Scrollerwheel

[1] Scrollerwheels are related in operational principle to rolamite linear bearings (developed at Sandia National Labs in the late 1960s), and like them, they display only rolling friction, and not the kinetic friction inherent in most mechanical bearings.

Unlike conventional rolling-element bearings, they do not require lubrication.

Consequentially, they can be employed in environments hostile to lubricants: underwater, in a vacuum (where grease will boil) and at elevated temperatures.

They can be constructed from a wide variety of materials, have zero backlash, and they are not fouled by gritty particulates.

Scrollerwheels cannot have an aspect ratio (diameter compared to thickness) as high as conventional mechanical bearings.