,fork and shovel movements.


Electrical Actuator

It is one of the cleanest and readily available forms of actuating system as it does not involve oil; as there is no need to compress air, hence no extra machinery. Electrical energy is always available. Basic example are electrical motor operated valve and magnetic valve actuator or solenoid valve.

In solenoid valve the electrical signal which will magnetize the upper portion of the valve, which will then attract the valve seat and open the system. When electrical supply is removed, valve gets shut by spring action. or in some other cases double solenoid valve is used where two positions of the valve is magnetized by two separate solenoids and when both solenoids are deenergized. valve will closed by a spring action.

>How does a 5/2 way directional valve work?single solenoid operated valve


Hybrid Actuator

These are mixture of some of the above systems which control the mechanical part of the system. Common example is a thermo hydraulic Electronic actuator used in operating valves in hot water system, wherein hot water liquid is used along with electronic system acting as control for the valve.



There we go. Now we already know what actuators are,  there types, and on what they used for. The next time we encounter a machine. let us test ourselves if we really learned something about this article. Try to identify what kind of actuators used in the process and ask the operator or the person in charge to verify your answer. Thanks for reading.  Keep following and stay connected for more basic knowledge and ideas of the process control world.