This pump is also known as sole pump, rotary lobe pump, tri lobe pump is equipped with two rotors. It transported continuously from sequence a-d. Its pump produces suction force at the inlet(vacuum),which intakes the material delivered. When the 2 simultaneous reverse rotating rotors with 2-4 gears revolve. Housing I will only be filled with medium when it revolves to position A. When it revolves to position b, housing B encloses part of the medium,when it goes to position c, housing A encloses medium, and finally it goes to position d, then housing A,B and II are interlinked and the medium is transported to the outlet.