- Contact fatigue damage occurring before the expected service life may be primary or secondary damage
- Primary premature contact fatigue results from adverse or unaccounted for running conditions
- Secondary premature contact fatigue results from crack initiation and propagation from surface damage
- Heavier loads than expected
- Excessive preloading or loss of clearance due to incorrect fits or thermal expansion
- Surface damage and geometrical nonconformities (roundness/taper) of housing or shaft seats
- Shaft/housing deflection under load
- Changes in contact geometry resulting from wear
- Surface Damage
- Handling and Installation damage – denting, smearing
- Corrosion – acid etching, rust
- Fine grain spalling (micropitting) due to marginal lubrication
- Impact damage (brinelling)
- Vibration damage (false brinelling)
- Electrical current damage
Contact fatigue spalling on a cone raceway resulting from edge loading due to misalignment and heavy loading.
Contact fatigue spalling on a cylindrical inner race resulting from isolated surface damage.
Contact fatigue spalling on a cylindrical outer race resulting from surface corrosion.
Contact fatigue spalling on a cylindrical outer race resulting from misalignment.
Contact fatigue spalling on a cone raceway resulting from impact damage (brinelling).
Contact fatigue spalling at surface distress (micropitting) resulting from marginal lubrication.