What Is a Linear Actuator?

A linear actuator is a device that converts rotary motion (typically from an electric motor) into linear motion. Unlike hydraulic or pneumatic actuators, electric linear actuators use electricity to create movement—making them cleaner, quieter, and more precise.

• TV lifts and pop-up cabinets
• Automated windows and hatches
• Industrial automation systems
• Robotics and aerospace
• Medical equipment and home accessibility

In a linear actuator, motor power is fixed for a given voltage — the gearbox only redistributes that power between force and speed. You cannot have both.

"The motor gives you a fixed amount of power. Everything after the motor — the gearbox, the screw lead — is just trading that power between force and speed. Once you accept that tradeoff, sizing an actuator becomes straightforward." — Robbie Dickson, Founder and Chief Engineer of FIRGELLI Automations

What are the core components of an electric linear actuator?

• DC or AC Motor: Generates rotary motion
• Gearbox: Reduces speed and increases torque
• Lead Screw or Ball Screw: Converts rotary to linear motion
• Drive Nut: Attached to the rod and rides the screw
• Extension Rod: Moves in and out
• Limit Switches: Prevent overtravel
• Hall Sensor (optional): For position feedback

Component	Function
DC or AC motor	Generates rotary motion.
Gearbox	Reduces speed, increases torque.
Lead screw or ball screw	Converts rotary motion to linear motion.
Drive nut	Translates screw rotation into rod travel.
Extension rod	Delivers linear motion to the load.
Limit switches	Cut motor power at end of stroke.
Hall sensor (optional)	Provides position feedback.

How does the mechanism actually work?

The motor spins the lead screw, moving the internal nut. As it moves, it extends or retracts the rod, generating controlled linear motion. Limit switches shut off movement at either end of the stroke.

For a complete engineering reference on selecting the right linear actuator — including detailed guidance on force, stroke, duty cycle, mounting geometry, control strategies, and real-world sizing models — see the Linear Actuator Engineering Guide: https://www.firgelliauto.com/pages/linear-actuator-engineering-guide

What types of linear actuators are available?

• Mini Linear Actuators
• Heavy Duty Actuators
• Feedback Actuators
• Track Actuators
• Rod-Style Actuators

Type	Best for	Note
Rod-Style	General-purpose push/pull	Most common form factor.
Track	Tight spaces, fixed envelope	Sliding block; overall length doesn't change.
Mini	Small mechanisms, low force	Compact stroke and force.
Heavy Duty	Industrial loads	Higher force, larger envelope.
Feedback	Position-controlled systems	Built-in potentiometer or hall sensor.

What are the advantages of electric linear actuators?

• Precision control and clean operation
• No leaks or fluids to manage
• Quiet and compact design
• Easy integration with Arduino or PLCs

What does a real-world linear actuator application look like?

A FIRGELLI actuator mounted in a cabinet lifts a hidden TV when powered. It stops at full extension automatically, and retracts just as smoothly with the press of a button.

A concrete sizing example. Suppose you need to lift a 40 lb hatch through 12 inches of stroke at 12V DC. Two actuators in the same product line might be specified as: (A) 150 lb force at 0.5 in/sec, or (B) 50 lb force at 1.5 in/sec. Both run on the same 12V DC motor; the difference is gear ratio. For a 40 lb static load, either is mechanically capable, but option A gives a comfortable force margin (roughly 3.75x) for friction, off-axis loading, and cold-weather stiffening, while option B finishes the stroke in 8 seconds versus 24. The choice depends on whether speed or margin matters more for the application.

How do you choose the right linear actuator?

Factors to consider:

• Force, stroke, speed, voltage
• Feedback requirements
• Environment and IP rating

Use our Linear Actuator Calculator to find the right model.

What usually goes wrong with linear actuators?

1. Side loading. The rod is designed to push and pull along its axis. If the load tugs the rod sideways, the internal nut and bushings wear quickly and the rod can bind. Use a separate guide rail or hinge so the actuator never becomes the guide.
2. Undersized force margin. Sizing an actuator to exactly the calculated load leaves no headroom for friction, dust, cold-weather grease stiffening, or wear. A 25–50% force margin is standard practice.
3. Environmental ingress without matching IP rating. Outdoor, marine, or wash-down applications need the IP rating to match the environment. An IP54 actuator installed in a salt-spray environment fails fast.
4. Mounting geometry that wastes stroke. If the pivot points are placed without checking extended and retracted lengths, the actuator either bottoms out or never reaches full travel.
5. Wiring shortcuts. Undersized wire over long runs causes voltage drop, which reduces available force at the motor. Reversing polarity through a non-rated switch burns contacts.

How should you test a linear actuator before trusting it in a build?

1. Cycle it under real load, not bench load. A free-hanging actuator extends fine. Bolted into the actual mechanism with the actual mass, friction and angle change everything.
2. Measure current at the hardest part of travel. The hard part is usually near full extension under load, or at the moment of breakaway from rest — not the easy middle. If current spikes near the motor's stall rating there, the actuator is undersized.
3. Run repeated cycles, not single moves. A single successful extend/retract proves the idea. Twenty cycles back-to-back at rated load prove the build.
4. Test at the worst expected temperature. Grease stiffens in cold; motors lose torque when hot. Both reduce available force.
5. Verify the limit switches actually stop motion at both ends and that the system rests without drawing current.

Frequently Asked Questions

How do I wire a linear actuator?

Two wires control direction via polarity. Use a DPDT switch or relay. Wiring Guide

Can I run multiple actuators together?

Yes. For synchronized motion, use a sync controller with hall sensors.

What’s the difference between track and rod-style?

Track actuators don’t extend outward—ideal where space is limited. Compare here

Is electric better than hydraulic or pneumatic?

