can you extend leaf chain by reversing endsCan you extend the life of leaf chain by reversing ends?

Leaf chain wear is a direct result of load, together with the articulating movement, as the leaf chain rotates over the pulley. If there is no load and no articulating movement then the leaf chain will not wear. This means that the only section of a leaf chain that can wear, is the portion that moves over the pulley. Some applications use almost all of the leaf chain to rotate over the pulley. In set-ups where there is little movement, or longer lengths of spare leaf chain, there could be long sections of the leaf chain that do not touch the pulley and are unaffected by wear.

What is meant by 'reversing ends'? Put simply, following the leaf chain being measured for wear, it is removed, cleaned and inspected for continued suitability. If it is considered fit for purpose, it is then refitted to the application, with the ends reversed. In practical terms this means that the end previously fitted to the top anchor bolt will, when re-attached, be fitted to the bottom bolt and vice versa, rather like top to toeing in a bed.

Is it possible to use this unaffected section to increase leaf chain life?

We are sometimes asked whether, in our opinion, this is either advisable or possible. The traditional view is that it is not the best practice or strategy - although at FB we would prefer to consider each individual situation on its own merit as not all applications are the same and chain set-ups vary considerably with regard to usage, chain cost, chain length and the operating environment.

It must be remembered that chain fatigue failures are notoriously difficult to spot. One way that they are reduced is by virtue of a good chain wear inspection regime that should involve using the chain wear gauge to measure how worn the chain is. By extending the usage life of the chain without careful consideration, it could be argued that fatigue failures may well increase.

Usage

Generally engineers would only consider this option when the usage is high enough to justify the time and effort involved, thereby making it financially beneficial. If the usage is not high then it is probable that the overall cost of ‘top to toeing’ the chain would far outweigh any potential savings.

Chain cost

It is likely that to make this procedure viable the replacement chain cost will need to be relatively high. The smaller, high volume, popular chains are normally sold at low pricing levels that would not usually make this worthwhile. Larger pitch sizes and longer chain lengths could, however, be viable.

Chain length

Chain length is not only important from a cost perspective, but more crucially, from a safety and technical standpoint. If by reversing the chain any part of any link that previously rotated over the pulley will do so once fitted in reverse, then the process is not recommended and can be considered a waste of effort.

Operating environment

How and where the chain is used is vitally important to the correct assessment of suitability. If there is any chance that the operating environment could induce early fatigue, then this procedure must not be used. It is also not recommended to use this process in cold store applications, since they often induce hidden fatigue.

To protect the viability of the chain, the worn section should be no more than 2% worn, and the chain should only be reversed once, before being replaced.

If in any doubt then the opinion of a ‘competent person’ must be sought.