Abstract: A gear box having an input shaft and an output shaft which are coaxial and two lay shafts parallel to and spaced from the input shaft, the lay shafts having respective gears fixed to them, said gears engaging with a gear fixed to the output shaft and the lay shafts carrying gears which mesh with respective gears which are non rotatably carried on the input shaft, the said meshing input and lay shaft gears providing respective ratios through which torque is transmitted from the input shaft to either one of the lay shafts, through the appropriate permanently meshing gears to the output shaft and clutch means for selectively engaging the gears on the lay shafts with said shafts.