Air cylinders are pneumatic linear actuators that are driven by a pressure differential in the cylinder's chambers. They may be single-acting (with a spring return) or double-acting.
Electric linear actuators have an output rod that provides linear motion via a motor driven ball screw, lead screw, or ACME screw assembly. The actuator's load is attached to the end of a screw or rod and is often unsupported.
Magnetoresistive linear position sensors and switches have a linear resistance output signal representing the distance an object is from a reference point.