Contact fatigue failure refers to the failure of the working surface of a bearing under the action of alternating stress. Contact fatigue peeling occurs on the working surface of forklift bearings, often accompanied by fatigue cracks. It first occurs at the maximum alternating shear stress below the contact surface, and then extends to the surface to form different peeling shapes, such as pitting or pitting peeling, and peeling into small flakes is called shallow peeling. Due to the gradual expansion of the peeling surface, it often extends towards deeper layers, forming deep peeling. Deep peeling is the fatigue source of contact fatigue failure.

Wear failure refers to the failure caused by the relative sliding friction between surfaces, resulting in continuous wear of the metal on the working surface. Continuous wear will cause gradual damage to bearing components, ultimately leading to loss of dimensional accuracy of forklift bearings and other related issues. Wear may affect shape changes, increase fitting clearances, and alter the morphology of the working surface, which may affect the lubricant or cause contamination to a certain extent, resulting in complete loss of lubrication function and loss of rotational accuracy and even inability to operate normally.

1. When the bearings run for a certain period of time (or maintenance period), remove all bearings;

2. Soak the bearings in diesel or kerosene for cleaning, and if there are technical conditions, it is best to open the sealing cover for cleaning;

3. After cleaning, dry the oil and inspect the appearance for any damage;

4. Use a wooden rod (preferably a hollow tube) with a diameter of approximately 150mm and equal to the inner diameter of the bearing, and fix one end of the bearing;

5. While quickly rotating the bearing by hand, place the other end of the wooden stick (tube) against the ear or audio amplifier microphone to listen for bearing rotation noise;

6. After fixing the bearing, move the wooden rod horizontally to check whether the bearing is worn or loose;

7. Forklift bearings with severe looseness, excessive rotational noise, and serious defects should be eliminated and replaced with the same model;

8. Take a bucket and melt an appropriate amount of lubricating grease (high-quality yellow dry oil) over low heat (do not overheat). Soak the tested bearings in the bucket until no bubbles overflow.

Remove the bearing before cooling the lubricating grease, as there is less residual lubricating grease. After cooling the lubricating grease, remove the bearing and there is a large amount of residual lubricating grease. Determine the amount of lubricating grease residue as needed.

9. Use a soft cloth or toilet paper to wipe off the lubricating grease on the outside of the bearings and assemble the forklift bearings onto the pulleys in their original state. The maintenance work is now complete.