The proper operation of rotation resistant ropes depends on maintaining the torsional balance of the rope during use. Imbalance between inner and outer layers of the rope can be caused by twist induced in the rope as a result of undesirable operating conditions. Common causes of twist are improper fleet angles (Figure 39), sheave alignment, or poor spooling. Odd part reeving with off center attachment of the dead end to the block or improper reeving can cause misalignment of the traveling block inducing twist into the rope.

Although these ropes are classified as rotation resistant it must be realized that some slight rotation may occur, particularly in the early stages of rope life. This rotation may result in undesirable “cabling,” in multipart systems, or twisting of the load in single part. If this occurs, it is advisable to relieve the twist by disconnecting the most accessible end of the rope, and then reconnecting it. In some applications, swivels are used to relieve accumulated rope twist during installation and periodically during operation. The swivel would be locked off after twist is relieved to prevent uncontrolled rotation.

The use of an open swivel (allowed to rotate freely) continuously during operation of the rope is a practice that must be carefully considered. Open swivels are not recommended for use with 8 x 19, 19 x 7, and 19 x 19 rope classifications. For other multi-strand constructions, consult the rope manufacturer for recommendations regarding the use of swivels.

Compacted Strand Wire Rope

Compacted strand wire rope is a wire rope manufactured from strands which have been compacted or reduced in diameter prior to laying strands around the core into a finished wire rope. There are various known methods for compacting; drawing the strand through a compacting die, roller reduction and rotary swaging are several examples. The compacting process flattens the surface of the outer wires and reforms internal wires of the strand to increase the metallic area of the strand. The result is a smoother bearing surface at the strand crowns and an increase in nominal strength over round strand rope of the same diameter and classification. Cross section diagrams of rope with compacted strands are found in Figure 12.

Page 4 shows compacted strand rope strengths commonly available in 6 strand rope, and 19 strand rotation resistant rope. For information on the exact nominal strength available on a particular rope, consult the manufacturer of the rope or our Technical Department.

6 x 26 Warrington Seale
Compacted Strand
IWRC
8 x 26 Warrington Seale
Compacted Strand
IWRC
19 x 19 Scale
Compacted Strand

Figure 12. Compacted Strand Wire Rope Cross-sections.

Compacted (Swaged) Wire Rope

The entire cross section of a rope is compacted or reduced in diameter following laying strands around the IWRC to produce compacted or swaged wire rope. Rotary swaging is the most common process for compacted rope although other processes may be used. As illustrated in Figure 13 the wires and strands of the rope are flattened to produce a relatively smooth and wear resistant outer surface. Compacted rope generally has good wear resistance, crushing resistance and high strength, however bending fatigue life may be reduced by the compacting process.

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