Screw Vacuum Pump: A rotary screw pump is amongst the earliest formulated beneficial displacement pumps which was generally known as the Archimedes‘ screw. In its easiest type, this pump consists of only one screw within a hollow cylinder. Modern day styles include double or triple screws meshing from each other. https://heavydutyracking8.azzablog.com/26942384/getting-my-vacuum-pump-to-work