Want to know how does a Linear Actuator work?
If a picture says a thousand words as they say then this animation below should explain alot about how a linear actuator works. This video shows all the moving parts from the rotary Electric motor turning the gears that turn the main Leadscrew that convert that rotary motion into linear motion of the main shaft.
We created this blog to help you understand all the terminology used in Linear Actuators, and to give you an understanding on how an Actuator works When you understand the basics, it makes it much easier for you to understand whats important for you're application and what important features to look out for when ordering a Linear Actuator
In addition we have created an article called “Don’t by a Linear Actuator until you read these 5-steps” this can help you avoid the many pitfalls of buying a Linear Actuator.
How does a Linear Actuator work?
Before we get started explaining in detail how a Linear Actuators works, we think we should mention our Linear Actuator selection calculator. This Actuator Calculator is graphical and allows you to input all your parameters such that you can accurately determine what the correct actuator type, force, and speed is going to be required for your particular application.
here is the link to the Calculator "Linear Actuator Calculator"
Now lets get into how a Linear Actuator works:
An electric linear actuator is a device that converts the rotational motion of a motor into linear motion. This will provide both push and pull movements via the main extending shaft on the Actuator. This pushing and pulling action makes it possible to lift, drop, slide, adjust, tilt, push or pull things, simply by pushing a button.
Installing a Linear actuator is very simple compared to pneumatic or hydraulic systems because they take up much less space. Electric Linear Actuators have no pumps or hoses, or tanks. They are also cheaper than Hydraulic or Pneumatic Actuators for the same reason.
An electric linear actuator consists of a DC or AC motor, a series of gear and a Lead screw including a nut. This is in essence what all Linear Actuator consist of, and all that changes from one model to another, are the motor sizes, the gearing ration inside the gearbox, and the lead-screw style and pitch. Some other electronics may help to perform the amount of stroke, positioning, or limit switching, but basically an Actuator is nothing more than a motor, some gears and a lead-screw, with extending shaft.
Why use an Electric Linear Actuator instead of Hydraulic?
Electric linear actuators are the perfect solution when you need simple, safe and clean movement with accurate and smooth motion control, with no mess or accessories required.
A hydraulic system is capable of very large forces, but those systems require high pressure hydraulic Pumps, high pressure liners and valves, plus a tank to store the Hydraulic fluid.
Hydraulic actuators use fluid to push a piston backwards and forwards, where as an electric linear actuator uses an electric motor to drive a lead screw. The lead screw is fitted with a nut that runs up and down the lead screw converting rotary motion into linear motion, its that simple.
There are drawbacks to using Hydraulics from an operating standpoint. And that is control. You have very little precision control when it comes to these systems. A linear actuator has a long lifetime with little or no maintenance at all. This ensures a very low total operating cost compared to Hydraulic or pneumatic systems.
Electric actuator systems are quiet, clean, non-toxic and energy efficient. They fulfill the ever increasing demands and legislation concerning environmentally sound equipment.What are some real world examples of what a Linear Actuator can do?
Linear actuators move things and we have seen thousands of applications over the years.
Some examples of practical automation applications are:
- Motorized door hatches
- hidden secret doors
- solar panels
- sliding doors
- sliding window treatments
- farming equipment
- Animations and Robotics.
- kitchen appliance lifts
- throttle control
- marine engine hatch
- slide out steps
- Snow plow adjusters
- Home Automation
- Office Automation
- Transportation Automation
What is the difference between Static Load and Dynamic Load?
You may see on our Spec sheets we mention both of these. Dynamic, working, or lifting load is the force that will be applied to the linear actuator while it is in motion. Static load, sometimes called the holding load, is the force that will be applied to the linear actuator when it is not in motion. The Dynamic load is what you need to move something and the static load is what you need to then keep that something in place.
In what direction can loads be applied to Linear Actuators?
Linear actuators can be used in tension, compression or combination applications. We refer to this as the pushing or pulling force. Side loading or cross loading should be avoided. But in these situations we suggest to customers to use linear Slide rails or guide rails in their system, to be able to handle any side loading, and rely on the Actuator to provide the pure push and pulling work.
