When faced with a choice of AL, EL-LL or BL-LH series leaf chain, we almost always recommend handling equipment designers to specify BL series leaf chain due to its superior consistency, strength and availability.
In most chain manufacturers’ catalogues you will find leaf chains according to three main standards – AL (American Light), EL-LL (European Light – Light Leaf) and BL-LH (Leaf Heavy) series. There are some applications where the use of AL or EL series leaf chain makes sense, for example, where plate height is a major concern. However, we almost always advise those designing a new piece of handling equipment to opt for BL series leaf chain and here’s why.
1. BL series leaf chain is the only leaf chain constructed from specific leaf chain components.
AL series (American Light) leaf chain, manufactured to the ANSI B29.9 standard, is a lightweight leaf chain constructed from American standard roller chain components for light load lifting applications and machine tools.
EL-LL series (European Light – Light Leaf) leaf chain, manufactured according to ISO4347, DIN8152 and NFE26107, is similar to AL series leaf chain in that it is also a lightweight leaf chain constructed from roller chain components for light load lifting applications and machine tools, but it is made to European standards.
BL-LH series (Leaf Heavy) leaf chain, manufactured to ISO4347, DIN8152, ANSI B29.8 and NFE26107, is a heavier duty leaf chain than AL and EL series and is the only leaf chain constructed from specific leaf chain components.
2. BL leaf chain is the only leaf chain included in the both the international chain standard ISO4347 and BS29.8.
EL chains are only in the ISO standard, while AL chains are not covered in any current standard so could have dimensions determined by the individual chain manufacturer. Specifying this type in a new design could, therefore, leave equipment manufacturers tied to one chain supplier or create issues with the interchange of chain brands with other parts
3. BL series leaf chain offers the greatest consistency in length.
Because it is constructed from specific leaf chain components, you can rely on new BL leaf chain to have a consistent pitch and length. AL and EL series, however, can be made from links with large variances in pitch, resulting in chains that vary in length. This can cause problems with machine set-up and when calculating the safe working life as inspection is based on the nominal pitch.
4. The construction of BL series leaf chain allows for a greater bearing area and longer working life.
Unlike AL and EL chains, BL series leaf chain offers the option of odd lacing, such as 4×6, which increases bearing areas by 66% and results in the chain having a longer working life as the load is spread across more links.
5. BL series leaf chain can be used with smaller pulleys that save on space.
BL series leaf chains can be used with smaller pulleys than comparable AL and EL chains, enabling handling equipment designers to fit the mechanism into a more compact space. AL644 and BL544, for example, both have the same tensile strength but AL644 has a minimum pulley diameter of 95mm while BL544 has a minimum pulley diameter of just 79mm. This is because, to get the best wear life, you should have a pulley that is a minimum of five times the pitch of the chain and BL chain has the same strength as the next pitch size up of AL chain.
6. BL leaf chain has a better tensile strength ratio than AL or EL chains.
The tensile strength to weight per metre ratio is much better on BL than AL or EL series chains. This means that BL series leaf chain has a higher tensile strength and lower weight. In general, the tensile strength ratio on BL chains is 15% better than EL leaf chain, which can make a big difference on multi-stage forklift masts or telescopic booms. A lighter chain at the same strength allows you to lift more because when you lift a load the weight of the chain and other parts are included in the capacity.
7. BL series leaf chain and associated parts are widely available at competitive prices.
BL series leaf chain is the most popular type of leaf chain in the world, which makes it easy to purchase and at a good price. There is also a wide choice of associated parts, including chain anchor bolts and clevis pins. AL or EL series leaf chain, however, may not always be held in stock – and especially not works standard or country-specific standard chain such as the single lacing FLC chain common in the UK up until the 1980s. This can lead to long lead times and the chain anchor bolts and clevis pins may have to be produced in costly small batches.
For these reasons, we see BL series leaf chain as the best choice in most cases when designing a new piece of handling equipment.
For further advice and recommendations, feel free to get in touch with our leaf chain experts and discuss your leaf chain requirements.
