What is a linear actuator

A linear actuator is a device that works by converting energy (which is non-linear) into motion (which is linear). These actuators use a variety of energy sources, such as electricity, heat and air pressure. Different types of actuators are used for different purposes based on their output, potential, power requirements and size.

There are several machines and processes that use linear actuators ranging from the tray of a DVD player to the hydraulic lift in a car repair shop. Regardless of the size, the principle behind them is all the same: a small, non-linear source of energy is enlarged and transformed into linear motion. Each energy source has a different conversion mechanism, such as a pressure of fluid input or rotary motion.

The rotary linear actuator gets its input energy from an electric motor and it uses either lead screws or knobs to convert the motor's energy into straight line motion. With a lead screw arrangement, the electric motor turns a screw that runs through a nut attached to the actuator arm. The actuator and nut are not rotated, inserted and retracted into the guide screw. Linear Actuator

A cam-driven linear actuator uses link to connect a cam to the actuator arm. When the eccentric cam rotates, the actuator arm is either pushed forward or retracted. These devicvers do not have as much range of motion as the lead screw type, but they are very accurate in their input. These actuators often use electric stepper motors which allow for greater control of progress.

Pneumatic or hydraulic linear actuators use fluid or gas under pressure to achieve movement and have the greatest potential. A pneumatic or hydraulic actuator consists of a piston in a pipe having valves at both ends. The piston is connected to an actuator rod passing through a seal at the end of the tube. Air or oil is injected into the cylinder through a valve and the direction of the piston depends on which end of the pipe the fluid is injected from.

There are less commonly used types of linear actuator, like the thermal actuator, which uses the expansive properties of certain materials to provide linear motion. Other less common types are magnetic, piezoelectric and rack and pinion actuators. The simplest type of these actuators is a manual screw that uses the same basic principle as a lead screw type, but comes with a finer thread and greater adjustability.