metal gears
An actuator is any device that creates motion in a system. A gear actuator is a specific type of actuator that typically creates motion using a basic worm gear. This style of gear consists of a threaded screw and a common toothed gear. As the screw turns, it turns the gear. This style of actuator is preferred in two circumstances: when manual power is used to operate the device or when the system cannot have power traveling backwards through the actuator.
A good example of a gear actuator in action is a basic car jack.
The basis of almost all gear actuators is a worm gear. These devices are extremely simple, being a combination of two of the earliest simple human machines. A threaded rod, the screw, rotates against a toothed gear. As the screw pushes against the gear teeth, it moves in the direction of the screw thread. The screw does not move, when one thread moves away from the gear teeth, another takes its place. This rotation allows the screw to remain stationary but creates movement in the gear.
This rotation can power almost any device with the correct settings, from turning a wheel to powering a radio. In its simplest form, the gear actuator is directly connected to a shaft that rotates as part of a larger machine. This rotary motion is often directly transformed into usable force by the motion of a machine or the effect of an object.
A good example of a gear actuator in action is a basic car jack. When a person pumps the lever on the jack, it causes a threaded rod to rotate. The rotating rod drives a gear, usually around a second threaded rod. The rotating gear pushes the rod up, which will lift a heavy object. This also shows the two common reasons for using a gear actuator: hand feed and not reverse.
Screws have the ability to increase power by creating a large moving surface relative to the size of the screw. As a result, these systems are good at amplifying human power to a much greater force. This allows a person without assistance to do things that he or she would not normally do, such as lifting a car to change a tire.
Along with power amplification, the motion in a worm gear is one-sided. The screw can turn the gear, but the gear cannot move the screw. This restriction prevents power from traveling in both directions through the gear drive. In the example above, the person can lift the car, but the car cannot cause the jack to launch the person backwards.