Commonly used half shafts in modern automobiles are of two types: full floating and semi floating, depending on their support type. (There are also three types, namely full floating, 3/4 floating, and semi floating)
Full floating half shaft
A half shaft that only bears torque during operation and does not bear any force or bending moment at both ends is called a full floating half shaft. The outer end flange of the half shaft is fastened to the wheel hub with bolts, and the wheel hub is mounted on the half shaft sleeve through two bearings that are far apart. Structurally, the inner end of the full floating half shaft has a spline, the outer end has a flange, and there are several holes on the flange. It is widely used in commercial vehicles because of its reliable work.
3/4 floating half shaft
In addition to bearing all torque, it also has to bear part of the bending moment. The most prominent structural feature of the 3/4 floating half shaft is that there is only one bearing at the outer end of the half shaft, and the bearing supports the wheel hub. Since the support stiffness of one bearing is poor, this type of half shaft, in addition to bearing torque, also has to bear the bending moment caused by the vertical force, driving force and lateral force between the wheel and the road surface. 3/4 floating half shafts are rarely used in automobiles.
Semi-floating half shaft
The semi-floating half shaft is directly supported on the bearing located in the inner hole of the outer end of the bridge housing with the journal near the outer end, and the end of the half shaft is fixedly connected to the wheel hub with a journal with a conical surface and a key, or directly connected to the wheel disc and brake hub with a flange. Therefore, in addition to transmitting torque, it also has to bear the bending moment caused by the vertical force, driving force and lateral force transmitted from the wheel. Semi-floating half shafts are used in passenger cars and some common vehicles due to their simple structure, small mass and low cost.