Leaf Chains

Leaf Chains

Leaf chains are high-strength articulating chains used in forklift mast systems, hydraulic cylinder linkages, counterbalance mechanisms, and machine tool applications where a flexible tension member with high load capacity and precise pitch is required. Unlike roller chains, which transmit power through sprocket engagement, leaf chains are used as purely tensile members — carrying load through the chain links rather than transmitting rotary motion. AIMS Industrial stocks leaf chains for forklift maintenance and industrial machinery applications across Australia.

Leaf Chain Construction

Leaf chains consist of interlaced sets of flat link plates joined by hardened steel pins. The link plates carry the tensile load in parallel, with more link plates per joint producing a higher-strength chain. Two standard series are used in industrial applications: AL (or BL) series chains with the link plate arrangements specified by standards including ISO 4347 and ASME B29.8. The BL series (also called Balancer Leaf Chain or LH series) is the most widely used in forklift mast applications in Australia, available in pitches from 3/8 inch through to 2 inches and link configurations providing a range of minimum breaking loads to match different forklift capacities.

Forklift Mast Applications

Leaf chain is a critical safety component in forklift mast systems. The chains connect the mast carriage to the hydraulic lift cylinder and bear the full load of the carriage, forks, and any load being carried. Leaf chains in forklift applications are subject to strict inspection and replacement requirements — Australian forklift maintenance standards require regular chain inspection for wear, elongation, corrosion, and link plate cracking. A chain that has elongated beyond 3% of its nominal length must be replaced regardless of its apparent visual condition. Forklift leaf chains should be lubricated regularly with a penetrating chain lubricant that reaches the pin-to-plate interface where wear occurs.

Chain Inspection and Replacement

Leaf chain wear occurs primarily at the pin-to-plate bearing contact, causing the chain pitch to increase as the pin bore elongates. Measurement of chain elongation over a specified number of pitches against a new chain gauge is the standard inspection method. Side-to-side looseness of the link plates, rust staining, and visible corrosion or pitting on the link plate surfaces are additional indicators that replacement is required. Cracked link plates — even small cracks at the pin holes — require immediate replacement, as a cracked plate can fail suddenly and catastrophically under load. Never repair a damaged leaf chain; always replace the full chain as a matched assembly.

Selection and Sizing

Leaf chain selection requires matching the chain pitch, link plate configuration, and minimum breaking load to the application. For forklift replacements, the OEM specification from the forklift nameplate or service manual provides the chain pitch and BL series number required. For machinery and hydraulic linkage applications, selection is based on the maximum load the chain will carry with an adequate factor of safety applied — typically a minimum factor of 5:1 on the chain's rated minimum breaking load. Chain end terminations (chain anchors, clevises, and connecting links) must also be matched to the chain series and load rating.

For leaf chain specifications, forklift chain replacement assistance, or bulk supply pricing, contact our team at AIMS Industrial.