Patent ID: 8251855

Claim:
A multi-speed automatic transmission of a planetary design for a motor vehicle, the transmission comprising: an input first shaft (AN) and an output second shaft (AB); first, second, third and fourth planetary gear sets (RS 1 , RS 2 , RS 3 , RS 4 ), and each of the first planetary gear set (RS 1 ), the second planetary gear set (RS 2 ), the third planetary gear set (RS 3 ) and the fourth planetary gear set (RS 4 ) comprising a sun gear, a carrier and a ring gear; at least third, fourth, fifth, sixth, seventh and eighth rotatable shafts ( 3 , 4 , 5 , 6 , 7 , 8 ), first, second, third, fourth and fifth gearshifting elements (A, B, C, D, E) whose selective engagement creates different gear ratios between the input first shaft (AN) and the output second shaft (AB) so that eight forward gears and at least one reverse gear can be implemented; wherein the first gearshifting element (A), when engaged, couples the third shaft ( 3 ) with a housing (GG) of the transmission; the second gearshifting element (B), when engaged, couples the fourth shaft ( 4 ) with the housing (GG) of the transmission; the third gearshifting element (C), when engaged, couples the input first shaft (AN) with the fifth shaft ( 5 ); the eighth shaft ( 8 ) is coupled with the fourth gearshifting element (D); the fifth gearshifting element (E), when engaged, couples the fifth shaft ( 5 ) and the seventh shaft ( 7 ); the carrier (ST 4 ) of the fourth planetary gearset (RS 4 ) and the input first shaft (AN) are coupled with one another; the carrier (ST 3 ) of the third planetary gearset (RS 3 ) and the output second shaft (AB) are coupled with one another; the sun gear (SO 1 ) of the first planetary gearset (RS 1 ) and the sun gear (SO 4 ) of the fourth planetary gearset (RS 4 ) are coupled with one another and form the third shaft ( 3 ); the ring gear (HO 1 ) of the first planetary gearset (RS 1 ) forms the fourth shaft ( 4 ); the sun gear (S 03 ) of the third planetary gearset (RS 3 ) forms the fifth shaft ( 5 ); the carrier (ST 1 ) of the first planetary gearset (RS 1 ) and the ring gear (HO 3 ) of the third planetary gearset (RS 3 ) are coupled to one another and form the sixth shaft ( 6 ); the ring gear (HO 4 ) of the fourth planetary gearset (RS 4 ) forms the seventh shaft ( 7 ); and the ring gear (HO 2 ) of the second planetary gearset (RS 2 ) forms the eighth shaft ( 8 ).