The clutch release bearing is installed between the clutch and the transmission. The release bearing seat is loosely sleeved on the tubular extension of the first shaft bearing cover of the transmission. The shoulder of the release bearing is always against the release fork through the return spring and retracts to the final position. , Keep a gap of about 3~4mm with the end of the separation lever (separation finger).
Since the clutch pressure plate, the release lever and the engine crankshaft operate synchronously, and the release fork can only move axially along the clutch output shaft, it is obviously impossible to directly use the release fork to dial the release lever. The release bearing can make the release lever rotate side by side. The output shaft of the clutch moves axially, which ensures that the clutch can engage smoothly, disengage softly, reduce wear, and extend the service life of the clutch and the entire drive train.
The clutch release bearing should move flexibly, without sharp noise or jamming, its axial clearance should not exceed 0.60mm, and the wear of the inner race should not exceed 0.30mm.
If the separator bearing of the commercial combiner fails to meet the above requirements, it is deemed to be malfunctioning. After a failure occurs, the first thing to judge is which phenomenon belongs to the damage of the release bearing. After the engine is started, lightly step on the clutch pedal. When the free stroke is just eliminated, the "rustling" sound that appears is the release of the bearing.
When checking, you can remove the clutch bottom cover, and then depress a little accelerator pedal to slightly increase the engine speed. If the noise increases, you can observe whether there are sparks. If there are sparks, it means that the clutch release bearing is damaged. If the sparks burst out one after another, it means that the release bearing ball is broken. If there is no spark, but there is a metal cracking sound, it means excessive wear.
1. Working conditions and forces of clutch release bearings
The release bearing is subjected to axial load, impact load, and radial centrifugal force during high-speed rotation. In addition, because the fork thrust and the reaction force of the release lever are not on the same straight line, a torsional moment is also formed. The clutch release bearing has poor working conditions, intermittently rotating at high speed and bearing high-speed friction, high temperature, poor lubrication conditions, and no cooling conditions.
2. Causes of damage to the clutch release bearing
The damage of the clutch release bearing has a lot to do with the operation, maintenance and adjustment of the driver. The reasons for the damage are roughly as follows:
1) The working temperature is too high to cause overheating
Many drivers often half-depress the clutch when turning or decelerating, and some have their feet on the clutch pedal after shifting; some vehicles have too much adjustment of the free stroke, which makes the clutch disengagement incomplete and in a semi-engaged and semi-disengaged state. A large amount of heat generated by dry friction is transferred to the release bearing. The bearing is heated to a certain temperature, and the butter melts or dilutes and flows, which further increases the temperature of the release bearing. When the temperature reaches a certain level, it will burn out.
2) Lack of lubricating oil and wear
The clutch release bearing is lubricated with grease. There are two ways to add grease. For the 360111 release bearing, open the back cover of the bearing and fill in the grease during maintenance or when the transmission is removed, and then reinstall the back cover. Just close; for the 788611K release bearing, it can be disassembled and immersed in molten grease, and then taken out after cooling to achieve the purpose of lubrication. In actual work, the driver tends to ignore this point, causing the clutch release bearing to run out of oil. In the case of no lubrication or less lubrication, the amount of wear of the release bearing is often several to several tens of times the amount of wear after lubrication. As the wear increases, the temperature will also be greatly increased, so that it is more vulnerable to damage.
3) The free stroke is too small or the number of loads is too much
According to the requirements, the clearance between the clutch release bearing and the release lever is 2.5mm. The free stroke reflected on the clutch pedal is 30-40mm. If the free stroke is too small or there is no free stroke at all, it will cause the separation lever to interact with each other. The release bearing is in a normally engaged state. According to the principle of fatigue failure, the longer the working time of the bearing, the more serious the damage; the more times the bearing is loaded, the easier it is for the release bearing to produce fatigue damage. Moreover, the longer the working time, the higher the temperature of the bearing, 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 release bearing return spring is good, also has a great influence on the damage of the release bearing.
1) In accordance with the operating regulations, avoid the clutch half-engaged and half-disengaged and reduce the number of times the clutch is used.
2) Pay attention to maintenance. Regularly or during annual inspection and maintenance, use the steaming method to soak the butter so that it has sufficient lubricant.
3) Pay attention to leveling the clutch release lever to ensure that the spring force of the return spring meets the requirements.
4) Adjust the free stroke to meet the requirements (30-40mm) to prevent the free stroke from being too large or too small.
5) Minimize the number of engagements and separations, and reduce impact load.
6) Step on lightly and easily to make it join and separate smoothly.
|BEARING NO.||Inner Dia.||Outer Dia.||High|
|BEARING NO.||Inner Dia.||Outer Dia.||High C||High B|