That is a really fascinating thing!<br><br>My question is what is the benefit to rotating the tube, over rotating the screw? And why is it better, if it <i>is</i> better?,(reply>), @Jesse H. as others have said, your moving parts are also on the outside and can be supported or driven at multiple points  and bearings that need lubrication are further from the grain or whatever.,(reply>), that's a decent guess! 👍,(reply>), At a guess, the main difference is that the rotating screw disrupts the material at the top, shaking loose particulates and dust. The rotating tube instead is pushing the material up from the bottom, so the material at the top is not overly disturbed as it rises and exits the screw.