What happens to the effective strength of a wire rope when bent over a small diameter sheave?

• A. It remains the same
• B. It increases
• C. It decreases significantly
• D. It can become stronger

Answer: (C)

When a wire rope is bent over a small diameter sheave, its effective strength decreases significantly. This occurs due to the bending stress exerted on the wire strands as they wrap around the sheave. Sharp bends result in individual wire strands experiencing increased fatigue and potential damage because the outer strands are stretched while the inner strands are compressed.

The decreased effective strength can be attributed to several factors, including the alteration of the distribution of forces within the rope and the increase in wear and tear due to friction against the sheave. Over time, this can lead to a premature failure of the rope, making it crucial to avoid sharp bends or to use sheaves with larger diameters whenever possible to maintain the health and integrity of the wire rope.

Thus, the correct choice reflects the understanding of how bending affects the material properties of wire rope, emphasizing the importance of proper rigging techniques to ensure safety and operational efficiency.