What surface pitting is
Pitting is a contact fatigue mechanism. Under repeated high stress at the roller and tooth or pin and bush contact, small particles of surface material detach and leave pits. Pits then act as stress raisers and the damage spreads into spalling and loss of the hardened case.
Common causes
- Contact stress above the material's fatigue limit for the duty
- Hard particles embedded in a bearing surface
- Worn sprocket teeth concentrating load on a small contact area
- Thin or broken down lubricant film allowing metal to metal contact
Warning signs
- Pitting on roller outer surfaces or bush bores
- Grey, gritty debris in the chain case
- Progressive localised pitting that turns into spalling
- Noise and vibration that build gradually
Prevention and correction
- Match chain and sprocket hardness so load is distributed across the tooth flank
- Keep lubricant clean and replace it if it is contaminated
- Replace worn sprockets at the same time as the chain
- Reduce load or increase pitch to lower contact stress
Fix it with the right product
Sprockets, chain and drive componentsNeed a second opinion?
Send us the chain, the running hours and a photo. Our engineers will confirm the failure mode and quote the right replacement.
All chain failure modes
Chain ElongationFatigue FailureSide Plate CrackingPin and Bush WearRoller Wear and SpallingAbrasive WearAdhesive WearCorrosionStress Corrosion CrackingHydrogen EmbrittlementGallingSurface PittingTensile OverloadShock LoadingImpact FractureLubrication StarvationTight Links and KinkingMisalignmentChordal ActionSprocket Tooth Wear
Same & Next-Day Delivery Areas
Roller chain supply across South Yorkshire & the North
Dispatched from our Rotherham depot — order by 1pm for next-working-day delivery, or collect same-day within our 30-mile radius.
RotherhamDepot location
Sheffield9 mi · ~25 min
Barnsley6 mi · ~15 min
Doncaster16 mi · ~30 min
Mexborough3 mi · ~8 min
Maltby5 mi · ~12 min
Wath-upon-Dearne4 mi · ~10 min
Wakefield20 mi · ~35 min
Leeds25 mi · ~45 min
Huddersfield30 mi · ~50 min
Scunthorpe22 mi · ~35 min
Mansfield28 mi · ~45 min
Chesterfield18 mi · ~30 min
Worksop14 mi · ~25 min