Hi Zooen,
have looked at the 3D of Albert Karlen's Hourglass_12 and there's an option for section analysis so you can see the elevator screw.
It looks like the elevator screw is stationary and mounted to outer frame and the hour glass pivots around it.
So don't think it's motor driven just rotated by hand thus elevating the balls.
Hope this helps.
Barry
Ps are going to make one ?