Finally, load severeness of the transmission and PTO input shafts were evaluated. Severeness levels of the transmission and PTO input shafts increased as both the ground speed and PTO rotational speed increased. The severeness of the transmission input shaft increased by 573–746% when the ground speed increased by 201% as the transmission gear was shifted from L1 to L3 at the same PTO rotational speed. At the same ground speed, the severeness increased by 187–340% when the PTO rotational speed increased by 185% as the PTO gear was shifted from P1 to P3. The
fatigue life of the transmission input shaft decreased when the combined speed increased, and effects of the ground speed were more significant. The severeness of the PTO shaft increased significantly by 1078–1655% when the PTO rotational speed increased by 185% as the PTO gear was shifted from P1 to P3 at the constant ground speed. The severeness increased by 139–213% when the ground speed increased by 201% as the transmission gear
was shifted from L1 to L3 at the same PTO rotational speed. The fatigue life of the PTO shaft was similar in the case of the transmission input shaft.