A crane's sheave groove is measured, and its diameter is found to be 52 mm for a 50 mm wire rope. The maximum allowable sheave groove diameter for a new rope is 1.03 times the rope's nominal diameter. What is the condition of this sheave according to CSA Z150, and what action is required?

Question: A crane's sheave groove is measured, and its diameter is found to be 52 mm for a 50 mm wire rope. The maximum allowable sheave groove diameter for a new rope is 1.03 times the rope's nominal diameter. What is the condition of this sheave according to CSA Z150, and what action is required?

Answer options:

• The sheave is acceptable as it's within the tolerance for a new rope.
• The sheave is acceptable; the tolerance is for worn rope, not new rope. ✅ The sheave groove is too large, promoting excessive rope wear and early retirement.
• The sheave groove is too small, pinching the rope and causing abrasion.

Correct answer: The sheave groove is too large, promoting excessive rope wear and early retirement.

Explanation: CSA Z150, Clause 5.2.2.3, typically specifies that the sheave groove diameter should be between 1.00 and 1.03 times the nominal rope diameter for new rope. A 52 mm groove for a 50 mm rope results in a ratio of 1.04, which exceeds the maximum allowable of 1.03. An oversized sheave groove allows the rope to flatten and wear excessively, significantly reducing its lifespan and creating a safety hazard. This sheave requires replacement or re-machining.