Quick Answer 

A leaf chain consists of interlaced steel plates and pins engineered strictly for high-load tension lifting without sprockets. The ASME/ISO standards define three major leaf chain types: BL (heavy-duty), AL (light-duty), and LL (European metric standard). 

Universal Chain manufactures a complete series of certified leaf chains that meet ISO 4347, ASME B29.8M, and DIN 8152 standards. Our factory produces over 30 million meters of chain annually with zero critical defect rates across 80+ export markets.

What are Leaf Chain Grades? 

The leaf chain consists of stacked steel plates, which are connected with hardened steel pins. Leaf chains do not have rollers, bushing, or teeth like ordinary roller chains.

The plates are driven over sheaves to perform motion in reciprocating lifting operations. Thus, it is designed to produce the highest level of tensile strength within a minimum frame size. Leaf chains are recommended to use in mechanical engineers’ forklift mast chain assemblies, counterweight systems, and overhead hoists.

You can examine the lacing of the plates and the diameter of the pin to determine a leaf chain. Moreover, you can calculate the pitch by measuring the distance between pin centers. For further information about mechanical differences of the chains, visit Universal Chain’s article leaf chain vs roller chain differences and applications.

What are the Specifications and Common Applications of BL Series Leaf Chain? 

The BL series leaf chain (also classified as LH series under ISO standards) is equipped with thick plates and large pins. The plate thickness is equal to the outer link plate of the larger-sized ANSI roller chain.

For instance, the plate thickness and the diameter of pins in BL6 chain is similar to that of ANSI 80 Roller Chain. In such a way, the fatigue resistance and tensile strength of the chain will be increased under high impact loads.

BL series leaf-type chain is widely used in industries for the manufacture of lifting machinery with heavy capacity. These include heavy counterweight lifts, primary forklift masts, and port container handlers.

Where are AL Series Leaf Chains Best Utilized?

The AL series leaf chain consists of link plates having the same thickness and shape as those in ANSI roller chain pin links. The slender construction results in lower chain weight as well as good linear pull capacity. This chain finds application in areas where there are no severe shock loading or fatigue cycles.

The light-duty material handling systems make use of these chains for slow-speed lifting operations. Typical usage is for counterbalance in machine tools, small boom lifts, and light balancing systems. 

What are the Heavy-Duty and Special Applications of LL Series Leaf Chain? 

The LL series leaf chain conforms to the metric standards used in Europe as per ISO 4347 and DIN 8152 specifications. The design uses link plate sizes made according to British Standard (BS) Roller Chains.

The chain profile uses flat plate profiles which evenly distribute the load on the surface resulting in less wear due to contact when articulating continuously. Europeans use this series of leaf chains in export machinery, automated hoists and lift trucks used in Europe.

BL vs AL vs LL Series: Comparison Table

Choosing the right lifting chain grades involves considering dimensional pitch, tensile strength, and plate lacing. The following table shows the leaf chain size chart covering key performance parameters:

How to Read a Leaf Chain Size Chart?

The typical chart for leaf chain size has the alphanumeric format, in which pitch, plate lacing, and series are represented.

• Series: Represents the design characteristics of the chain (BL = Heavy ANSI, AL = Light ANSI, LL = Metric ISO).

• Pitch: The first digit(s) represent the pitch, measured in 1/8 inches (e.g., 6 = 6/8″ = 3/4″ pitch).

• Lacing: The last digits represent lacing configuration (e.g., 44 = 4×4 lacing, 66 = 6×6 lacing).

How Do You Select a BL Series Forklift Mast Chain by Lift Capacity?

A forklift mast chain should be chosen based on tensile strength compared to the maximum safe working load (SWL). There is a safety ratio of 5:1 for handling of equipment, as per industrial safety standards.

Shock load factors must always be considered during hydraulic acceleration. Chain working life will depend on lubrication maintenance under consistent loading. Learn more in the company’s detailed article on leaf chain lubrication for forklifts.

Which LL Series Chains Work Best for Hoisting and Cranes?

The overhead crane hoists and straddle carriers require precise linear movements without any twist in the chains. The LL series of leaf chains provides tight tolerance for pitch and symmetry for the plates.

In case of heavy lifting, use 4 x 4 or 6 x 6 plate lacing. This is done to distribute tensile load among various shear planes on each pin. It is the responsibility of the rigging engineers to confirm that the profile of the sheave groove suits the chain width.

Leaf Chain Installation & Safety Inspection Checklist

Proper inspection helps avoid accidental tensile fatigue of overhead lift chains.

• Elongation Check of Chain: Measure distance between any 10 to 20 links. Replace chain if elongation is greater than 3% of its original length.

• Inspect Pin Joint: Turned pins and protruding heads indicate galling of chain inside.

• Plate Edge Inspection: Inspect plates for wear from riding on sheaves that are worn out.

• Fatigue Crack Inspection: Non-destructive examination of link plate pinhole for stress cracks.

Proper maintenance prevents downtime. Read Universal Chain’s complete guide on how to inspect and maintain a forklift chain for detailed safety protocols.

Why is Sourcing ISO-Certified Leaf Chains Essential?

Lifting chains for industrial use are required to conform to strict safety standards, both locally and internationally, such as ISO. Chains that do not meet these requirements are likely to fail due to fatigue and can risk the overall safety of the workplace. 

Safety standards for leaf chains include: 

• ISO 9001: Quality Management System Controls    

• ISO 4347:Leaf Chain Dimensional Standards     

• API 2C: Marine & Offshore Hoisting Compliance   

• CE Mark: European Industrial Safety Conformance

Leaf chain（AL series）

AL leaf chain is a light load series, mainly used in manual hydraulic forklifts, small tonnage electric forklifts and small tonnage diesel forklifts.

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Frequently Asked Questions (FAQs) 

What is a lift chain on a forklift?

• A lift chain on a forklift is a steel chain that carries the lifting force provided by the hydraulic system into the fork carriage. Even though the power is supplied by the hydraulic system cylinder, the lifting process is carried out by the lift chains.

Is grade 43 or 70 chain better?

• Grade 70 chain will be more suitable for strength purposes since it is approximately 20% stronger and lighter compared to Grade 43. Nevertheless, Grade 43 will be more suitable for utility, outdoor, or marine purposes since it usually provides good protective coatings against corrosion such as galvanization.

What is 3/8 chain rated to lift?

• A 3/8-inch chain’s lifting capacity depends strictly on its grade, with alloy grades such as Grade 80, Grade 100, or Grade 120 can be used for overhead lifting at the following loads ranging from 7,100 to 10,600 lbs (Working Load Limit).

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