10-shift power train of automatic transmission for vehicle

A 10-shift power train of an automatic transmission for a vehicle, comprising first to fourth planetary gear sets, first to fourth clutches, and first and second brakes,

• wherein the first planetary gear set comprises a first sun gear selectively connected to a transmission casing, a first ring gear selectively connected to the transmission casing, and a first planetary carrier for integrally connecting a plurality of single pinions engaged between the first sun gear and the first ring gear,
• the second planetary gear set comprises a second sun gear directly connected to the first sun gear, a second planetary carrier directly connected to an input shaft and selectively connected to a third sun gear, and a second ring gear selectively connected to a fourth ring gear,
• the third planetary gear set comprises the third sun gear selectively connected to the second planetary carrier, a third planetary carrier selectively connected to the second ring gear, and a third ring gear selectively connected to the second ring gear, and
• the fourth planetary gear set comprises a fourth sun gear directly connected to the third planetary carrier of the third planetary gear set, the fourth ring gear directly connected to an output shaft, and a fourth planetary carrier directly connected to the first planetary carrier and directly connected to the third ring gear.