Multi-ratio transmission

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 (P1, P2, P3, P4) which are disposed 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) and at least six shift elements (03, 04, 13, 27, 28, 35, 36) comprising first and second brakes (03, 04) and first, second, third and fourth clutches (13, 27, 28, 35, 36) 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 (P1) is connected to the drive shaft (1), a carrier of the first planetary gear set (P1) is connected to the third shaft (3) which is connectable to the housing (G) of the transmission via the first brake (03) and is detachably 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 (P2), to a sun gear of the third planetary gear set (P3) and to a sun gear of the fourth planetary gear set (P4), and the drive shaft (1) is connected to a carrier of the fourth planetary gear set (P4);
• the sixth shaft (6) is connected to a ring gear of the first planetary gear set (P1) and to a carrier of the second planetary gear set (P2);
• a sun gear of the second planetary gear set (P2) is connected to the fourth shaft (4) which is connectable, via the second brake (04), to the housing (G) of the transmission;
• a ring gear of the third planetary gear set (P3) is coupled to the housing (G) of the transmission;
• the output shaft (2) is detachably connectable, via the fourth clutch (28), to the eighth shaft (8) which is connected to a carrier of the third planetary gear set (P3) and, via the third clutch (27), to the seventh shaft (7) which is connected to a ring gear of the fourth planetary gear set (P4);
• and
• the first planetary gear set (P1) can be blocked by engagement of the first clutch (13 or 36).