Patent ID: 8398522

Claim:
A multi-stage transmission of a planetary design for an automatic transmission of a motor vehicle, the multi step transmission comprising: a drive shaft ( 1 ) and an output shaft ( 2 ) which are disposed in a transmission housing (G); first, second, third and fourth planetary gear sets (P 1 , P 2 , P 3 , P 4 ), 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 at least one eighth rotatable shaft ( 8 ); at least six shift elements ( 03 , 05 , 07 , 13 , 16 , 18 ) comprising a first brake ( 03 ), a second brake ( 05 ), a third brake ( 07 ), a first clutch ( 13 ), a second clutch ( 16 ), and a third clutch ( 18 ) whose selected engagement produces different transmission ratios between the drive shaft ( 1 ) and the output shaft ( 2 ) such that nine forward gears and a 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 ring gear of the second planetary gear set (P 2 ) is connectable to the housing (G) of the transmission by the fifth shaft ( 5 ) via the second brake ( 05 ); the seventh shaft ( 7 ) is connected to at least one element of the main gear set, and is connectable to the housing (G) of the transmission via the third brake ( 07 ); the sixth shaft ( 6 ) is connected to at least one further element of the main gear set, and is connectable to the drive shaft ( 1 ) via the second clutch ( 16 ); the output shaft ( 2 ) is connected to at least one other element of the main gear set; the front-mounted gear set is shiftable; 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 an additional element of the main gear set; 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 eighth shaft ( 8 ) which is connectable to the drive shaft ( 1 ) via the third clutch ( 18 ); and the sun gear of the first planetary gear set (P 1 ) is connectable to the housing (G) of the transmission by the third shaft ( 3 ), via the first brake ( 03 ), and the third shaft ( 3 ) is connectable to the drive shaft ( 1 ) via the first clutch ( 13 ).