In this project, the aim is to evaluate standardized gear design methods and develop new ones against actual performance of large sized bevel gears. Comprehensive endurance testing is conducted on specific large-sized gear sets with advanced design and manufacturing methods. Areas of interest are the effects of case hardening on fatigue performance of the gears, differences in failure modes with different designs and operation conditions, effects of different materials on endurance performance of gears as well as fundamental understanding of fatigue induced failure modes of large sized bevel gears.