170. As shown in the illustration, what is the purpose of pressurizing the main bearing lube oil sumps on a typical marine gas turbine

Pressurizing the main bearing lube oil sump maintains a slightly higher internal pressure than surrounding cavities, directing any leakage inward with air and minimizing oil leakage from the rotor shaft. This controlled pressure differential, managed through pressurizing ports and vents, prevents oil from escaping along the shaft and is distinct from oil distribution, penetration, or cooling, which are handled by other system components.