Aug. 11, 2025
Those I've seen are simply a lead screw driven by a DC motor with limit switches at each end. There may be other types but based on that...
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Do they act like servos or motors?
Motors.
Are they some how settable or programmable such that its normal balanced position is half of the stroke or is that something done via software?
No help from the device, all done in software.
And if it doesnt act like a servo how does it know how far out it has extended?
Timing?
Or are they all the same strength going in and out and thats marketing?
Same both ways.
As I said this is just for the ones I've dealt with, there may be smarter ones around.
The ones you linked to only appear to have two wires, so I'd say they are as as I described.
Rob
thanks for the reply. I found a couple more. Im going to call on them in the am and see. It does look like most are as you describe.
Im going to use this for steering so not sure timing the motor movement will be good enough to reliably center the shaft when there are other forces applied to the wheels. It ranges from x seconds per inch at no load and half that at full load. Thats why im looking for position feedback.
cheaper
http://www.ebay.com/itm/NEW-XSCORPION-6-Linear-Actuator-12-Volt-DC-450-LB-Static-w-Adjustable-Stroke-/?pt=LH_DefaultDomain_0&hash=item51a08b51bc
Potentiometer: 10K
i like these guys I just got a servo from them and the customer service was really good:
http://www.servocity.com/html/115_lbs__thrust__linear_actuat.html
Built in potentiometer can be easily accessed for position feedback but is not necessary for operation.
Some linear actuators have built in potentiometers (typically linear) that can be used to detect position; in such actuators, you monitor a change in voltage from the potentiometer (set up as a variable voltage divider), which is proportional to position.
Other linear actuators use either an optical slot interrupt detector, a hall-effect switch, or a reed switch, which output a series of pulses. The way these actuators are used is to drive them to one end of their travel (depending on how things are set up, you can monitor the motor current, or an external limit switch to detect end-of-travel), then reset a counter and count every pulse of the detector (via an interrupt most likely) as you drive the actuator to the other end (until you detect the other limit switch). Once you have the count in one direction, you can use that (or count backwards as you drive again in the opposite direction - then take the floor() average).
Some linear actuators have built-in limit switches to shut the motor off at the end of travel for the actuator (which may or may not be the same as the end of travel for -your- application!); if that length is the same as your application, you can detect end of travel by looking for the current being drawn by the motor to rapidly fall to "0" (vs rapidly rising beyond a certain threshold when detecting a stall condition).
Finally - there are linear actuators that can be controlled digitally ($$$) via RS232 or other serial communications method, as well as ones that can be controlled just like a common R/C servo ($$).
Oh - a couple more things to be aware of: 1) Some linear actuators move at different speeds depending on whether they are extending or retracting, and 2) some linear actuators have a special (usually manually adjusted) mode to allow the "ram" to be decoupled from the gear mechanism, and be extended or retracted manually. You generally find both kinds of features on actuators meant for medical equipment, like beds and chairs.
...and just for sake of completeness:
nice great reply and links. Funny ive been searching around for the last few weeks and never hit on them. Prices look to be not astronomical.
Just converting newtons to pounds though even the biggest one with the highest gear reduction is only about 44 pounds. And thats at about .5"/s. slow. But maybe useable if I make my angle shorter so it doesnt have to push out very far.
Just blathering here... I'm going to use this for steering a ROV. So I need my wheels straight position to be at the halfway point of the stroke. To turn one direction I pull the shaft in and the other way I push it out and with no input on the joystick it should return to the "center".
I dont care about controlling the speed it goes in or out.
I think I dont care about limit switches other than to stop from burning it up. If it worked like a servo that would never be a problem because I would just never send it to end of travel in either direction.
I may need some type of controller to make it act like a servo.
Looking at http://store.firgelli.com/L16_Linear_Actuators_p/l16-p.htm
it shows an additional controller to "
Turn your L16 -P into a Linear Servo using the LAC board listed in the "Controllers and Switches" section here. This combination has all the same functionality as the L12-I plus USB support, speed control, sensitivity control, position control, and adjustable end limits.
