What is a key feature of thrust bearings in relation to turbine operation?

A key feature of thrust bearings is their ability to hold clearance to prevent rubbing. In turbine operations, thrust bearings support the axial loads generated by the turbine's rotating components. By maintaining a precise clearance between the bearing surfaces, these bearings ensure that there is no direct contact during operation, which is critical for reducing wear and tear on both the thrust bearing and the shaft. This clearance allows for thermal expansion and movement, ensuring smooth operation without friction that could lead to damage or failure.

Other options do have important roles in systems involving thrust bearings, but they do not specifically target the primary function of thrust bearings in terms of preventing rubbing. The prevention of leakage and noise reduction may be characteristics of other components in the system but are not main functions of thrust bearings. Changing directions of thrust is also not a primary function, as thrust bearings typically support axial loads in a specific direction rather than alter their direction.