Power shift gearbox

The invention discloses a power shift gearbox which is suitable for engineering machines and particularly suitable for wheel loaders. The power shift gearbox comprises six shafts and thirteen gears, four forward gears and four reverse gears are formed, the forward gears are achieved through closing of two clutches and four times of gear meshing, and the reverse gears are achieved through closing of two clutches and three times of gear meshing. Along the transmission paths of the shafts, the input shaft I, the intermediate shaft II and the intermediate shaft III are arranged in a triangular mode when seen from the end face, and the intermediate shaft III, the intermediate shaft IV, the intermediate shaft V and the intermediate shaft VI are arranged in a quadrilateral mode when seen from the end face. According to the power shift gearbox, the structure is simple, the transmission path is short, transmission efficiency is high, the number of teeth of a fixed gear Z11 on the output shaft VI, the number of teeth of a fixed gear Z12 on the output shaft VI, the number of teeth of a fixed gear Z7 on the intermediate shaft V and the number of teeth of a fixed gear Z10 on the intermediate shaft IV can be adjusted within a wide range, and thus different transmission ratios can be designed and obtained according to different requirements.