The wheel hub bearing unit is developed on the basis of standard angular contact ball bearings and tapered roller bearings. It integrates two sets of bearings into one. It has the advantages of good assembly performance, no need for clearance adjustment, light weight, compact structure, large load capacity, grease can be pre-loaded for sealed bearings, no external wheel hub seals and no maintenance. It has been widely used in cars and there is a trend of gradually expanding its application in trucks.

Spherical roller bearings have a spherical raceway on the outer ring, with the center of the sphere coinciding with the bearing center. The inner ring has two raceways inclined at an angle to the bearing axis, providing excellent self-aligning performance. These bearings are mainly used to support radial loads and can also accommodate axial loads in either direction. They are suitable for heavy-duty machinery used in mining, metallurgy, papermaking, construction and other industries.

Cylindrical roller bearings are separable bearings. The inner ring, outer ring and rollers are in line contact, offering a low friction coefficient and high limiting speed. Double row cylindrical roller bearings feature a compact structure, high rigidity, strong load-carrying capacity and low deformation under load, making them suitable for machine tool spindle supports. Cylindrical roller bearings are widely used in heavy-duty machinery such as cold and hot rolling mills. The basic radial clearance of single row cylindrical roller bearings is normal clearance, and other clearance grades such as C3 and C4 can be selected according to actual requirements.

Spherical roller thrust bearings are separable bearings with spherical rollers and a spherical raceway in the housing washer, providing self-aligning capability. Because the load line forms an angle with the bearing axis, these bearings can carry both axial and radial loads and can be used under extremely heavy load conditions. They also allow relatively high speeds and are generally lubricated with oil. Spherical roller thrust bearings are similar in principle to spherical roller bearings. The raceway surface of the housing washer is spherical, centered on a point consistent with the bearing center axis. The spherical rollers provide automatic self-aligning performance and make the bearing less sensitive to coaxiality errors and shaft deflection.

Tapered roller bearings are mainly used to carry combined radial and axial loads. Their axial load-carrying capacity depends on the raceway angle of the outer ring; the larger the angle, the greater the axial load capacity. Double row and four row tapered roller bearings can carry combined radial and axial loads primarily based on radial loads, and can also accommodate axial loads in both directions. They are generally suitable for medium- and low-speed applications.

Backing bearings are rolling bearings with an especially thick outer ring. They are installed in sets on a stationary shaft to function as support rollers. The pressure from the work roll is transmitted through the intermediate roll to the support rollers and then through the saddle system to the mill stand. They are generally used in multi-roll cold rolling mill equipment and may also be used in other applications such as straightening machines. Backing bearings are multi-row cylindrical roller bearings with very high precision requirements. In particular, after radial clearance is eliminated, the section height from the inner diameter to the outer diameter, known as the T value, is especially important and must be controlled within 0.005 mm on each shaft. This requires very high precision of bearing components. Backing bearings are specially used for multi-roll thin-strip mills, including the rolling of cold-rolled silicon steel sheets for the power industry, high-quality sheets for the automotive industry, coated sheets, stainless steel sheets and other high value-added thin sheets. This type of bearing directly functions as a support roll. Structurally, its outer ring wall thickness is much greater than that of ordinary bearings, and both radial runout of the outer diameter and the mutual difference in assembled wall thickness are extremely small. The bearing has a high dynamic load rating and can rotate with high precision under heavy loads.

Deep groove ball bearings consist of four basic components: the inner ring, outer ring, balls and cage. During normal operation, the inner raceway, outer raceway and balls carry the load, while the cage separates and stabilizes the balls. Single row radial deep groove ball bearings have a simple structure, non-separable inner and outer rings, and are easy to use. They are widely applied in precision instruments, low-noise motors, automobiles, motorcycles, woodworking machinery, textile machinery, mining machinery, electromechanical equipment, plastic machinery, office equipment, medical devices, fitness equipment, defense, aviation, aerospace, sports equipment and general machinery. They are one of the most widely used types of bearings in the machinery industry. They are mainly used to carry radial loads and can also carry a certain amount of axial load. When the radial clearance is increased, they have the characteristics of angular contact ball bearings and can carry larger axial loads. This type of bearing can limit axial displacement in both directions. Depending on the clearance, the inner and outer rings are allowed to tilt relative to each other by 8 to 16 minutes.

