The mast and lift chains are critical components that enable a forklift to perform its core functions. During every work shift and every lifting operation, they bear the full weight of the load. Chain wear can lead to breakage, insufficient lubrication of rollers can cause seizure, and poorly maintained mast rails can result in binding. Once a mast malfunction occurs, the load may fall, leading to equipment damage, personal injury, or even more serious consequences. The following four checks help ensure safe mast operation:

1. Check chain tension regularly

The lift chains must maintain equal tension on both sides of the mast. Uneven tension can cause the fork carriage to tilt, resulting in uneven wear of the rollers and guide rails. Raise the forks approximately 300 mm off the ground and measure the slack (sag) at the midpoint of each chain. For most forklifts, the slack should be between 20 and 30 mm (refer to the operator's manual for details). If one chain is looser than the other, adjust the anchor bolts evenly. Never operate the forklift when the chain tension on both sides is uneven, as this will cause premature wear of the rollers and guide rails.

2. Inspect chain links for wear and corrosion

Chain links stretch and wear over time. Measure a specified length of chain (typically 10 or 20 links) and compare it with the manufacturer's specified wear limit. If the chain has elongated by more than 3% to 5% of its original length, it must be replaced. Also inspect for rust, pitting, or cracked links. Even a single cracked link can break under load. Clean and lubricate the chains weekly using the recommended chain oil (never use ordinary grease, as it tends to attract dirt). Dirt and grit accelerate chain wear, so always wipe the chains clean before lubrication.

3. Lubricate mast rollers and rails

Mast rollers move up and down along the inner and outer mast rails. Insufficient lubrication causes friction, resulting in flat spots from wear and eventually seizure. Every 50 operating hours, apply grease through the grease fittings on all roller bearings. In addition, apply a thin layer of grease to the mast rail surfaces on which the rollers run. Before operation, wipe away old, dirty grease. For masts equipped with side-thrust rollers, check that they are in close contact with the rails—excessive clearance can cause wobbling and unstable load control.

4. Check rails for bending or damage

Bent mast rails can cause the fork carriage to bind, move unevenly, and cause premature roller wear. Raise the forks to mid-height, stand in front of the mast, and look upward along the full length of the rails. If any obvious bending or twisting is found in the mast, it must be straightened by a professional. In addition, if lifting or lowering feels sluggish or uneven, it usually indicates damaged guide rails or seized rollers. Never force a binding mast to operate; always identify the cause before continuing use.

Quick on-site check: Before the first lifting operation of the shift, raise the forks to eye level and observe how the chains run over the sheaves. Listen for clicking or rubbing noises—these usually indicate worn chain pins or insufficient lubrication in the sheave bearings. Also check whether the chains are twisted or rubbing against the mast structure.

Would you like a mast and chain inspection checklist for your forklift? Please reply with your forklift model and mast type—we will send you a PDF file containing chain wear limits, lubrication points, and a weekly inspection record form.