Types of car axle shafts

Update:09-12-2021
Summary:

According to the different types of axle shaft and driv […]

According to the different types of axle shaft and drive wheel hubs on the axle housing and the different forces on the axle, 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, 3/4-floating and semi-floating according to the different types of outer end support.
The full-floating half shaft only bears torque. The bending moments of the three are transmitted to the axle housing through the bearing by the hub. The force and bending moment acting on the driven bevel gear of the main reducer are all borne by the differential housing, that is, The half axis is irrelevant. The half-shaft that only bears torque at both ends of this kind of half-shaft, and does not bear other moments, is called a full-floating half-shaft.
The semi-floating half shaft not only bears the reaction torque, but the three reaction forces and the resulting bending moment are transmitted to the axle housing through the axle shaft by the hub. This kind of half shaft that bears both the torque and the torque is called the half shaft. Floating half shaft.
Full-floating half shafts are widely used in various types of trucks, and the half shafts have no direct connection 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.
Semi-floating half shafts are mostly used in various types of cars. A floating sleeve thrust block is installed in the middle of the differential planetary bevel gear shaft to prevent the wheels from moving inward when the wheels are subjected to inward lateral forces.
The axle sleeve is equipped with a ventilation device and a hose to prevent excessive pressure inside the drive axle housing from causing lubricating oil leakage. A half shaft is installed on the left and right sides of the half shaft sleeve, and the outer end of the half shaft is equipped with half shaft bearings and oil seals. Therefore, when disassembling the half shaft, the vehicle body must be lifted so that the half shaft is pulled out from the rear drive axle sleeve. .
3/4 floating half shaft
In addition to bearing the full torque, it also bears a 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.
The full-floating type is more complicated, with two sets of bearing structures, while the semi-floating type has only one set of bearing structures.
In addition to the torque transmission function of the semi-axle we mentioned before, the force of the road on the wheels is pressed on the semi-axle. In this way, the semi-axle bears the bending moment caused by the vertical force, the lateral force and the longitudinal force at the same time, which is as hard as a model worker.
The flange at the outer end of the full-floating half shaft is connected to the hub with bolts, and the hub is supported on the half shaft sleeve by two tapered roller bearings. The bearing is connected to the wheel to carry the weight, so the impact on the ground is completely affected by the axle. Bear, while the axle shaft only bears the torque from the engine at this time in theory. It is also easier to disassemble, only need to unscrew the nut on the flange of the half shaft, and then the half shaft can be drawn out from the half shaft sleeve. At this time, the wheels and the integral axle housing can still support the entire car.
Therefore, in general, the force on the half-bearing in the full-floating half-shaft is much simpler, and the two tapered roller bearing sets bear outward and inward axial forces respectively to stabilize the wheel. When various actions such as flying off-road occur, the full-floating structure is relatively stronger, the structure has a high load-bearing capacity, and the semi-shafts and bearings are not easy to deform or break.
However, although the full-floating semi-axle is theoretically stronger, most off-road vehicles currently on the market use semi-floating semi-axle. For example, we are familiar with Jeep Wrangler, Land Rover Defender, Mercedes-Benz G500 and so on. Under the premise that the structure and materials can be guaranteed, the semi-floating half shaft can also be made with good strength.
The full-floating semi-axle is a heavy-duty truck-it's strong enough to run fast.
The full-floating type and the semi-floating type can be distinguished in appearance. Two rings of fixing bolts can be seen on the wheel hub, the outer ring is connected with the sleeve flange, and the inner ring is connected with the drive shaft. But like the half shaft of the BJ40, the screws are inside, which is not easy to find. However, as long as the wheels of all vehicles are removed, it is immediately possible to see whether the structure is fully floating.
Of course, there are also off-road wheel rims with two circles of screws. In addition to the screws in the middle of the hub, there is a circle of smaller and denser bolts on the side of the tire. This is an anti-drop ring and has nothing to do with the half axle.

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