Why is the drive shaft of the car hollow and the half shaft is solid?

We know that the power output of the engine does not directly act on the wheels to drive the car, but the force is transmitted through the drive shaft. The transmission shaft is the shaft that can transmit power in the transmission shaft of the universal transmission. It is an important component of the transmission power in the vehicle transmission system. Its function is to transmit the power of the engine to the wheels together with the gearbox and the drive axle, so that the transmission of the vehicle Driving force. It is a high-rotation, low-supporting rotating body, so it must be balanced at high speed. Generally, the drive shaft must be tested for dynamic balance before leaving the factory and adjusted on the balancer. For the front engine rear-wheel drive vehicle, the rotation of the transmission is transmitted to the shaft of the final drive. The transmission shaft can be two or several sections, and the joints can be connected by a universal joint.
In general, the connection between the gearbox and the differential is called the drive shaft. The drive axle is called the half shaft and is divided into the front half shaft and the rear half shaft. Generally speaking, if the gearbox and the differential are integrated, there is only a half shaft. Mostly for the front drive. If the gearbox and the differential are separated, then there is a drive shaft.
There are several drive shafts in a car that are related to the drive mode:

The front drive generally has two half shafts, called the front left and right axles;
Rear-drive, generally two rear axles and one drive shaft are connected to the gearbox and the rear differential;
4WD, generally having two front axles, two rear axles, a rear drive shaft between the gearbox and the rear differential, a front drive shaft between the gearbox and the front differential, and a shifting A small drive shaft between the box and the transfer case.

Why are the drive shafts of the car hollow and the half shafts solid?
The shaft tube of the main drive shaft is hollow, because the drive shaft drive shaft only needs to withstand the torsional stress, that is to say, the deformation on the drive shaft is only distorted, so to tell you, the cross section of the drive shaft is a circle, when the shaft is twisted When the force is strong, the distance from the center of the circle is the greatest. The closer to the center of the circle, the stress is actually very small, and the force received at the center of the circle is 0. Therefore, the center of the circle is hollowed out and there is no axis. What impact, but for the manufacturer, it can save a lot of materials, it needs to be emphasized that this is not a cut-off, which is a very reasonable promotion.
However, in addition to torsional stress, the half shaft needs to withstand shear stress and bending stress. The force of the half bearing is much larger and more complicated. In order to meet the requirements of strength and rigidity, the half shaft is solid.