Linear actuator
From Wikipedia, the free encyclopedia
A linear actuator is a type of electric motor that develops force and motion linearly.
Contents |
[edit] Basic operation
Linear actuators utilize an electric motor that produces rotational motion used to spin a gearbox. The gearbox is connected to the base of a threaded shaft which is mounted inside a hollow tube, the outer tube. A nut-like piece is threaded onto the shaft and a second hollow tube (smaller in diameter than the first), the inner tube, is mounted to this nut over the shaft, facing away from the motor and gearbox side. The outer tube is designed to interlock with the nut and keep it from rotating. When the shaft is turned via the motor and gears, because the nut cannot rotate with the shaft, it rides up or down the threads depending on the direction of rotation, which also pushes or pulls the inner tube, causing extension or retraction.
Think of the simple nut and bolt. If you were to thread a nut onto a bolt, if you held the nut and kept it from rotating and twisted the bolt, the bolt will extend from its original position. Linear actuators work on the same basic principle.
Some designs use the electric motor to spin a chain drive, allowing the extending section to ride along the chain.
Linear actuators are in function similar to hydraulic systems, only using an electric motor and mechanical interactions to provide extension and retraction, rather than fluid and pumps as in hydraulics.
[edit] Advantages
They are self-contained, requiring only electrical power and a control interface. They can be operated in parallel, using multiple actuators to perform a single task. They can be very precise and controlled.
[edit] Disadvantages
Typically very weak in “pulling” operations where they are placed in tension. Offset loads, which create a moment on the actuator, can cause uneven bearing wear and reduce lifespan.
[edit] See also
- Linear motor, an actuator converts an electrical signal (V/I) to mechanical displacement. Mostly used in robotics, actuators are also used in applications such as televisions, and for opening and closing windows in cars.
- Power screw
