Patent ID: 7390281

Claim:
A gearbox ( 1 ) for a motor vehicle and configured to be connected to an output side of a basic gearbox, said gearbox ( 1 ) comprising: an input shaft ( 2 ) from the basic gearbox, an output shaft ( 3 ) to a transmission, and a planetary gear ( 4 ) arranged between the input shaft ( 2 ) and the output shaft ( 3 ); the ring gear ( 18 ) of the planetary gear ( 4 ) is axially displaced by a first means ( 27 ) for instituting axial displacement of the ring gear ( 18 ); a first coupling ring ( 10 ) for engaging a high-range mode and a second coupling ring ( 16 ) for engaging a low-range mode, the ring gear ( 18 ) being alternatively engagable with the coupling rings ( 10 , 16 ); at least one synchronizing means ( 15 ) with at least one friction surface ( 14 , 22 ), the synchronizing means ( 15 ) being configured to synchronize rotational speed difference between the ring gear ( 18 ) and one of the coupling rings ( 10 , 16 ) by interaction with a corresponding friction surface ( 13 , 23 ) arranged on the respective coupling ring ( 10 , 16 ); the synchronizing means ( 15 ) and the second coupling ring ( 16 ) being arranged coaxially outside the ring gear ( 18 ); at least one second means ( 25 ) for engaging at least the second coupling ring ( 16 ) and a third means ( 25 , 25 b ) for driving said synchronizing means ( 15 ) are arranged on a radially external side of the ring gear ( 18 ) and the second coupling ring ( 16 ) is arranged between the synchronizing means ( 15 ) and the first means ( 27 ).