A variable-speed gearbox comprises a main transmission (2) arranged in a housing (30) and a downstream range-change transmission (32), the range-change transmission having power distribution on two countershafts (12, 14). On a main shaft (4) of the main transmission (2), a gear wheel (6) is arranged in a radially movable manner which meshes with respective first gear wheels (8, 10) each on one of the countershafts. In the housing of the variable-speed gearbox, a drive output shaft (22) is radially and axially fixed which is connected a gear wheel (20) that meshes in each case with a second gear wheel (16, 18), respectively, on each of the countershafts. The gear wheel on the main shaft that meshes with the first gear wheels on the countershafts is maintained in its axial position relative to the drive output shaft by way of pressure combs (50, 52, 54, 56).