Screw pump

A later screw pump design from Egypt had a spiral groove cut on the outside of a solid wooden cylinder and then the cylinder was covered by boards or sheets of metal closely covering the surfaces between the grooves.

[1] A cuneiform inscription of Assyrian king Sennacherib (704–681 BC) has been interpreted by Stephanie Dalley[3] to describe casting water screws in bronze some 350 years earlier.

This is consistent with classical author Strabo, who describes the Hanging Gardens as watered by screws.

This ancient construction is still used in many low-tech applications, such as irrigation systems and in agricultural machinery for transporting grain and other solids.

The two side screws can then be made as internally-hidden free-floating rollers, lubricated by the pumped liquid itself, thus eliminating the need for bearings on those axles.

They are suited for a variety of applications such as fuel-injection, oil burners, boosting, hydraulics, fuel, lubrication, circulating, feed, and to pump high-pressure viscous fluids in offshore and marine installations.