A forklift mast chain is a leaf chain that transfers lifting force from the hydraulic cylinder to the carriage and forks. Unlike roller chains used for power transmission, leaf chains are specifically designed for vertical lifting applications.
How Mast Chains Work
The forklift's hydraulic cylinder raises the inner mast rails, but the mast chains are what actually lift the carriage and forks. Each chain attaches to the carriage, routes up and over a chain wheel (sheave) acting as a pulley, and bolts to the inner mast rail. When the mast rails rise, the chains rise—and the carriage goes with them.
Failure Warning Signs
Problem What to Look For
Elongation (Stretch) Replace when wear exceeds 2-3% of original length
Cracked plates Found through pitch holes perpendicular to pitch line
Protruding/turned pins Pin heads no longer aligned; indicates internal failure
Rust or corrosion Reduces load capacity and causes cracking
Tight joints Links don't flex freely; caused by bent pins or rust
Chain side wear Wear pattern on pin heads = misalignment
Use a chain wear gauge to measure elongation. If wear exceeds tolerance markers (2-3% depending on manufacturer), replace the chain immediately.
Safety: Always Replace in Pairs
Forklifts use two mast chains for balanced lifting. Replacing just one chain creates uneven tension, which can twist the mast carriage or cause sudden tilting during lifts. Always replace mast chains in matched pairs.
Daily Inspection Checklist
Look for broken links, rust, or visible damage
Check chain anchors and sheaves for wear
Listen for popping or clicking during lifting
Never place hands inside mast to check tension—use a stick
The Bottom Line: Mast chains wear gradually from thousands of lift cycles. Measure elongation every 1,000 operating hours or 6 months. Replace at 2-3% wear, always in pairs. A chain that fails at height drops the load instantly—no warning, no second chance.