Progressive Cavity/Screw pump that allows a certain volume of fluid to pass through a stator and rotor. It is not as accurate as a diaphragm/plunger pump and is only suitable for high viscosity fluids that have a self-lubricating effect to minimize wear.

Progressing cavity pumps or eccentric screw Pumps belong to the group of positive displacement pumps. The main components are the rotating rotor and stationary stator. The rotor, hinged or elastically attached on one side, is a round-threaded screw. 

On the output side, the axial position oscillates. The hollow stator is elastic and has the same pitch length as the rotor. This leaves conveying spaces between the stator and the rotor, which move continuously from the inlet to the outlet side.