Crane Net Capacity After Deductions
Net capacity for the hook after the load-chart deduction stack...
Example
You enter
- Gross chart capacity at radius (lb) 30000
- Hook block / overhaul ball (lb) 800
- Wire-rope deduction (lb) 400
- Below-the-hook gear (lb) 600
- Load weight (lb) 22000
You get
- Net capacity for the hook 28800 lb
- Total hook load 22600 lb
- Percent of net 78.5%
Checked against published worked examples from: OSHA 1926.1417(o) / ASME B30.5.
Details, formula, and sources
ScopeNet capacity for the hook after the load-chart deduction stack (hook block, jib, wire rope; ASME B30.5 and the manufacturer's chart notes), the total hook load, the percent of net, and the 75 / 90 / 100 percent flags. The manufacturer's load chart governs.
Formula or tablenet = gross_chart - hook_block - jib - wire_rope; total_hook = load + below_hook; pct_of_net = total_hook / net x 100; flags at 75 / 90 / 100%.
Source and editionASME B30.5 (Mobile and Locomotive Cranes) and the manufacturer's load-chart notes by name for the deductions; OSHA 29 CFR 1926.1417(o) for the rule against exceeding rated capacity. Arithmetic on chart numbers.
Free accessOSHA 1926 Subpart CC is free at osha.gov. The capacity numbers come from the manufacturer's load chart.
What governsEstimate. Head rigger and manufacturer working-load-limit charts govern. Inspect every piece of hardware before the show.
API field namesgross_chart_lb, hook_block_lb, wire_rope_lb, below_hook_lb, load_weight_lb, net_capacity_lb, total_hook_lb, pct_of_net
- Deduction stack hook block / overhaul ball, erected jib, and wire-rope deduction per the chartmanufacturer load-chart notes / ASME B30.5
- Flags 75% critical / engineered, 90% margin gone, 100% over chart (STOP)rigging planning practice