Hmmm.
Then I look at something like this which includes the controller:
http://www.servocity.com/html/heavy_duty_linear_servo__180__.html
vs
http://www.servocity.com/html/115_lbs__thrust__linear_actuat.html
which has no controller but does have position feedback.
I'm thinking that with a position sensor I should be able to make it a servo right? Or is my whole problem I'll still need a controller because ITS NOT A SERVO and i cant swap polarity to run it in the other direction with out using a controller or creating some type of H bridge myself. (which i just avoided by buying a motor controller for another part of the project.)
So now I think its sounding like I need an actuator with position feedback + arduino + the other half of my Dual motor controller Pololu - Dual VNH3SP30 Motor Driver Carrier MD03A
(I'm only using one side of it to control my forward and reverse drive motor)
With that I think I can create a linear actuator that acts like a servo and I already have 2 of 3 of the peices. And a prebuilt servo type actuator or one bundled with a controller is infinately more expensive than this combo that I'm thinking will work.
I have spent a lot of money trying to build things cheaper...
step 3: Profit
Hello,
this is Luigi,
from Rome, Italy.
I am a newby in the arduino world with great interest in any application of it.
My question is this:
I wish to operate an actuator 12V /5 A on board of my experimental airplane to control the flap system in an auto mode.
The flap has only 4 positions Up, 10, 20 and full Down.
Right now I command the actuator directly and when it reaches a reference on the wing I stop it. Then till full down an the retract during take-off.
The actuator has already the end of travel. I need a system that allows to reach the next position just sending an impulse and with a longer signal to reach the full travel. More or less like the windows of a car. I can install some switch during the run or a pot to feedback or eveything may be useful.
Which is the best way to have this ? In term of hardware and software, of course.
Thank you for the help may arise
Luigi
Author: Robbie Dickson
Wikipedia: Robbie Dickson
Did you know that there are hundreds of actuators in a typical car?, in fact, it is estimated there are over 50 actuators of many different types within a car that you never get to see. How about in the home? there are also many different types used at home for multiple applications and use cases. The point is that Actuators come in many different forms and types, they can use used to automatically turn the water on and of in a washing machine, to lift a TV out of a cabinet, or to operate that coffee machine every morning. The point is that Actuators have been around for decades in applications we all take for granted every day.
FIRGELLI is a world leader, supplier, and manufacturer of Electric Actuators, we have been around for over 20 years and partner with thousands of customers for very specific applications in every industry you can imagine. Our focus is on creating devices that suit our customer's needs which is why we have one of the largest ranges of actuators possible. From Tesla to the Terminator we supply an insane range of companies with diverse product ranges and we do that globally.
This Ultimate Guide to actuators is about educating people on everything that is an actuator. We will go into them in great detail and cover them from every angle. Our primary focus will be on electric actuators as this is our primary product range, however, we cannot forget about other types and we will cover them also, because its important to understand the pros and cons of all these different types regardless of whether we develop these other types or not.
Electric linear actuators are devices that convert a source of energy into a physical-mechanical motion in a straight line (linear actuator) or a rotary motion (rotary actuator). They are different from hydraulic and pneumatic actuators, as they use either compressed air or fluid to make something move. They are also more reliable, require less maintenance, and are often less expensive, but let’s go into this in greater detail.
The operation of an electric actuator is achieved by converting the rotational motion of an AC or DC motor into a linear motion or rotary motion but geared down from a typical RPM+ speed of a motor, to something more suitable for creating motion (linear or rotary) that can then be made useful to do something practical. By useful we mean increasing the torque by lowering the speed, a necessary process for any electric actuator. For linear Actuators, depending on the direction of the screw's rotation, the shaft attached to the screw (leadscrew) moves in a straight line, up or down, providing a push or pull effect on the load. Electric linear actuators can also be easily integrated with positioning feedback for precise control. DC voltage is typically considered safer than AC voltage, but Actuators are available in either source.
