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Since Archimedes time there has been a desire to vary the output and performance of a pump. This was originally achieved by changing the rotational speed of the screw or by varying the depth of water over the intake of the screw. Both concepts still hold true today. In 1972 the Swiss engineer, Martin Stähle, invented the ‘Prerostal’ system that much like the Archimedes Screw, varies the output of a Hidrostal screw centrifugal pump without changing its speed! Prerostal uses gravity to drive the pump inlet head, but with the addition of controlled pre-swirl through a specially designed pump basin. This system holds all the non-clog benefits of the Archimedes Screw but with the added advantages of a smaller footprint and lower power consumption and is a great example of how the pump industry tends to enhance and build upon successful designs and experience that have gone before.

All engine driven pumps can adjust performance by changing the shaft speed and or gear ratios on the drive train to the pump. With the fixed speed electric motor driven pump, adjustment to performance was initially possible through belt and pulley drives between pump and motor. This was not really improved upon until dual speed motors became commercially available from the late 1950's on.

It was not until the late 1980's that the possibility to infinitely vary the speed and performance of an electric motor driven pump became commercially available to the wider market. This took the form of the variable speed drive or frequency converter.Archimedes and the modern equivalent Prerostal system.