Consider the following factors when diagnosing bearing condition:
• | General condition of all parts during disassembly and inspection. |
• | Classify the failure with the aid of the illustrations. |
• | Determine the cause. |
• | Make all repairs following recommended procedures. |
The pattern on the races and the rollers is caused by fine abrasives.
The pattern on the roller ends is caused by fine abrasives.
The metal smears on the roller ends are due to overheating, lubricant failure, or lubricant overload.
The bearing surfaces appear gray or grayish black in color, with related etching away of material usually at roller spacing.
When a cage is damaged due to improper handling or improper tool usage.
Replace the bearing.
The cage may be damaged due to improper handling or improper tool usage. Replace the bearing.
The wear around the outside diameter of the cage and the roller pockets is caused by abrasive material or inefficient lubrication.
The surface depressions on the race and the rollers are caused by hard particles of foreign matter.
The corrosion caused by small relative movement of parts with no lubrication.
The smearing of the metal is due to slippage. Slippage can be caused by the following factors:
• | Poor fits |
• | Lubrication |
• | Overheating |
• | Overloads |
• | Handling damage |
If this condition occurs, perform the following:
The discoloration on the bearings is caused by incorrect lubrication or moisture and ranges in color from light brown to black. Reuse the bearing if you can remove the stains with light polishing and there is no evidence of overheating. Check the seals and the related parts for damage.
The discoloration on the bearings ranges from faint yellow to dark blue and results from overload or an incorrect lubricant. Excessive heat causes softening of the races or the rollers. In order to check for loss of temper on the races and the rollers, perform a file test. A file drawn over a tempered part will grab and cut the metal and fail the file test. A file drawn over a hard part will glide readily with no metal cutting.
If overheating damage is indicated, perform the following:
The outer race is misaligned due to a foreign object.
The race is cracked due to improper fit, cocking, or poor bearing seats.
The surface is flaked with metal due to bearing fatigue.
The surface indentations in the race way are caused by the rollers under impact loading or from vibration while the bearing is not rotating. Replace a rough or noisy bearing.