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

What happens to the leverage of the load on a crane as the boom is being lowered?

1. It increases

2. It decreases

3. It stays the same

4. It depends on the weight of the load being lifted

The correct answer is: It increases

When a crane's boom is lowered, the leverage exerted by the load is impacted by the angle of the boom relative to the ground. As the boom lowers, the horizontal distance from the crane's pivot point (the base) to the load decreases. This reduction in distance leads to a decrease in leverage, as leverage in this context is essentially the ability of the load to create a moment or rotational force around the pivot point. While it's important to consider the interaction of weight and boom angles, the primary factor when lowering the boom is the decreasing horizontal distance to the load. Therefore, as the boom lowers, the leverage on the crane decreases, making it easier for the crane to manage the load without overstressing the system.