actuator

actuator

[′ak·chə‚wād·ər]

(control systems)

A mechanism to activate process control equipment by use of pneumatic, hydraulic, or electronic signals; for example, a valve actuator for opening or closing a valve to control the rate of fluid flow.

(engineering acoustics)

An auxiliary external electrode used to apply a known electrostatic force to the diaphragm of a microphone for calibration purposes. Also known as electrostatic actuator.

(mechanical engineering)

A device that produces mechanical force by means of pressurized fluid.

(ordnance)

Part of the receiver mechanism in certain types of automatic weapons.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

actuator

A mechanical, electrical, or hydraulic device, or their combination, used to effect some predetermined linear, rotary, or oscillating movement. An actuator essentially converts hydraulic or air pressure into mechanical force. Basically, there are two types of actuators: single-acting and double-acting. In the single-acting actuator, the piston moves in a single direction as a result of system pressure. In a double-acting system, the actuator's piston moves in either direction. The fluid enters from one side of the piston and is drained out of the other. The double-acting actuator may be balanced or unbalanced. In the former case, movement in both directions is equal, whereas in the latter case, the movement to one side is greater than the other.

An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved

actuator

A mechanism that causes a device to be turned on or off, adjusted or moved. The motor and mechanism that moves the head assembly on a disk drive or an arm of a robot is called an actuator. See access arm.

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