| 摘要 |
The purpose of the present invention is to provide a planetary gear train of an automatic transmission for a vehicle, which improves power transmission performance, fuel efficiency, and quiet driving performance. In order to achieve this purpose, the planetary gear train of an automatic transmission for a vehicle in accordance with an embodiment of the present invention, comprises: an input shaft which receives power of an engine; an output shaft which outputs shifted power; a first planetary gear set consisting of a first sun gear, a first planetary carrier, and a first ring gear; a second planetary gear set consisting of a second sun gear, a second planetary carrier, and a second ring gear; a third planetary gear set consisting of a third sun gear, a third planetary carrier, and a third ring gear; a fourth planetary gear set consisting of a fourth sun gear, a fourth planetary carrier, and a fourth ring gear; a first rotary shaft which includes the first and second sun gears, and is selectively connected to a transmission housing; a second rotary shaft including the first planetary carrier and the fourth ring gear; a third rotary shaft which includes the first ring gear, and is selectively connected to the transmission housing; a fourth rotary shaft which includes the second planetary carrier, and is directly connected to the input shaft; a fifth rotary shaft including the second ring gear and the third sun gear; a sixth rotary shaft including the third planetary carrier; a seventh rotary shaft which includes the fourth sun gear, is selectively connected to the input shaft, and simultaneously, is selectively connected to the fifth rotary shaft or the sixth rotary shaft; an eighth rotary shaft which includes the third ring gear and the fourth planetary carrier, and is directly connected to the output shaft; and six friction elements arranged on parts where the rotary shafts are selectively connected to each other, and the rotary shafts are selectively connected to the transmission housing. |
