How a Three Lobe Root's Pump Works?

This is a Flash Animation of a helical three Lobes Roots Pump ( Blower ).

In order to make 3D visualization of the lobes I set transparency of the lobes very low. Each layer is 5 degrees off from the previous layer. I found this adequate to demonstrate the idea.

The Roots type supercharger or Roots blower is a positive displacement pump which operates by pulling air through a pair of meshing lobes not unlike a set of stretched gears. Air is trapped in pockets surrounding the lobes and carried from the intake side to the exhaust. The supercharger is driven directly from the engine's crankshaft via a belt or, in a two-stroke diesel engine, by spur gears.

It is named for the brothers Philander and Francis Marion Roots of Connersville, Indiana, who first patented the basic design in 1860 as an air pump for use in blast furnaces and other industrial applications. In 1900, Gottlieb Daimler included a Roots-style supercharger in a patented engine design, making the Roots-type supercharger the oldest of the various designs now available.