Linear actuator guide
Straight-line motion, sized properly
A linear actuator converts energy into controlled straight-line motion. Learn how electric linear actuators work, how to compare force, stroke, speed, duty cycle, feedback, and IP ratings, and how to choose the right actuator for your application.
Linear actuator quick answer
A linear actuator is a device that creates motion in a straight line. Electric linear actuators usually use a motor, gearbox, and lead screw to extend and retract a rod, allowing them to push, pull, lift, tilt, slide, or position a load.
Animated cutaway: linear actuator motion
Original 3D engineering animation by FIRGELLI Automations, published July 16, 2026. It shows the motor, gearbox, lead screw, drive nut, and output rod converting rotary motion into straight-line extension and retraction.
What is a linear actuator?
A linear actuator creates controlled motion along a straight line. A rotary motor spins; a linear actuator uses extra mechanical parts to turn that rotation into push-pull travel. That makes it useful when a mechanism must lift, lower, slide, open, close, tilt, or hold a position.
In the FIRGELLI hierarchy, Actuators Explained is the broad parent guide for all actuator types. This article focuses specifically on electric linear actuators: rod actuators, track actuators, feedback actuators, industrial actuators, micro actuators, and lifting columns.
How does a linear actuator work?
The mechanical chain is simple:
The motor creates rotation. The gearbox reduces speed and increases torque. The lead screw rotates inside the actuator body. A drive nut travels along that screw, pushing or pulling the output rod. Limit switches stop the travel at the endpoints so the motor does not stall against the mechanical stops.
For the broader definition, including rotary, hydraulic, and pneumatic devices, see what is an actuator?
Inside a linear actuator
Provides the initial rotary power, usually from a 12 VDC or 24 VDC supply.
Trades speed for torque. Higher reduction usually means more force and slower travel.
Converts rotation into linear travel. Screw pitch strongly affects force, speed, and self-locking behavior.
The nut moves along the screw and drives the extending rod in or out.
Protect the mechanism and keep the moving parts aligned.
Stop motion at full extension and full retraction.
Types of linear actuators
Choose the actuator style based on the load path, available space, required feedback, and whether the actuator must resist side loading.
| Type | Best for | Strengths | Limitations | Relevant FIRGELLI link |
|---|---|---|---|---|
| Standard rod linear actuators | Hatches, vents, furniture, general automation | Simple, compact, broad force and stroke range | Rod must not be side loaded | Linear actuators |
| Heavy-duty linear actuators | Higher-force lifting, industrial fixtures | High load capacity and rugged construction | Usually slower and physically larger | Industrial actuators |
| Mini / micro linear actuators | Robotics, small devices, compact mechanisms | Very small package and light weight | Lower force and shorter stroke | Micro linear actuators |
| Track actuators | Sliding doors, drawers, guided travel | Carriage supports side-load style motion | Less suitable where an extending rod is required | Track linear actuators |
| Feedback linear actuators | Position control and synchronization | Position signal for controllers | Requires compatible controller and wiring | Feedback actuators |
| Lifting columns | Desks, medical equipment, vertical lifts | Guided telescoping lift in a compact package | Designed for vertical lifting, not every linkage | Column lifts |
| Rotary actuators | Valves, pivots, angular motion | Useful for turning motion | Not linear actuators; use only when the load must rotate | Alternative motion type |
Electric vs hydraulic vs pneumatic linear actuators
Electric, hydraulic, and pneumatic systems can all create linear motion. Electric actuators are usually easiest to wire, control, and maintain. Hydraulic systems are favored for very high force. Pneumatic systems are fast and simple when compressed air already exists.
| Type | Power source | Precision | Force | Maintenance | Best use case |
|---|---|---|---|---|---|
| Electric | Electric motor and power supply | High with feedback | Low to high, model dependent | Low | Clean automation, furniture, hatches, robotics, controlled positioning |
| Hydraulic | Pressurized fluid, pump, valves | Moderate without servo control | Very high | High | Construction, heavy machinery, very high-force applications |
| Pneumatic | Compressed air | Lower because air compresses | Moderate | Moderate | Fast cycling in plants with existing air systems |
For deeper comparisons, see electric actuator vs hydraulic actuator and pneumatic vs electric actuators.
