Firgelli automations publishes info sheet to help you understand all the terminology used, and to give you an understanding on how Linear Actuators work and operate.
What is a Linear Actuator?
An electric linear actuator is a device that converts the rotational motion of a motor into linear motion – that is, it will provide both push and pull movements.
By pushing and pulling it is possible to lift, drop, slide, adjust, tilt, push or pull objects, simply by pushing a button.
Additionally, Linear Actuators provide a safe and clean movement with accurate motion control that you the operator have full control over. They are energy efficient and have a long lifetime with little or no maintenance.
Installing an actuator is very easy compared to hydraulic or pneumatic systems and it takes up much less space, as it has no pumps or hoses. They are also significantly cheaper that 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 Leadscrews including a nut. This is in essence what all Linear Actuator consist of, and all that changes is the motor size, the gearing and the leadscrew style. Some other Electronics helps to perform the amount of stroke limit switching and positional feedback options, but basically an Actuator is nothing more than a motor, some gears and a leadscrew.
What is a Lifting Column?
Lifting columns are another form of Linear Actuators. Typically, they provide a longer stroke because they have multiple stages, that allows them to expend and contract in a longer length than they are when fully closed. Another way to put it is that a Column Lift is an Actuator within an Actuator.
Why use an Electric Linear Actuator instead of say Hydraulic?
Electric linear actuators are the perfect solution when you need simple, safe and clean movement with accurate and smooth motion control. You can choose actuator systems for adjustments, tilting, pushing, pulling and lifting with fairly high forces.
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 puling force. Side loading or cross loading should be avoided. But in these situations we tell customers to use linear Slide rails or guide rails in their system to be able to handle any side loads, 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.
Are 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.
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.
What type of enclosures do the Linear Actuators have?
Linear Actuators have different IP ratings. The lower the number the lower the protection is. IP54 offers basic protection such as dust, and a higher IP66 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.
What are the common factors in the failure of a Linear Actuator?
Improper loading, Improper installation, excessive duty and extreme environments may contribute to premature actuator failure. The most popular by far is over loading due to amplification of force.
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.
Are the actuators lubricated for life?
Linear actuators are grease lubricated for the internal parts of the actuator including gearbox assemblies and the leadscrew 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.
What are some real world examples of what a Linear Actuator can do?
Some examples of practical automation applications are:
• Motorized hatches
• kitchen appliance lifts
• throttle control
• marine engine hatch
• slide out steps
• Snow plow adjusters
• hidden doors
• solar panels
• sliding doors
• sliding window treatments
• farming implementations
• animatronics and Robotics.
Industrial applications include:
• damper control and height adjustable work stations
• Home Automation such as moving TV’s or Projectors.
To know more about Linear Actuators, read the original post here - https://www.firgelliauto.com/blogs/news/linear-actuators-101
For a much more detailed overview on how a Linear Actuator works, read more here - Inside a Linear Actuator - How an Actuator works
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