Differential supported by rolling element bearing with a shaft and gears and a method of manufacturing the rolling elements, the races, the shaft and the gears by hardening including carbonitriding

摘要

A structure (1) supporting a differential (10) rotatably includes an inner ring (3a-3d) arranged at the differential (10), an outer ring (2a-2d) arranged at an external peripheral portion (19a,19b) formed to surround the differential (10), and a tapered roller (4a-4b) rolling between the inner ring (3a-3b) and the outer ring (2a-2b). At least any one of the inner ring (3a-3d), the outer ring (2a-2d), the tapered roller(4a-4d), the shaft and gear components are made of steel and are carbonitrided, quenched, cooled and subjected to a secondary quench hardening treatment. The hardened components have a carbo-nitrided layer with an austenite grain number falling within a range exceeding 10, which provides a fracture stress value of at least 2650 MPa and has a hydrogen content of no more than 0.5 ppm. Thus the structure can be provided with increased anti-crack strength and dimensional stability, and increased rolling contact fatigue life.