In a steam turbine, what is the function of the Kingsbury thrust bearing?

• A. Limit radial movement
• B. Absorb rotor vibrations
• C. Maintain axial positioning of the rotor shaft
• D. Drive the rotor

Answer: (C)

Kingsbury thrust bearings are there to carry the axial thrust and keep the rotor correctly positioned along the shaft. In a steam turbine, steam pressure pushes on the rotor in the axial direction, and the thrust bearing resists that force to hold the rotor in place, preventing it from moving forward or backward and staying aligned with the rest of the machine. This axial positioning is crucial for smooth operation and to avoid rubbing or contact with end seals.

Radial movement is handled by other bearings, and driving the rotor is accomplished by the steam flow itself, not by the thrust bearing. So the main role here is maintaining the rotor’s axial position under load.