The rotating nut turns the threaded screw, creating a smooth in-and-out linear motion. Thread friction drives the shaft, directly converting rotary motion to linear motion. This means:
* No parasitic drag - less wasted power
* Zero backlash (with a light pre-load)
* Very high stiffness
* Nanometer resolution and high force
* High torque at low speeds, with no gearbox
* Smooth velocity at microscopic speeds
* Off-power hold
* Very small diameter
* Manual screw rotation for off-power positioning
