Below is a list of Vertical Screw Conveyors manufacturers from St. Louis, Missouri. Vertical screw conveyors, sometimes called screw lifts, are material transportation systems that use a long, rotating helical screw inside a tubular casing. The screw rotates within a linear, upright path and elevates dry to semi-dry material that may be free flowing or sluggish. The central shaft has helical paddles in the shape of a screw, and when they rotate upwards, the material is carried along.