Load Charts, Capacity, and Configuration
This domain rewards precision. A candidate must be able to locate the correct chart for the machine's configuration-boom length, jib, counterweight, outrigger or track setting, and whether the chart is for lifting or for travel-then read capacity at the actual radius, measured horizontally from the crane's rotation center to the load's center of gravity. Understand that radius changes as the boom is raised or lowered and as the load swings, so the governing radius is the worst case during the lift.
Know the deductions that reduce net capacity: rigging and hook block weight, jib and auxiliary head, and any special attachments. Understand the meaning of structural versus stability limits, and why a chart may show different values for the same radius depending on boom angle or quadrant of operation. Area-of-operation charts and on-rubber versus on-outrigger charts are frequent topics.
Traps: reading radius to the boom tip instead of the load line; using the boom length you intended rather than the one installed; forgetting to deduct rigging; interpolating between chart values when the manufacturer forbids it; and applying an on-outrigger chart while traveling. Another trap is assuming a chart's capacity is available through 360 degrees when only certain quadrants are rated.
Rule of thumb: chart the lift at the largest radius and lowest capacity point the load will reach, with all deductions applied. If the load will travel, use the travel chart.
Worked example: chart capacity at 50 ft radius is 6,000 lb. Rigging weighs 400 lb and the jib deduction is 300 lb. Net available is 5,300 lb; a 5,500 lb load is over capacity even though it is below the raw chart number.