The main role of the automotive axle housing includes supporting and protecting transmission parts such as the main reducer, differential and half-shafts, as well as serving a variety of functions as an important part of the traveling system. 
First of all, the axle housing is the substrate for mounting the main reducer, differential, half-shafts and wheel assemblies, and its main role is to support and protect these transmission parts. The axle housing of an ordinary non-disconnected drive axle is a rigid hollow beam supporting the left and right drive wheels, in which the transmission parts are mounted. The axle housing should have sufficient strength and rigidity, small mass, easy to disassemble and adjust the main gearbox. Structurally, the axle housing can be divided into three categories: integral, divisible and combined.

Secondly, the bridge shell and the front axle together with the mass of the car, so that the axial relative position of the left and right driving wheels is fixed. When the car is traveling, the axle shell bears the counterforce in all directions, bending moment and braking moment transmitted from the driving wheels, and is transmitted to the frame or body through the suspension. It also has the following specific roles:

Supporting the mass of the vehicle and bearing the road reaction forces and moments transmitted from the wheels to the frame (or body) through the suspension.
Acts as a support and containment member for the main reducer, differential, half shafts and other components.
The housing contains lubricating oil to lubricate gears, bearings, etc.
The airtight shell prevents the intrusion of dirt and protects the working environment of the internal parts.
The axial relative positions of the left and right drive wheels are made fixed.
In addition, the axle housing is subjected to complex forces, including static bending stresses, strength calculations under impact loads, strength calculations when traveling with maximum traction, strength calculations during emergency braking, and strength calculations when subjected to maximum lateral forces. These calculations ensure the strength and durability of the axle housing under various operating conditions.