Bearings are widely used in automobiles and assume important responsibilities. From the engine, the chassis to the electrical assembly, it is applied to the bearing. The bearings used in automobiles are divided into two categories: sliding bearings and rolling bearings.

Sliding bearings are mainly used on engines. Sliding bearings are usually divided into two types, one is a bush-type thin-walled bearing, which is similar to a tile, commonly known as a bearing bush; the other is a bushing, also known as a copper bushing, which is shaped like a hollow cylinder. The bush type thin-wall bearing is mainly used to support the engine crankshaft and connecting rod. Bushings are mainly used to support camshaft journals and piston pins, but are also used in other parts of the car, such as the steering knuckle kingpin bushings of the chassis, shock absorber steel plate pin bushings, gear bushings and motor bushings, etc. The role of friction reducing intermediates.

The crankshaft and connecting rod bearings seem to have a single tile structure, but their performance requirements are very high. Although the lubricating oil of the lubricating system separates the contact surface between the parts and the bearing, in recent years, with the continuous development of the engine to high speed and supercharging, the oil film pressure of the bearing increases, the thickness of the oil film decreases, and the working environment of the bearing deteriorates. And the material and manufacturing requirements of connecting rod bearings are also getting higher and higher. Generally, bearings are in the form of double-layer metal, and some are in the form of multiple layers. The first layer is steel backing to ensure mechanical strength, and the second layer is bearing alloy to ensure surface working performance. A material called babbitt is commonly used. ; The third layer is plated with a very thin alloy on the basis of the above two layers to further improve the surface performance.

Compared with the bearing bush, the working pressure of the camshaft bushing is relatively small. Its material is usually bronze or steel backed alloy. The bushing of this kind of material is also widely used in the king pin, brake shoes, door hinges. , seat belt reels, etc. There are many bushing materials used in automobiles, such as oil-impregnated metal bushings for starters and fans, bushings made of polymer materials for shock-absorbing steel plate pins and wipers, and so on.

Rolling bearings are widely used in various mechanical and electrical assemblies in automobiles. There are mainly transmission, steering gear, water pump, fan, clutch, differential, front and rear wheels and drive shaft.

There are two types of rolling bearings: spherical and roller. According to the size and direction of the load, they are divided into radial bearings and thrust bearings. The radial bearing is suitable for bearing radial (heavy and straight to the axis line) load, and the thrust bearing is suitable for bearing axial load. (parallel to the axis) load, there is also a radial thrust bearing that bears both radial and axial forces. In fact, almost all rolling bearings now can bear radial load and lateral load at the same time under certain conditions, but they only focus on which one or both. Rolling bearings are mainly divided into ball bearings, roller bearings and needle bearings, which are located in various parts of the car according to different functions.

Transmission shafts are generally supported at both ends. Because the transmission shaft is relatively long, the bearing on one side is usually taken as the fixed side bearing in the design, which bears both radial and axial loads and plays the role of relative axial displacement between the fixed shaft and the gearbox. Centripetal thrust ball bearings. The bearing on the other side is called the free side bearing, which only bears the radial load and can move relatively in the axial direction to solve the problem of expansion and contraction of the shaft caused by the temperature change during the operation of the transmission gear and the error during installation. column bearing.

The bearing rings and rolling elements of rolling bearings are generally made of high-purity special chromium alloy steel with high hardness. However, if the lubrication is poor, the selection is improper, and the installation is not good, it may cause failure. However, even if the bearing is used under normal conditions, the rolling surfaces of the internal elements will experience material fatigue under the influence of alternating compressive stress, and even peel off and become unusable, so the bearing has its life limit. According to the data provided by Japan's ntn, even if a group of the same bearing operates under the same conditions, its life is also very different. This is because the material fatigue itself has "discreteness". Therefore, the so-called basic rated life of a rolling bearing is the total number of revolutions or the total revolution time during which 90% (90% reliability) of rolling fatigue peeling does not occur when a group of identical bearings are operated under the same conditions. Bearings are like joints, and their quality is directly related to the running quality of the car. However, in mass-produced bearings, it is difficult to ensure that each bearing fully meets the average quality standard. It is not surprising that some new cars will have this or other failures in advance during use.