| 摘要 |
A differential casing contains a pair of helical side gears as well as a pair of helical pinion gears 41 accommodated in bores formed in the casing. The long and short pinion gears and have first gear portions 45 meshing with the side gears, respectively, and second gear portions 47 meshing with each other. The pinion gears are designed to prevent occurrence of localised contact of the pinion gears with the meshing gears even if the pinion gears are slanted relative to the axes of the bores while transmitting torque. In one embodiment (Fig. 8), each gear tooth of the long pinion gear 41 is so tapered that its tip thickness is gradually decreased from an axial end of one gear portion toward the other gear portion. Even if the long pinion gear is inclined by meshing reactive forces, it is possible to ensure sufficient tooth bearing areas at respective tooth faces of the pinion gears. In another embodiment, each gear tooth is curved conversely from an axial end of one gear portion toward the other gear portion. In a further embodiment, a correction is applied to the tooth trace angle of the pinion gear which is inclined while transmitting torque.
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