A transmission system comprising: - a clutch module, having a single input and a first and a second output (o1, o2), where between the first output and the input is located a first and a third clutch device (B1, B2) equipped with first and third energizing means and transmission means formed by a bypass transmission comprising at least four rotational members, a first rotational member of which is connected to the input, a second rotational member of which is connected to the first output and a third and a fourth rotational member (r3, r4) of which are connected to the first and the third clutch device (B1, B2) respectively, and between the second output and the input is located a second clutch device equipped with second energizing means, and - a transmission module, having a single output and a first and a second input (in1, in2), where between the first input and the output is located a first sub-transmission equipped with at least a single speed transforming gear and/or a single transmission clutch, and between the second input and the output is located a second sub-transmission also equipped with at least a single speed transforming gear and/or a single transmission clutch, where: the two outputs (o1, o2) of the clutch module are connected to the two inputs (in1, in2) of the transmission module, - the first and/or third clutch device is arranged as a brake or as an electromotor in which the stator is connected to the firm world and the rotor is connected to the rotational member involved, and - the second clutch device is arranged as a clutch or as an electromotor, characterized in that between the first output and the input there is a first transmission path and between the second output and the input there is a second transmission path which is parallel to the first transmission path, where the first and third clutch device and the bypass transmission are present in the first transmission path only and the second clutch device is located in the second transmission path only. - a clutch module, having a single input and a first and a second output (o1, o2), where between the first output and the input is located a first and a third clutch device (B1, B2) equipped with first and third energizing means and transmission means formed by a bypass transmission comprising at least four rotational members, a first rotational member of which is connected to the input, a second rotational member of which is connected to the first output and a third and a fourth rotational member (r3, r4) of which are connected to the first and the third clutch device (B1, B2) respectively, and between the second output and the input is located a second clutch device equipped with second energizing means, and - a transmission module, having a single output and a first and a second input (in1, in2), where between the first input and the output is located a first sub-transmission equipped with at least a single speed transforming gear and/or a single transmission clutch, and between the second input and the output is located a second sub-transmission also equipped with at least a single speed transforming gear and/or a single transmission clutch, - the first and/or third clutch device is arranged as a brake or as an electromotor in which the stator is connected to the firm world and the rotor is connected to the rotational member involved, and - the second clutch device is arranged as a clutch or as an electromotor,