GEARBOX ASSEMBLY AND POWER TRAIN ASSEMBLY FOR A VEHICLE AXLE, AND RELATED VEHICLE

Gearbox assembly (1) for a vehicle axle (100) which extends along a rotation axis (X), the assembly (1) comprising at least: - a planetary gear system (10) which is positioned along the vehicle axle (100) and is suitable to receive power from a motor (200) associated to the vehicle axle (100), the planetary gear system (10) comprising a ring gear (12), a sun gear (14), a planet comprising one or more planet gears (16), and a planet carrier (18) which comprises an output member (20); - a differential (30) comprising a differential shaft (31) which is positioned along the rotation axis (100) with a first end adjacent to the planet carrier (18) and comprises an output gear (32) positioned concentrically to the rotation axis (X) along the differential shaft (31); - a free wheeling gear (40) located concentrically to the output member (20) of the planet carrier (18); - a plurality of countershaft assemblies (50, 60, 70) each comprising: - a countershaft (52, 62, 72) positioned rotating about an axis (X1, X2, X3) parallel to the rotation axis (X); - two countershaft gears (54, 64, 74; 56, 66, 76) which are mounted on the corresponding countershaft (52, 62, 72) spaced apart from each other and are configured to engage one (54, 64, 74) with the free wheeling gear (40) and the other (56, 66, 76) with the output gear (32), respectively; - a clutch (80) which is configured to be operated at least between a first position where it couples the planet carrier (18) with the free wheeling gear (40) and a second position where it couples the planet carrier (18) directly with the differential (30).