There are several different styles of electric linear actuators available on the market, each with its own advantages and disadvantages depending on the specific application. In this article, we'll explore the three main styles of electric linear actuators: Inline, L-shaped, and Parallel, Rotary, and Track (slide actuator)
Inline electric linear actuators are a popular choice for applications that require high speed and force capabilities in a compact design. These actuators feature a motor and actuator rod that are aligned on the same axis, allowing for a streamlined design that saves space. Inline actuators do have a major disadvantage however, and that is that they tend to be longer than any other type of actuator, because the Motor and gearbox have to sit behind the drive leadscrew which requires the overall length to be longer, whereas most other actuator types the Motor can sit along the side of the main body. The big advantage however is that they tend to be a much nicer design to look at, they appear sleeker and more attractive which makes them ideal for applications where they are seen.
L-shaped electric linear actuators are another popular option, particularly for applications where space is limited. These actuators feature a motor and gearbox mounted at a right angle to the actuator rod, creating an L-shape. L-shaped actuators are often used in furniture automation, industrial automation, and automotive applications.
Parallel electric linear actuators are perhaps the most common style of actuator designed for high force and precision applications and feature a motor and gearbox mounted parallel to the actuator body thereby allowing the overall length to be more compact. The drive mechanism is typically Spur gears which can make them noisier, but that's the trade-off for a more compact Actuator.
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A Rotary Actuator is a type of actuator where the final drive motion is rotary instead of linear. In contrast, a Linear Actuator can be thought of as a rotary actuator with a leadscrew, drive nut, and rod, which converts rotary motion from a rotary actuator into linear motion via the leadscrew. Rotary actuators have a continuous driving motion in either direction, with no stops or limits unless a stopping component is added.
Rotary actuators are versatile and can be used by attaching something to the driving flange to create the desired motion in the final application. However, it's important to consider the torque and speed required for the application. As rotary actuators have angular force, they are selected based on torque and speed dimensions. It's worth noting that torque and speed trade-off against each other, so high torque results in lower speed, and vice versa. This is due to the way gear ratios work in any type of motion where there are gears between the driving motor and the final driving wheel.
The Track Actuator, also known as the Slide Actuator, operates differently from other actuators as it doesn't have a shaft or rod that slides in and out of the actuator's end. Instead, a carriage slides along the main body or track of the actuator. This unique design makes it ideal for specific applications, such as massage chairs or industrial assembly lines where the track needs to slide something in and out repeatedly.
One significant advantage of this type of actuator is its versatility when it comes to installation. The carriage or nut, as they're sometimes called, have various threaded holes that make it easy to attach things to them. Additionally, it's possible to install more than one carriage on the same track, which increases strength and rigidity.
When selecting an electric actuator, it is crucial to consider the specific requirements of your application. With various actuator models, such as parallel, L-shaped, or inline motors, available for a wide range of applications, choosing the right one can be challenging. We have written a separate article specifically on the subject of the different types of electric actuator styles here.
Comparison of Different Actuator Systems: Pneumatic, Hydraulic, and Electric
Actuators are essential components in the manufacturing and automation industry. They are used to create movement in machines and systems, converting energy into motion. There are several types of actuator systems, with the three most common being pneumatic, hydraulic, and electric. We will discuss each actuator system's characteristics, advantages, and drawbacks, and compare them with one another.
Pneumatic actuator systems are widely used in the industry due to their low cost and simplicity. They consist of a simple piston inside a hollow cylinder, which moves in a linear motion. These actuators require air compressor, regulator, and an air cylinder to hold pressure. When pressure is applied to the cylinder, the piston moves, creating the necessary linear force. Retraction can be accomplished by either a spring-back force or by providing fluid to the opposite side of the piston.
One of the major drawbacks of pneumatic actuators is that it is difficult to achieve position accuracy. Mid-stroke positioning requires additional components and user support, making it challenging to achieve the desired results. Additionally, pneumatic actuators have a limited load rating compared to hydraulic and electric actuators.
