Patent ID: 7850568

Claim:
A power train of an automatic transmission, comprising: an input shaft; an output gear; a transmission case; a speed reduction unit comprising a first variable input member that is variably connected to the input shaft, first and second variable stopped members that are variably stopped by being variably connected to the transmission case, and a reduced speed output member that outputs first and second reduced rotational speeds; an output unit comprising a reduced speed input member that is fixedly connected to the reduced speed output member, second and third variable input members that are variably connected to the input shaft, a third variable stopped member that is variably stopped by being variably connected to the transmission case, and a shifted speed output member that always acts as an output element by being fixedly connected to the output gear, wherein the output unit generates eight forward speeds and two reverse speeds at the shifted speed output member by operations of the reduced speed input member, the second and third variable input members, and the third variable stopped member; a first clutch for variably connecting the first variable input member to the input shaft; a second clutch for variably connecting the second variable input member to the input shaft; a third clutch for variably connecting the third variable input member to the input shaft; a first brake for variably stopping the third variable stopped member; a second brake for variably stopping the first variable stopped member; a third brake for variably stopping the second variable stopped member; and a one-way clutch disposed between the third variable stopped member and the transmission case in parallel with the first brake; wherein the speed reduction unit comprises: a first planetary gear set comprising a first sun gear, a first planet carrier, and a first ring gear; and a second planetary gear set comprising a second sun gear, a second planet carrier, and a second ring gear; wherein the second ring gear is the first variable input member; the first planet carrier is the first variable stopped member; the first sun gear is the second variable stopped member; the first ring gear is the reduced speed output member; the first ring gear is fixedly connected to the second planet carrier; and the first sun gear is fixedly connected to the second sun gear.