What do the "full-floating" and "semi-floating" types of automobile axle shafts refer to?

When discussing three-wheeled motorcycles, light trucks, and vans, they often say that this axle is fully floating and that one is semi-floating. What do "full-floating" and "semi-floating" mean here? Let's answer this question below. The so-called "full-floating type" and "semi-floating type" refer to the installation and support type of the automobile half-axle. As everyone knows, the axle shaft is a solid shaft that transmits torque between the differential and the drive wheels. Its inner side is connected with the side gear through a spline, and the outer side is connected with the hub of the driving wheel by a flange. Because the semi-shaft needs to withstand very large torque, its strength is required to be very high. Generally, alloy steel such as 40Cr, 40CrMo or 40MnB is quenched and tempered and high-frequency quenched, and the surface has high strength, hardness and resistance. Abrasion, the core has good toughness, can withstand greater torque, and can withstand a certain impact load, which can meet the needs of the car under various conditions. According to the different types of semi-axle support, the semi-axes are divided into two types: "full-floating" and "semi-floating". The full-floating axles and semi-floating axles we often refer to actually refer to the type of semi-axle. The "float" here refers to the bending load after the half shaft is removed. The so-called full-floating half shaft means that the half shaft only bears torque, but does not bear any bending moment. The inner side of such a half shaft is connected to the differential side gear through a spline, and the outer side has a flange plate, which is fixed to the hub by bolts, and the hub is installed on the axle through two tapered roller bearings. In this way, the various shocks and vibrations received by the wheels and the weight of the vehicle are transmitted from the wheels to the hub and then to the axle, and ultimately are borne by the axle housing. The half shaft just transmits the torque from the differential to the wheels to drive the car. In this process, the two ends of the half shaft only bear torque, not any bending moment, so it is called "full floating type". The structure and installation of the full-floating half-axle of an automobile, its structural feature is that the hub is installed on the axle through two tapered roller bearings, the wheel is installed on the hub, the supporting force is directly transmitted to the axle, and the half-shaft is fixed by eight screws On the wheel hub, the torque is transmitted to the wheel hub to drive the wheel to rotate. The full-floating half-shaft is easy to disassemble and replace, and the half-shaft can be taken out only by removing the fixing bolts fixed on the flange of the half-shaft. After removing the half axle, the entire weight of the car is supported by the axle housing and can still be reliably parked on the ground; the disadvantage is that the structure is relatively complex and the parts are relatively large in quality. It is the most widely used type in automobiles, and most light, medium, and heavy trucks, off-road vehicles and passenger cars use this type of half-axle. The so-called semi-floating half shaft means that the half shaft not only bears torque, but also bears bending moment. The inner side of such a half shaft is connected with the differential half shaft gear through a spline, the outer end of the half shaft is supported on the axle housing through a bearing, and the wheel is fixedly installed on the cantilever at the outer end of the half shaft. In this way, the various forces acting on the wheels and the resulting bending moments are directly transmitted to the half shaft, and then to the drive axle housing through the bearing. When the car is running, the half shaft not only drives the wheels to rotate, but also To support the full weight of the car. The inner end of this semi-shaft only bears the torque but not the bending moment, and the outer end has to bear the torque and all the bending moment at the same time, so it is called "semi-floating". The structure and installation of the semi-floating semi-axle of an automobile, its structural feature is that the outer end is fixedly supported on a tapered roller bearing with a tapered surface and a key and the hub. The outward axial force is borne by the tapered roller bearing, and the inner The axial force is transmitted to the tapered roller bearing on the other side of the axle through the slider. The semi-floating semi-axle support structure is compact and light in weight, but the force of the semi-axle is complicated and it is inconvenient to disassemble and assemble. If the half axle is removed, the car cannot be supported on the ground. It can generally only be applied to small vans and light vehicles with small car loads, small wheel diameters, and rear integral axles.