National Commission for the Certification of Crane Operators (NCCCO) Mobile Crane Practice Exam

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Prepare for the National Commission for the Certification of Crane Operators Mobile Crane Test. Utilize engaging flashcards and multiple-choice questions, complete with hints and explanations. Maximize your chances of passing the exam!

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The pitch diameters of load hoist sheaves and boom tip sheave must be at least how many times the nominal diameter of the rope used?

The correct answer is: 18

The correct answer is 18. This requirement is grounded in the need to ensure that the bending stresses on the rope are minimized during operation. When the pitch diameter of the sheave is significantly larger than the rope's nominal diameter, it reduces the sharpness of the bend that the rope experiences as it passes around the sheave. This is crucial for prolonging the life of the rope and ensuring safe operation. Using a pitch diameter that is at least 18 times the nominal diameter of the rope helps to maintain a smooth operation and minimizes wear and tear on both the rope and the sheaves. This standard is often established by industry best practices and manufacturer recommendations to enhance safety and efficiency in crane operations. Understanding this ratio is important for operators and maintenance personnel, as it directly impacts the longevity of the equipment and the safety of the load being lifted.