Patent ID: 7846058

Claim:
A power train of an automatic transmission, comprising: an input shaft; an output gear; a transmission case; a first planetary gear set comprising a first operating member fixed to the transmission case, a second operating member receiving torque from the input shaft, and a third operating member outputting a reduced rotational speed by operations of the first and second operating members; a second planetary gear set comprising a fourth operating member fixedly connected to the third operating member and receiving the reduced rotational speed therefrom, a fifth operating member selectively connected to the transmission case, and a sixth operating member selectively connected to the transmission case or outputting a reverse rotational speed by operations of the fourth and fifth operating members, wherein two of the fourth, fifth, and sixth operating members are selectively connected to each other; a third planetary gear set comprising a seventh operating member fixedly connected to the sixth operating member and receiving the reverse rotational speed therefrom or selectively connected to the transmission case, an eighth operating member selectively connected to the fourth operating member, a ninth operating member selectively receiving the torque from the input shaft by being selectively connected thereto, and a tenth operating member outputting eight forward speeds and one reverse speed to the output gear by operations of the seventh, eighth, and ninth operating members, wherein two of the seventh, eighth, ninth, and tenth operating members are connected to each other; and a plurality of friction members selectively connecting the operating members of the first, second, and third planetary gear sets to one of the input shaft, other operating members, or the transmission case.