A mechanical actuator is a device designed to remotely control or move a secondary mechanism via an external power source, which may include include electric current and high pressure oil or gas. The internal mechanisms used to convert the input power to a working motion differ according to the intended output orientation and the specific power source used. They include gear trains, hydraulic pistons, and lead screws. The orientation of the output motion is either liner or rotary, and dictated by the specifics of the secondary or actuated mechanism. The mechanical actuator is generally more powerful than electromagnetic types and, typically, the preferred choice for high-torque applications such as industrial and earth-moving machinery parts.
The need to automatically or remotely actuate system components is an inescapable reality in a wide range of industries, such as manufacturing, agriculture, and mining, to name but a few. Installations that span great distances typically include many system components located far from staff locations. Industries that deal with poisonous, corrosive, or explosive materials often include components located in areas that pose unacceptable risks for personnel. Many industries feature large numbers of components that require constant adjustment. All of these, and many other scenarios, require the remote or automated component control made possible by the mechanical actuator, amongst others.
The mechanical actuator is simply a device that takes a remotely-controllable power source and translates it into a working motion of a power, direction, and range suitable for the required actuation. The most common power sources are electric current, hydraulic, and pneumatic. The actuator power source may be manually activated or switched on or off by an automated system. As many mechanical actuators operate completely independently of operator intervention, most include various safety mechanisms to protect against overloading and associated actuator or system damage.
Various internal mechanisms are used to translate the power source input into a working output. In the case of electrically-driven actuators, these include gear trains, lead screws, and chain or belt drives. Hydraulic or pneumatic mechanical actuator variants typically feature captive piston or vane mechanisms that provide their actuation motion. These actuators tend to be the more powerful types and are more often than not utilized on mechanisms with high-torque requirements. Rotary hydraulic or pneumatic actuators are also limited in their range of motion, typically only producing a single complete turn or less, making them ideal for the actuation of large, quarter-turn valves.