Center of Gravity from Two Scales
Total weight, CG distance, and the load split from a two-point weigh by moment balance (ASME B30.9 / ITI rigging).
Example
You enter
- Mode two-scale-weigh
- Reading at point 1 (lb) 3000
- Reading at point 2 (lb) 1000
- Distance between points (ft) 10
You get
- Total weight (lb) 4000
- CG from point 1 (ft) 2.5
- Percent at 1 75
Details, formula, and sources
Two-scale weigh: W = S1 + S2; CG distance from point 1 = S2*L / (S1+S2) (moment balance); percent at each point = S_i / W. Inverse solves the reading each pick point would see from a known total weight and CG.
Center of gravity from a two-point weigh by moment balance (x = S2*L / (S1+S2)), per the standard rigging practice in the ASME B30.9 / ITI rigging references, by name; first-principles statics.
First-principles statics. A field aid - the lift plan, the rated rigging, and the qualified rigger / lift director govern.
Estimate. Head rigger and manufacturer working-load-limit charts govern. Inspect every piece of hardware before the show.
Field names used by the API: mode, reading_1_lb, reading_2_lb, span_ft, total_weight_lb, cg_from_point_1_ft, percent_at_1
- Two-point support the load rests on exactly two scales/pick points along one lineITI rigging handbook