Actuators are devices commonly used to make other devices move, and there are many types of actuators that are useful for different purposes. Among the available varieties are the wheel and axle actuator, which uses a wheel to move an axle and cause the actuator to move in a certain direction. Manual actuators have largely been phased out, but they are still used in old installations and when users are concerned about cost; with these, operators manually move the parts to cause the actuator to perform its function. An electrical actuator uses a motor to move the actuator parts, and the rotary movements of the motor cause the actuator to function. With hydraulic actuators, pressure is used to move the actuator back and forth.
Wheel and axle actuators are one of the types of actuators that are based on a very simple mechanical instrument. To start the actuator’s movement, a wheel is turned; the axle connected to the wheel also turns. For example, with a door knob, the knob — which represents the wheel — is turned, which causes the internal axle to turn with relatively low force. Modern wheel and axle actuators are often powered by electricity or by mechanical means, but this also may be a manual actuator.
Manual actuators are one of the types of actuators that are completely human-driven. If any mechanical, electrical or pressure-based energy is used to move the actuator, then it is no longer considered manual. The operator must move a valve, which causes the actuator to move in the intended direction. These actuators are commonly used for small objects and are the cheapest type of actuator.
With the electrical actuator, electricity is used to power a motor attached to the actuator. Unlike most other actuators, which have linear force, this is one of the types of actuators that produce rotary force that must be converted to linear. For the best accuracy, stepper motors are commonly used, because the motor can be precisely controlled.
Hydraulic actuators are another one of the types of actuators that make the actuator function via hydraulic energy. These actuators have a piston, and fluid is pushed in and out of the piston to cause the actuator to move up and down. Speed-wise, these actuators are slower, because it takes longer for the piston to move. At the same time, this lack of speed can be useful, because these actuators work better in fail-safe systems in which the actuator has to stop immediately.