Patent ID: 8333676
Filing Date: 2012-12-18
Classification: F16H

Abstract:
1. A gear train of an automatic transmission for a vehicle, the gear train comprising: first, second, third, and fourth planetary gear sets; a plurality of friction members; and first, second, third, fourth, fifth, sixth, seventh, and eighth rotation elements, wherein the first planetary gear set is fixedly connected to the second planetary gear set via the fourth rotation element, the second planetary gear set is fixedly connected to the third planetary gear set via the eighth rotation element, the third planetary gear set is fixedly connected to the fourth planetary gear set via the fifth rotation element, and the fourth planetary gear set is fixedly connected to the first planetary gear set via the second rotation element, wherein the first rotation element is selectively connected to a transmission housing so as to be operated as a selective fixed element, the third rotation element is operated as a final output element, the fourth rotation element is selectively connected to the transmission housing so as to be operated as a selective fixed element, the fifth rotation element is selectively connected to an input shaft so as to be operated as a selective input element, the sixth rotation element is fixedly connected to the input shaft so as to be always operated as an input element, the seventh rotation element is selectively connected to the third rotation element, and the eighth rotation element is selectively connected to the second rotation element and selectively connected to the fifth rotation element, and wherein the plurality of friction members comprises first, second, third, and fourth clutches and first and second brakes, wherein the first planetary gear set is a single pinion planetary gear set having a first sun gear, a first planet carrier, and a first ring gear, the second planetary gear set is a single pinion planetary gear set having a second sun gear, a second planet carrier, and a second ring gear, the third planetary gear set is a double pinion planetary gear set having a third sun gear, a third planet carrier, and a third ring gear, and the fourth planetary gear set is a single pinion planetary gear set having a fourth sun gear, a fourth planet carrier, and a fourth ring gear, and wherein the first sun gear is fixedly connected to the second sun gear, the second ring gear is fixedly connected to the third sun gear, the third planet carrier is fixedly connected to the fourth sun gear, and the first planet carrier is fixedly connected to the fourth ring gear such that the first ring gear is operated as the first rotation element, the first planet carrier and the fourth ring gear are operated as the second rotation element, the fourth planet carrier is operated as the third rotation element, the first and second sun gears are operated as the fourth rotation element, the third planet carrier and the fourth sun gear are operated as the fifth rotation element, the second planet carrier is operated as the sixth rotation element, the third ring gear is operated as the seventh rotation element, and the second ring gear and the third sun gear are operated as the eighth rotation element.