What is the difference between working radius and hook height?

• A. Working radius is the horizontal distance from the crane's rotation axis to the load CG, while hook height is the vertical distance from the ground to the hook.
• B. Both are horizontal distances.
• C. Hook height is horizontal; working radius is vertical.
• D. They are the same distance in all lifts.

Answer: (A)

The working radius is the horizontal reach of the crane from its rotation axis to the load’s center of gravity. The hook height, on the other hand, is the vertical distance from the ground up to the hook. These two measurements describe different directions of the lift: one is how far out the crane can extend the load, the other is how high the load will be above the ground.

They’re independent and change with different crane configurations. Extending the boom or changing the swing angle can increase the radius without changing how high the hook is, and vice versa. That’s why the two are not the same distance, and why the hook height can be quite different from the horizontal radius.

So the correct understanding is that the working radius is a horizontal distance from the crane’s rotation axis to the load CG, while the hook height is the vertical distance from the ground to the hook.