Question 60Gas Turbine - 1st Asst/Chief

The correct answer is A) Bull gear. The main thrust bearing directly positions the bull gear, which is the large, low-speed gear in the main reduction gear assembly. The thrust bearing absorbs the axial loads and forces generated by the rotating gears and shafts, and it ensures the proper positioning and alignment of the bull gear within the reduction gear system. The other answer choices are incorrect because the low-speed pinion, high-speed pinion, and high-speed gear are not directly positioned by the main thrust bearing. These other components are positioned and supported by other bearings and components within the reduction gear assembly.