The transmission comprises: an input shaft coupled to a prime mover of the tractor; an output shaft; a hydrostatic unit including a pump driven by the prime mover shaft and a motor driven by the pump; an epicyclic torque splitter unit, including a first and a second input shaft and a first and a second output shaft, the rotational speeds of the first and second output shafts varying, respectively, in a first and a second range adjacent to each other as the rotational speed of the first input shaft varies between a maximum value and a minimum value; a clutch unit, arranged to couple the output shaft of the transmission selectively to the first or second output shaft of the torque splitter unit to provide a pair of forward operating ranges, at high and low speed respectively; and a reversing unit, arranged to provide a reverse operating range.