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

What effect does the deflection of a boom have on the load?

1. It side loads the boom

2. It decreases the radius

3. It increases the radius

4. It has no effect

The correct answer is: It increases the radius

The deflection of a boom when a load is applied causes a change in the effective radius from the center of rotation to the load. As the boom deflects—often due to the weight or dynamic effects of the load—this deflection effectively increases the distance of the load from the pivot point of the crane, leading to a longer radius. Understanding this behavior is crucial for crane operation, as an increased radius can also affect the stability and load capacity of the crane. The operator must be aware that as the boom deflects, the dynamics of lifting change, which can lead to increased leverage against the crane's base, necessitating adjustments in operations to maintain safety and efficiency.