Patent ID: 8357068

Claim:
An automatic transmission comprising: a first planetary gearset including: a first sun gear; a first ring gear; and a first planet-pinion carrier arranged to carry a first planet pinion in mesh with the first sun gear and the first ring gear; a second planetary gearset including: a second sun gear; a second ring gear, wherein the second ring gear is constantly coupled to the first planet-pinion carrier so as to constitute a first rotor unit; and a second planet-pinion carrier arranged to carry a second planet pinion in mesh with the second sun gear and the second ring gear; a third planetary gearset including: a third sun gear, wherein the third sun gear is constantly coupled to the first ring gear so as to constitute a second rotor unit; a third ring gear; and a third planet-pinion carrier arranged to carry a third planet pinion in mesh with the third sun gear and the third ring gear; an input shaft constantly coupled to the second sun gear; an output shaft constantly coupled to the third ring gear; a first coupling member arranged to be selectively applied to couple the first sun gear to the third planet-pinion carrier independently of operation of other coupling members; a second coupling member arranged to be selectively applied to hold the first sun gear stationary independently of operation of other coupling members; a third coupling member arranged to be selective applied to couple the second sun gear to the third planet-pinion carrier independently of operation of other coupling members; a fourth coupling member arranged to be selectively applied to couple the second planet-pinion carrier to the second rotor unit independently of operation of other coupling members; a fifth coupling member arranged to be selectively applied to couple the second planet-pinion carrier to the third planet-pinion carrier independently of operation of other coupling members; and a sixth coupling member arranged to be selectively applied to hold the first rotor unit stationary independently of operation of other coupling members, wherein at least first to eighth gear ratios and one reverse gear ratio are obtained between the input shaft and the output shaft by simultaneous application of three of the first to sixth coupling members.