Bucket Elevators, Rotor Lifts, Screw Conveyors, Belt conveyors Screw conveyors are volumetric conveying devices. With each revolution of the screw, a fixed volume of material is discharged. The purpose of a screw conveyor is to transfer product from one point to the next. Screw conveyors are always control fed at the inlet by another conveyor or metering device The device consisted of a hollow cylinder with a center shaft and a spiral fixed to the inner wall of the cylinder and center shaft. As the assembly rotated