What happens to the rated capacity as the radius increases?

As the radius increases, the rated capacity of the crane generally decreases due to the principles of leverage and the mechanical advantage involved in lifting loads. When a load is lifted further away from the crane's center of rotation (which is essentially what increasing the radius entails), the crane has to work harder to maintain stability and control. This is due to the increased moment arm created by the distance from the center, which in turn increases the risk of tipping or overloading the crane.

Consequently, manufacturers provide specific ratings for cranes that take into account the load radius. As you extend the boom or the reach of the crane, the maximum weight it can safely lift and hold diminishes to ensure safe operation and prevent accidents. Understanding this dynamic is crucial for operators to ensure they are working within the crane's capabilities and maintaining safety standards in lifting operations.