Hydraulic actuator systems are known for their ability to produce very high forces and long strokes. They use an incompressible liquid supplied by a pump to move the cylinder in a linear motion. These actuators consist of two essential components: a control device, such as variable throttles or paired slide valves, and an actuation component, such as a piston or controlling valve slide. They are capable of very high forces and long strokes but are not programmable.
Hydraulic actuators are explosion-proof, shock-proof, and spark-proof, making them suitable for hazardous environments. However, they are also very complex, requiring a high-pressure pump, high-pressure regulators, and a hydraulic fluid reservoir. The hydraulic fluid leaks and disposal can also be challenging and require maintenance.
Electric actuator systems are highly precise, making them suitable for high-speed, force, precision, and controlled acceleration and deceleration applications. These actuators convert the rotational force of a motor into linear movement, using a screw to create a push/pull effect. By rotating the actuator's screw via the motor, the nut will move up and down in a linear motion. Electric actuators are also programmable, offering flexibility in motion control capabilities with an electronic controller.
Compared to hydraulic and pneumatic actuators, electric actuators are the most reliable and require almost zero maintenance. They are also environmentally friendly and have minimal effects. However, they have a limited ability to handle shock loads, which can cause mechanical damage. They are also slow to high, but highly correlated to force, meaning high speed will mean low force, but low speed means high force capabilities.
In the table below, we have summarized the characteristics of each actuator system. Electric actuators are the simplest and most cost-effective option, Pneumatic come in second, but they have limited load ratings, and are difficult to achieve position accuracy. Hydraulic actuators are capable of producing very high forces and long strokes, making them suitable for heavy-duty applications, but they are complex and require maintenance. Electric actuators are the most reliable and precise, but they are limited in handling shock loads.
When it comes to efficiency and operating costs, electric actuators are the clear winner, with low operating and maintenance costs. Pneumatic actuators have moderate purchase and operating costs, while hydraulic actuators have high purchase and operating costs. However, hydraulic actuators have a long lifespan, making them a cost-effective solution in the long run.
In conclusion, choosing the right actuator system for your application requires careful consideration of your specific needs, as each has its advantages and disadvantages. Pneumatic, hydraulic, and electric actuator systems all have unique characteristics that make them suitable for certain applications. Pneumatic systems are ideal for simple applications that require high speed, while hydraulic systems are best suited for heavy-duty applications that require high force and long strokes. Electric systems are highly precise and reliable, making them the best option for applications that require accuracy and repeatability.
Characteristics Pneumatic Hydraulic Electric Complexity Requires an Air compressor, regulator and possibly an Air cylinder to hold pressure Very complex system. Requires High pressure Pump, high pressure regulators, Hydraulic fluid reservoir Very Simple. Actuators are a single self contained system. Peak Power High Very high High Control Simple valve control, operated via solenoid actuators Simple valve control, operated via solenoid actuators Flexibility of motion control capabilities with electronic controller Position Very difficult to achieve position accuracy Mid-stroke positioning requires additional components and user support Positioning capabilities and velocity control allow for synchronization and many other control options down to micron control levels. Speed Very high Moderate Slow to High, but highly correlated to force. So high speed will mean low force, but low speed means high force capabilities Load Ratings High Very high Can be high depending on the speed trade-off Lifetime Moderate Long Long Acceleration Very high Very high Moderate Shock Loads Able to handle shock loads Explosion-proof, shock-proof, and spark-proof Limited ability to handle shock loads - can cause mechanical damage. Environmental High noise levels Hydraulic fluid leaks and disposal Minimal effects Utilities Compressor, power, pipes Pump, power, hydraulic reservoir, pipes Power only Efficiency Low Low High Reliability Excellent Good Good Maintenance High user-maintenance High user-maintenance Little to no maintenance Purchase Cost Medium High very Low Operating Cost Moderate High Low Maintenance Cost Low High LowThere are many components inside a typical electric actuator. Here are some of the common components that can be found inside an electric linear actuator:
Note that the specific components and their configurations may vary depending on the type and application of the electric linear actuator. The image below is a very high level picture that shows the main components.
