Šori Marko, PhD.

The aim of this study is to check the possibility of replacing the pinion gear made of structural
steel with the one made of sintered material. The pinion is part of the gear pair mounted
in front of the gearbox of the skidder Ecotrac 55V to increase the speed and lower torque. In
larger series, powder metallurgy (PM) gears are used as a cost-effective alternative for wrought
metal gears in a number of industries including the one producing forest products. The present
paper discusses the computational and experimental approach for determining the service
life of sintered PM gears in regard to tooth bending fatigue. The proposed computational
model is based on the stress-life approach, where the stress field in a gear tooth root is determined
numerically using finite element method. The needed material data have been taken
from the authors’ previous work. Due to the scattering nature of fatigue, the statistic approach
has also been considered by presentation of computational results. The experimental procedure
was done on a custom made back-to-back gear testing rig. The comparison between computational
and experimental results has shown that the proposed computational approach is an
appropriate calculation method for estimating the service life of sintered gears regarding tooth
root strength. Namely, it has been shown that, in case of proper heat treatment of tested gears,
tooth breakage occurred in the interval with 95% probability of failure, which has been determined
using the proposed computational model.