Patent ID: 8657717

Claim:
A multi step transmission, of a planetary design for an automatic transmission for a motor vehicle, 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 ) disposed in a transmission housing (G), each of the first, the second, the third, and the fourth planetary gear sets (P 1 , P 2 , P 3 , P 4 ) comprising a sun gear, a carrier and a ring gear; a third rotatable shaft ( 3 ), a fourth rotatable shaft ( 4 ), a fifth rotatable shaft ( 5 ), a sixth rotatable shaft ( 6 ), a seventh rotatable shaft ( 7 ), and an eighth rotatable shaft ( 8 ); at least six shift elements ( 03 , 04 , 05 , 13 , 36 , 37 , 68 ) comprising a first brake ( 03 ), a second brake ( 04 ), a third brake ( 05 ), a first clutch ( 13 , 37 ), a second clutch ( 36 ) and a third clutch ( 68 ) whose selected engagement produces different transmission ratios between the drive shaft ( 1 ) and the output shaft ( 2 ) such that nine forward gears and one reverse gear can be achieved; wherein the sun gear of the first planetary gear set (P 1 ) is connected to the drive shaft ( 1 ); the carrier of the first planetary gear set (P 1 ) is connected to the third shaft ( 3 ) which is connectable to the housing (G) via the first brake ( 03 ), and the third shaft ( 3 ) is connectable to the sixth shaft ( 6 ) via the second clutch ( 36 ); the sixth shaft ( 6 ) is connected to the ring gear of the second planetary gear set (P 2 ) and the sun gear of the third planetary gear set (P 3 ), and the sixth shaft ( 6 ) is connectable, via the third clutch ( 68 ), to the eighth shaft ( 8 ) which is connected to the sun gear of the fourth planetary gear set (P 4 ); the drive shaft ( 1 ) is connected to the carrier of the fourth planetary gear set (P 4 ); the seventh shaft ( 7 ) is connected to the ring gear of the first planetary gear set (P 1 ) and the carrier of the second planetary gear set (P 2 ); the sun gear of the second planetary gear set (P 2 ) is connected to the fourth shaft ( 4 ), and the fourth shaft ( 4 ) is connectable to the housing (G) via the second brake ( 04 ); the ring gear of the third planetary gear set (P 3 ) is connected to the fifth shaft ( 5 ) which is connectable to the housing (G) via the third brake ( 05 ); the output shaft ( 2 ) is connected to the carrier of the third planetary gear set (P 3 ) and the ring gear of the fourth planetary gear set (P 4 ); and the first planetary gear set (P 1 ) is blockable by engagement of the first clutch ( 13 , 37 ).