Load Chart (Crane Capacity Chart)

Every crane is shipped with a load chart (also called a rated-capacity or lift chart) specific to that machine and configuration. It is a grid: down one axis the operating radius (the horizontal distance from the center of rotation to the load), across the other the boom length, with each cell giving the maximum rated load the crane may lift at that geometry. Charts are further divided by counterweight, outrigger extension, on-rubber vs. on-outriggers, and whether the lift is over the front, rear, or side.

The rated capacities in the chart already include the manufacturer's stability and structural safety factors, but those factors assume the crane is level, on firm ground, set up exactly as the chart specifies, and lifting a known weight with the correct rigging deductions taken. Operators must subtract the weight of the hook block, headache ball, slings, spreader bars, and any below-the-hook device from the chart figure to get the net liftable load.

As the load moves farther from the crane (greater radius) or the boom extends, rated capacity drops sharply — a crane that lifts 60 tons at a tight radius may be rated for only a few tons at full boom and maximum reach. Crossing into the shaded or no-lift zones of the chart, or operating beyond the chart's listed radius, is operating beyond rated capacity, a leading cause of crane tip-overs.

The load chart is also why a faded, water-damaged, or wrong-configuration chart in the cab is a common and serious inspection finding: without a legible chart matching the rigged configuration, the operator has no defensible way to know they are within rated capacity, and percent-of-chart is the number that drives critical-lift classification.