What is the recommended proven load ratio for planning rope routing over sheaves?

What is the recommended proven load ratio for planning rope routing over sheaves?

• A. 5 to 1
• B. 20 to 1
• C. 2 to 1
• D. 50 to 1

Answer: (B)

When you route a rope over sheaves, the turn in the path, plus any sudden movement or acceleration of the load, can push the tension in the rope higher than the static load. A proven load ratio is used to estimate that peak tension and ensure the entire rig—rope, pulleys, and anchors—has enough headroom. Twenty to one is the standard guideline because it comes from field-tested experience and accounts for deflection, friction, and dynamic loading when the rope is redirected. This ratio gives a safe, practical margin without being overly conservative. Using smaller ratios would risk underestimating peak forces, while much larger ratios would be unnecessarily restrictive and costly. Therefore, twenty to one is the recommended approach for planning rope routing over sheaves.

When you route a rope over sheaves, the turn in the path, plus any sudden movement or acceleration of the load, can push the tension in the rope higher than the static load. A proven load ratio is used to estimate that peak tension and ensure the entire rig—rope, pulleys, and anchors—has enough headroom. Twenty to one is the standard guideline because it comes from field-tested experience and accounts for deflection, friction, and dynamic loading when the rope is redirected. This ratio gives a safe, practical margin without being overly conservative. Using smaller ratios would risk underestimating peak forces, while much larger ratios would be unnecessarily restrictive and costly. Therefore, twenty to one is the recommended approach for planning rope routing over sheaves.