Gerotors
A gerotor is a positive displacement machine element used in pumps and motors. It consists of two intermeshing gears: an inner rotor and an outer stator. The inner rotor has fewer teeth than the outer stator, and its teeth are cycloidal in shape. The outer stator has a trochoidal inner shape that perfectly complements the inner rotor's teeth.
As the inner rotor rotates, the spaces between its teeth and the outer stator's inner surface change
Gerotor pumps are known for their simple design, compact size, and quiet operation. They are commonly used