Abstract: A gear change for a commercial vehicle comprising a main group defining a plurality of transmission ratios and an auxiliary group with two transmission ratios actuated by an actuator with three positions corresponding respectively to two coupling positions and one neutral position; the actuator is controlled by a control unit in response to actuating signals received by manual selectors, and it is adapted to place the auxiliary group in the neutral position if the speed of rotation of the input shaft exceeds a predetermined threshold value.

Abstract: A gear change for an automobile vehicle comprising a box, a main train, an input shaft of which is connected to the engine and a primary shaft of which can be connected angularly to the input shaft by a plurality of pairs of gears, and an auxiliary epicyclic gear train comprising, in turn, a sun gear angularly coupled to the primary shaft, a train carrier angularly rigid with an output shaft of the gear change and comprising a plurality of planet gears engaging with the sun gear, and an outer crown having inner teeth engaging with the planet gears, which crown can be displaced along the longitudinal axis between a first operating position in which it is coupled to the box by the engagement of a first and a second toothed wheel and a second operating position in which it is coupled to the train carrier by the engagement of a third and a fourth toothed wheel; the sun gear, the planet gears and the inner teeth of the crown comprising respective helical teeth and the first, second, third and fourth toothed wheels

Abstract: A gear change for an automobile vehicle comprising an outer box, an input shaft and a driven shaft coaxial with one another, and at least one countershaft that can be angularly coupled with the input shaft and with the driven shaft by means of a plurality of pairs of gears in order to define a plurality of transmission ratios between the input shaft and the driven shaft; the input shaft and the driven shaft are borne via bearings by respective walls of the box in the vicinity of respective first end portions opposite one another and comprise respective second portions mounted one inside the other and mutually supporting one another via a pair of axially spaced bearings.