PLANETARY GEAR TRAIN OF AUTOMATIC TRANSMISSION FOR VEHICLE

PROBLEM TO BE SOLVED: To provide a planetary gear train of an automatic transmission for a vehicle.SOLUTION: The planetary gear train includes: an input shaft to which power of an engine is transmitted; an output shaft for outputting the transmitted rotary power; a first complex planetary gear set having five rotation elements, and primarily changing a rotation speed of the input shaft to six rotation speeds and outputting it; a second complex planetary gear set having four rotation elements including rotation elements connected to the rotation elements of the first complex planetary gear set, and secondarily changing the rotation speed inputted from the first complex planetary gear set and the rotation speed of the input shaft inputted through one variable input passage into forward 11-speed and backward 1-speed gear shift stages and finally outputting it; eight rotation shafts comprising two or one of the rotation elements of the first and second complex planetary gear sets; and seven friction members comprising four clutches interposed between the rotation shafts or between the rotation shaft and the input shaft, and three brakes for variably connecting the rotation shaft to a transmission housing.