In the image below you can see a typical FIRGELLI actuator and all of its components in much more detail. This level of detail is still missing many parts such as O-rings, wiring etc, as this would clutter the image far too much, so we removed some non-core components for easier viewing.
All electric actuators have a motor that is either AC or DC. Most are DC because they are safer to handle and DC can be controlled much easier. The size of the motor is what gives the actuator its power, and so larger motors mean more power and vice versa.
When it comes to Motors there are two types, Brushed, and Brushless. A brushed motor, which is the most common type, is a type of DC motor that uses brushes (made of carbon or graphite) to transfer electrical power to the rotor (the rotating part of the motor). The basic components of a brushed motor include the stator (stationary part), the rotor (rotating part), and the commutator.
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The stator contains one or more coils of wire that are wound around a metal core. These coils are usually arranged in a circular pattern around the rotor. The rotor, on the other hand, consists of a shaft that is mounted on bearings and a series of wire windings or permanent magnets that are arranged in a cylindrical pattern around the shaft.
The commutator is a segmented cylindrical conductor that is mounted on the shaft and is connected to the rotor windings. The brushes make contact with the commutator, allowing electrical power to be transferred from the power source to the rotor.
When electrical power is applied to the stator coils, it creates a magnetic field around the rotor. The magnetic field interacts with the magnetic field produced by the rotor, causing the rotor to rotate. As the rotor turns, the commutator segments move past the brushes, switching the polarity of the current flowing through the rotor windings, which produces the torque that drives the motor.
The commutator segments are arranged in a specific pattern so that the polarity of the current in the rotor windings changes at the appropriate time during each rotation of the rotor. This switching of the current allows the motor to continue rotating in the same direction.
Brushed motors are relatively simple in design and construction, but they have some limitations. One of the main disadvantages is that the brushes and commutator wear over time, leading to increased friction and reduced efficiency. This wear can also generate sparks and cause electromagnetic interference. Additionally, brushed motors tend to be less efficient and have a lower power-to-weight ratio compared to brushless motors. However Brushed motors are more common, much lower price points, and much easier to control. This is why they are most commonly used in Electric Actuators.
A brushless motor (BLDC) uses a different configuration where the rotor is the rotating part, and the stator (fixed part) has the winding. The rotor in a BLDC motor typically consists of a series of permanent magnets arranged in a circular pattern around the shaft. The stator, which surrounds the rotor, has multiple coils of wire wound in a specific pattern. The stator windings are energized by an electronic controller that uses sensors to determine the position of the rotor magnets and control the flow of current to the stator coils, producing a rotating magnetic field that interacts with the permanent magnets on the rotor, causing it to spin.
A clevis (sometimes spelled "clevice") is a mechanical fastener that is used to join two objects together, typically a rod or shaft to a load or linkage. It consists of a U-shaped metal bracket with holes at the ends of the arms that allow for the attachment of a pin or bolt. The clevis can be used to transmit forces or motion between the objects while allowing for some degree of rotation or pivoting. Clevises are commonly used in various industrial applications, such as in the construction of machinery, vehicles, and aircraft. They can also be found in hydraulic and pneumatic systems, where they are used to attach cylinders, pistons, or other components to a load or actuator.
Below is an image of the Clevis on both the Rod end (the part that moves) and the motor end (the part that stays fixed into place)
The purpose of the Clevis ends of an Actuator is that one end stay fixed (usually the motor end) and the rod end which is the part that extends in and out has a clevis mount too. The U-shaped brackets that fit on both ends use a round pin and this allows the bracket to rotate around one axis. This is very important because as an Actuator is pushing something open and closed, the actuator also changes the angle, without it being able to rotate around at least one axis the system would fail.
Some Actuators come with a built-in overload current protection system called a Thermistor.
