As the screw shaft rotates, the material's gravity and the friction created by the material's friction with the trough walls force the material forward along the conveyor's trough bottom, driven by the blades. This is similar to a non-rotating nut moving horizontally along a rotating screw. The primary driving force for the material's advancement comes from the axial rotation of the screw blades, which propels the material upward and forward along the tangential direction of the blades.
To maximize the tensile strength of the screw shaft, the drive unit and discharge port are typically located at the same end of the conveyor, with the feed port positioned as close to the rear as possible at the other end. The rotating screw blades propel the material, preventing it from rotating with the screw conveyor blades. The forces that prevent the material from rotating with the screw conveyor blades are the material's own weight and the frictional resistance of the screw conveyor casing. The blade surface can be solid, belt, or vane, depending on the material being conveyed. The screw shaft of a screw conveyor has thrust bearings at the ends of the material's travel to provide axial reaction force to the screw along with the material. For longer conveyors, intermediate hanger bearings should be added.