Patent ID: 8517886

Claim:
A planetary gear train of an automatic transmission for vehicles, comprising: an input shaft adapted to receive engine torque; an output gear adapted to output a shifted torque; a first compound planetary gear set having four rotation elements by combining first and second planetary gear sets and adapted to primarily shift torque input through two input paths into six speed ratio and to output the primarily shifted torque; a second compound planetary gear set having four rotation elements by combing third and fourth planetary gear sets and adapted to secondarily shift the torque input from the first compound planetary gear set and the torque input from the input shaft through one path into multiple shift-speeds and to output the multiple shift-speeds; eight rotational members including two rotation elements connected to each other or one rotation element among the rotation elements of the first and second compound planetary gear sets; and seven friction members including three clutches interposed between a selected rotational member among the rotational members and the input shaft and adapted to selectively transmit the torque and four brakes interposed between a selected rotational member among the rotational members and a transmission housing; wherein the second compound planetary gear set comprises: the third planetary gear set being a single pinion planetary gear set having a third sun gear, a third planet carrier, and a third ring gear; the fourth planetary gear set being a single pinion planetary gear set having a fourth sun gear, a fourth planet carrier, and a fourth ring gear; a fifth rotational member including the fourth sun gear and adapted to be directly connected to the first planet carrier and the second ring gear of the first compound planetary gear set; a sixth rotational member including the third ring gear and the fourth planet carrier and adapted to be selectively connected to the input shaft; a seventh rotational member including the third planet carrier and the fourth ring gear and adapted to be directly connected to the output gear; an eighth rotational member including the third sun gear and adapted to be selectively connected to the transmission housing; a third clutch interposed between the input shaft and the sixth rotational member; a third brake interposed between the eighth rotational member and the transmission housing.