The wear characteristics on bearing outer ring of planetary gear in conflux planet gear train of power-shift steering transmission

Aimed at the bearing outer ring of planetary gear in planetary transmission, the failure mechanism of wear between the planet gear bearing and thrust washer was investigated. The reasons for its failure and ways to reduce wear were also studied. A typical wear failure of bearing outer ring was analyzed in terms of the morphology observation with scanning electron microscopy (SEM), the metallographic analysis on radial cross section and microhardness testing. Through the comprehensive analysis of metallographic structure and microhardness, the temperature distribution of bearing outer ring was obtained. The results showed that the adhesive wear was the main wear type for thrust washer while the fatigue wear was a small part; a great axial force existed in the working mechanism, which lead to big contact stress and speed up wear; the high temperature on the friction surface could reach about 700°C and cause the tempering process in the material; Inadequate cooling effect due to lack of lubrication oil may be another main reason for the high temperature caused by wear.