In a gear shift transmission comprising at least two input shafts, which can be connected to a drive shaft via at least two power shift clutches and a plurality of gear wheels disposed in gear wheel planes and comprising an output shaft, which can be operatively connected to the input shafts, the transmission includes at least two sequentially shiftable forward gears and a shifting device, which is provided for shifting one of the gear wheel planes as an input constant for forming at least one gear and as a gear wheel pair for forming a further gear and the gear wheel plane comprises an idler wheel which is connectable to one of the input shafts in a torque proof manner.
