Patent ID: 8246504

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 disposed in 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 ) and at least six shift elements ( 03 , 04 , 13 , 18 , 35 , 36 , 67 ), comprising first and second brakes ( 03 , 04 ) and first, second, third and fourth clutches ( 13 , 18 , 35 , 36 , 67 ) whose selected 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 connected to the drive shaft ( 1 ); a carrier of the first planetary gear set (P 1 ) is directly connected to the third shaft ( 3 ) which is connectable to the housing (G) of the transmission, via the first brake ( 03 ); the third shaft ( 3 ) is directly connected to the second clutch ( 35 ), and the second clutch ( 35 ) is directly connected to the fifth shaft ( 5 ) so that third shaft ( 3 ) is detachably connectable, via the second clutch ( 35 ), to the fifth shaft ( 5 ); the fifth shaft ( 5 ) is directly connected to a ring gear of the second planetary gear set (P 2 ), to a sun gear of the third planetary gear set (P 3 ) and to a sun gear of the fourth planetary gear set (P 4 ); the drive shaft ( 1 ) is detachably connectable, via the third clutch ( 18 ), to the eighth shaft ( 8 ) that is connected 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 is detachably connectable, via the fourth clutch ( 67 ), to the seventh shaft ( 7 ) that is connected to a carrier of the second planetary gear set (P 2 ); a sun gear of the second planetary gear set (P 2 ) is coupled to the housing (G) of the transmission; a ring gear of the third planetary gear set (P 3 ) is connected to the fourth shaft ( 4 ) which is connectable to the housing (G) of the transmission, via the second brake ( 04 ); the output shaft ( 2 ) is connected to a ring gear of the fourth planetary gear set (P 4 ) and to a carrier of the third planetary gear set (P 3 ), and the first planetary gear set (P 1 ) can be locked by engagement of the first clutch ( 13 or 36 ) such that, when locked, the sun gear, the planet carrier and the ring gear of the first planetary gear set (P 1 ) all rotate together in unison with one another.