that provide push/pull force are often referred to as electric actuators. These actuators are telescopic and use push tubes that use lead screws, ball screws or roller screws. They come with a basic motor of 24VDC or 12VDC, but AC versions are also available) and gears to provide fixed speed and force selection. They typically have travel in the 50mm – 700mm range and forces from 50N to 500kN (from the high performance version). Electric actuators are used where duty cycles are typically in the 10-25% range.
High-performance linear actuators are also based on telescopic push/pull capabilities. However, they usually do not come with a motor, so it is possible to choose the motor that is best for a specific application. Servo motors are also common (servo linear actuators), which allow external control of motion profiles, speed, torque, etc. High-performance linear actuators are available with motors delivering forces up to 500kN. Due to the control and environmental advantages offered by such actuators, there has been increasing interest in such actuators as an alternative to hydraulic actuators.
Positioning linear actuators are used to provide linear positioning of loads, usually large loads. Many different versions are available, offering different performance characteristics. These actuators typically provide repeatable positioning from a few microns to 100 microns and loads from a few grams to 1000 kg. The structure is usually an aluminum extrusion with linear guides mounted on it, and the drive comes from a belt or ball screw. Belt-driven actuators are useful for long stroke applications, where strokes may exceed 10m. Various motors are installed depending on the application.
Servo linear actuators are actuators combined with servo motors that can be push/pull telescopic or positioning. Servo motors allow the motor to exchange information with and be controlled by an external control system. This allows for changes in speed, stroke, torque control, etc. Servo actuators can also be used when 100% duty cycle is required.
Pneumatic linear actuators are also widely used. These tend to be simple push/pull applications. They have the advantage of potentially higher speed and lower cost. However, due to the control and environmental advantages provided by these systems, pneumatic actuators have significantly transformed into electric and servo actuators.