In a lobe pump, two lobes are placed inside a casing and are made to rotate to pump out liquids.
The case of the pump is made of cast iron. Both the lobes get rotational power separately to rotate at same speed. Both the shafts will be extending outside to receive power. The are secured prop- erly in the case with proper packing to avoid leakage of oil.
The pump is provided with an inlet and an outlet. The gap between the lobes and the case is minimum and so the oil is pumped through the gaps from the inlet to the outlet.
Screws having helical grooves are used in this pump. When the screw starts rotating, the oil is allowed through the helical grooves. The action of the pump is simple and smooth and pumps out the liquid at high speed. They are used mostly in submarines.