Tech-Info 09.1: Breaking strength

The calculated breaking strength of a wire rope is defined as the metallic cross-section of a wire rope (as the sum of the individual cross-sections of all the wires that make up a wire rope) multiplied by the nominal strength of the wires in the rope. The minimum breaking load of the wire rope is the calculated breaking load of the rope multiplied by the strand factor. The actual or real breaking load of a wire rope is the breaking load found in a breaking test of this rope. For a new wire rope, an actual breaking load must always be achieved; if a wire rope is not flexible enough, it must be forced to bend around a sheave of a specified diameter. This reduces the bending fatigue strength of the rope. Which is as high or higher than the minimum breaking load. The breaking load of a wire rope can be increased by increasing the metal cross-section in the rope, for example, by using strands with higher fill factors, by compacting the strands, by hammering the rope. Breaking strength can also be increased by increasing the tensile strength of the individual wires or by increasing the strand factor. The latter can be achieved, for example, by improving the contact surfaces between the rope elements or by using a plastic insert.