While screw shaft is rotating, the friction is produced from the material’s gravity and trough.The friction will make materials move forward by push of screw blades .Just like the fixed nut make horizontal movement along the rotating screw shaft . Materials are moved in the middle bearing which depends on the push force of materials .Thus, materials is a sliding movement during the screw conveyors . In order to make the screw shaft exist at the pulling condition, usually we set up the drive device with the discharging outlet at the same side .Meanwhile, we set up the inlet at the other side. Rotating screw flights push materials forward ,the force which prevent materials from being rotating with screw flight is from which come from the material’s gravity and the friction resistance of screw shell.Screw blades are divided into the following types ,such as solid face type, screw ribbon type, screw blading type, cutting screw blade,etc . There is a bearing at the end of transportation to give an opposite force on screw bladed when screw shaft is rotating with materials. So if screw conveyor with long distance ,there shall set up hanger bearing in the middle.