Abstract: Provided is a lubricating oil composition for a differential gear unit that is effective in limiting the generation of noise and vibrations even when a limited-slip differential is operated. The lubricating oil composition contains (A) a mineral oil and/or (B) a synthetic oil and (C) a friction modifier selected from amide- and imide-based friction modifiers and derivatives thereof in an amount of 0.01 to 10 percent by mass on the basis of the total mass of the composition. Also provided is a differential gear unit that is lubricated with the lubricating oil composition.

Abstract: A plurality of microscopic grooves are created on the surface of the teeth of planetary gears, and thus, irregular unevenness is created. This irregular unevenness includes a plurality of first microscopic grooves which function as lubricant grooves and a plurality of second microscopic grooves which are shallower than the first microscopic grooves.

Abstract: A plurality of microscopic grooves are created on the surface of the teeth of planetary gears, and thus, irregular unevenness is created. This irregular unevenness includes a plurality of first microscopic grooves which function as lubricant grooves and a plurality of second microscopic grooves which are shallower than the first microscopic grooves.

Abstract: Five receiving holes 2e extending along the axis of a circular cylindrical portion 2b of a housing are formed in the circular cylindrical portion 2b. Those five receiving holes 2e are arranged at equal intervals in the peripheral direction of the circular cylindrical portion 2b. Each receiving hole 2e rotatably receives therein a planetary gear 5. The respective planetary gears 5 are in engagement with an inner gear 3 and a sun gear 4. The teeth of the inner gear 3, the sun gear 4 and the planetary gears 5 are helical teeth. The numbers of teeth of the inner gear 3, the sun gear 4 and the planetary gears 5 are set to 36, 24 and 6, respectively. As a result, the numbers of teeth of the inner gear 3 and the sun gear 4 located between adjacent two planetary gears 5 in the peripheral direction become 7.2 and 4.8, respectively, which are values each having a fraction below the decimal point.

Abstract: A carrier 2 is fixed to one end opening part of a circular cylindrical apparatus main body 1. A plurality of receiving holes 2d, which extend in parallel with a rotation axis L, are formed in the carrier 2 at the same interval in a peripheral direction. A planetary gear 4 is received in each receiving hole 2d such that the planetary gear 4 can rotate on its own axis. An inner gear 5 and a sun gear 9, which are arranged with their axes aligned with the rotation axis L of the apparatus main body 1, are disposed within the apparatus main body 1. The inner gear 5 is engaged with the planetary gears 4 at the outside thereof. The sun gear 9 is engaged with the planetary gears 4 at the inner side thereof. An engagement part between the inner gear 5 and the planetary gear 4 and an engagement part between the sun gear 9 and the planetary gear 4 are displaced from each other in a direction of the rotation axis L so that they are not overlapped with each other in a direction of the rotation axis L.

Abstract: Five receiving holes 2e extending along the axis of a circular cylindrical portion 2b of a housing are formed in the circular cylindrical portion 2b. Those five receiving holes 2e are arranged at equal intervals in the peripheral direction of the circular cylindrical portion 2b. Each receiving hole 2e rotatably receives therein a planetary gear 5. The respective planetary gears 5 are in engagement with an inner gear 3 and a sun gear 4. The teeth of the inner gear 3, the sun gear 4 and the planetary gears 5 are helical teeth. The numbers of teeth of the inner gear 3, the sun gear 4 and the planetary gears 5 are set to 36, 24 and 6, respectively. As a result, the numbers of teeth of the inner gear 3 and the sun gear 4 located between adjacent two planetary gears 5 in the peripheral direction become 7.2 and 4.8, respectively, which are values each having a fraction below the decimal point.

Abstract: A carrier 2 is fixed to one end opening part of a circular cylindrical apparatus main body 1. A plurality of receiving holes 2d, which extend in parallel with a rotation axis L, are formed in the carrier 2 at the same interval in a peripheral direction. A planetary gear 4 is received in each receiving hole 2d such that the planetary gear 4 can rotate on its own axis. An inner gear 5 and a sun gear 9, which are arranged with their axes aligned with the rotation axis L of the apparatus main body 1, are disposed within the apparatus main body 1. The inner gear 5 is engaged with the planetary gears 4 at the outside thereof. The sun gear 9 is engaged with the planetary gears 4 at the inner side thereof. An engagement part between the inner gear 5 and the planetary gear 4 and an engagement part between the sun gear 9 and the planetary gear 4 are displaced from each other in a direction of the rotation axis L so that they are not overlapped with each other in a direction of the rotation axis L.