Linear actuator specifications explained
How much push or pull the actuator can apply. Dynamic force matters while moving.
The usable travel between full retraction and full extension.
Travel rate under load. Higher force usually means lower speed.
Common options include 12 VDC and 24 VDC. Voltage affects current and controller choice.
Motor current rises with load. Size the power supply for startup and stall risk.
Allowed run time versus rest time before heat becomes a problem.
Ingress protection against dust and water.
Position reporting from potentiometers, Hall sensors, or encoders.
Holding force when stopped.
Moving force while extending or retracting.
Physical envelope at both ends of travel.
Clevis and bracket dimensions that set pin and hardware fit.
Important for furniture, medical, home, and office applications.
ACME or ball screw choices affect efficiency, holding, and cost.
Sets the force-speed tradeoff with the motor and screw pitch.
Static load vs dynamic load
Dynamic load is the force the actuator can move. Static load is the force it can hold while stopped. Always size the actuator from the dynamic load requirement, then check that the static rating and safety factor are appropriate for the final position.
Loading direction and side loading
A rod actuator is designed for axial push and pull. Side loading bends the rod, damages bushings, increases friction, and can shorten actuator life. If the load must slide sideways or carry off-axis force, use guides, linkages, a track actuator, or separate rails so the actuator only supplies force along its intended line.
Force, stroke, speed, and gearing
Force, speed, current, and duty cycle are connected. More gear reduction can increase output force while reducing output speed. Screw lead, efficiency, motor characteristics, voltage, load, and thermal limits all affect the final load-speed-current relationship. Use the model's data sheet and load-speed information rather than inferring performance from screw pitch alone.
Estimate force for inclined loads and friction.
Work out travel for hinged lids, hatches, and linkages.
Convert extension time, travel distance, and velocity.
Connect distance, time, velocity, and acceleration.
Understand motor speed, gear ratio, and output motion.
Duty cycle
Duty cycle is a thermal operating limit defined for the manufacturer's stated load, ambient conditions, and cycle period. A 25 percent rating means powered motion may occupy one quarter of that stated period; it does not establish a universal one-minute run time. Use the Actuator Duty Cycle Calculator, read the linear actuator duty cycle guide, and follow the selected product's data sheet.
Limit switches and stroke control
Limit switches stop travel at the endpoints. Without them, the motor can stall at the mechanical end of travel, draw high current, and overheat. Internal limit switches are enough for many applications; adjustable stops or external controls are useful when the mechanism needs custom endpoints.
Mounting and brackets
Most linear actuator installations use dual-pivot mounting: one clevis bracket at the rear and one at the rod end. This lets the actuator rotate as the mechanism moves through an arc. Fixed mounting can work only when the actuator and load stay aligned through the full stroke.
Use the Actuator Mounting Angle Calculator and match the hardware with compatible mounting brackets.
IP ratings and environmental protection
IP ratings describe protection against solids and water. Indoor furniture may not need the same protection as marine, agricultural, or washdown environments. Check cable exits, seals, mounting orientation, and condensation risk, not just the headline IP number. Start with the IP ratings of linear actuators guide when the actuator will see dust, rain, spray, or water.
Feedback, Hall sensors, potentiometers, and encoders
Feedback matters when the controller needs to know position. A potentiometer gives an analog position signal. Hall sensors and optical encoders provide pulses for digital position tracking. Limit switches only indicate endpoints; they do not provide continuous position information.
Compare common sensor choices.
Choose digital pulse feedback for control systems.
Use analog position feedback for simple control loops.
Keep two or more actuators aligned under changing load.
Linear actuator wiring and control
Most two-wire DC linear actuators reverse direction by reversing polarity. You can control them with switches, relays, remote control boxes, motor drivers, Arduino, Raspberry Pi, or dedicated synchronization controllers. The controller must handle motor current and any feedback signals.
