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

The deflection of a boom will cause the load to _____.

1. decrease the speed

2. increase the radius

3. decrease the radius

4. remain unchanged

The correct answer is: increase the radius

The deflection of a boom occurs when a load is applied, causing the boom to bend or sag under the weight. This deflection can lead to an increase in the effective radius at which the load is being lifted. As the boom deflects downward, the load moves further away from the pivot point of the crane, thereby increasing the horizontal distance from the center of the crane's rotation to the load. Considering this, when the boom deflects, the load position can actually shift outward, increasing the radius from the rotation center of the crane. This is a crucial component of crane operation because it affects the crane's stability and lifting capacity. Understanding this concept is essential for operators to ensure safe and efficient crane operation, as increased radius means that the crane may be more susceptible to tipping, requiring careful calculations to maintain safety margins.