Improvements in transmission systems for motor vehicles with four-wheel drive

Claim 1

Transmission system for a motor vehicle with a front-mounted engine and gearbox disposed transverse the longitudinal axis of the motor vehicle, comprising: a front differential (3) having a cage (10) driven by a gear (4) carried by the driven shaft of the gearbox, for transmitting torque to the front wheels of the motor vehicle; , a rear differential (7) for transmitting torque to the rear wheels of the motor vehicle; an intermediate differential (18) constituted by an epicyclic train housed with the front differential in a casing rigid with the gearbox, the epicyclic train (18) including: a ring gear (24) driven by said gear (4) carried by the driven shaft of the gearbox; a sun wheel (25) rigid with the cage (19) of the front differential, and a planet carrier (19) carrying a series of planet wheels (22) interposed between the sun wheel (25) and the ring gear (24); a bevel gear (28) rigid with the planet carrier (19) of the intermediate differential (18), and a bevel pinion (29) meshing with the bevel gear (28) and connected kinematically to the rear differential (7), characterised in that the epicyclic train (18) is housed in a part (9a) of the gearbox while the front differential (3) is housed in a separate casing (9b) fixed to the gearbox (9a).