Patent ID: 8303456

Claim:
A gear train of an automatic transmission for a vehicle, comprising: a first planetary gear set (PG 1 ) that is a double pinion planetary gear set, and includes a first sun gear (S 1 ) that is operated as a fixed element, a first ring gear (R 1 ) that forms a first intermediate output path (MOP 1 ) to output a reduced rotation speed, and a first planetary carrier (PC 1 ) that forms an input path (IP) that is connected to an input shaft (IS) and forms a second intermediate output path (MOP 2 ) to output the same speed; a second planetary gear set (PG 2 ) that is a single pinion planetary gear set, and includes a second sun gear (S 2 ) that is directly connected to the first intermediate output path (MOP 1 ) to form a first intermediate input path (MIP 1 ), a second planetary carrier (PC 2 ) that forms a third intermediate output path (MOP 3 ), and a second ring gear (R 2 ) that is directly connected to the second intermediate input path (MIP 2 ) to form a second intermediate input path (MIP 2 ); a third planetary gear set (PG 3 ) that is a single pinion planetary gear set and a double pinion planetary gear set that are combined with each other to be a Ravigneaux compound planetary gear set, and includes a third sun gear (S 3 ) that is engaged with a long pinion (P 1 ) to form first and second variable input paths (VIP 1 ) and (VIP 2 ) that are variably connected to the first intermediate output path (MOP 1 ) and the third intermediate output path (MOP 3 ), and is simultaneously operated as an selectively fixed element, a third planetary carrier (PC 3 ) that is variably connected to the input shaft (IS) to form a fourth variable input path (VIP 4 ), and is simultaneously operated as a fixed element, a third ring gear (R 3 ) that is connected to an output shaft (OS) to form a final output path (OP), and a fourth sun gear (S 4 ) that is engaged with a short pinion (P 2 ) to be variably connected to the first intermediate output path (MOP 1 ) and to form a third variable input path (VIP 3 ); and a plurality of friction members including a plurality of clutches that are disposed on the first, second, third, and fourth variable input paths (VIP 1 -VIP 4 ) and a plurality of brakes (B 1 and B 2 ) that are disposed between an operating member as a fixed element and a transmission housing (H).