| 摘要 |
An 8-speed power train of an automatic transmission is provided to decrease a speed shifting time by changing only one of two or three operation elements during a speed shifting process. A single pinion planetary gear set(SPG) includes a first linear gear, a first planetary carrier, and a first ring gear. A Ravigneaux gear set(RG) includes second and third linear gears, second to fourth planetary carriers, and second and third ring gears. The second linear gear is connected to the first planetary carrier through a second clutch. The fourth planetary carrier is gear-coupled with the second linear gear and connected to a case through a first one-way clutch and a second brake. The third linear gear is gear-coupled with the second and third planetary carriers. The second and third ring gears are gear-coupled with the second and third planetary carriers and connected to the case through the second brake. A double pinion planetary gear set(DPG) includes a fourth linear gear, fifth and sixth planetary carriers, and a fourth ring gear. The fifth and sixth planetary carriers are gear-coupled with the fourth linear gear and directly connected to the second and third planetary carriers. The fourth ring gear is gear-coupled with the fifth and sixth planetary carriers and directly connected to an output shaft.
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