In many use cases, yes—due to simplicity, safety, and precision.

Explore Further

• What is a Linear Actuator? (Beginner Guide)
• Feedback Systems Explained
• Shop FIRGELLI Actuators
• Download this article as a PDF

• How they work
• Which Actuator to use
• Actuator Speed

Deep Dive: How Linear Actuators Really Work 

If you read the previous section, we covered Actuators at the high level, for those that want to go into  more detail, we cover that in this section below.  

Many people, rather, most people have never needed to use an actuator before, and typically refer to them as 'rams', 'activators', 'electric pistons', or other wild variations. All in all, they all mean the same thing, and we don't mind if you don't like using the technical terms. First thing to know, is that a linear actuator does exactly what its name implies: it actuates (or 'moves') in a linear (or 'straight') fashion

There are many different ways that a motor can do this, and their motion is commonly achieved with a rod extending and retracting, or a slider which moves on a track. Uses for these linear motors vary widely, and they can be used on everything from TV lifts (including drop down lifts), wheelchair ramps, industrial machinery, toys, office and home automation, and even aerospace technology.

So how does a Linear Actuator work?

 

The linear motion is created by using a screw, or lead screw as they are more correctly called. The screw turns either clockwise or counter-clock-wise and this causes the shaft, which is basically a nut on the screw to move up and down the screw as the screw turns. This is what convert rotary motion from the electric motor to linear motion.

The motors used are either AC or DC motors, most however run on 12v dc, but other voltages are also optional.  To make the Actuator go the other way you simple reverse the wires from the Actuator (reverse polarity) from the battery or power supply. This is typically done through a switch that automatically reverses the polarity to the motor for you.

Different speeds and forces are achieved by using different gear ratios inside the linear actuator gearbox system. Please remember in a Linear Actuator, force and speed trade-off against each other. That means if you want high force you have to settle for a lower speed than if you require lower force. This is because the only constant in a Linear Actuator is the Motor speed and force for a given input voltage. Everything after the motor is what is available to be used to create speed and force. 

Actuators are available in different strokes, all this means is the screw and shafts are longer or shorter to get the stroke you want. They are also available in different speeds and forces. This is achieved by simple changing the gears that go between the DC motor and the screw. Typically the faster the screw turns the lower the force, because speed and force trade-off against each other.

To make the shaft stop when it gets to the end of the stroke the Actuators have built in limit switches or micro switches as they are sometime known. These limit switches are inside the main actuator shaft and are nothing more than a small switch that are triggered by the nut inside that slides up and down the screw. There is one for the top extended position and one for the lower retracted position. Once the limit is reached the switch is triggered and cuts power to the DC motor. Only if the polarity is reversed can the actuator move which would be in the opposite direction. Without any power the actuator cannot more at all.

 

Firgelli Automations is a proud supplier for thousands of companies in the above sectors, and more for over fifteen years. In these years, we've learned a thing or two about what first-timers want to know. This will be a regularly updated article with all the links and videos you could possibly need to start your own project with actuators.

What Actuator should I use?

With such a selection of Actuators we manufacture, it can be very easy to get confused and frustrated if you don't know anything about electric motors or actuators in particular. Typically when helping a new client choose the right unit for his or her application, we will ask the following:

1. What are you using it for?

2. How much force do you need?

3. How much stroke ('travel') do you need?

4. How fast do you need it to move?

5. And finally, how often do you need it to do this?

The significance of these questions is to determine what sort of load will be placed on your future actuator, and what requirements you have. Most people start off with needing a product with X amount of force, which is a fantastic place to begin your search. The Actuator finder page will help you pick the right unit based on force, and narrow your search down, or use our Linear Actuator Force Calculator to determine what force of Actuator you really need. Typically we would recommend a certain type of actuator based on what you tell us you're using it for, but for those of you who are just tuning in, see below for common applications for various types of actuators and see if you can pick your project out.

• Track Actuators - Used for tight spaces where a sliding block is ideal due to its unchanging retracted and extended length.

• Rod-Style Actuators - These are the most common actuators you will find, and simply feature a shaft which extends and retracts, providing linear motion. 

• Feedback Actuators - For applications which have systems to read the actuators' position, these potentiometer pod equipped actuators are ideal; they provide accurate information for precise control over your application.

Now that you know how much force you need, and an idea of what type of actuator you require, we can move on to the next step of determining what stroke length you'll be wanting.

How long should an Actuator be?

Here is where most people get slightly misinformed. The difference between the open and closed position for an actuator is simply known as the 'stroke length'. For example, if we had a to move a sliding block twelve inches, we would want to make sure that the actuator we chose for the job would have a stroke length of at least twelve inches.

Do I need a High Speed Actuator?

So to re-cap: You know now how much force you need, as well as the type of actuator you'll be using and the stroke length. Finally you are now ready to figure out the speed of the actuator.  Most of the product lines found on our site feature several different forces, this is important because within those product lines, as you increase in force, you decrease in speed due to varying gear ratios, much like the transmission in a car. So by now you've narrowed your selection down to one or maybe two product lines that we carry. At this point, it is a good idea to go to the 'Specifications' tab of each unit and have a look at their speed rating. Keep in mind, speed ratings are assuming the unit is being used at full load.

You're now equipped with the thought process that the pro's in large scale engineering projects follow on a daily basis. If you have further questions or concerns, you will find a wealth of helpful staff at the ready via email or phone on our contact page.

Watch Videos and Read Articles on Linear Actuators Below

• How to use a linear actuator to control a snow blower

• How to use an Arduino with relays to control a linear actuator

• If a 7-year old can install a linear actuator, then so can you!