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Crane Operator Certification Exam Prep · Question

What does the D/d ratio refer to in the context of wire rope slings?

The D/d ratio is the ratio of the diameter of the sheave, pin, or bearing surface (D) to the nominal diameter of the wire rope (d). This ratio is crucial as per

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Question: What does the D/d ratio refer to in the context of wire rope slings?

Answer options:

  • The crane's designated capacity to the dynamic load. ✅ The diameter of the bearing surface to the diameter of the wire rope.
  • The deflection of the boom to the distance of the load.
  • The total depth of the load to the width of the load.

Correct answer: The diameter of the bearing surface to the diameter of the wire rope.

Explanation: The D/d ratio is the ratio of the diameter of the sheave, pin, or bearing surface (D) to the nominal diameter of the wire rope (d). This ratio is crucial as per CSA Z150 for preventing premature wear and strength loss in wire rope slings due to bending stress.

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