January 16, 2020
The main function of a hub bearing is to support the load and provide precise guidance for the rotation of the hub. It bears both axial and radial loads and is a very important component. Traditional automotive wheel bearings are composed of two sets of tapered roller bearings or ball bearings. The installation, oiling, sealing and clearance adjustment of the bearings are performed on the automobile production line. This structure makes it difficult to assemble, high cost, and poor reliability in an automobile production plant, and the bearing needs to be cleaned, oiled, and adjusted when the automobile is maintained at a repair point. The hub bearing unit is developed on the basis of standard angular contact ball bearings and tapered roller bearings. It integrates two sets of bearings, has good assembly performance, can eliminate clearance adjustment, light weight, compact structure, and load capacity. Large, sealed bearings can be pre-installed with grease, omitting the external hub seal and maintenance-free, etc., has been widely used in cars, there is also a trend to gradually expand the application in trucks.
In the past, wheel hub bearings for cars have used single-row tapered roller or ball bearings in pairs. With the development of technology, cars have widely used car wheel units. The range and quantity of hub bearing units are increasing day by day, and now it has developed to the third generation: the first generation is composed of double row angular contact bearings. The second generation has a flange for fixing the bearing on the outer raceway. The bearing can be simply sleeved on the wheel shaft and fixed with a nut. Makes car maintenance easier. The third-generation hub bearing unit uses a bearing unit and an anti-lock brake system ABS. The hub unit is designed with an inner flange and an outer flange. The inner flange is bolted to the drive shaft. The outer flange installs the entire bearing together. Worn or damaged hub bearings or hub units can cause your vehicle to fail inappropriately and costlyly on the road, or even cause damage to your safety.
In the use and installation of hub bearings, please note the following:
1. In order to ensure the maximum safety and reliability, it is recommended that you always check the wheel bearing regardless of the age of the car-pay attention to the early warning signal of wear of the bearing: including any frictional noise when turning or the suspension combination wheel turning Unusual deceleration. For rear-wheel drive vehicles, it is recommended to lubricate the front wheel bearings when the vehicle travels up to 38,000 kilometers. When replacing the brake system, check the bearings and replace the oil seal.
2. If you hear noise from the hub bearing, first of all, it is important to find where the noise occurs. There are many moving parts that may generate noise, or some rotating parts are in contact with non-rotating parts. If it is confirmed that the noise is in the bearing, the bearing may be damaged and needs to be replaced.
3. Because the working conditions of the bearing failure on both sides caused by the front hub are similar, even if only one bearing is broken, it is recommended to replace them in pairs.
4. Wheel hub bearings are relatively sensitive. In any case, correct methods and suitable tools need to be used. During storage, transportation and installation, the bearing components must not be damaged. Some bearings require a larger pressure to press in, so special tools are required. Be sure to refer to the car manufacturer's instructions.
5. The bearing should be installed in a clean and tidy environment. Fine particles entering the bearing will also shorten the service life of the bearing. It is important to maintain a clean environment when replacing bearings. It is not allowed to hit the bearing with a hammer. Be careful not to drop the bearing on the ground (or similar improper handling). The condition of the shaft and the bearing seat should also be checked before installation. Even slight wear can cause poor fit and cause early failure of the bearing.
6. For the hub bearing unit, do not attempt to disassemble the hub bearing or adjust the seal ring of the hub unit, otherwise the seal ring will be damaged and water or dust will enter. Even the raceways of the seal and the inner ring are damaged, causing permanent failure of the bearing.
7. There is a magnetic thrust ring inside the seal ring equipped with ABS device bearing. This kind of thrust ring cannot be impacted, impacted or collided with other magnetic fields. Remove them from the box before installation, and keep them away from magnetic fields, such as motors or power tools used. When installing these bearings, change the operation of the bearings by observing the ABS alarm pin on the dashboard through a road test.
8. For wheel hub bearings equipped with ABS magnetic thrust rings, in order to determine which side the thrust rings are mounted on, you can use a small and light object * near the edge of the bearing. The magnetic force generated by the bearing will attract it. When installing, point the side with the magnetic thrust ring inward, facing the sensitive components of the ABS. Note: Improper installation may cause the brake system to fail.
9, many bearings are sealed, this type of bearing does not need to add grease throughout the life cycle. Other non-sealed bearings such as double-row tapered roller bearings must be greased during installation. Because the inner cavity of the bearing is different in size, it is difficult to determine how much grease is added. The most important thing is to ensure that there is grease in the bearing. If there is too much grease, excess grease will leak out when the bearing rotates. General experience: During installation, the total amount of grease should account for 50% of the bearing clearance.
10. When installing the lock nut, due to the different bearing types and bearing housings, the torque varies greatly .
Car wheel bearing atlas
Car wheel bearing atlas (5 photos)
Maintenance attention edit
During the maintenance process, it is often found that some cars have a large driving noise, check that the tires are not abnormally worn, and there are no obvious abnormal noises when turning the wheels on the lift. This phenomenon is often caused by abnormal damage to the hub bearing. The so-called abnormality refers to bearing damage caused by installation. The front wheel bearing of a car is usually a double-row ball bearing. If a hammer is used to install the bearing, or when the bearing is installed in the bearing seat by pressing the inner ring of the bearing, it will cause the bearing raceway on one side. damage. Noise is generated when the vehicle is driving, and no obvious noise is heard when the wheels are off the ground due to the better side of the raceway. Proper installation operation is the key to long bearing life .
What happens to automobile wheel bearing damage
When one of the four wheel hub bearings of the vehicle is damaged, you will hear a continuous buzzing sound in the car while the car is moving. This sound ca n’t tell where it is coming from, and it feels like it is in the whole compartment. It's full of this hum, and the louder the faster the speed. Here's how to judge:
Method 1: Open the window to see if the sound comes from outside the car;
Method 2: After increasing the vehicle speed (when there is a large hum), set the gear to neutral to let the vehicle coast, and observe whether the noise comes from the engine. If the hum does not change during neutral, it is likely that the wheel bearings are defective;
Method 3: Temporarily stop, get out of the car and check whether the temperature of the axles is normal. The method is: touch the four wheels separately with your hands, and roughly feel whether their temperatures are consistent. If there is a gap, the front wheel must be higher), if you do n’t feel the difference, you can continue to drive slowly to the pit;
Method 4: Use a lifter to lift the car (previously release the handbrake and suspend the neutral gear). When there is no lifter, you can use a jack to raise the wheels one by one. The human power quickly turns the four wheels. The sound is completely different from other axles. With this method, it is easy to tell which axle is the problem.
If you encounter serious damage to the hub bearing, it has cracks, pits or ablation, and it must be replaced. Lubricate before installing new bearings, and then reinstall in the reverse order. After replacement, the bearings must be flexible and free of debris and vibration.