Bearings and Dampers for Advanced Jet Engines

Sophisticated mainshaft support systems must be developed because present jet engines demand long life and the next generation of engines will require higher levels of performance and higher thrust to weight ratios. Consequently, the bearings in these support systems must operate at higher speeds and for longer periods of time than ever before. To achieve this performance three of the factors considered in the design are surface finish and waviness control, duplexing vs. single ball thrust bearings, and lubrication and cooling systems. In addition, oil film dampers mounted integral with or immediately surrounding the outer race of these bearings provide significant reductions in vibration amplitudes transmitted to the engine supporting structure and in static structure stresses, and can prolong life or provide the option of reducing structural weight without increasing stress.