There are dozens of kinds of bearings on the car are rolling bearings, which almost include all the common bearing types, and the collision and damage of rolling bearings are also more common. Because the rolling bearing is generally installed in the mechanism, so it is not convenient for intuitive inspection, can only make a brief judgment according to the fault phenomenon, and then disassemble and check. The correct use of rolling bearings is a reliable guarantee to reduce bearing failure and extend bearing life, which includes correct installation and reasonable lubrication.

The use requirements and common faults and damages of rolling bearings are introduced below.

First, the correct use of rolling bearings

1. Bearing disassembly bearings should be cleaned before installation. When installing, special tools should be used to press the auxiliary flat and straight into the machine evenly. Do not knock with a hand hammer, especially do not knock directly on the bearing. When the bearing seat ring is loose with the seat hole, the seat hole should be repaired or the bearing should be replaced. Do not use the method of making pitting or copper pad on the bearing mating surface. When the bearing is disassembled, the appropriate puller should be used to pull out the bearing, and the bearing should not be knocked with chisel or hand hammer.

2. Lubrication of bearings There are two kinds of lubricants commonly used in rolling bearings: lubricating oil and grease. When the circular speed of the shaft is less than 4-5m/s, or the parts of the car that cannot be lubricated with lubricating oil, grease lubrication is used. The advantage of grease lubrication is that the sealing structure is simple, the grease is not easy to lose, is not affected by the temperature, and the grease can be used for a long time. The use of grease should pay attention to two problems, one is to choose the right grade of grease according to the requirements of the automobile manual. For example, automobile water pump bearings should not be selected naki grease, because of its poor water resistance. Second, the grease added to the bearing should be appropriate, generally only filling 1/2-l/3 of the bearing cavity is appropriate, too much is not only useless, but also will increase the running resistance of the bearing, so that it will heat up. Special attention should be paid to automobile hub bearings. "Empty hub lubrication" should be advocated, that is, only an appropriate layer of grease can be coated on the bearings. Otherwise, it will not only waste and poor heat dissipation, but also make the grease heat spill, which may affect the braking performance. The advantages of lubricating oil lubrication are small friction resistance, and can dissipate heat. It is mainly used for bearings with high speed and high working temperature. The brand of lubricating oil should be selected according to the requirements of the car manual, and the car maintenance cycle should be replaced in time. After the release of the old oil, the mechanism should be cleaned and then the new oil is added. The oil should be added to the specified line, or even with the refueling mouth (depending on the specific structure and requirements of the car), and can not be added.

The fault phenomenon of rolling bearings is generally manifested in two kinds, one is that the temperature of the bearing installation part is too high, the other is that there is noise in the bearing operation.

1. The bearing temperature is too high. When the mechanism is running, the installation part of the bearing is allowed to have a certain temperature. The reasons for the high temperature of the bearing are: the quality of the lubricating oil does not meet the requirements or deterioration, the viscosity of the lubricating oil is too high; The mechanism assembly is too tight (insufficient clearance); Bearing assembly is too tight; The bearing seat ring rotates on the shaft or in the shell; Excessive load; Bearing cage or rolling body fracture, etc.

2. Bearing noise Rolling bearings are allowed to have slight running sound during work. If the sound is too large or there is abnormal noise or crash, it indicates that the bearing is faulty. The reasons for the noise of rolling bearings are more complex, one is the wear of the inner and outer rings of bearings with the surface. Due to this wear, the fit relationship between bearings and housing, bearings and shaft is damaged, leading to the axis deviated from the correct position, and abnormal sound is generated when the shaft moves at high speed. When the bearing is tired, the surface metal spalling will also increase the radial clearance of the bearing and produce abnormal sound. In addition, insufficient bearing lubrication, the formation of dry friction, and bearing breakage will produce abnormal sound. After the bearing is worn loose, the cage is loose and damaged, and there will be abnormal sound.

When disassembling and checking rolling bearings, the failure and damage causes of bearings can be judged according to the damage situation of bearings.

1. The rolling body of metal spalling bearing on raceway surface and the raceway surfaces of inner and outer rings are subjected to periodic pulsating loads, resulting in periodically varying contact stress. When the number of stress cycles reaches a certain value, fatigue spalling will occur on the working surface of the rolling body or the inner and outer ring raceway. If the load of the bearing is too large, this fatigue will be aggravated. In addition, bearing installation is not straight, shaft bending, will also produce raceway spalling phenomenon. Fatigue spalling of bearing raceway will reduce the running accuracy of shaft and cause vibration and noise of the mechanism.

2. Bearing burns Burned bearings have reignition color on their raceways and rolling bodies. The causes of burns are generally insufficient lubrication, lubricating oil quality does not meet the requirements or deterioration, and bearing assembly is too tight.

3. Uneven pits appear on the contact surface between raceway and roller of the plastic deformation bearing, indicating that the bearing has plastic deformation. The reason is that under the action of a large static load or impact load, the local stress on the working surface exceeds the yield limit of the material, which generally occurs on the bearings of low speed rotation.

4. Bearing ring crack The causes of bearing ring crack may be too tight bearing fit, bearing foreign or inner ring loosening, bearing inclusion deformation, mounting bearing surface machining is poor, etc.

5. The reason for cage breakage is insufficient lubrication, rolling body breakage, seat ring skew, etc.

6. The possible reason for the metal adhesion of the cage to the rolling body is that the rolling body is stuck in the cage or has insufficient lubrication.

7. Serious wear of the raceway of the seat ring may be caused by foreign bodies falling into the seat ring, insufficient lubricating oil or improper lubricating oil grade