| 主权项 |
1. A multi-speed automatic transmission for a motor vehicle, the transmission comprising:
an input shaft, an output shaft, and four planetary gear sets arranged in a housing; six rotatable shafts in addition to the input shaft and the output shaft; six shifting elements, the shifting elements comprising brakes and couplings whose selective intervening brings about different transmission ratio relationships between the input shaft and the output shaft such that at least nine forward gears and one reverse gear are able to be realized; a sun gear of the first planetary gear set connected to a third shaft that is detachably connectable to the input shaft through a first coupling and is attachable to the housing through a first brake; the input shaft, through a second coupling, detachably connectable to a fourth shaft that is connected to a bar of the third planetary gear set, which is attachable to a bar of the first planetary gear set through a second brake that is coupled to the housing; the input shaft connected to a sun gear of the fourth planetary gear set; an eighth shaft connected to a ring gear of the first planetary gear set, a sun gear of the second planetary gear set, and a sun gear of the third planetary gear set; a fifth shaft connected to a bar of the second planetary gear set and a ring gear of the third planetary gear set and, through a third coupling, detachably connectable to a seventh shaft that is connected to a ring gear of the fourth planetary gear set; and a sixth shaft connected to a ring gear of the second planetary gear set and, through a fourth coupling, detachably connectable to the output shaft that is connected to a bar of the fourth planetary gear set. |
