Gearbox for an electric powertrain, said gearbox comprising: a primary shaft, on which are arranged a first primary gear which is fixed in rotation with respect to the primary shaft, a second primary gear and a third primary gear; a secondary shaft, on which are arranged a first secondary gear that is meshing with the first primary gear and that is by default free to rotate around the secondary shaft, a second secondary gear meshing with the second primary gear and a third secondary gear meshing with the third primary gear; a first coupling member, which is arranged along the secondary shaft and which can be moved between: - an engaged position (figure 6), in which it couples the first secondary gear in rotation with the secondary shaft; and - a neutral position (figure 4), in which the first secondary gear can rotate around the secondary shaft; characterized in that the gearbox further comprising a second coupling member, which is arranged along one shaft among the primary and secondary shafts (20, 30) and which is movable between: - a first position (figure 4) in which it couples one of the second and third gears (22, 23) in rotation with said one shaft; - a second position (figure 5) in which it couples the other of the second and third gears (22, 23) in rotation with said one shaft; and - a neutral position (figure 6) in which the second and third gears (22, 23) can rotate around said one shaft. a primary shaft, on which are arranged a first primary gear which is fixed in rotation with respect to the primary shaft, a second primary gear and a third primary gear; a secondary shaft, on which are arranged a first secondary gear that is meshing with the first primary gear and that is by default free to rotate around the secondary shaft, a second secondary gear meshing with the second primary gear and a third secondary gear meshing with the third primary gear; a first coupling member, which is arranged along the secondary shaft and which can be moved between: - an engaged position (figure 6), in which it couples the first secondary gear in rotation with the secondary shaft; and - a neutral position (figure 4), in which the first secondary gear can rotate around the secondary shaft; - an engaged position (figure 6), in which it couples the first secondary gear in rotation with the secondary shaft; and - a neutral position (figure 4), in which the first secondary gear can rotate around the secondary shaft; characterized in that the gearbox further comprising a second coupling member, which is arranged along one shaft among the primary and secondary shafts (20, 30) and which is movable between: - a first position (figure 4) in which it couples one of the second and third gears (22, 23) in rotation with said one shaft; - a second position (figure 5) in which it couples the other of the second and third gears (22, 23) in rotation with said one shaft; and - a neutral position (figure 6) in which the second and third gears (22, 23) can rotate around said one shaft. - a first position (figure 4) in which it couples one of the second and third gears (22, 23) in rotation with said one shaft; - a second position (figure 5) in which it couples the other of the second and third gears (22, 23) in rotation with said one shaft; and - a neutral position (figure 6) in which the second and third gears (22, 23) can rotate around said one shaft.