Main engine bearings support which rotors and permit rotation?

Main engine bearings support which rotors and permit rotation?

• A. Piston assemblies
• B. The compressor and turbine rotors
• C. Accessory shafts and gears
• D. Drive shafts only

Answer: (B)

Main bearings carry the rotating core of a gas turbine and let those rotors turn smoothly. In a jet engine, the two main rotating assemblies are the compressor rotor at the front and the turbine rotor at the rear. The main bearings support the shafts that carry these rotors and accommodate the radial loads as they spin, keeping everything aligned and reducing friction. Piston assemblies belong to reciprocating engines and don’t form the rotating core of a turbofan or turbojet, so they aren’t what these bearings support. Accessory shafts and gears are driven by the main shafts and have their own bearings, not the primary rotors that the main bearings support. Drive shafts alone don’t capture the full role, since the main bearings support both the compressor and turbine rotors.

Main bearings carry the rotating core of a gas turbine and let those rotors turn smoothly. In a jet engine, the two main rotating assemblies are the compressor rotor at the front and the turbine rotor at the rear. The main bearings support the shafts that carry these rotors and accommodate the radial loads as they spin, keeping everything aligned and reducing friction. Piston assemblies belong to reciprocating engines and don’t form the rotating core of a turbofan or turbojet, so they aren’t what these bearings support. Accessory shafts and gears are driven by the main shafts and have their own bearings, not the primary rotors that the main bearings support. Drive shafts alone don’t capture the full role, since the main bearings support both the compressor and turbine rotors.