When setting up the crane with three outriggers fully extended and one halfway, what must the operator utilize?

Using the "On rubber" load chart is essential when setting up a crane with three outriggers fully extended and one halfway. This situation indicates that the crane is not operating on full outrigger support, which affects its stability and lifting capabilities.

The "On rubber" load chart is specifically designed to guide operators regarding safe lifting capacities when the crane is on its wheels rather than fully supported on outriggers. It provides the necessary information to ensure that the crane can perform lifts safely even when one outrigger is not fully extended, as it accounts for the reduced stability that comes with being partially distributed on rubber tires instead of a full four-outrigger setup.

This load chart helps to prevent potential accidents by ensuring that the operator only lifts loads within the safe capacity limits specified for that configuration. In situations where the outriggers are not all deployed, relying on the standard load chart or the "Off rubber" load chart would not be appropriate, as those do not consider the crane's specific configuration and the resultant stability dynamics.