What Is a Linear Actuator and How Does It Work?

A linear actuator is a device that converts the rotary motion of an electric motor into a push and pull movement along a straight line. It is used wherever a load must be moved in a controlled way over a certain distance, such as raising the backrest of a bed, adjusting the height of a desk or opening and closing a hatch.

Main parts of an electric linear actuator

• DC motor: The source of motion, usually running on 12 V or 24 V DC.
• Gearbox: Reduces the motor’s high speed and increases force.
• Spindle and nut: Convert the rotary motion from the gearbox into linear motion. As the nut travels along the spindle, the inner tube extends or retracts.
• Inner tube (piston rod): The part connected to the load that moves back and forth.
• Limit switch: Protects the actuator by stopping the motor at the beginning and end of the stroke.
• Housing and mounting points: The housing protecting the mechanism, and the front and rear mounting clevises.

How does it work?

When voltage is applied, the motor turns; the gearbox slows this motion down, increases its force and turns the spindle. As the spindle rotates, the nut and the inner tube attached to it move linearly. When the motor’s direction is reversed (polarity reversed), the inner tube retracts. The direction and timing of movement are usually managed by a control box and a hand control or foot control.

Key values that define an actuator

• Push / pull force (N): The load the actuator can move.
• Stroke (mm): The total distance the inner tube can travel.
• Speed (mm/s): Movement speed; decreases somewhat as the load increases.
• Duty cycle (%): Shows how long the actuator can run without overheating.
• IP rating: Resistance to dust and water.

We explain how to choose these values in detail in our actuator selection guide.

Where are they used?

• Hospital beds, treatment and examination chairs, patient lifting systems
• Height-adjustable desks and workstations
• Adjustable furniture (recliners, beds, TV lifts)
• Industrial automation, hatch and ventilation systems, agricultural machinery

Advantages of electric actuators

Electric linear actuators operate cleanly, quietly and precisely; they need no air compressor or hydraulic lines and require little maintenance. Position control is easy, and several actuators can be controlled together by the same control box.

Explore Polimot electric linear actuators.

Let us choose the right product for your application together. Send us your load, stroke, speed and operating environment details via our contact page, or use the Request a Quote button on the relevant product page; our technical team will recommend the most suitable solution.