Create wiring diagrams for switches, relays, remotes, and controllers.
Starter guide for microcontroller control.
Use position input and feedback for controlled travel.
Understand remotes, channels, synchronization, and controller choices.
Real-world applications
Hidden doors, vents, appliance lifts, and adjustable fixtures.
Compact push-pull motion where a rotary joint is not the right fit.
Guards, diverters, small lifts, fixtures, and repeatable positioning.
Vent control, gates, hoppers, sprayers, and rugged outdoor mechanisms.
Hatches, seats, vents, and compartments where clean electric motion helps.
Spoilers, panels, bed covers, seat mechanisms, and custom motion systems.
Adjustable beds, chairs, supports, and controlled positioning devices.
TV lifts, desks, recliners, monitor lifts, and storage lifts.
Panel tilt systems that follow seasonal or daily sun angle changes.
Top-hinged doors, truck hatches, cellar doors, and enclosure lids.
Platform assists, ramps, lifts, and adjustable access mechanisms.
How to choose the right linear actuator
- Define the motion: lift, slide, tilt, push, pull, or position.
- Calculate force with load, friction, pivot geometry, and safety factor.
- Choose stroke length from the required travel, not just the gap size.
- Decide speed under load.
- Choose voltage and size the power supply for current draw.
- Check duty cycle against the expected run-rest pattern.
- Match the IP rating to dust, rain, washdown, or outdoor exposure.
- Decide whether feedback or synchronization is required.
- Check mounting geometry and side-load risk.
- Use the Linear Actuator Selector Tools and confirm with the Linear Actuator Calculator.
For a more detailed decision guide, read how to select the right linear actuator.
Engineering assumptions and limitations
- This guide explains common electric linear actuator behavior. The selected model's data sheet, load-speed information, current limits, duty-cycle conditions, and mounting dimensions take precedence.
- For hinged loads and linkages, required force changes through travel. Check the worst-case geometry, not only the average position.
- An IP rating describes enclosure protection under defined tests. It does not by itself establish corrosion, chemical, continuous-submersion, or washdown suitability.
- Safety-critical lifting, medical, accessibility, vehicle, and machinery applications require a system-level risk assessment, appropriate guarding or redundancy, and review by a qualified person.
Worked linear actuator selection example
Suppose a guided slide must travel 6 inches in 12 seconds. The required average speed is 6 / 12 = 0.5 inches per second. If a separate mechanism analysis shows that the worst-case dynamic force, including friction and acceleration, is 180 lbf, screen for actuator models whose load-speed data meets at least 180 lbf at 0.5 inches per second.
That calculation only narrows the candidates. Final selection still requires the retracted and extended dimensions, mounting geometry, duty cycle, current and power supply, feedback needs, environmental rating, and an engineering margin appropriate to the uncertainty and consequence of failure.
Common mistakes and commissioning checks
- Applying side load to a rod-style actuator instead of supporting the load with guides or rails.
- Using average linkage force instead of calculating the hardest point in the motion.
- Comparing no-load speed when the application depends on speed under load.
- Undersizing the power supply, controller, relay, wiring, or overcurrent protection for the selected actuator.
- Assuming an IP rating or duty-cycle percentage covers conditions not stated in the product data sheet.
- Expecting two open-loop actuators to remain synchronized without compatible position feedback and control.
During commissioning, inspect bracket alignment and binding, verify endpoint operation, and test the complete travel under a representative load while remaining within the specified duty cycle. Compare current and temperature behavior with the product documentation, and validate guarding, interlocks, and fail-safe behavior where the risk assessment requires them.
Engineering references
- IEC 60529, Degrees of protection provided by enclosures (IP Code), for the scope of enclosure ingress classifications.
- ISO 12100:2010, Safety of machinery - risk assessment and risk reduction, for system-level machinery safety principles.
- NIST Special Publication 330, The International System of Units (SI), for SI quantities and unit notation.
- FIRGELLI Linear Actuator Selection Guide and the selected product data sheet for model-specific sizing and operating limits.
Linear Actuator Calculators and Engineering Tools
Related learning path
- Start here to understand linear actuator basics.
