Rotor-Type Oil Pump: Many engines are equipped with rotor type oil pump. It has a central rotor with outer lobes which continuously rotates inside the outer ring having internal lobes.

The fin­ished powerplant is much more like a set of siamese twins than a single 4-Rotor engine. They share a common oil pump, submerged in a single sump, and a com­mon water pump, but each has ...

If you take the gearbox off, withdraw the rotor and leave the oil pump end cover in place, otherwise you won’t be able to line up the oil pump drive plate on re-assembly. This will lead to tears.