The wheel bearing is the part that connects the tire (rotating part) / brake disc (rotating part) with the steering knuckle (fixed part). Their main function is to reduce the friction for the rotating part and also to transmit the force. It is subjected to very high radial loads (vehicle weight) and axial loads (lateral force of the tire during steering or lateral impact).
The difference lies mainly in whether the shape of the rolling medium (roller) inside is spherical or tapered.
Unless it is a particularly large load car (engineering vehicles and large SUVs, pickup trucks, etc.), the wheel bearings of passenger cars in general are ball bearings.
The structure of a generation of bearings is the simplest, mainly an inner ring, an outer ring and steel balls. And the cost is also the lowest.
Although the first generation bearings have the advantages of simple structure and cost, they also have many disadvantages.
First of all, it is not easy to assemble in the car factory for assembly.
The assembly process is complicated, so the requirements for equipment and process control are high.
The second is that the performance is not good.
Because the process can not be precisely controlled during installation, resulting in the performance deviation of the bearing after press fitting is also large, and the overall performance is low.
The structure of the second generation wheel bearing is a little more complicated, and the hub is integrated on the basis of the first generation bearing.
Compared with the first generation of wheel bearings, the assembly process of pressing into the hub is omitted, but the assembly of interference fit with the steering knuckle is also required, and the assembly accuracy is only slightly higher than that of the first generation of wheel bearings.
But also has the disadvantage of poor performance.
Currently, in addition to some car manufacturers still adhere to the use of the rear hub (I will not say that this car manufacturer is VW), also like a generation of wheel bearings with less and less, and eventually die out.
In terms of integration, the third-generation wheel bearings have an integrated hub on the inner ring and a flange connecting the steering knuckle on the outer ring, which can be connected to the steering knuckle by bolts. The assembly accuracy is greatly improved.
Moreover, since all dimensions are precisely controlled at the supplier, the performance is the best.
Because of these two advantages, although the cost is a little higher, the third generation wheel bearing is still favored by almost all mainstream car manufacturers.
Excess and clearance design (mainly for Gen 1 and Gen 2 bearings)
Bearing strength/stiffness
Bearing dragging torque
Bearing life
Sealability
