Typical Characteristics




Tension wire breaks typically have one end of broken wire coned or cupped. Necking down of the broken ends is typical of this type of break. Where tension breaks are found, the rope has been subjected to overloading, either for its original strength (new rope) or for its remaining strength in the case of a used rope. Tension breaks frequently are caused by the sudden application of a load to a slack rope, thereby setting up incalculable impact stresses. Abrasion breaks typically have broken ends worn to a knife-edge thinness. Abrasive wear obviously is concentrated at points where the rope contacts an abrasive medium, such as the grooves of sheaves and drums, or other objects with which the rope comes into contact. Unwarranted abrasive wear indicates improperly grooved sheaves and drums, incorrect fleet angle, or other localized abrasive conditions. Wire breaks are usually transverse or square showing granular structure. Often these breaks will develop a shattered or jagged fracture, depending on the type of operation. Where fatigue breaks occur, the rope has repeatedly been bent around too small a radius. Whipping, vibration, slapping and torsional stresses will also cause fatigue. Fatigue breaks are accelerated by abrasion and nicking.



Easily noted by the wire's pitted surface, wire breaks usually show evidence of tension, abrasion and/or fatigue. Corrosion usually indicates improper lubrication. The extent of the damage to the interior of the rope is extremely difficult to determine; consequently, corrosion is one of the most dangerous causes of rope deterioration. Wire will be pinched down and cut at broken ends, or will show evidence of a shear-like cut. This condition is evidence of mechanical abuse caused by agents outside the installation, or by something abnormal on the installation itself, such as a broken flange.