The lubrication principal used by the Kingsbury thrust bearing is which of the following?

Correct Answer: Option D — Wedge-shaped oil film.

Kingsbury thrust bearings utilize the hydrodynamic principle of a wedge-shaped oil film. As the bearing surfaces move, the oil is drawn into a converging gap, creating high pressure that supports the load. This design is highly effective for managing the significant axial thrust loads generated by marine turbines.