Patent ID: 8210981

Claim:
A multi step transmission of a planetary design for an automatic transmission of 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 ) 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 ( 8 ), and an eighth rotatable shaft ( 9 ); at least six shift elements ( 03 , 05 , 13 , 16 , 18 , 49 ) comprising a first brake ( 03 ), a second brake ( 05 ), a first clutch ( 13 ), a second clutch ( 16 ), a third clutch ( 18 ), and a fourth clutch ( 49 ) 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; the first and the second planetary gear sets (P 1 , P 2 ) form a shiftable front-mounted gear set and the third and the fourth planetary gear sets (P 3 , P 4 ) form a main gear set; wherein the carriers of the first and the second planetary gear sets (P 1 , P 2 ) are coupled together via the fourth shaft ( 4 ) which is connected to the sun gear of the third planetary gear set (P 3 ); the ring gear of the first planetary gear set (P 1 ) is coupled to the sun gear of the second planetary gear set (P 2 ) via the seventh rotatable shaft ( 8 ), and the seventh rotatable shaft ( 8 ) is connectable to the drive shaft ( 1 ) via the third clutch ( 18 ); the sun gear of the first planetary gear set (P 1 ) is connectable to the housing (G) by the third shaft ( 3 ), via the first brake ( 03 ), and is connectable to the drive shaft ( 1 ), via the first clutch ( 13 ); the ring gear of the second planetary gear set (P 2 ) is connectable to the housing (G) by the fifth shaft ( 5 ) via the second brake ( 05 ); the sun gear of the fourth planetary gear set (P 4 ) is connected by a fixed ninth shaft ( 7 ) to the housing (G); the sixth shaft ( 6 ) is connected to the carrier of the third planetary gear set (P 3 ) and is connectable to the drive shaft ( 1 ) via the second clutch ( 16 ); the eighth shaft ( 9 ) is connected to the ring gear of the fourth planetary gear set (P 4 ) and is connectable to the fourth shaft ( 4 ) via the fourth clutch ( 49 ); and the output shaft ( 2 ) is connected to the ring gear of the third planetary gear set (P 3 ) and to the carrier of the fourth planetary gear set (P 4 ).