- Use the broader Actuators Explained page if you need rotary, hydraulic, pneumatic, or servo context.
- Move to the Linear Actuator Engineering Guide when you need deeper specification and design detail.
- Use calculators and selectors before choosing a product category.
Frequently Asked Questions
What is a linear actuator?
A linear actuator is a device that creates motion in a straight line. Electric models usually use a motor, gearbox, lead screw, drive nut, and output rod to push, pull, lift, slide, tilt, or position a load.
How does a linear actuator work?
A motor creates rotation, gears trade speed for torque, a lead screw converts rotation into linear motion, and a drive nut moves the output rod in or out.
What is the difference between a linear actuator and a motor?
A motor normally produces rotary motion. A linear actuator contains a motor plus mechanical parts that convert that rotation into controlled straight-line motion.
What are linear actuators used for?
They are used for hatches, doors, adjustable furniture, robotics, industrial automation, agricultural equipment, marine hardware, solar tracking, accessibility systems, and positioning mechanisms.
What are the main types of linear actuators?
Common types include standard rod actuators, heavy-duty actuators, mini or micro actuators, track actuators, feedback actuators, industrial actuators, and lifting columns.
How much force can a linear actuator produce?
Force depends on the model, gear ratio, screw pitch, voltage, and duty cycle. Small actuators may produce only a few pounds, while heavy-duty units can produce thousands of pounds.
What is stroke length?
Stroke length is the distance the actuator rod travels between fully retracted and fully extended positions.
How fast do linear actuators move?
Speed depends on the gear ratio, screw pitch, voltage, and load. Higher-force actuators usually move more slowly than lower-force actuators.
Why are force and speed connected?
The gearbox and screw trade speed for mechanical advantage. More force usually requires more gear reduction or a finer screw pitch, which slows movement and increases heat.
What voltage do linear actuators use?
Many electric linear actuators use 12 VDC or 24 VDC. Industrial systems may use other voltages depending on controller and power supply requirements.
What is duty cycle?
Duty cycle is the amount of run time allowed before the actuator must rest. A 25 percent duty cycle means the actuator should rest for about three times as long as it runs.
Can linear actuators push and pull?
Yes. Most rod-style electric linear actuators can extend to push and retract to pull, within their rated force limits and mounting geometry.
Can linear actuators hold position without power?
Many lead screw actuators are self-locking enough to hold position when power is removed, but the holding ability depends on the screw design and static load rating.
What are limit switches?
Limit switches stop the actuator at full extension and full retraction so the motor does not stall against the end of travel.
What is actuator feedback?
Feedback is a position signal from a potentiometer, Hall sensor, or encoder. It lets a controller know where the actuator is during travel.
Can two linear actuators be synchronized?
Yes, but reliable synchronization normally requires feedback actuators and a controller that compares position and adjusts motor output.
Can linear actuators be used outdoors?
Yes, if the actuator has an IP rating and material protection suitable for rain, dust, washdown, salt spray, or temporary water exposure.
What IP rating do I need?
Use the environment to choose the rating. Sheltered indoor use needs less protection than marine, washdown, outdoor, or dusty industrial applications.
How do I mount a linear actuator?
Most applications use clevis brackets at both ends so the actuator can pivot as the mechanism moves. Avoid side loading the rod.
How do I calculate actuator force?
Use the load weight, pivot points, lever arms, mounting angle, friction, acceleration, and safety factor. Hinged applications need geometry-based calculations.
How do I choose the right linear actuator?
Define the motion, calculate force, choose stroke, decide speed and voltage, check duty cycle and IP rating, decide whether feedback is needed, verify mounting geometry, then use a selector or calculator.
Author and review process
Founder of FIRGELLI Automations, with more than 20 years of actuator, automotive mechanism, and motion-control experience. Profile: Robbie Dickson. Wikipedia: Robbie Dickson on Wikipedia.
This guide is maintained by the FIRGELLI engineering team and is reviewed against actuator sizing, mounting, wiring, control, feedback, and environmental selection requirements.
