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.

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

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

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

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

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

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

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

Electrical Pitting Damage The shaft from the previous slide.

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

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

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.

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