Main lift chain system – 7120

12.3.8 Stretching

The amount of stretch on a lift chain is measured on the part of the chain that runs over the chain sprocket. The amount of stretch may, at the most, be 2% on the most worn section of the chain. Measurement is suitably made over 300-1000 mm of the chain.

The nominal and maximum permitted chain lengths for lift chains are stated in the table below.

Table 38: Stretching

Wear to the bolts and around the holes on the discs are a reason why the chain stretches. The chain should be replaced if stretching is more than 2%.

12.3.9 Damage

The chain should be replaced if damaged in any way.

12.3.10 Damaged discs

If a disc has broken on the chain, this can be due to overloading or corrosion. The chain should be replaced.

12.3.11 Damaged bolts

It can be difficult to discover whether a bolt has broken. It can appear as bolt rotation and/or that the outer disc is loose. The chain should be replaced.

12.3.12 Dirty chain

If a chain is very dirty it is first and foremost recommended that it is replaced. It can also be dismantled and cleaned as set out in the chapter “Cleaning”.

12.4 Cleaning

If a chain is very dirty it is recommended that it is replaced. Dirty chains should be cleaned before they are lubricated, e.g. by washing with solvent such as diesel or petrol.