Lobe pump.

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A lobe pump is a type of positive displacement pump that moves fluids by means of rotating lobed rotors inside the pump casing. To learn more about this pump, check out http://www.mekanizmalar.com/menu_pump.html and view an image of a two-lobe roots blower at https://commons.wikimedia.org/wiki/File:Roots_blower_-_2_lobes.svg?uselang=fr. You can also find pumps "CAD" drawings at http://www.inoxpa.fr/telechargements/documents/composants. Have a great day!