What is the recommended D/d ratio for wire rope sheaves?

Prepare for the NWSA TTT-2 exam. Study fall protection, rigging standards with flashcards, and multiple-choice questions, each with hints and explanations. Ace your test!

The recommended D/d ratio for wire rope sheaves is 20:1. This ratio indicates that the diameter of the sheave (D) should be at least twenty times the diameter of the wire rope (d) being used. This guideline is critical for ensuring proper bending of the rope as it passes over the sheave.

When the sheave diameter is too small in relation to the wire rope diameter, it can lead to increased wear on the rope, potential flattening of the strands, and ultimately result in reduced lifespan or failure of the rope. A 20:1 ratio helps maintain a gentle curve for the wire rope, significantly reducing stress and fatigue, which improves the overall safety and efficiency of rigging and lifting operations.

Using a proper D/d ratio is essential in telecommunications tower work and other rigging scenarios to uphold safety standards and ensure the integrity of the equipment being utilized.

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