WIRE ROPE MISHANDLING/DEFORMATIONSWIRE ROPE MISHANDLING/DEFORMATIONSWIRE ROPE MISHANDLING/DEFORMATIONSWIRE ROPE MISHANDLING/DEFORMATIONS

Figure 1Figure 1Figure 1Figure 1 A wire broken under a tensile load that exceeds its strength is recognized by the “cup and cone” configuration at the fracture point (a). The necking down of the wire at this point shows that failure occurred while the wire retained it ductility. Shear-tensile fracture (b) occurs in wire subjected to a combination of transverse and axial loads. Fatigue breaks are usually characterized by squared-off ends perpendicular to the wire either straight across or Z-shaped (c&d). Additional Discard Criteria based on damage/deformation/overload: Warning: For safety reasons crane ropes have to be discarded if showing one of the following criteria.

• Number of wire breaks as defined in table Discard Criteria

• (fig.2)(fig.2)(fig.2)(fig.2) Basketlike distortion

• (fig.3)(fig.3)(fig.3)(fig.3) Loosening of rope structure (inner core)

• (fig.4) (fig.4) (fig.4) (fig.4) Kinks, bends or local crushing (also called “dog-leg”) The following conditions (figs 11 & 12) can be caused by a sudden release of tension and the resulting rebound of the rope from its overloaded condition. The strands and wires will not return to their original position. These conditions can also result from the rope operating through a tight groove.

• (Fig.5)(Fig.5)(Fig.5)(Fig.5) Improper handling, rope rotation, sudden release of a load or core slippage can cause a “popped core”.

• (Fig.6)(Fig.6)(Fig.6)(Fig.6) A “birdcage” is damage to the rope structure due to a sudden release of the load.

• (Fig.7)(Fig.7)(Fig.7)(Fig.7) This is an example of a wire rope that has jumped a sheave. The deformation is in the shape of a curl – as if it had been around a circular shaft. On close examination, the wires show two types of breaks – the normal tensile cup and cone and the shear break which appear as having been cut with a cold chisel on an angle (see fig. 1).

If special rope damage is found, the cause has to be determined and eliminated before a new rope is installed. If in doubt, discard rope or consult our company for further assistance.