Types of Actuators

by CL Hardy; Updated September 26, 2017

An actuator is a mechanism used in the manufacturing of machines and equipment to initiate valves required to stop or start a function. An important part in machines, such as computer-operated machines or audio equipment, actuators can use fluid, air or electric current to facilitate motion. Actuators generally fall in one of two categories: acoustic system or haptic system.

Linear Actuators and Lorentz Actuators

Acoustic system actuators facilitate high frequency vibrations most commonly used to enhance or amplify sound through the air or structures. Vibrations in the air are commonly driven by linear actuators that convert electrical signals into pressure waves in the air. Lorentz actuators rely on electric current and magnetic presence to facilitate activity. Also called magnetic or electromagnetic actuators, this actuator type can harness a lot of force and is often used in applications requiring high bandwidth motion. Acoustic system actuators are most commonly used in loudspeakers and other audio equipment.

Haptic System Actuators

Haptic system actuators are designed to produce slower vibrations at lower frequencies than what is required with acoustic systems. Most commonly used in products that require interaction with the human motor system, haptic system actuators are different from acoustic actuators as they can be initiated by coming in contact with a pressurized force like air, fluid, manual effort or electric motor. Several actuators that fall into this category type including manual, hydraulic or electric actuators.

Manual and Automatic Actuators

Manual actuators use levers, gears or wheels to facilitate movement. Automatic actuators are commonly linked to an external electrical power source to generate force and motion. Manual actuators are used for smaller valves and equipment while automatic actuators power large valves that require more horsepower to function. Automatic actuators also work well in environments where manual force to operate valves may prove toxic or hazardous to people.

Hydraulic Actuators

Hydraulic actuators operate with minimal mechanical parts. They use fluid to pressurize pistons used to facilitate mechanical operation. As hydraulic fluid cannot be compressed, hydraulic actuators typically take longer to gain speed and power while requiring more time to slow back down. Because they are more commonly used over extended periods of time in power equipment that will run steadily with infrequent stops, they can also be equipped with fail-safe features to permit quick stops for emergency conditions.

Pneumatic Actuators

Pneumatic actuators also operate with minimal parts, but use air to pressurize pistons. As air can be compressed, pneumatic actuators do not require regulation. As the power source does not need to be stored in reserve for operation, pneumatic actuators can respond quickly in starting and stopping, which makes them more desirable for mechanical equipment that requires frequent changes in pressure to execute a desired result.

Electric Actuators

Electric actuators are powered by a motor that provides torque to operate the valves in mechanical equipment. Electric actuators are commonly used when equipment requires multi-turn valves like gate or globe valves. Since these valves are used on devices that are used frequently in machines with constant shifts in activity, these actuators can be fairly busy. They also require a battery backup to ensure safe operation should electric current somehow be prohibited.

About the Author

CL Hardy is a communication professional based in Austin, Texas. In addition to writing corporate newsletters, proposals and technical white papers for Fortune 500 clients for more than 12 years, Hardy has been published in "Black Collegian" magazine; her articles on human resources, business and art topics can be found on eHow. She graduated from the University of Pennsylvania with a B.S. in communication.