Symptom

Appearance

Probable cause

Correction

Worn contour

 why-has-the-roller-chain-got-a-worn-contour

 

 

 Abnormal wear rubbing on

guides

Replace roller chain when 5% worn

 

Check roller chain alignment or increase clearance

Pin

galling

 

 

 

 

Inadequate

lubrication

Reduce load or roller chain drive speed

 

Provide proper roller chain lubrication

Tight joints

 

 

 

why-has-the-roller-chain-got-tight-joints

Dirt or foreign substance

packed in joints

or

corrosion or rust

or

bent pins

 

Clean & re-lubricate roller chain

 

 

Replace roller chain

 

Replace roller chain

 

Hooked

sprocket
teeth

 

 

Excessive roller chain wear

 

Replace roller chain and roller chain sprocket

 

Abnormal protrusion or

turned pins

 

 

 

 roller chain pins turned or protruding abnormally

Excessive internal friction

caused by high loading and

inadequate lubrication

 

Replace roller chain, improve lubrication and eliminate

overload conditions

 

Cracked plates (fatigue)

 

 

why are the plates cracked

 

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

 

 

Symptom

Appearance

Probable cause

Correction

Fractured plates

(tension mode)

chain link plates fractured due to high overload

Note material distortion

High overload

 

Replace roller chain and correct cause of overload

Arc like cracked plates

(stress corrosion)

 

 

 arc like cracked plates caused by 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 holes

 

 why are the link plates holes enlarged

 

 

High overload

 

Replace roller chain and correct cause of overload

 

Corrosion pitting

 

 

Exposure to corrosive environment

 

Replace roller chain and protect from hostile environment.

 

Broken,

cracked or

deformed

rollers

 

 

Speed too high

 

 

Sprockets too small

Replace roller chain and reduce speed

 

Replace roller chain and use larger roller chain sprockets

Broken

pins

 

 

 

 

Extreme overload

Replace roller chain.

Eliminate cause of overload or redesign roller chain drive

Rusted chain

 

Exposed to moisture

 

 

Water in lubricant

 

Inadequate lubrication

Replace roller chain and protect from moisture

 

Change roller chain lubricant

 

Replace roller chain and improve roller chain lubrication