Patent ID: 8647227

Claim:
A planetary gear train of an automatic transmission for vehicles, comprising: an input shaft adapted to receive engine torque; an output shaft adapted to output a shifted torque; a first planetary gear set adapted to always output a negative rotation speed by using a rotation speed input from the input shaft; a second planetary gear set adapted to convert the negative rotation speed input from the first planetary gear set into a positive rotation speed and to output the positive rotation speed; a compound planetary gear set formed by combining third and fourth planetary gear sets, and adapted to change the rotation speed selectively input from the input shaft through two paths and the negative rotation speed and the positive rotation speed input, respectively, from the first and second planetary gear sets into nine forward speeds and one reverse speed, and to output the nine forward speeds and the one reverse speed; eight rotational members including two rotation elements connected to each other or one rotation element among rotation elements of the first and second planetary gear sets and the compound planetary gear set; and six friction members including clutches interposed between a selected rotational member among the rotational members and the input shaft or between selected rotational members, and brakes interposed between a selected rotational member among the rotational members and a transmission housing.