A thermistor is a type of resistor whose resistance varies with temperature. The name "thermistor" is a combination of "thermal" and "resistor". Thermistors are commonly used in electronic circuits as temperature sensors, in which their resistance changes with temperature are measured and used to determine the temperature of the surrounding environment.
There are two types of thermistors: positive temperature coefficient (PTC) and negative temperature coefficient (NTC). PTC thermistors have a resistance that increases with increasing temperature, while NTC thermistors have a resistance that decreases with increasing temperature.
Thermistors are made of semiconductor materials such as metal oxides, which have a high sensitivity to temperature changes. The resistance-temperature relationship of a thermistor is non-linear, which means that the resistance change is not constant with temperature. The relationship between resistance and temperature can be approximated by a mathematical equation called the Steinhart-Hart equation.
Thermistors are used in a wide range of applications, including temperature measurement and control in electronic circuits, temperature compensation in oscillator circuits, and protection of electronic devices from overtemperature conditions. They are also used in automotive, HVAC, and medical applications for temperature sensing and control. FIRGELLI has them built into one of our Actuator models for the customer who likes this feature.
Not all actuators have thermistors built in because to reset the Thermistor once it kick in, you have to remove the load that caused the cut-out to begin with and then reverse polarity to the actuator. This can be very easy to do with a control program, but for an analog setup with just a power supply and a switch, it may not be best suited. But this type of safety is very effective and ideal for applications where children or fingers could be injured otherwise.
Different features of the actuator can affect its speed and load capacity, including voltage, leadscrew type, and motor specifications. Here are some of the features and their effects:
1. Voltage: The voltage supplied to the actuator affects the speed and torque that can be produced. Higher voltages typically result in higher speeds and torque. However, using higher voltages may also result in higher power consumption, and may require more expensive power supplies and controllers. The choice of voltage for a DC motor depends on the application requirements and constraints. Here are some benefits and drawbacks of using 12V, 24V, and 48V DC motors
Voltage Benefits Drawbacks 12V Widely available and affordable; lower power consumption and cost for batteries and power supplies Limited power output and speed; may not be suitable for heavy-duty or high-performance applications 24V More power output and speed than 12V motors; more efficient and can handle higher loads; commonly used in industrial applications May require a more expensive power supply and motor controller than 12V motors 48V High power output and speed compared to lower voltage motors; more efficient and can handle even higher loads; suitable for high-performance applications More expensive than lower voltage motors; requires a higher voltage power supply and motor controller than lower voltage motors2. Leadscrew type: The leadscrew is responsible for converting rotary motion from the motor into linear motion of the actuator. Different types of leads crews can affect the speed and load capacity of the actuator due to the friction they each create. ACME lead screws are less expensive and can handle heavier loads, but have lower efficiency and may produce more heat. Ball screws, on the other hand, are more efficient and have higher speeds, but can be more expensive but still have high load capacities.
3. Motor specifications: The motor is responsible for providing the power to move the actuator. Different motor specifications can affect the speed and torque that can be produced. Higher RPM motors can produce higher speeds but may have lower torque, while higher torque motors can handle heavier loads but may have lower speeds. The size and weight of the motor can also affect the overall size and weight of the actuator.
Here's a table summarizing some of the features, pros, and cons of different AC electric actuator components:
Contact us to discuss your requirements of Variable Speed Linear Actuator(fr,ko,pt). Our experienced sales team can help you identify the options that best suit your needs.
Feature Pros Cons Voltage to control speed Higher voltage can result in higher speeds and torque Higher voltage may require more expensive power supplies and controllers ACME Leadscrew Less expensive and can handle heavier loads Lower efficiency and may produce more heat Ball Screw More efficient and have higher speeds More expensive and complex and they require more space High RPM Motor Higher speeds Lower torque High Torque Motor Can handle heavier loads Lower speeds Size and Weight Smaller size and weight can be advantageous for certain applications Larger size and weight may limit some applicationsPrevious: “Beat the Heat: Essential Insights for Importing Large Factory Fans Effectively!”
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