Are side loading permissible on Linear Actuators?
Side loading, or radial loading is a force applied perpendicular to the linear actuator center-line. Eccentric loading is any force whose center of gravity does not act through the longitudinal axis of the actuator. Both side loading and eccentric loading should always be avoided as they can cause binding and shorten the life of the linear actuator.
Do Linear Actuators have limit switches?
Most Linear actuators come with limit switches built into them. The type of limit switches available varies with each product range, these include electro-mechanical, magnetic proximity and rotary cam. Limit switches are normally pre-set on actuators to stop the Actuator stroke when it gets to its full extension, and full retraction.
The limit switches are important because it prevents the Actuator from burning and stalling the motor when it reaches the end of stroke. The limit switch simply cuts power to the motor.
External Limit switches allow you the flexibility to set the limits of travel in your system to fit your particular application. The customer is responsible for properly setting the limit switch in the unit. If the limit switches are not set, or are improperly set, the unit may be damaged during operation.
What type of motors do the Linear Actuators use?
Linear Actuators are available with AC or DC motor variants, however each range has preferred standard types. DC Motors are the most popular and in 12-v typically. 24-v motors are used for more industrial applications or in high force Actuators. 24-v is more efficient for higher force applications
Can you get Linear Actuators available in different speeds?
Linear actuators are available in a variety of linear speeds and a standard list is detailed with each product. All that will change in the Actuator to achieve different speeds is that the gearing will change. But please note when the gears are changed to get a different speed then so too will the force. Force and Speed always trade-off against each other. Here is a link to all our Linear Actuators
What is the duty cycle capability of a Linear Actuator?
Duty cycle rating for a linear actuator is generally expressed as a percentage of “on time” (the ratio of on time to total time) or as distance traveled over a period of time. The duty cycle rating is expressed differently for different actuator types.
What type of mounting do the Linear Actuators have?
The linear actuators generally have a mounting points we call clevises at each end of the actuator to allow a pivoting movement. There are a number of options, double clevis as standard. Here is a link to all our Brackets
What type of enclosures do the Linear Actuators have?
Linear Actuators have different IP ratings. The lower the number the lower the protection is. IP-54 offers basic protection such as dust, and a higher IP-66 rating offers a water proof protection and ideal for outdoor use.
Is back-driving possible in electro-mechanical Linear Actuators?
Unless otherwise stated back-driving is possible in all electric linear actuators. Back-driving is when a force is applied that’s greater than the static force, allowing the Actuator shaft to move without any power applied to it. Actuators that use a ball screw are normally fitted with an electrical brake (typically motor mounted) to prevent the load from back-driving the actuator.
Can a Linear Actuator be run into a hard stop?
We don't recommend applications that have possible hard stops because it can lead to the Actuator becoming jammed. Examples of jamming include over-travelling the limit switches and jamming the nut and screw internally at the extreme ends of the stroke or driving the actuator against an immovable object and thus overloading the actuator severely.
Can two or more Linear Actuators be synchronized?
Small differences in motor speed is fairly normal. And different actuator loading may cause the units to get out of synchronization very easily. The units cannot therefore be guaranteed to run in synchronization. For exact synchronization a closed loop control system is recommended. This is possible using an Actuator with built in Feedback and that feedback data is sent to a controller where that controller then calculates how to make actuators run together regardless of their loading or speed differences. Feedback Actuators include Potentiometers, Optical sensors, or Hall sensors. We do have a control box that can sync up to 4 Linear Actuators together. Here is the link
Are the actuators lubricated for life?
Linear actuators are grease lubricated for the internal parts of the actuator including gearbox assemblies and the lead-screw and nut assemblies. The actuators are greased for life.
In the temperature test the actuators are tested to operate in extreme temperatures as well as to endure rapid changes in temperature. In most cases tests are performed on the actuator to withstand going from a +100°C environment to -20°C repeatedly and still maintain full functionality.
For a much more details overview on how a Linear Actuator works, we created this article "Inside a Linear Actuator - How an Actuator works"