The D/d ratio is calculated using which measurements?

The D/d ratio is calculated using which measurements?

• A. The curvature of the sling and the rope/chain diameter
• B. Load weight and hoist speed
• C. Number of rigging points and sling length
• D. Distance between hoist and load and rope type

Answer: (A)

The key idea is how sharply the rope or chain is bent as it passes around a support. The D/d ratio is found by taking the diameter of the curvature (the sheave, pulley groove, or contact radius the rope wraps around) and dividing it by the diameter of the rope or chain. This tells you how severe the bend is: a larger ratio means a gentler bend with less wear on the rope, while a small ratio indicates a tight bend that can cause extra wear or damage. Other factors like load weight, hoist speed, number of rigging points, sling length, or rope type don’t determine this geometric ratio.

The key idea is how sharply the rope or chain is bent as it passes around a support. The D/d ratio is found by taking the diameter of the curvature (the sheave, pulley groove, or contact radius the rope wraps around) and dividing it by the diameter of the rope or chain. This tells you how severe the bend is: a larger ratio means a gentler bend with less wear on the rope, while a small ratio indicates a tight bend that can cause extra wear or damage. Other factors like load weight, hoist speed, number of rigging points, sling length, or rope type don’t determine this geometric ratio.