Bergen Cable and the adverse effects of bending wire rope

Wire rope and cable are available from Bergen.

In addition to the company’s broad selection of industrial cable solutions, customers rely on Bergen Cable for its inventory of wire rope. Not only does the Bergen team provide quality products – it also serves as a crew of experts who advise clients on how to get the most out of them. The Bergen website includes ample resources about using cable and wire rope properly, for instance. This includes a guide to the risks of bending wire rope.

Bending around sheaves or drums

According to Bergen’s online guide, wire rope is often subject to bending around sheaves or drums, and its usefulness may depend on the sheave and drum locations. As wires and strands slide on each other during bending, wire rope should always be lubricated properly to make it effective around these areas.

Loss of rope strength can result from the inability of wires and strands to adjust to changed positions when users bend wire rope. Strength often decreases to a substantial degree when the sheave diameter gets smaller relative to rope diameter, and the strength loss from bending over sheaves is usually around four per cent. Even when within the wire’s elastic limit, repeated flexing of wires develops bending loads that set up points of stress concentration.

Another frequent result of bending wire rope is fatigue, which appears in the form of small cracks in the wires at over-stressed foci. These propagate under repeated stress cycles until the last sound metal cannot handle the bending load, and this results in broken wires that exhibit no sign of cross-section contraction, according to Bergen.

It is impossible to figure out the smallest size of sheave or drum that allows the most effective wire-rope performance, as various factors affect the lifespan of this product. With slow speeds and light loads, smaller sheaves and drums can be employed without resulting in premature fatigue, while reverse bends – i.e., bending wire rope in one direction and then bending it in the opposite direction – may lead to high, premature fatigue. Larger sheaves will be required if the application needs reverse bends.

To learn more, contact Bergen.

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