With the development of automobile technology, the design, manufacture, test and application technology of automobile bearings have made great progress. However, from the perspective of application, the development of automotive bearings can be summarized as the expansion of general-purpose bearings, the development of special bearings, and the improvement of bearing performance and its life.
(1) Expanded application of general bearings
The improvement of automobile structure and the diversification of automobile design and bearing design have led to the expansion of the application range of general bearings.
So far, general-purpose bearings directly used in automobiles have covered almost all basic structural types, more and more series and more and more specifications of general-purpose bearings have been directly applied in the area, which has led to some new general bearing series and special bearings.
(2) The development of special bearings
On the basis of general bearings, some automotive special bearings have gradually developed structural and functional features that are not available in traditional rolling bearings and are closely related to automotive applications. Among these automotive bearings, the expansion of the structure and function of wheel hub bearings and clutch release bearings has attracted the most attention.
1. The earliest wheel hub bearing
The earliest used wheel hub bearings consist of two sets of single-row radial ball bearings or tapered roller bearings. The disadvantage is that installation and maintenance need to be filled with grease and adjust the clearance. The type and amount of grease are improper or not clean enough and the clearance adjustment is improper. It often brings serious consequences that the life of the bearing is greatly reduced.
The improvement of the hub bearing composed of two sets of single row bearings leads to the use of sealed double row bearings with pre-adjusted clearance. The clearance of this bearing has been adjusted correctly during manufacture, and the sealing and lubrication of the bearing itself can be free of installation. When the dirt enters and the type and amount of grease are wrong. This kind of hub bearing with extended lubrication, sealing and clearance adjustment functions is called the first-generation hub bearing.
The outer ring of the first-generation hub bearing is provided with a flange to form the second-generation hub bearing. The expansion of the structure and function of the hub bearing greatly simplifies the support structure of the hub, reduces the amount of hub parts required, and the installation becomes simpler and easier. The third-generation hub bearing produced by the further expansion of the structure and function of the hub bearing has both bearings. The function of itself, the short shaft and the ordinary wheel hub, the inner ring flange is used to support the wheel and the brake disc, and the outer ring flange is used to connect the suspension device. This kind of bearing assembly not only has many technical advantages such as simplifying the design of automobile wheels and suspension devices, reducing the volume, simplifying assembly, easy handling, and extremely small possibility of installation errors, etc., it also effectively reduces the cost of automobile components. cost.
At present, the expansion of structure and function has enabled the wheel hub bearing to develop to the fourth generation integrated with the constant velocity universal joint, so that the technical performance and economic effect of the wheel hub bearing have reached a new level.
The main function of the hub bearing is to support the load and provide precise guidance for the rotation of the hub. It bears both axial load and radial load, and is a very important component.
Traditional automobile 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 all carried out on the automobile production line. This structure makes it difficult to assemble in automobile production plants, high cost, and poor reliability, and the bearings need to be cleaned, oiled and adjusted when the automobile is maintained at the repair point. The hub bearing unit is developed on the basis of standard angular contact ball bearings and tapered roller bearings. It combines two sets of bearings as a whole. It has good assembly performance, can omit clearance adjustment, light weight, compact structure, and load capacity. Large, sealed bearings can be pre-loaded with grease, omit external wheel hub seals and avoid maintenance. They have been widely used in cars, and there is a trend to gradually expand their applications in trucks.
2. Installation and use of automobile wheel bearings
In the past, single-row tapered roller or ball bearings were used in pairs for the most common wheel hub bearings for cars. With the development of technology, car hub units have been widely used in cars. The use range and usage of wheel 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, and the bearing can be simply sleeved on the axle and fixed with a nut. Makes the maintenance of the car easier. The third-generation wheel hub bearing unit uses the bearing unit to cooperate with the 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, and the outer flange installs the entire bearing together. Worn or damaged hub bearings or hub units will cause inappropriate and costly failures of your vehicle on the road, and even cause damage to your safety.
3. Please pay attention to the following matters in the use and installation of hub bearings
1) In order to ensure maximum safety and reliability, it is recommended that you always check the hub bearings regardless of the age of the vehicle-pay attention to early warning signs of wear of the bearings: including any frictional noise during rotation or the suspension combination wheel turning deceleration abnormally
at times. For rear-wheel drive vehicles, it is recommended that the front wheel hub bearings should be lubricated when the vehicle has traveled to 38,000 kilometers. When replacing the brake system, check the bearing and replace the oil seal.
2) If you hear the noise from the hub bearing part, first of all, it is important to find the location of the noise. There are many moving parts that may produce noise, and it may also be that 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 front wheel hub causing the bearing failure on both sides are similar, even if only one bearing is broken, it is recommended to replace it in pairs.
4) Hub bearings are more sensitive, in any case, you need to use the right method and the right tools. In the process of storage, transportation and installation, the components of the bearing cannot be damaged. Some bearings require greater pressure to press in, so special tools are required. Be sure to refer to the automobile manufacturing manual.
5) The bearing should be installed in a clean and tidy environment. Small particles entering the bearing will also shorten the service life of the bearing. It is very important to maintain a clean environment when replacing bearings. It is not allowed to hit the bearing with a hammer, and 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 abrasion can lead to poor fit and cause early bearing failure.
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 sealing ring and the inner ring are damaged, causing permanent failure of the bearing.
7) There is a magnetic thrust ring in the sealing ring of the bearing equipped with ABS device. This thrust ring cannot be collided, impacted or collided with other magnetic fields. Take them out of the packaging box before installation and keep them away from magnetic fields, such as motors or power tools used. When installing these bearings, observe the ABS alarm pin on the instrument panel through a road condition test to change the operation of the bearing.
8) For wheel hub bearings equipped with ABS magnetic thrust ring, in order to determine which side the thrust ring is installed on, you can use a small object* near the edge of the bearing, and the magnetic force generated by the bearing will attract it. When installing, point the side with the magnetic thrust ring toward the inside, facing the sensitive component of ABS.
Note: Incorrect installation may result in failure of the brake system.
9) Many bearings are sealed. This type of bearing does not need to be greased throughout its life. Other non-sealed bearings, such as double-row tapered roller bearings, must be lubricated with grease during installation. Due to the different sizes of the inner cavity of the bearing, it is difficult to determine how much grease to add. The most important thing is to ensure that there is grease in the bearing. If there is too much grease, the excess grease will leak out when the bearing rotates. General experience: When installing, the total amount of grease should account for 50% of the bearing clearance.
10) When installing the lock nut, the size of the torque varies greatly due to the difference of the bearing type and the bearing seat.
4. Maintenance attention
During the maintenance process, some vehicles are often found to have loud driving noise. Check that the tires are not abnormally worn, and there is no obvious abnormal noise when turning the wheels on the lift. This phenomenon is often caused by abnormal damage to the hub bearing. The so-called abnormal refers to the bearing damage caused by installation. The front wheel bearings of automobiles are generally double row ball bearings. If you use a hammer to install the bearing when installing the bearing, or install the bearing by pressing the inner ring of the bearing when installing the bearing into the bearing housing, it will cause the raceway on one side of the bearing. damage. Noise is generated when the vehicle is driving, and when the wheels are off the ground, there is no obvious noise due to the better side of the raceway. Correct installation operation is the key to long bearing life.