Why measuring wear isn't always the best leaf chain inspection method

Roller Chain inspection check-list

Another FB Chain speciality is our ability to manufacture high-quality sprocket segments. Split sprocket solutions can save large amounts of downtime when it comes to replacing large, difficult-to-access drives.

SymptomAppearanceProbable causeCorrection
Worn contourAbnormal wear rubbing on guidesReplace roller chain when 5% worn. Check roller chain alignment or increase clearance.
Pin gallingInadequate lubricationReduce load or roller chain drive speed. Provide proper roller chain lubrication.
Tight jointsDirt or foreign substance packed in joints or corrosion or rust or bent pinsClean & re-lubricate roller chain. Replace roller chain.
Hooked sprocket teethExcessive roller chain wearReplace roller chain and roller chain sprocket.
Abnormal protrusion or turned pinsExcessive internal friction caused by high loading and inadequate lubricationReplace roller 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 roller chain of larger dynamic capacity or eliminate high load condition or dynamic (impulse) overloading.
SymptomAppearanceProbable causeCorrection
Fractured plates (tension mode)
Note material distortion
High overloadReplace roller 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 roller chain and protect from hostile environment.
Enlarged holesHigh overloadReplace roller chain and correct cause of overload.
Corrosion pittingExposure to corrosive environmentReplace roller chain and protect from hostile environment.
Broken, cracked or deformed rollersSpeed too high. Sprockets too smallReplace roller chain and reduce speed. Replace roller chain and use larger roller chain sprockets/
Broken pinsExtreme overloadReplace roller chain. Eliminate cause of overload or redesign roller chain drive/
Rusted chainExposed to moisture. Water in lubricant. Inadequate lubricationReplace roller chain and protect from moisture. Change roller chain lubricant. Replace roller chain and improve roller chain lubrication.

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