The axle housing is cast with integral high-quality alloy steel, which has high stiffness, high strength and strong bearing capacity, and is easy to form a beam. The flaw detection meets the standard of GB / t9444-2007. Bearings, brake friction plates and seals are imported parts with reliable quality and not easy to aging. Automatic ring welding is adopted for welding, and the flaw detection meets the standard of GB / t11345-2013. The whole bridge has advanced manufacturing technology, strong bearing capacity, large reduction ratio, impact resistance, optimized design of parts and components and low cost.