When the main girder is seriously deformed, the protruding parts must be fixed with suitable fixtures. Straighten the deformed girder first, and then pull it in the opposite direction of girder deformation. If the deformation is large, please stretch it several times instead of once. In that case, the overall damage will become much larger. Similarly, it would be nice if the two diagonals were the same length. Measure the length of threaded holes on both sides of the iron bar with a dial indicator, and then measure the length of threaded holes on the corresponding two beam heads to confirm whether they are consistent. There is an error, the error is between 3mm and 5mm (mm is enough). If the lengths are different, continue to stretch until the lengths are the same. Install iron bars on the two beams and check whether the heads of the beams are correct. If the beams are inclined, it is unsuccessful to insert the screws into the four threaded holes, so the skull positions of the two beams must be correct. Next time, measure the diagonal lines. If the diagonal lines are the same and the iron bars are installed properly, the rectification of the beam will generally succeed. Main girder rectification method: 1, equipment preparation. First of all, you need to prepare the equipment needed to correct the girder. Girder orthosis, several clamps, a small hammer, a middle hammer and several tools. Then check whether the beam orthosis is clean, and drive the damaged vehicle to the beam orthosis; 2. The vehicle is fixed. Fixing the four tires of the vehicle with a fixture to prevent the vehicle from being towed away in the beam pulling process, rotating the straightening stretching arm to the beam position, and then stopping the fixation below to prevent the stretching arm from shaking in the beam pulling process, and straightening the stretching arm; 3. Determine the deformation degree of the main girder. For us light people, we just need to stretch in the opposite direction of deformation. In order to find the measuring point on the car body during stretching, please measure the diagonal lines with a box ruler until the two diagonal lines are equal in length.