Function of the automotive separation bearing
The automobile clutch release bearing (Automobile clutch release bearing) is a key component of the automotive transmission system. It is installed between the clutch and the transmission, and through the coordinated rotation and axial movement of the release lever, it enables the smooth engagement and disengagement of the clutch, reducing wear and extending the service life of the transmission system. Its structure is loose and mounted on the bearing cap of the first shaft of the transmission, relying on the return spring to maintain the gap with the end of the release lever, ensuring stability in operation.
This bearing must meet the technical standards of an axial clearance of ≤ 0.60mm and an internal raceway wear of ≤ 0.30mm. Faults often manifest as abnormal noises or stalling, mainly caused by insufficient lubrication, frequent semi-release operations, or improper adjustment of the free travel. Maintenance requires regular lubrication with lithium-based grease, adjustment of the flatness of the release lever, and control of the free travel within the range of 30-40mm. Relevant specifications can refer to "JB/T5312-2001 Automobile Clutch Release Bearing and Its Unit".
If the clutch release bearing does not meet the above requirements, it is considered to be faulty. Faults often manifest as abnormal noises or stalling. The main causes are insufficient lubrication, frequent semi-release operations, or improper adjustment of the free travel. Maintenance should be carried out regularly by using lithium-based grease for lubrication, adjusting the flatness of the release lever, and controlling the free travel within the range of 30-40mm. Relevant specifications can refer to "JB/T5312-2001 Automobile Clutch Release Bearing and Its Unit".
If the clutch release bearing fails to meet the above requirements, it is considered to be faulty. After a fault occurs, the first step is to determine which phenomenon belongs to the damage of the clutch release bearing. After the engine starts, lightly press the clutch pedal. When the free travel is just eliminated, a "squeaking" or "clicking" sound occurs. Continuing to press the clutch pedal, if the sound disappears, it is not a problem with the clutch release bearing. If there is still a sound, it is the clutch release bearing that is faulty.
During inspection, the clutch base cover can be removed, and then slightly step on the accelerator pedal, slightly increase the engine speed. If the sound increases, observe for any sparks. If there are sparks in bursts, it indicates that the clutch release bearing is damaged. If the sparks flow out in a continuous manner, it indicates that the clutch release bearing balls have broken. If there are no sparks but a metallic cracking sound occurs, it indicates excessive wear.
Working conditions
Clutch release bearing
During use, it is subjected to axial load, impact load, and radial centrifugal force at high speed. In addition, due to the thrust of the shift fork and the reaction force of the release lever not being on the same straight line, a torsional moment is also formed. The working conditions of the clutch release bearing are poor, with intermittent high-speed rotation and high-speed friction, high temperature, poor lubrication conditions, and no cooling conditions.
Damage causes
The damage of the clutch release bearing is closely related to the driver's operation and maintenance, as well as adjustment. The causes of damage are roughly as follows:
Excessive working temperature leads to overheating
Many drivers often half-engage the clutch when turning or decelerating, and some shift gears and still keep their foot on the clutch pedal; some vehicles have excessive free travel, causing the clutch to not disengage completely and being in a semi-engaged and semi-disengaged state. This state causes dry friction and generates a large amount of heat that transfers to the clutch release bearing, causing the bearing to reach a certain temperature, with the grease melting or being diluted and flowing, further increasing the temperature of the clutch release bearing. When the temperature reaches a certain level, it burns out.
Lack of lubricating oil leads to wear
The clutch release bearing is lubricated with grease. There are two methods of adding grease: for the 360111 clutch release bearing, the rear cover of the bearing should be opened and grease filled during maintenance or when the transmission is disassembled, and then the rear cover should be reassembled; for the 788611K clutch release bearing, it can be removed and immersed in melted grease, cooled, and then taken out to achieve lubrication. In practical work, drivers often overlook this point, resulting in the clutch release bearing lacking lubricating oil. In the absence of lubrication or with insufficient lubrication, the wear of the clutch release bearing is often several times to dozens of times that of the lubricated condition. The increase in wear will also cause a significant increase in temperature, making it more prone to damage.
Too small free travel or excessive loading times
According to the requirements, a gap of 2.5mm between the separation bearing of the clutch and the separation lever is considered to be the most appropriate. This corresponds to a free travel of 30-40mm on the clutch pedal. If the free travel is too small or there is no free travel at all, the separation lever and the separation bearing will remain in a constantly engaged state. According to the principle of fatigue failure, the longer the working time of the bearing, the more severe the damage will be; the more times it is loaded, the easier the separation bearing is to suffer from fatigue failure. Moreover, the longer the working time, the higher the temperature of the bearing will be, making it more prone to burning out, thereby reducing the service life of the separation bearing.
In addition to these three reasons, whether the adjustment of the separation lever is smooth, and whether the return spring of the separation bearing is in good condition, also have a significant impact on the damage of the separation bearing.
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