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How Do Electric Linear Actuators Work?

Posted on September 01, 2017 by Anna

A linear actuator may seem complicated, but it is not the case. The linear actuator working principle was specifically designed to be easier to work with, both to decrease the amount of maintenance and repairs which are necessary for equipment that carries out the types of jobs linear actuators were created for, and also to allow more people to be able to use them (as seen in the inclusion of linear actuators in a big way in many aspects of home automation). As a result, the learning curve for how to use linear actuators is fairly smooth for most people, particularly if they use the 12-volt electric actuator, which is becoming commonplace and is the subject of this article. The article will cover what a linear actuator is, what the different parts of an electric linear actuator are, and describe how the actuator works in order to fully explain how use identify and use a linear actuator to anyone who needs the information.


Linear Actuator – Definition and Types

A linear actuator is a piece of equipment that turns rotational motion into linear motion, through the application of linear force. This happens because a linear motor is modified in such a way as to the only move in linear directions rather than rotational ones. Linear actuators are used in a huge variety of machines and all sorts of equipment where linear motion is required, including valves, disc drives, printers, dampers, and much more.

    • Hydraulic actuators – these have a hollow cylinder for moving a piston and works by applying unequal pressure to the piston in order to move it in the direction needed.

    • Mechanical actuators – mechanical actuators convert energy through a number of means, be that wheel and axle, screw, or cam. They are notable for quite often being one-way actuators.

    • Magnetic actuators – these actuators use a magnetic force to convert the electric current provided by the motor into linear motion. This magnetic force can be used to create different force strokes and movements in the actuators.

    • Pneumatic actuators – pneumatic actuators function in almost the same way as hydraulic actuators except that the gears and cylinder are controlled using compressed air to control when they move and when they stop.

    • Electric actuators – to take a look at the inner workings of an electric actuator, the actuator is specifically designed to have fewer working parts than other actuators, something which cuts down on both maintenance and the difficulty of operating it. These actuators run directly on a current and are therefore not able to be hand-operated, although they can be slaved to remote control sometimes if the user wants to be able to control them remotely.

Well, now let's take a look at the inner parts of the electric linear actuator.

Electric Linear Actuator Parts

Inside a linear actuator is a number of different components, all of which work together to form the movements that are needed from the equipment. While electric screw actuators were specifically designed to have fewer moving parts, both to reduce the potential for breakdowns and maintenance, and also to make the actuators lighter and easier to use, there are many parts that are integral to its overall functioning.

Here is how the linear actuator looks like and what parts it has on the example of our mini linear actuator:

linear actuator parts

Linear Actuator Parts
linear actuator parts description

Linear Actuator Parts Description


    • Motor – the motor is what makes the motion possible, and what interacts with the other parts of an electric linear actuator. The most common type of motor is a 12v DC motor, but for stronger or weaker actuators, this can be switched to a different format. The motor provides the movement. The motor is also subject to what is called the duty cycle of the actuator, the length of time it can operate before needing to rest.
PA-14 DC Motor
    • Gears – the gears are what attaches the motor to the lead screw, and allow them to move freely.
PRT-14-7-150 Gears
    • DC brushes – DC brushes bring current into the actuator by conveying it between stationary wires within the equipment.
DC brush set
    • Cylinder – The cylinder is the part of the actuator which contains the motion created by the motor. It does not move but contains the parts that do move.

    • Lead screw - lead screw actuators are the most common form of electric actuator. The lead screw is attached inside the cylinder, and it is this part of the actuator that actually turns the rotational motion into linear motion. The lead screw travels up and down the cylinder, creating the motion which is needed.
lead screw
    • Limit switch – a limit switch is incorporated into most (although definitely not all) models of the electric actuator, and acts as a means of limiting the movement of the actuator. When the limit switch is triggered, then all movement stops.
limit switch

How does an Actuator Work?

How do electric actuator 12v’s work? The motor provides the actual movement, to be changed into linear energy by the lead screw running up and down the cylinder, with a limit switch set to keep things from moving too far. The rotor and stator assemblies of the linear actuator both come into play at this point, as the primary and secondary workings of the motor. The stator assembly (as the primary workings) is hit with voltage first, which then gets turned into a current to be shunted into the rotor assembly (the secondary workings). The two workings together create a field, which is ultimately what causes motion. Once this motion has been created within the motor, it moves into the cylinder, where it turned into the linear motion through interaction with the limit switch.

The gears are what actively turns the cylinder, which is how the linear motion is created. DC brushes are used within the motor to help convey the electric current between it and the lead screw.

Summary

This article discussed various aspects of linear actuators, including what types were available, how they worked in general, and how electric actuators specifically worked. It is hoped that anybody who has need of this article will find the breakdown of the separate parts of an actuator, and the explanation of how it works, valuable to them and their work in whatever industry they are in.

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