Damage Caused by Faulty Assembly
Under this heading are included:
- Fretting damage due to inadequate interference fit in flimsy housing.
- Excessive interference fit causing bearing bore distortion.
- Effect of joint face stagger or absence of joint face relief in bearing causing overheating and damage in region of bearing split.
- Fouling at crankshaft fillets due to incorrect shaft radii.
- Misalignment or shaft deflection causing uneven wear of bearing.
- Entrapment of foreign matter between bearing and housing during assembly causing bearing bore distortion and localised overheating.
- Effect of grinding shaft in wrong direction.
JOURNAL BEARINGS
Fig. 6 Fretting between back of bearing and housing due to inadequate interference fit. Could also be due to flimsy housing design
Fig. 7 Overheating and fatigue at joint faces due to excessive interference fit causing bearing bore distortion. Could also be caused by joint face stagger on assembly or flimsy housing
Fig. 8 Fretting at joint faces of connection rod due to inadequate bolt tension.
Fig. 9 Uneven wear of overlay plated bearing due to misalignment.
Fig. 10 Fouling between shaft radius and end of bearing, causing overheating.
Fig. 11 Severe scoring of whitemetal-lined compressor bearing, due to wrong direction of shaft grinding.
Fig. 12 Back of tin aluminium bearing showing “flat” on steel shell caused by swarf entrapped between shell and housing.
Fig. 13 Bore of bearing shown in Fig. 12. Entrapped swarf has deformed bearing bore resulting in flexure and fatigue damage.
Fig. 14 Angular misalignment of shaft or housing, or dirt trapped behind carrier ring, causing damage to pads on one side only.
RECOMMENDED ACTION
Investigate and if necessary
correct interference conditions
and housing design.
Correct misalignment.
Scrap bearings and fit new
bearings or pads.
