What is an example of a rotary mechanical actuator?

A rotary mechanical actuator is designed to generate rotational motion. Electric motors serve this purpose effectively by converting electrical energy into mechanical energy, producing rotational output that can be utilized in various applications such as driving machinery, fans, and pumps.

In contrast, hydraulic cylinders and pneumatic actuators are primarily linear actuators, creating movement along a straight line rather than rotation. These types of actuators use fluid power (hydraulic) or compressed air (pneumatic) to produce linear force, which is not the case for rotary applications. A linear actuator, as its name implies, also focuses on creating motion in a straight line.

Thus, among the given choices, the electric motor stands out as the example of a rotary mechanical actuator due to its ability to produce continuous rotational motion.