Patent ID: 7618342

Claim:
A gear train of an automatic transmission having first and second planetary gear sets comprising simple planetary gear sets and a third planetary gear set comprising a compound planetary gear set, and a plurality of friction members, wherein: the first planetary gear set reduces an engine speed received from an input shaft through a first input path and outputs the reduced speed through a first intermediate output path; the second planetary gear set receives the reduced speed through first and second intermediate input paths, and outputs the reduced speed or a reversed speed through a second intermediate output path, the second planetary gear set selectively acting as a fixed element; and the third planetary gear set selectively receives the engine speed from the input shaft through a second input path, selectively receives input speeds from the first and second planetary gear sets through third and fourth intermediate input paths, and outputs a plurality of changes speeds through a final output path; wherein the first planetary gear set comprises: a sun gear acting as a fixed element; a planet carrier that forms the first intermediate output path; and a ring gear that forms the first input path by being directly connected with the input shaft; and wherein the third planetary gear set comprises: a smaller-diameter sun gear that forms the third intermediate input path by being variably connected to the first intermediate output path of the first planetary gear set; a larger-diameter sun gear that forms the fourth intermediate input path by being directly connect to the second intermediate output path of the second planetary gear set; a planet carrier that forms the second input path by being variably connected with the input shaft; and a ring gear that is variably connected with the larger-diameter sun gear of the third planetary gear set and forms a final output path.