How do you call the Z-axis mechanism in a Cartesian 3D Printer? How do you call the mechanism that allows linear motion along the Z-axis in a Cartesian 3D Printer? 



I know what the individual parts are; it is a lead screw, a smooth rod ... but how do you call the mechanism that allows this linear motion?

Mechanism is defined as: an assembly of moving parts performing a complete functional motion, often being part of a large machine

So I guess, it has to have a name, doesn't? .. but I am unable to find it
Linear actuator would be the proper name for the mechanism driving the movement along a single axis. There are 2 linear actuators driving the X-axis platform (for a Prusa i3 Cartesian printer, or the build platform for a raising bed Cartesian printer like a CoreXY, H-bot, etc.), the collection of parts could be named the Z-axis assembly.