Undercarriage & wear parts
Track keeps loosening? It is usually not the adjuster
The 4-link measurement, done properly
The industry convention is to measure across four links (five pins) and divide by four to get the average pitch. Measure under tension, on a clean section of chain, with the chain straight — a chain measured around a curve reads long and gives you a false replacement verdict.
Compare the average against the nominal pitch. Two thresholds are commonly used: around 3% elongation is the point to plan replacement, and around 5% is considered fully worn. Exact figures vary by manufacturer and by chain type, so treat these as planning anchors rather than absolute limits — and check what your manual says.
What not to do with a stretched chain
Do not keep tensioning it. A chain past its elongation limit cannot be brought back into specification by the adjuster, and forcing tension onto it loads the sprocket, the rollers and the idlers beyond design. The result is that instead of replacing one chain you end up replacing the undercarriage.
When a track goes loose, the instinct is to pump more grease into the adjuster. That works temporarily and hides the real cause. Here is how to tell what is actually happening.
Three possible causes, in order of likelihood
- Packing material. Mud, rock or debris packed between the sprocket and the idler effectively shortens the frame, so the chain reads loose. Clean it out before concluding anything.
- Leaking adjuster seal. Grease escapes slowly. If you are re-tensioning weekly, the seal is gone, not the chain.
- Genuinely worn pins and bushings. Wear between pin and bushing increases chain pitch, and a longer chain cannot be tensioned within range. This is the only one that means replacement.
How to tell wear from a leak
Clean the adjuster, tension the track correctly, then check it again after a few days of normal work. If it has lost tension in that time, grease is escaping — look for oil at the adjuster cylinder. If tension holds but the sag is still above specification at maximum adjustment, the chain has stretched beyond its limit.
The measurement that settles it
Measure the chain pitch: the distance across several links, divided by the number of links. Compare with the specification. A chain measurably longer than nominal is worn out, regardless of how it looks.
Do not keep tensioning a worn chain. Over-tensioning a stretched chain loads the sprocket and rollers beyond design and accelerates their failure — you will replace the whole undercarriage instead of one chain.
Ordering a replacement chain
You need: link count, chain pitch, shoe bolt pattern, and the machine serial number. Send to alfrun@gmail.com for a fitment confirmation before a quote.
Before you order
Send machine make, model, serial number and a photo of the casting mark. We confirm the part number and fitment basis before any price discussion.
Trademark notice
Machine brand names and part numbers are used only to describe fitment and application. We are not an authorised dealer of any machine manufacturer.
Reviewed by Zhonglei M&E parts desk — export trading partner for undercarriage and wear parts. Last updated 2026-11-13.