The (8 inch) **3mm mecanum wheel is a heavy duty wheel.
Each wheel is comprised of a series of rollers, mounted so that
their axis of rotation is *5 to the axis of the main wheel. As the
wheels rotate in sync, the vehicle moves forwards or backwards
normally, but by spinning pairs of wheels in opposite directions,
the rollers enable sideways movement. Put it all together, and you
can move laterally, diagonally, or spin in a circle.
