Spiral bevel gears are some of the most important elements used in truck differential. In this study, the fracture of spiral bevel gear for truck differential produced from case hardening steel is investigated. In order to study the causes of the failure, specimens prepared from the damaged spiral bevel gears were subjected to experiments, such as visual inspection, hardness, chemical analysis and metallurgical tests. Pitting occurrence on gear surfaces was observed. The effect of microstructure on the fracture was considered. Low surface hardness values were found. The calculated contact stress was higher than the allowable contact stress which is emphasized in literature. From the experimental observations and calculations, the following conclusions may be made: 1. In order to obtain same hardness and microstructure, the gear materials should be of same chemical composition. 2. The surface hardness of gears is low. In order to obtain maximum pitting resistance, the gears outer surface hardness should be increased to 58-60 HRC. 3. In order to obtain different microstructure between core and surface, carburising heat treatment should be made proper conditions, such as time, case depth. The case depth should be under control. 4. Due to the high tooth-contact pressures, oil film thickness may not be enough. The lubrication could be difficult. Therefore, the pitting occurrence increases. On the examination of fractured parts, it can be concluded that the gears expose to overloading. In order to decreasing contact pressure, the gears geometry can be optimized in design stage or the pinion design torque can be decreased.
Pitting failure of truck spiral bevel gear
Lochfraßfehler an LKW-Spiralkegelrädern
Engineering Failure Analysis ; 14 , 4 ; 614-619
2007
6 Seiten, 5 Bilder, 6 Tabellen, 7 Quellen
Aufsatz (Zeitschrift)
Englisch
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Decision Fusion Analysis Detects Spiral Bevel Gear Damage
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