The D/d ratio in rigging refers to what?

The D/d ratio in rigging refers to what?

• A. The ratio between the curvature taken by the sling, D, and the diameter of the wire rope, synthetic rope or chain
• B. The ratio of load weight to rope diameter
• C. The distance between hoist and load
• D. The duty cycle of the hoist

Answer: (A)

The main idea here is how the bend the sling makes relative to its own diameter affects its performance. The D/d ratio compares the curvature diameter the sling follows (D) to the sling’s diameter (d). A larger bend radius (larger D relative to d) means the sling is bent more gently, putting less stress on the fibers at the bend. A tighter bend (smaller D relative to d) concentrates stress where the sling is wrapped, increasing wear and the potential for damage or reduced strength at the bend. This ratio helps you decide if the bend is safe or if you need a larger radius, padding, or a different sling arrangement. It isn’t about load to rope diameter, the distance between hoist and load, or the hoist’s duty cycle.

The main idea here is how the bend the sling makes relative to its own diameter affects its performance. The D/d ratio compares the curvature diameter the sling follows (D) to the sling’s diameter (d). A larger bend radius (larger D relative to d) means the sling is bent more gently, putting less stress on the fibers at the bend. A tighter bend (smaller D relative to d) concentrates stress where the sling is wrapped, increasing wear and the potential for damage or reduced strength at the bend. This ratio helps you decide if the bend is safe or if you need a larger radius, padding, or a different sling arrangement. It isn’t about load to rope diameter, the distance between hoist and load, or the hoist’s duty cycle.