The axle housing of drive axle is one of the main parts of automobile, and the axle housing of non-disconnecting drive axle plays the role of supporting automobile load and transmitting the load to wheels. Traction force, braking force, lateral force and vertical force acting on driving wheels are also transmitted to suspension and frame or carriage through axle housing. Therefore, the bridge is not only a load-bearing part but also a force-transmitting part. At the same time, it is also the shell of the main reducer, differential and driving wheel transmission device (such as half axle).