I didn't get the benefit of rotating the sleeve over rotating the auger, if anything rotating the sleeve is more complex and expensive due to the number and size of the bearings, can anyone explain it?,(reply>), To lift vertically the auger would need to be closely fitting to the casing and ridged, possibly vacuum assisted.<br>  There would be a lot more heat with wear to both auger and casing while binding on the products inside.<br>Instead think of the buckets gently pushing the product up a slight hill, which cascades at the top.<br><br>Means you can totally isolate heat, air diffusion(think dust explosions) and grease from the product as well.