We just learned about the Rack and Pinion gears.
Another type of thing used in machines is a Linear Actuator.
The word actuator really just means "mover" and there are lots of types of actuators out there.
Linear means moving in a straight line.
So a linear actuator is a type of machine that moves something in a straight line.
We learned before about rotors that spin around in circles in electric motors.
So this is different because it might be moving a rod up or down, back or forward but in a straight line.
Sometimes this is done by having a bolt or screw that has lines on it, and then a nut spinning around on the screw that makes the screw go up and down.
This is a roller screw linear actuator.
(from: wikipedia - linear actuator)
Kid Facts - Blast from the past: Bellifortis Rockets
