The lubrication principal used by the Kingsbury thrust bearing is the _________.

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 tapered gap, creating high pressure that supports the load. This prevents metal-to-metal contact, allowing the bearing to carry massive axial loads with minimal friction and wear.