For load-hoisting sheaves, the pitch diameter must be at least how many times the nominal diameter of the rope?

The correct answer is that the pitch diameter must be at least 18 times the nominal diameter of the rope. This requirement is crucial for ensuring that the sheaves are adequately sized to handle the rope under load without causing excessive wear or damaging the rope itself.

The pitch diameter is a key factor in the performance of the rope and sheave system. A larger pitch diameter relative to the rope diameter helps to reduce the bending stress on the rope as it travels over the sheaves. This reduction in stress is essential for prolonging the life of the rope and ensuring safe operation, as tighter bends can lead to abrasion, fatigue, and ultimately rope failure.

By adhering to this minimum ratio, operators can achieve smoother operation and maintain the overall integrity and safety of the crane's load-handling capabilities. Ensuring the correct pitch diameter promotes optimal performance and enhances safety standards in crane operation.