How Electric Linear Actuators Work
An electric actuator must move the load within the required time and reach the right position throughout the production cycle. For one machine, that may mean a fast transfer across a work area. For another, it may mean a short pressing stroke with substantial force.
Screw drives, belt drives, and linear motors each create straight-line motion in a different way. Understanding those differences helps you choose an electric linear actuator that fits the application.
First, separate the drive from the layout
Screw, belt, and linear motor describe how the electric linear actuator creates motion. Rod and rodless describe its layout. A rod-style electric cylinder extends and retracts a rod. A rodless actuator moves a carriage along its body. Screw drives come in both forms, while belt axes commonly use a rodless layout.
Also check how the design supports the load. Some actuators include guides and load-bearing carriages; others need external guidance. Thrust capacity and load support are separate requirements.
Screw-driven electric linear actuators turn rotation into thrust
In a common screw-driven actuator, a rotary motor turns a threaded screw. A nut travels along the screw without rotating, moving the rod or carriage. Screw actuators are worth considering for pressing and clamping, as well as positioning tasks that need substantial push or pull force.
The screw design matters. Acme screws use sliding contact between the screw and nut. Ball screws use recirculating balls to reduce friction. Roller screws use threaded rollers and can provide high force capacity in a compact assembly.
Screw lead is the distance traveled per revolution. At the same screw speed, a higher lead moves the load faster. At the same input torque and efficiency, a lower lead produces more thrust. Actual operating limits still depend on the selected components. Check lubrication needs and screw speed limits during sizing.
Belt drives suit fast moves over longer travel
A belt-driven actuator uses a rotary motor to turn a pulley. A toothed belt moves around the pulleys and carries the attached carriage along the axis. This approach often suits fast transfers between stations or movement across a wide work area,
A belt avoids the critical-speed limit of a rotating screw, which can help on longer strokes. Belt stiffness and tension still matter. Check the specified accuracy and repeatability under the expected load, and follow the manufacturer's tensioning guidance.
A belt actuator does not always need a gearbox. Some axes couple the motor directly to the drive shaft. Others use reduction to match motor speed and torque to the load. The choice follows the sizing calculation.
Linear motors create straight motion directly
A linear motor uses electromagnetic force to move directly along an axis. It does not need a screw or belt to convert rotary motion into linear travel. A complete axis still needs suitable load guidance and position feedback.
Direct linear motion can suit rapid starts and stops, frequent reversals, and precise positioning. Packaging and assembly equipment are common areas to consider it.
Check both peak and continuous force. Peak force is available for limited periods. Continuous force depends on thermal limits and cooling conditions. Size the motor for the full cycle, including acceleration and any time spent holding force. A linear motor is not automatically the strongest or most accurate choice for every application.
Where to start your actuator comparison
Use the task to narrow the first options, then check the complete axis against the requirements.
Application priority | Start by considering | Key checks |
High thrust or stiffness under load | Screw drive | Screw type and lead, rated life, speed limits |
Fast travel over a longer stroke | Belt drive | Belt tension, load support, positioning tolerance |
Rapid repeated moves with precise control | Linear motor | Peak and continuous force, cooling, guidance |
Define the motion before choosing a part number
A useful actuator review starts with six questions:
What must move? Include the payload and moving tooling. State any process force needed to press, clamp, or push.
How far and how fast? Define the stroke and move time, including acceleration and deceleration.
How often will it cycle? Record moves per minute, dwell time, and hours of operation.
How closely must it position? Accuracy describes closeness to the target. Repeatability describes consistency when returning to the same position.
How will it mount? Identify orientation and load support. For a vertical axis, define how the load must behave when power is removed.
What must it work with? Check the control platform and power supply. Include space limits and exposure to heat, dust, or washdown.
These details let the supplier review the actuator and its supporting components against the same operating conditions.
Compare the price of the complete axis, including the motor and drive. Add any required gearbox or guides, then consider maintenance and expected service life. A low component price alone does not establish the lowest cost for the application.
Get help selecting your next electric actuator
Planning a new axis or replacing an actuator that limits production? Bring the application to elliTek before you order. Send us the load and required stroke. Add your target cycle time and a sketch of the mounting arrangement.
We can help you compare IAI America electric actuators, Tolomatic electric actuators, and LinMot linear motor systems. For axes that use rotary motors, elliTek also offers Yaskawa drives. Nidec gearboxes are another option when the application calls for reduction.
Our Field Sales Engineers and Applications Engineering team can help review product fit and coordinate manufacturer input. We also support sourcing, so your team can address component choices while the design is still taking place.
Talk with elliTek about your actuator application or call (865) 409-1555.
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