Clutch release bearing is an important part of the car. If the maintenance is not good, it will not only cause economic loss, but also a very difficult disassembly and assembly, which will take a lot of time. Therefore, it is of great significance to find out the causes of the failure of clutch separation bearing and to maintain and maintain reasonably in use, which is of great significance to extend the life of the separation bearing, improve the labor productivity and obtain better economic benefits.
The clutch release bearing is installed between the clutch and the transmission. The release bearing seat is loosely sheathed on the tubular extension of the bearing cover of the first shaft of the transmission. Through the return spring, the shoulder of the release bearing is always against the release fork and retreats to the final position, maintaining a clearance of about 3 ~ 4mm with the end of the release lever (release finger).
Since the clutch pressure plate and release lever operate synchronously with the engine crankshaft, and the release fork can only move along the axial direction of the clutch output shaft, it is obviously not feasible to use the release fork to shift the release lever directly. Through the release bearing, the release lever can rotate and move along the axial direction of the clutch output shaft, so as to ensure the smooth engagement of the clutch, soft separation and reduce wear, Extend the service life of clutch and the whole transmission system.
The clutch release bearing shall move flexibly without sharp noise or sticking. The axial clearance shall not exceed 0.60mm and the wear of inner race shall not exceed 0.30mm.
If the clutch release bearing fails to meet the above requirements, it will be regarded as a failure. In case of failure, it is necessary to determine which phenomenon belongs to the damage of release bearing. After the engine starts, gently step on the clutch pedal. When the free stroke is eliminated, the "rustle" or "squeak" sound will appear. Continue to step on the clutch pedal. If the sound disappears, it is not the problem of release bearing. If there is still a sound, it is the problem of release bearing.
When checking, you can remove the clutch bottom cover, and then step down a little accelerator pedal to slightly increase the engine speed. If the sound increases, you can observe whether there is Mars. If there is spark, it means that the clutch release bearing is damaged. If the Mars is in the shape of one by one, it means that the release bearing ball is broken. If there is no spark, but there is a sound of metal breakage, it indicates excessive wear.
In the process of use, it is affected by axial load, impact load and radial centrifugal force when rotating at high speed. In addition, because the thrust of the fork and the reaction force of the separation lever are not in the same line, it also forms torsional torque. The clutch release bearing has poor working conditions, intermittent high-speed rotation and high-speed friction, high temperature, poor lubrication conditions and no cooling conditions.
The damage of clutch release bearing is closely related to the driver's operation, maintenance and adjustment
1) Overheating occurs when the working temperature is too high
When many drivers are turning or decelerating, they often step on the clutch half way, and some of them put their feet on the clutch pedal when they are in gear; Some vehicles' free stroke adjustment is too large, so that the clutch is not completely separated, and it is in the state of half engagement and half separation. This state causes dry friction and produces a lot of heat transfer to the release bearing. When the bearing heat reaches a certain temperature, the butter melts or dilutes, which further increases the temperature of the release bearing. When the temperature reaches a certain degree, it will burn out.
2) Wear due to lack of lubricating oil
The clutch release bearing is lubricated with grease. There are two ways to add grease. For the 360111 release bearing, the rear cover of the bearing should be opened and filled with grease during maintenance or removal of the transmission, and then the rear cover should be reassembled; For 788611k release bearing, it can be disassembled, dipped in molten grease, cooled and taken out to achieve the purpose of lubrication. In practical work, the driver is easy to ignore this point, resulting in the clutch release bearing oil shortage. In the case of no lubrication or less lubrication, the wear amount of release bearing is often several times to dozens of times of that after lubrication. With the increase of wear, the temperature will also be greatly increased, which makes it easier to damage.
3) Too small free stroke or too many loads
According to the requirements, the clearance between the clutch release bearing and release lever is generally 2.5mm, which reflects that the free stroke on the clutch pedal is 30-40mm. If the free stroke is too small or there is no free stroke at all, the release lever and release bearing will be in a constant engagement state. According to the principle of fatigue damage, the longer the bearing working time is, the more serious the damage is; The more loading times, the easier the release bearing fatigue failure. And the longer the working time is, the higher the temperature of the bearing is, the easier it is to burn, which reduces the service life of the release bearing.
4) In addition to the above three reasons, whether the release lever is adjusted smoothly and whether the return spring of the release bearing is good also has a great influence on the damage of the release bearing.
1) According to the operation regulations, avoid the clutch in half engaged and semi separated state and reduce the number of clutch usage.
2) Pay attention to maintenance. During regular or annual inspection and maintenance, use cooking method to soak butter to make it full of lubricant.
3) Pay attention to leveling the clutch release lever to ensure the spring spring spring conforms to the regulations.
4) Adjust the free travel to meet the requirements (30-40mm), and prevent the free travel from being too large or too small.
5) Try to reduce the number of joints and separation, and reduce the impact load.
6) Step on and relax gently to make it join and separate smoothly.