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to Technical Information Main Page |
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| Using
your rope for the first time |
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Break-In Period
After installing a new rope it is necessary to run it through its operating
cycle several times under light load and at reduced speed. This allows the
rope to adjust itself to the working conditions and enable all strands and
wires to become seated. Depending on rope type and construction some rope
stretch and a slight reduction in rope diameter will occur as the strands
and core are compacted. The rope is less liable to be damaged when full
load is applied.
The initial stretch (constructional stretch) is a permanent elongation that
takes place due to slight lengthening of the rope lay and due to a slight
decrease in rope diameter.
Constructional stretch generally takes place during the first 10-20 lifts,
and increases the rope length by between 1/2% for fiber core rope, approx.
1/4% for 6-strand steel core rope, and approaches zero for compacted Python
ropes.
I you have the chance and the equipment configuration allows this, disconnect
the rope end after the break-in-period to allow any possible torque and
twists which may have developed during installation and the break-in-period
to be released at the end connection. |
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Equipment Testing
In many cases the crane equipment has to be tested prior to use. Proof testing
requires to purposely overload the crane to varying degrees. The magnitude
of overloading depends on the type and capacity of the crane and which governing
authority certifies the equipment. The test may impose an overload of between
10% and 100% of the crane's rated capacity.
Under NO circumstances must the crane be tested prior to
the break in procedure of the wire rope. If you overload a rope which has
not yet been broken in, you may inflict permanent damage to the rope.
Equipment with multiple layer windings call for additional caution. As mentioned
before, severe overloads of the top layers may damage the lower ones or
may crush the rope. If possible, test the crane with the rope spooled in
the first drum layer only.
If the crane is equipped with a smooth drum, special care must be taken
to ensure that the rope does not cross-wind over itself when testing the
crane. After testing (overloading) you have to repeat the spooling procedure
as outlined here 'Winding on
smooth or flat faced drums'. |
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