The operating radius is defined as...

• A. Distance from the base of the crane to the load.
• B. Vertical distance from the ground to the center of gravity of the load.
• C. Distance from the center of rotation to the center of gravity of the load when the boom is loaded.
• D. Height from the center of rotation to the top of the load.

Answer: (C)

The operating radius is the horizontal distance from the crane’s center of rotation to the load’s center of gravity when the boom is loaded. This distance matters because it is the lever arm that the load’s weight creates about the crane’s rotation point. The larger this radius, the greater the tipping moment, which directly affects stability and the crane’s lifting capacity in that configuration. So the radius isn’t about how high the load sits or how far the base is from the load; it’s about how far the load’s weight acts from the crane’s rotation axis, measured to the load’s CG in the configuration being used. The other descriptions describe vertical heights or base-to-load distances that don’t capture the motion about the rotation point and the actual moment produced by the load.