Manufacturers' Load Charts: Configuration, Radius, and Deductions
Manufacturers' Load Charts
The Load Charts domain tests whether you can find the correct capacity for the actual machine configuration and subtract everything hanging below the boom.
Chart rules
- Capacity depends on outrigger configuration, boom length, boom angle/radius, quadrant (over front, side, or rear), jib stowed or deployed, counterweight, and attachments.
- Radius is the horizontal distance from the center of rotation to the center of the load. For a jib, use the jib radius, not the main boom tip.
- Deduct the hook block, slings, spreader bars, jib, auger, basket, and any load-handling device from the gross chart capacity.
- Use the chart row for the actual radius. If the radius falls between rows, use the next longer radius-the lower capacity-unless the manufacturer explicitly permits interpolation.
- Confirm the notes: some charts prohibit lifting over certain quadrants or require full outrigger extension.
Worked example: Chart for a 22 ft boom, outriggers fully extended, over the side: 12 ft = 6,000 lb; 15 ft = 4,800 lb. The load is 4,200 lb and rigging is 300 lb, so gross = 4,500 lb. At a measured 14 ft radius, use the 15 ft row: 4,800 lb capacity. 4,500 < 4,800, so the lift is acceptable-provided the quadrant and outrigger configuration match the chart.
Traps: reading radius to the boom tip instead of the load, forgetting the jib or hook block weight, using an on-rubber chart while set on outriggers, mixing boom lengths, and ignoring a “boom over front only” note.