Self-aligning ball bearings allow the inner ring, balls and cage to rotate freely around the bearing center, providing self-aligning capability. This feature compensates for misalignment, shaft deflection and deformation of the bearing housing. Self-aligning ball bearings are suitable for applications where shaft and housing alignment is difficult or where shaft deflection is likely to occur. The outer ring raceway of a self-aligning ball bearing is spherical, and the inner ring has two deep groove raceways, forming a double row ball bearing with self-aligning performance. It is mainly used to carry radial loads and can also carry a small amount of axial load, but it is generally not suitable for pure axial loads. Its limiting speed is lower than that of deep groove ball bearings. This type of bearing is often used on dual-supported shafts that are prone to bending under load, or in applications where the two housing bores cannot maintain strict coaxiality. However, the relative inclination between the centerline of the inner ring and that of the outer ring must not exceed 3 degrees. It is suitable for heavy loads and impact loads, precision instruments, low-noise motors, automobiles, motorcycles, metallurgy, rolling mills, mining, petroleum, papermaking, cement, sugar processing and general machinery.

Angular contact ball bearings can carry both radial and axial loads, and can also carry pure axial loads. Their axial load-carrying capacity depends on the contact angle and increases as the contact angle becomes larger. They offer high limiting speed and rigidity, and can be preloaded, making them suitable for high-speed and high-precision applications. Single row angular contact ball bearings can only carry axial load in one direction, so they are usually installed in pairs. Double row angular contact ball bearings can carry large combined radial and axial loads as well as moment loads, and are mainly used in components that limit axial displacement of the shaft or housing in both directions. Four-point contact ball bearings are separable bearings that can carry axial loads in both directions and have the functions of single row and double row angular contact ball bearings.

The design of double row angular contact ball bearings is basically the same as that of single row angular contact ball bearings, but they require less axial space. Double row angular contact ball bearings can carry radial loads and axial loads acting in both directions. They can limit axial displacement of the shaft or housing in both directions. With a contact angle of 30 degrees, they provide a bearing arrangement with high rigidity and can withstand overturning moments.

Insert ball bearings are essentially a variant of deep groove ball bearings. Their outer ring has a spherical outside surface, which can fit into the corresponding concave spherical surface of the bearing housing to provide self-aligning capability. They are mainly used to carry combined radial and axial loads with radial load as the primary load, and are generally not suitable for carrying axial load alone. This type of bearing allows the inner ring, together with the complete set of rolling elements and cage, and the outer ring to be mounted separately. The bearing does not allow the shaft to tilt relative to the housing. Under radial load, additional axial force may be generated. The axial clearance of this type of bearing is critical to normal operation. If the axial clearance is too small, the temperature rise will be high; if the axial clearance is too large, the bearing may be easily damaged. Therefore, special attention should be paid to adjusting the axial clearance during installation and operation. If necessary, preload or interference fitting can be applied to increase bearing rigidity.

Thrust ball bearings consist of washers with raceways, balls and a cage assembly. The raceway washer fitted with the shaft is called the shaft washer, while the raceway washer fitted with the housing is called the housing washer. This type of bearing includes single direction and double direction thrust ball bearings. Single direction thrust ball bearings can carry axial load in one direction and limit axial displacement in one direction. Double direction thrust ball bearings can carry axial loads in both directions and limit axial displacement in both directions. Neither type can carry radial load. In addition to designs with flat housing washers, there are also designs with spherical housing washers and seating washers. These bearings have high load capacity and very low limiting speed.