What defines the working radius of a crane?

The working radius of a crane is defined as the distance from the center of rotation (or pivot point) of the crane to the center of the load being lifted. This measurement is crucial because it directly impacts the crane's stability, lifting capabilities, and operational safety. As the working radius increases, the load that the crane can safely lift decreases due to the increased leverage and potential for tipping. Understanding the working radius ensures that operators can safely manage loads within the crane's specifications and prevents accidents that may arise from overextending the machine's capacity.

Considering the context of the other options, the boom length describes only the size of the crane's arm and doesn't take into account where the load is positioned relative to the crane's pivot point, which is essential for defining the working radius. The distance from the load to the operator and the height of the load above the ground are also not relevant measures for determining the working radius since they do not involve the crane’s operational mechanics in terms of stability and load management.