Receiving, Inspection and Storage
On receipt the product should be inspected to confirm that it corresponds to the one ordered. If the steel wire rope is not to be used immediately, it must be stored in a dry place. If it is to be stored for a longer period, it must be checked regularly to determine whether it requires lubrication (see also “Maintenance of Steel Wire Rope”, page 8-26).
Inspection of Dimensions
It is important that the steel wire rope’s dimension is checked before installation, and that it is checked that the dimension matches the equipment with which the steel wire rope is to be used (see also “Dimension Tolerances and Ovalness”, page 8-18).
Correct measurement of dimension (EN 12385-1 5.3.1) is undertaken with a calliper gauge equipped with a broad enough jaw to cover at least two strands (see fig. 31).
The measurement is undertaken at two places at least one metre apart on a straight section without any load. At each place two measurements are made at 90° angles. The average of these four measurements defines the diameter of the steel wire rope. The degree of ovalness in the steel wire rope is the greatest difference between the four measurements, expressed as a percentage of the nominal diameter of the steel wire rope.
Inspection of Guidance Equipment
Before the steel wire rope is fitted, it is important to ensure that all parts that will come into contact with the steel wire rope are in good condition and match the steel wire rope, e.g.:
- Distance between drum and first sheaf or lead sheaf
- Guide roll
If the equipment is not suitable, there is a significant risk that the steel wire rope will suffer unusually great wear and tear and will thus have a shorter life expectancy.
Check that the drum dimensions and possible rope grooves match the steel wire rope, and check the condition of the drum.
Randers Reb recommends that correct rope grooves are as follows (fig. 32):
B = diameter of groove = 1.06 x d
A = elevation of groove = 1.08 x d
C = depth of groove = 0.30 x d
R = upper radius = approx. 0.15 x d
where d = steel wire rope’s nominal diameter
If the rope grooves do not match the steel wire rope, the rope will suffer unusually high wear and tear, stresses will be introduced and the grooves will have to be repaired.
Please note that norms and standards often impose special requirements in respect of drum diameters, etc.
The steel wire rope’s life expectancy depends to a great extent on the drum’s dimensions, among other things. The larger the drum, the longer the life expectancy (see also “Sheaves/Blocks”, page 8-21).
Distance between Drum and First Sheaf or Lead Sheaf
The distance from the winch to the first sheaf is of importance for the consistency of the winding process.
Randers Reb recommends that the distance L or the fleet angle ß should be (fig. 33):
For drums without rope grooves:
Lmin = 20 x drum width.
For drums with rope grooves:
Lmin = 15 x drum width.
15 x drum width ~ ß = 2º,
and 20 x drum width ~ ß = 1.5º.
If the distance does not match these figures, the steel wire rope will be subject to unusually significant wear and tear; the distance should therefore be changed.
Check whether the guide rolls, e.g. those on the winch, are worn. If they are, the steel wire rope will be subject to unusually significant wear and tear; the guide rolls should therefore be replaced or repaired.
If the guide roll is repaired by welding, care should be taken to ensure that the hardness of the welding material is approx. 300 Brinel, and that it is the guide roll that is worn, and not the steel wire rope.
Check that the sheaf diameter and sheaf groove match the steel wire rope. The sheaves must also be able to turn freely.
When a steel wire rope is fed over e.g. a sheaf and bends, certain complex tensions (a combination of bending, tensile and compression stress) are generated in the wires. The greatest tensions occur in the wires furthest away from the steel wire rope’s bending centre. After repeated bends, stress failure will occur in these wires.
The steel wire rope construction and the size of the sheaves are decisive in determining when wire fracture occurs. The curve below (fig. 34) shows the influence of the D/d ratio (sheaf diameter/nominal steel wire rope diameter) on the life expectancy of steel wire rope of different types.
Please note that norms and standards often impose special requirements in respect of sheaf/drum diameters. If this is not the case, a minimum D/d = 25 is recommended for 6x7 steel wire ropes, minimum D/d = 20 for 6x19 and 6x36 and a minimum D/d = 10 for combination ropes.
If at all possible, S-bends (where the steel wire rope runs from the lower side of one sheaf to the upper side of the next) should be avoided. Such bends result in premature damage. The sheaf ratio (see below) should thus be increased by at least 25% in relation to the same change of direction. The problem is particularly great when the sheaves are placed close to each other.
The groove in the sheaf also has a significant influence on the steel wire rope’s life expectancy. The groove must be neither too large nor too small - the groove must match the steel wire rope’s dimensions (fig. 35).
