Moineau Progressing Cavity Pump
This Demonstration shows the functioning of a Moineau or progressive cavity pump.[more]
The French aeronautical engineer René Moineau received a patent on this type of pump in 1930. It is called a progressive cavity pump because the volume pumped is proportional to the rotation rate of the rotor and the volumes pumped progress with no interruption or deformation. This type of pump is typically used in the oil and gas industries and to pump sludge; cement; or thick, viscous fluids.
The pump consists of a helical rotor inside a hollow, helical stator. Unlike the usual helix, which has an elliptical cross section, this rotor has a circular cross section perpendicular to its axis. The stator has a stadium cross section with the same wavelength as the rotor.
The helical rotor rotates inside the stator driven by a hypocycloidal drive . This causes any circular section of the rotor to move along a straight line inside the stadium-shaped section of the stator. This moves the fixed-shape cavities along the length of the pump.
A ball inside the pump shows the progressive advance of the cavities inside the stator.[less]
 E. Maheiu. "Hypocyclic Mechanism" from the Wolfram Demonstrations Project—A Wolfram Web Resource. demonstrations.wolfram.com/HypocyclicMechanism.