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Particular attention should be paid to the condition of all bolts and safety components. If defects are
discovered the hoist must be taken out of service and repaired immediately.
TIP!
To detect surface damage and deformations on the external surfaces of the links, use a piece of cotton
fabric and pull the chain through. Any surface damage such as nicks or cracks will hook catch on the fibres
of the fabric and thus can be easily detected.
Discard criteria of chain:
The chain must be replaced if the average wire diameter (d
m
) has been reduced due to wear by more than
10% of the nominal thickness at any point on the chain link.
The average wire diameter d
m
=(d
1
+d
2
):2
≤ 0.9d, whereby the average wire diameter (d
m
) is calculated from
two individual values d
1
and d
2
measured rotated through 90° with respect to each other. The chain must be
replaced if a single chain link is permanently lengthened or if the inner pitch
t
of the individual link has
increased in size by more than 5% as a result of wear.
The chain must also be replaced if the inner pitch 11t has increased in size by more than 2% along a
measuring section of 11 chain links.
The lubricant shall sit at the contact points between to chain links as this part is subject to the utmost wear
and tear
Chain wheel inspection:
If the chain is found to have reached the point of wear of 2% pitch enlargement (over 11t), the lift wheels
must be inspected carefully. Damaged wheels have to be replaced together with the chain. If no severe wear
has occurred to the lift wheel pockets the lift wheels do not have to be replaced.
External chain guide inspection:
The external chain guide helps feed the chain properly into the lift wheel. Its shape is specially designed in
order to disentangle chain before entering the hoist.
Excessive wear makes to the guide reduces its functionality. Wear that is apparent on one side of the chain
guide clearly indicates side pull on a loaded hoist. In both cases the chain guide shall be replaced.
Figure 37:
“External chain guide plate”
