The weight is Q<=50t, and the size is b+60mm. When the weight is at 50t-100t, the size is b+100mm.The B is the distance between the center of the track and the outer end of the crane. The crane’s beam is <=2mm at the top of the bolt in the wide 400mm range, and the height difference of the top face of each bolt is 6m in any 6m length of the beam.