Patent ID: 8251859

Claim:
A multi step transmission of a planetary design for an automatic transmission for a motor vehicle, the multi-step transmission comprising: a drive shaft ( 1 ); an output shaft ( 2 ); first, second, third and fourth planetary gear sets (P 1 , P 2 , P 3 , P 4 ) which are arranged within a housing (G); and a rotatable third shaft ( 3 ), a rotatable fourth shaft ( 4 ), a rotatable fifth shaft ( 5 ), a rotatable sixth shaft ( 6 ), a rotatable seventh shaft ( 7 ) and a rotatable eighth shaft ( 8 ) as well as at least six shift elements ( 03 , 04 , 13 , 17 , 28 , 35 , 36 ) comprising first and second brakes ( 03 , 04 ) and first, second, third and fourth clutches ( 13 , 17 , 28 , 35 , 36 ) whose selective engagement produces different transmission ratios, between the drive shaft ( 1 ) and the output shaft ( 2 ), so that nine forward gears and a reverse gear can be achieved; wherein a sun gear of the first planetary gear set (P 1 ) is continuously connected to the drive shaft ( 1 ); a carrier of the first planetary gear set (P 1 ) is connected to the third shaft ( 3 ) which is releasably directly connectable to the housing (G) via the first brake ( 03 ), and the third shaft ( 3 ) is releasably connectable to the fifth shaft ( 5 ) via the second clutch ( 35 ), the fifth shaft ( 5 ) is connected to a ring gear of the second planetary gear set (P 2 ), a sun gear of the third planetary gear set (P 3 ) and a sun gear of the fourth planetary gear set (P 4 ); the drive shaft ( 1 ) is releasably connectable, via the third clutch ( 17 ), to the seventh shaft ( 7 ) and the seventh shaft ( 7 ) is connected to a carrier of the fourth planetary gear set (P 4 ); the sixth shaft ( 6 ) is connected to a ring gear of the first planetary gear set (P 1 ) and a carrier of the second planetary gear set (P 2 ); a sun gear of the second planetary gear set (P 2 ) is connected to the fourth shaft ( 4 ) which is connectable with the housing (G) via the second brake ( 04 ); a ring gear of the third planetary gear set (P 3 ) is continuously directly connected with the housing (G); the output shaft ( 2 ) is continuously connected to a ring gear of the fourth planetary gear set (P 4 ) and is releasably connectable, via the fourth clutch ( 28 ), to the eighth shaft ( 8 ) which is connected to a carrier of the third planetary gear set (P 3 ); and the first planetary gear set (P 1 ) is blockable so as to rotate as a unit by engagement of the first clutch ( 13 or 36 ).