According to the different types of axle shaft and drive wheel hubs on the axle housing and the different forces on the axle shafts, modern cars basically adopt two forms: full-floating half-shafts and semi-floating half-shafts. The semi-axles of ordinary non-disconnected drive axles can be divided into three types: full-floating, 34-floating and semi-floating according to the different types of outer end support.
1. Fully floating half shaft Full-floating half shafts are widely used in various types of trucks. The outer end of the half shaft is provided with a flange plate directly forged; the hub is connected to the flange plate by bolts; the hub is supported on the half shaft sleeve through two distant tapered roller bearings; The half shaft sleeve and the drive axle housing are press-fitted into one body, and the half shaft has no direct contact with the drive axle housing.
The installation direction of the two tapered roller bearings in the hub must be such that they can withstand inward and outward axial forces respectively to prevent axial displacement of the hub and the axle shaft under the action of lateral force. The pre-tightness of the bearing can be adjusted by adjusting nut 2 and locked with lock washer and lock nut.
2 Semi-floating half shaft Semi-floating half shafts are mostly used in various types of cars. The inner end support of the half shaft is the same as the full floating support, that is, the inner end of the half shaft does not bear bending moment. There are longitudinal key grooves and threads on the conical surface of the outer end of the semi-shaft.
The hub is connected to the conical part of the semi-shaft through the key and is fastened with a lock nut. The axle shaft is directly supported in the flange of the drive axle housing through the tapered roller bearing. It can be seen that the reaction forces in all directions acting on the drive wheels on the road surface must be transmitted to the drive axle housing via the half shaft.
In addition to bearing radial force, bearing also bears outward axial force. Therefore, a floating sleeve thrust block is arranged in the middle of the planetary bevel gear shaft of the differential, which can prevent the wheel from moving the semi-axial inward when the wheel receives an inward lateral force.
3.3/4 floating half shaft In addition to bearing the full torque, it also bears 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, which supports the wheel hub.
Due to the poor supporting rigidity of a bearing, in addition to the torque, this kind of semi-axle also bears 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.