Patent ID: 7452303

Claim:
An eight-speed powertrain of an automatic transmission, comprising: a first planetary gear set comprising operational elements of a first sun gear, a first ring gear, and a first planet carrier; a second planetary gear set comprising operational elements of a second sun gear, a second ring gear, and a second planet carrier; a third planetary gear set comprising operational elements of a third sun gear, a third ring gear; a third planet carrier; and a fourth planetary gear set comprising operational elements of a fourth sun gear, a fourth ring gear, a fourth planet carrier; an input shaft, at least one output gear, and a transmission case; wherein: the first sun gear is fixedly connected to the transmission case so as to operate as a fixed element; the first planet carrier is fixedly connected to the second ring gear; the second sun gear is fixedly connected to the input shaft so as to operate as an input element, the third ring gear and the fourth ring gear are formed together and fixedly connected to the output gear so as to operate as an output element, the first ring gear is variably connected to the third sun gear via a first clutch, the second ring gear is variably connected to the input shaft via a second clutch, the first ring gear is variably connected to the fourth sun gear via a third clutch, the fourth planet carrier is variably connected to the input shaft via a fourth clutch, the fourth sun gear is variably connected to the input shaft via a fifth clutch, the second planet carrier is variably connected to the transmission case via a first brake, and the third sun gear is variably connected to the transmission case via a second brake.