Driveline of two driving tandem axles comprising - a first vehicle axle and a second vehicle axle parallel to the first axle, having opposite ends, each suitable to support at least one wheel, and being adapted to be lifted, - an auxiliary shaft having a first end and a second end opposite the first end, wherein said first end is provided with an input to be guided directly in rotation by a main driveline shaft and wherein said second end is stably associated with said first axle to guide it in rotation, - an intermediate shaft having a first end and a second end opposite the first end, wherein said second end is stably associated with said second axle to guide it in rotation, - a transmission device reversibly connectable with said auxiliary shaft to transfer a rotation from said auxiliary shaft to said intermediate shaft, - actuation means (AT, SL) configured to lower said second axle when said transmission device operatively connects said auxiliary shaft with said intermediate shaft and vice versa, - a lifter associated with the second vehicle axle to allow the second vehicle axle to be lifted, characterized in that said transmission device comprises - a first gear (R1') associate with said auxiliary shaft and - a second gear operatively fixed on said intermediate shaft, wherein said second gear meshes operatively on said first gear and - a central differential having an input, a first and a second output, wherein said auxiliary shaft comprises a first part and a second part separated from each other, wherein said first part is associated with said input of the central differential and said second part is associated with said first output and wherein said first gear (R1') is selectively associable with said second output, and wherein said first output and said second output are selectively mutually lockable, wherein said actuation means comprise a first clutch suitable to mutually lock said first and second output and a second clutch suitable to selectively associate said second output with said first gear (R1'), and wherein said actuation means are configured so that when said second clutch is open, then said first clutch is closed and said lifter is activated, and vice versa, wherein said central differential comprises a casing defining said second output, a first planetary gear having a fulcrum integral with said casing and coaxial with said auxiliary shaft, a second planetary gear, parallel to the first planetary gear, defining said first output, a satellite carrier having a fulcrum coincident with said first part of the auxiliary shaft, defining said input and at least one satellite that meshes in said first and second planetary gear (S1, S2), and wherein said first clutch is a dog clutch type and sliding axially on said second part of said auxiliary shaft and suitable to make said second part of the auxiliary shaft reversibly integral in rotation with said casing and wherein said second clutch is of front type and sliding axially on a part of the casing with cylindrical symmetry coaxial with said auxiliary shaft (Ax1, AX2) and suitable to make said casing reversibly integral in rotation with said first gear (R1'). - a first vehicle axle and a second vehicle axle parallel to the first axle, having opposite ends, each suitable to support at least one wheel, and being adapted to be lifted, - an auxiliary shaft having a first end and a second end opposite the first end, wherein said first end is provided with an input to be guided directly in rotation by a main driveline shaft and wherein said second end is stably associated with said first axle to guide it in rotation, - an intermediate shaft having a first end and a second end opposite the first end, wherein said second end is stably associated with said second axle to guide it in rotation, - a transmission device reversibly connectable with said auxiliary shaft to transfer a rotation from said auxiliary shaft to said intermediate shaft, - actuation means (AT, SL) configured to lower said second axle when said transmission device operatively connects said auxiliary shaft with said intermediate shaft and vice versa, - a lifter associated with the second vehicle axle to allow the second vehicle axle to be lifted, characterized in that said transmission device comprises - a first gear (R1') associate with said auxiliary shaft and - a second gear operatively fixed on said intermediate shaft, wherein said second gear meshes operatively on said first gear and - a central differential having an input, a first and a second output,