What types of bearings are commonly used in gas turbine assemblies?

• A. Rolling Element Bearings (Ball and Roller Types) and, in Specialized Designs, Plain or Foil Bearings.
• B. Plain Bearings Only.
• C. Magnetic Bearings.
• D. Foil Bearings.

Answer: (A)

Gas turbine assemblies need bearings that can handle very high rotor speeds while carrying radial and axial loads with reliable lubrication and long life. Rolling element bearings, such as ball and roller types, are the workhorse because they tolerate high speeds, offer strong load-carrying capacity, and have well-established lubrication and maintenance practices. They form the backbone of most main-shaft and rotor-support applications in gas turbines.

In specialized designs, plain bearings (journal bearings) or foil bearings are used. Plain bearings provide a simple, compact option and can be effective where lubrication schemes suit sliding contact. Foil bearings use a flexible metal foil structure to support the rotor with a lubricant film, enabling very high-speed operation with very low friction and often reducing the need for heavy oil flow during certain operating phases. These choices come into play when specific performance, thermal, or startup requirements make rolling elements less ideal.

Magnetic bearings appear in some modern or experimental setups but are not the common choice across typical gas turbine assemblies due to their higher cost and control complexity.