Patent ID: 7909725

Claim:
An automatic transmission comprising: a first planetary gear set including a first sun gear whose rotation is constantly in stopped state, a first pinion engaged with the first sun gear, a first carrier supporting the first pinion, and a first ring gear engaged with the first pinion; a second planetary gear set including a second sun gear constantly connected with the first carrier, a second pinion engaged with the second sun gear, a second carrier supporting the second pinion, and a second ring gear engaged with the second pinion; a third planetary gear set including a third sun gear, a third pinion engaged with the third sun gear, a third carrier supporting the third pinion, and a third ring gear engaged with the third pinion; an input shaft constantly connected with the first ring gear; an output shaft constantly connected with the third ring gear; and at least five friction elements including a first clutch adapted to selectively connect the second carrier with the third carrier, a first brake adapted to selectively stop a rotation of the second carrier, a second brake adapted to selectively stop a rotation of a first rotating member having the second ring gear and the third sun gear, a second clutch adapted to selectively connect the first ring gear with the third carrier, and a third clutch adapted to selectively connect the first rotating member with the third carrier, the automatic transmission being adapted to achieve at least seven forward speed-ratios and one reverse speed-ratio, each of the at least seven forward speed-ratios and one reverse speed-ratio being achieved by engaging two friction elements selected from the first to third clutches and the first and second brakes.