Further explanation and comments
The in-feed scoops control the rate of handling and deliver material into the casing with a pressure that initiates motion up the lower portion of the screw flight. The internal mechanism then takes over to move the material along the inclined face of the screw flight by frictional drag of the product on the rotating boundary layer. This sealing and elevating motion of the product is reinforced at the inlet region by further material entering the in-feed scoops. The collection and transfer of material takes place in settled conditions, rather than the dilated turbulence of a dynamic vortex. The density difference and quiescent movement allows a greater mass of material to be elevated.