What happens when wire rope is bent around a sheave or a hook?

What happens when wire rope is bent around a sheave or a hook?

• A. Nominal strength is reduced
• B. Load capacity increases
• C. Fatigue resistance improves
• D. Size remains the same

Answer: (A)

Bending wire rope around a sheave or hook creates bending stresses that reduce the rope’s effective strength. In a bend, the outer wires are stretched while the inner wires are compressed, so the load is carried by a nonuniform cross-section and the rated (nominal) strength, which assumes a straight length, drops. The tighter the bend relative to the rope diameter, the greater the reduction in strength. This is why nomial strength decreases when the rope is bent. The rope’s size doesn’t change, and bending does not increase load capacity or improve fatigue resistance—those ideas don’t align with how stresses and wear develop in curved rope sections.

Bending wire rope around a sheave or hook creates bending stresses that reduce the rope’s effective strength. In a bend, the outer wires are stretched while the inner wires are compressed, so the load is carried by a nonuniform cross-section and the rated (nominal) strength, which assumes a straight length, drops. The tighter the bend relative to the rope diameter, the greater the reduction in strength. This is why nomial strength decreases when the rope is bent. The rope’s size doesn’t change, and bending does not increase load capacity or improve fatigue resistance—those ideas don’t align with how stresses and wear develop in curved rope sections.