A power train of an automatic transmission includes a Ravigneaux planetary gear set having a Ravigneaux ring gear, which always acts as an output member; a Ravigneaux planet carrier; and first and second Ravigneaux sun gears. The power train further includes a simple planetary gear set including an input member connected to an input shaft, a member fixedly connected to the Ravigneaux planet carrier, and a member variably connected to the Ravigneaux ring gear. The power train further includes a first brake variably stopping the Ravigneaux planet carrier, a second brake variably stopping the first Ravigneaux sun gear, a first clutch rotating the simple planetary gear set, a second clutch variably connecting the second Ravigneaux sun gear to the input shaft, a third clutch variably connecting the first Ravigneaux sun gear to the input shaft, and a fourth clutch variably connecting the variably connected member to the Ravigneaux ring gear.