Electrical Pitting Damage Results in damage to the

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.