Patent ID: 7780566

Claim:
An eight-speed automatic transmission for a vehicle, comprising a single pinion planetary gear set, a double pinion planetary gear set, a compound planetary gear set, a first clutch, a second clutch, a third clutch, a fourth clutch, a first brake, a second brake, and a one-way clutch, wherein the single pinion planetary gear set comprises a first ring gear fixedly connected to an input shaft, a first sun gear fixedly connected to a housing, and a first planet carrier; the double pinion planetary gear set comprises a second ring gear variably fixed to the housing by the first brake and the one-way clutch that are disposed in parallel, a second sun gear fixedly connected to the first planet carrier, and a second planet carrier variably connected to the second ring gear by the second clutch; the compound planetary gear set comprises a short sun gear variably connected to the second sun gear by the first clutch, a short pinion engaged with the short sun gear, a long sun gear fixedly connected to the second planet carrier, a long pinion engaged with the short pinion and the long sun gear and variably connected to the input shaft by the third clutch, and a third ring gear that is engaged with the long pinion, variably connected to the second planet carrier and the long sun gear by the fourth clutch, and is connected to an output shaft; the second brake variably fixes the second planet carrier and the long sun gear to the housing; the second clutch and the fourth clutch are disposed between the double pinion planetary gear set and the compound planetary gear set; and a center supporter is formed between the second clutch and the fourth clutch for supplying hydraulic pressure to the second clutch and the fourth clutch.