Views: 25 Author: Site Editor Publish Time: 2020-05-18 Origin: Site
When we tall about bearings, it may have many different kinds, such as rod end joint bearing, spherical plain bearings, etc. There are dozens of kinds of cylindrical roller bearings on automobiles. The large and small bearings include almost all common bearing types. The collision and damage of cylindrical roller bearings are also common. Because cylindrical bearings are generally installed inside the mechanism, it is inconvenient to visually inspect, and only rough judgments can be made based on the failure phenomenon before disassembly and inspection.
The proper use of cylindrical roller bearings is a reliable guarantee for reducing bearing failure and extending bearing life, and its contents include correct installation and reasonable lubrication. The following describes the requirements and common faults and damages of cylindrical roller bearings.
1) Disassembly and assembly of bearings
The bearings should be cleaned before installation. During installation, special tools should be used to press the auxiliary bearing straight and evenly. Do not hit it with a hand hammer. It is especially prohibited to hit directly on the bearing. When the bearing race is loose with the seat hole, the seat hole should be repaired or the bearing should be replaced. Do not use pitting or copper padding on the bearing mating surface to force it. When disassembling the roller bearing, use a suitable puller to pull the bearing out. Do not hit the bearing with a chisel, hand hammer, etc.
2) Bearing lubrication
Lubricating oil and greases are commonly used as lubricants for cylindrical roller bearings. When the peripheral speed of the shaft is less than 4-5m/s, or the parts of the automobile cannot be lubricated with lubricating oil, it can be lubricated with grease. The advantage of grease lubrication is that the sealing structure is simple, the grease is not easy to lose, and it is not affected by temperature. It can be used for a long time by adding grease once.
Pay attention to two problems when using grease. One is to choose the appropriate grade of grease according to the requirements of the automotive manual. For example, nano-grease is not suitable for automotive water pump bearings because of its poor water resistance. Second, the amount of grease added to the bearing should be appropriate, and generally only 1/2-1/3 of the bearing cavity is appropriate. Too much is not only useless, but also increases the running resistance of the bearing, which causes it to heat up and generate heat. Special attention should be paid to automotive wheel bearings. "Empty hub lubrication" should be promoted, that is, only a layer of appropriate grease should be applied to the bearings. Otherwise, it not only wastes but also causes poor heat dissipation, which may affecting braking performance.
The advantage of lubricating oil is that the friction resistance is small and it can dissipate heat. It is mainly used for bearings with high speed and high working environment temperature. The grade of lubricating oil should be selected according to the requirements of the automotive manual, and should be replaced in time after the car maintenance cycle. After the old oil is discharged, the mechanism should be cleaned and then refilled with new oil, depending on the specific structure and requirements of the automotive.
Cylindrical roller bearings generally show two kinds of failures. One is that the temperature of the bearing installation part is too high, and the other is that there is noise during the bearing operation.
1) The temperature of the bearing installation part is too high
When the mechanism is running, the part where the bearing is installed is allowed to have a certain temperature. When touching the housing of the mechanism with your hand, it should be normal to not feel hot, otherwise the bearing temperature is too high.
The reasons for the high temperature of the bearing are: the quality of the lubricant does not meet the requirements or deterioration, the viscosity of the lubricant is too high. The mechanism assembly is too tight (lack of clearance). The bearing assembly is too tight. The bearing race is rotating on the shaft or in the housing. The load is too large. The bearing brackets or rolling elements are broken.
2) There is noise during the bearing operation.
Cylindrical bearing are allowed to have a slight running sound during operation. If the sound is too loud or there is abnormal noise, it indicates that the bearing is faulty. The causes of noise produced by cylindrical roller bearings are more complicated. One is that the matching surfaces of the inner and outer rings of the bearings are worn. Due to this wear, the cooperation relationship between the bearing and the housing, and the bearing and the shaft is destroyed, causing the axis to deviate from the correct position, and an abnormal noise is generated when the shaft moves at high speed. When the bearing is fatigued, the surface metal peels off, which will also increase the radial clearance of the bearing and generate abnormal noise. In addition, insufficient lubrication of the bearing, the formation of dry friction, and broken bearings will produce abnormal sounds. After the bearings are worn and loose, the bracket will be loose and damaged, and abnormal noise will also occur.