1. Electrical Pitting Damage
Results in damage to the bearing by intermittent arcing of electrical current as a result of voltage discharge across the oil film.
The shaft and runner are usually effected as well.

2. Electrical Pitting Damage
Electrical pits in a journal shell in the minimum film area.

3. Electrical Pitting Damage
The shaft from the previous slide’s journal.

4. Electrical Pitting Damage
“Frosting” due to stray currents on a shaft.

5. Electrical Pitting Damage
Erosion of babbitt by electrical pitting.
Note the angle of attack as the minimum film areas are affected first.

6. Electrical Pitting Damage
More electrical pitting and similar angle of attack as previous slide.

7. Electrical Pitting Damage
This shoe has both loss of babbitt due to electrical pitting and oil deposits.
Note attack angle.

8. Electrical Pitting Damage
Heavy pitting and scoring damage in a gearbox journal shell.
The load pad on this 4-lobe bearing is effected.

9. Electrical Pitting Damage
The shaft from the previous slide.

10. Electrical Pitting Damage
Stray shaft currents on Kingsbury’s turbine driven test rig.
Note the shoes were crowned.

11. Electrical Pitting Damage
This damage was caused by welding. A large current was sent through the shoe and collar.

12. Abrasion
Scratches caused by dirt and contaminants that enter the lube system.
The particles must be small enough to enter the leading edge, by large enough to get caught before exiting the trailing edge.

13. Abrasion Scoring of thrust pad by dirt in oil.
Note that the scratches follow the collars circular path.