This type of gear pump has two lobes on each
shaft. The lobes nearly touch each other in the center forming a fairly tight
They also nearly touch the casing and when they revolve they carry fluid around the outer edge to the outlet, at the top in this drawing.
This type of gear pump, or a three-lobe version, is often used as a supercharger for diesel engines, forcing air (not liquid) into the power cylinder.
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