These types of pumps are known as rotary lobe pumps. Two intermeshed rotors are each affixed to gear driven shaft. The shafts rotate in oposite directions. The rotating motion of the rotors create an expanding cavity on the suction side. This allows fluid and solids to enter and fill the suction side of the pump. The rotors carry the fluid around the housing to the discharge side where it is expelled out of the pump by the closing cavity.
The efficiency is about at the rate of %97 as the friction loss is very less. Therefore it is highly economicalregardingelectricity and diesel consumption.