The mast and lift chains are what make a forklift a forklift. They take the full load weight, every lift, every shift. Worn chains snap. Dry rollers seize. Neglected rails bind. When the mast fails, the load drops — and that means damage, injury, or worse. Here are four checks that keep your mast lifting safely.
1. Check Chain Tension Regularly
Lift chains must be equally tensioned on both sides of the mast. Uneven tension causes the carriage to tilt, wearing rollers and guides unevenly. With the forks raised about 300mm off the ground, measure the slack at the midpoint of each chain. Slack should be 20–30mm for most forklifts (check your manual). If one side is looser than the other, adjust the anchor bolts evenly. Never run with one chain tighter than the other — it leads to premature roller and guide wear.
2. Inspect Chain Links for Wear and Corrosion
Chain links stretch and wear over time. Measure a set length (typically 10 or 20 links) and compare to the manufacturer's wear limit. If the chain has stretched beyond 3–5% of its original length, replace it. Also look for rust, pitting, or cracked links. A single cracked link can snap under load. Clean and lubricate chains weekly with the recommended chain oil (not general grease, which traps dirt). Dirt and grit accelerate chain wear — wipe chains clean before lubricating.
3. Lubricate Mast Rollers and Rails
The mast rollers ride up and down the inner and outer rails. Dry rollers create friction, wear flat spots, and eventually seize. Grease all roller bearings at their fittings every 50 operating hours. Also apply a light coat of grease to the mast rail surfaces where the rollers travel. Wipe off old, dirty grease first. For masts with side thrust rollers, check that they are snug against the rails — excessive gap causes sway and uneven load control.
4. Look for Bent or Damaged Rails
A bent mast rail causes the carriage to bind, jerky movement, and premature roller wear. With the forks raised halfway, stand in front of the mast and look up the full length. Any visible curve or twist means the mast needs professional straightening. Also feel for hesitation or roughness when lifting and lowering — this often indicates a damaged rail or a seized roller. Do not force a binding mast; investigate the cause before continuing.
Quick field check: Before your first lift of the shift, raise the forks to eye level and observe the chains as they pass over the sheaves. Listen for clicking or grinding — that indicates worn chain pins or dry sheave bearings. Also check that the chains are not twisted or rubbing against the mast structure.
Want a mast and chain inspection checklist for your forklift? Reply with your forklift model and mast type — we will send a PDF with chain wear limits, lubrication points, and a weekly log sheet.
