Which factor decreases as the number of rope layers increases on a drum?

As the number of rope layers on a drum increases, the allowable line pull decreases primarily due to the increased friction between the layers of rope and the drum itself. When more layers are added, the inner layers become tighter and exert more friction against each other, which can lead to a lower capacity to manage the load effectively. This reduction in allowable line pull is crucial for crane operators to understand, as it impacts the safe lifting and handling of loads.

The diameter of the drum does not change with additional layers of rope. Instead, it remains constant, although the effective diameter might vary depending on the number of layers. The cable length also does not necessarily decrease with additional layers; in fact, it might increase as more rope is coiled onto the drum. Lastly, the load capacity of the crane itself is influenced by many factors, but specifically regarding the layers of rope on a drum, it is the allowable line pull that is particularly affected. Thus, understanding the interaction of rope layers and the resulting friction is essential for safe crane operation.