1. Tapered Roller Bearings Facts & Failures

2. Standard Terms for Tapered Roller Bearings
Roller Cage
Inner Race

3. Standard Terms for Tapered Roller Bearings
D. Outer Race

4. Tapered Bearing Loading Patterns
Normal loading. When the bearings are installed properly, with the correct bearing pre-load, the load pattern will be symetrical (blue area).
Improper loading. Overtightening the adjusting nut, or not seating the bearing properly, causes a shift in the load pattern on the bearing surfaces.

5. Improper Bearing Adjustment
If larger end of roller shows smearing, spalling or galling, bearing adjustment is too tight.
Spalling - when the surface breaks up into chips or fragments.
Galling - when the surface is broken by friction or abrasion

6. Improper Bearing Adjustment
If the end of the roller is spalled, the roller has been running against the inner ring.
The inner ring has flanges on each edge to keep the rollers in line. If the bearing is overloaded (tightened too hard) during adjustment, the edges of the rollers will ride against the flange, producing the wear you see here.

7. Improper Bearing Adjustment
If you see wear, smearing or spalling, on the small end of the roller, it indicates that the bearing adjustment is too loose.

8. Improper Bearing Adjustment
When the race is worn, it indicates that the bearing may have been overloaded.

9. Misalignment
When bearings are in proper alignment their center lines are parallel to each other.

10. Misalignment
If the bearings are not seated properly their center lines will be at an angle to each other.
Causes of cocked bearings:
dirt or burrs preventing a flush mount
outer cup installed without proper tools
a warped shaft

11. Effects of Contamination
Scratch marks in the surface of the race are caused by hard particles in the lubricant.

12. Effects of Contamination
Etched metal surfaces are usually the result of water contamination.
The water allows oxidation and the metal becomes pitted and porous.

13. Effects of Contamination - rollers
Scoring around the rollers indicates contamination of the lubricant by dirt, girt or metal particles.

14. Effects of Improper Lubrication
When metal appears to be flaking off across the full surface of the race, suspect there is a lack of proper lubrication.

15. Effects of Improper Lubrication
Discolored steel anywhere, on the cup, cone or roller, indicates overheating.

16. Installation Damage
The rib of this cage design has been bent out of round. Even small distortions of the assembly can destroy a bearing.

17. Installation Damage
Nicks and dents. Damage like this dent in the cage or retainer is the result of a sharp tool being used to install or seat the bearing. A drift or screwdriver used on a bearing is guaranteed damage.

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Credits………
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