Outrigger reaction
Also called Outrigger load
The vertical load transmitted through an individual outrigger to the ground, which varies with the crane’s configuration, the load being lifted, and the radius at which it is working. Outrigger reactions, taken from the crane’s load chart, are the starting figures used to size mats or pads for a specific lift.
In practice
This is the number that starts the whole ground bearing chain, and it is the one most often supplied second-hand. It belongs to a specific machine in a specific configuration at a specific radius and slew position — change the counterweight fitted, the outrigger extension or where the boom is pointing and it changes with them. A reaction quoted without its configuration is not usable.
Where this comes from: Standard lift planning practice: reactions are read from the manufacturer’s data for the machine and configuration, not estimated from its weight.
Where it matters on site
Ask for the governing reaction — the worst-loaded foot at the worst slew position for the planned lift — rather than a typical or average figure. That single number, with the allowable ground bearing pressure, is what a mat is sized against; supply both and a mat can be specified in minutes, supply neither and any answer given is a guess with a company name on it.