| 摘要 |
A differential casing contains a pair of helical side gears 37, 39, as well as a pair of helical pinion gears 67, 69 accommodated in bores formed in the casing. When it is expected that the helix angle of the tooth trace of a helical pinion gear (e.g. 69) would be decreased by forward driving, the helical pinion gear is formed in advance so that the tooth depth gradually decreases from axial ends of the helical pinion gear toward the axial intermediate portion. Conversely, when it is expected that the helix angle would be increased by forward driving, the tooth depth gradually increases from the axial ends toward the axial intermediate portion. Alternatively, there may be a chamfered portion on the pinion gear. By these means, even if the helical pinion gear becomes slanted, it can be maintained in uniform contact with the bore over the whole tooth width, so that it is possible to prevent occurrence of eccentric abrasion and seizure. |
