Belt span is defined as the __________.

The definition of belt span as the distance between the points on the sheaves where the belt touches each sheave accurately reflects the operational characteristics of a belt drive system. This measurement is crucial for understanding how the belt interacts with the sheaves, as it directly affects belt tension, alignment, and the overall efficiency of power transmission.

Belt span is an important concept to grasp because it provides insights into the belt's working length and how it maintains contact with the sheaves during operation. This distance is critical for calculating the proper belt dynamics and ensuring that the belt maintains adequate tension to prevent slippage while minimizing wear.

In contrast, other definitions pertain to more specific aspects of a belt drive system. The sum of pitch diameters refers to a theoretical measurement related to gear ratios rather than direct belt interaction. The distance between the centers of the sheaves is relevant but does not encapsulate the specific point of contact crucial to belt performance. The width of the belt, while important for load capacity, does not define belt span in the context of its contact with the sheaves. Understanding these distinctions helps to clarify why the chosen definition is the most suitable one.