Randers Reb recommends that a correct sheaf groove should support approx. 1/3 of the circumference of the steel wire rope (~120°C) and have a groove diameter of Dsp = 1.06 x the steel wire rope’s nominal diameter (see fig. 36). The groove diameter may under no circumstances be less than the relevant steel wire rope’s diameter.
The curve in the diagram below (fig. 37) indicates the effect of the D/d ratio (sheaf diameter/steel wire rope diameter) on the steel wire rope’s life expectancy.
Always check whether the sheaf groove is worn at the base and along the edges. If it is not, the steel wire rope will be subject to unusually significant wear and tear and stresses will be introduced into the rope. Defect sheaves/blocks should therefore be replaced or repaired immediately.
If the groove is repaired by welding, Randers Reb recommends that the hardness of the welding material is approx. 300 Brinel, so that it is the sheaf that is worn, and not the steel wire rope. The size of the steel wire rope’s contact angle (angle change) on the sheaf also has an effect on the steel wire rope’s life expectancy (see fig. 38).
If the steel wire rope has to change direction, Randers Reb recommends avoiding changes in direction between 5° and 45°.
Installation of Steel Wire Rope
Steel wire rope from Randers Reb is produced in such a way that in an unloaded state it is tension-free. The steel wire rope is supplied either on reels or in coils. To avoid creating tension or kinks in the steel wire rope during installation, it is necessary to place the coil/reel on a revolving platform, or as shown in fig. 39. If this is not possible, the steel wire rope can be rolled out on the ground while the end of the rope is held in place.
Remember to secure the end of the steel wire rope against opening, regardless of whether or not it is pre-formed. This can be done by such means as tapered and welded ends, beckets, or seizing with soft or annealed wire or strand (see also “Cutting and Seizing of Steel Wire Ropes”, page 8-24).
During the unwinding of the steel wire rope, it must not:
- In any way pass over the edge of the reel or be taken from a coil on the ground, as this will create kinks in the steel wire rope (see fig. 40).
- Be dragged over a hard surface that can damage the wires.
- Be dragged through earth, sand or gravel, as abrasive particles will attach themselves to the greased surface of the steel wire rope.
Winding from Reel to Drum
During installation, when the steel wire rope is running directly from the reel to the drum, care must be taken to ensure that the reel is running in the same direction as the drum (fig. 41).
If this is done incorrectly, the steel wire rope is subjected to tension.
In order to achieve problem-free winding in multi-layer winding, it is extremely important that that the steel wire rope is under tension when applied to the drum. If the layers are too loose, the upper layers can damage or cut into the layers below when tension is applied, resulting in damage to the steel wire rope. The rope must be wound onto the drum at a tension corresponding to at least 2% of the tensile strength of the rope.
Braking of the drum can be done in several ways (see fig. 42). Please note: Steel wire rope should never be pressed between two wooden plates, as this will result in permanent damage to the rope.
Correct Fitting to Drum
Fig. 43 illustrates the correct way of installing and winding on to the drum for right and left hand laid steel wire rope respectively.
Cutting and Seizing of Steel Wire Rope
Randers Reb recommends that, as long as the steel wire rope does not have welded ends, it has to be seized before being cut. The following seizing method must be used (See Fig. 44):
Please note that low-rotation and rotation-resistant steel wire ropes must have at least four seizings on each side of the cutting point.
Running in Steel Wire Rope
After the steel wire rope has been installed, Randers Reb recommends that it is run through the system several times at low speed and moderate loading (e.g. 5% of tensile strength). In this way the steel wire rope will gradually become accustomed to the new conditions. The strands will settle, the steel wire rope will lengthen and the diameter will decrease a little due to the fact that the strands and the core are compressed. The steel wire rope will thus be less susceptible to damage when maximum load is applied. The time spent “running-in” the steel wire rope will be earned many time over, as the steel wire rope will thus have a longer life expectancy.
Maintenance of Guidance Equipment
Thorough maintenance of the equipment that the steel wire rope will come into contact with is of great significance for the steel wire rope’s life expectancy. Worn sheaf grooves, guide rolls, etc., crooked sheaves and jammed bearings all result in such effects as shock load and vibrations in the steel wire rope, which have a destructive effect on the steel wire rope, resulting in exaggerated wear and tear and fatigue.
Equipment that the steel wire rope comes into contact with must be inspected regularly. If there is a problem with the equipment, it must be replaced or repaired immediately. If the guidance equipment is repaired by welding, care should be taken to ensure that hardness of the welding material is approx. 300 Brinel, so that it is the sheaf that is worn, and not the steel wire rope (see also “Inspection of Guidance Equipment”, page 8-19).