The table below provides detailed information on the symptoms of leaf chain wear, the probable causes and the corrective measures that should be taken.
Symptom | Appearance | Probable cause | Correction |
Worn contour | Normal wear on sheave Abnormal wear rubbing on guides | Replace leaf chain when 5% worn Check Leaf chain alignment or increase clearance | |
Worn surfaces on outer plates or pin heads | Misalignment, rubbing on side flanges | Check leaf chain alignment and correct clearance as necessary | |
Tight joints | Dirt or foreign substance packed in joints or corrosion or rust or bent pins | Clean & re-lubricate leaf chain Replace leaf chain | |
Missing parts | Missing at original assembly | Replace leaf chain | |
Abnormal protrusion or turned pins | Excessive internal friction caused by high loading and inadequate lubrication | Replace leaf chain, improve lubrication and eliminate overload conditions | |
Cracked plates (fatigue) | Crack from aperture towards edge of linkplate at 90º to line of pull. Note there is no linkplate distortion | Loading beyond chain’s dynamic capacity (above fatigue endurance limit) | Replace chain with leaf chain of larger dynamic capacity or eliminate high load condition or dynamic (impulse) overloading |
Fractured plates (tension mode) | Note material distortion | High overload | Replace leaf chain and correct cause of overload |
Arc like cracked plates (stress corrosion) | Severe rusting or exposure to acidic or caustic medium, plus static pressure at press fit (between pin and pin linkplate). No cyclic stress is necessary for this phenomenon to occur. | Replace leaf chain and protect from hostile environment. | |
Enlarged holes | High overload | Replace leaf chain and correct cause of overload | |
Corrosion | Exposure to corrosive environment | Replace leaf chain and protect from hostile environment. | |
Worn leaf chain anchor bolt connecting pin | Normal wear | Replace worn leaf chain components and always when fitting new leaf chains |