Multi-Leg Sling Load per Leg
The tension in each sling leg of a multi-leg lift.
Example
You enter
- Total load (lb) 8000
- Number of sling legs 4
- Leg angle from horizontal (deg) 60
You get
- Tension per leg (conservative) 4618.8
- Equal-share reference 2309 lb
- Load factor (1/sin) 1.1547
- Share legs 2
Checked against published worked examples from: ASSP Professional Safety (Mitch Ricketts).
Details, formula, and sources
ScopePer ASME B30.9, a rigid load on 3 or more legs is assumed to hang from only 2, so the conservative tension divides the load over 2 legs and then by sin(angle from horizontal), with an equal-share reference and the 1/sin load factor. The qualified rigger and the sling tag govern.
Formula or tableshare_legs = (num_legs >= 3) ? 2 : num_legs; tension_per_leg = (total_load / share_legs) / sin(angle); load_factor = 1/sin(angle); equal-share reference = (total_load / num_legs) / sin(angle).
Source and editionASME B30.9 (Slings) by section; classical sling statics, no edition cycle.
Free accessThe statics are public; the qualified rigger and the sling's tag rating govern.
What governsEstimate. Head rigger and manufacturer working-load-limit charts govern. Inspect every piece of hardware before the show.
API field namestotal_load_lb, num_legs, horizontal_angle_deg, tension_per_leg_lb, equal_share_lb, load_factor, share_legs
- Two-leg rule per ASME B30.9 a rigid load on 3 or more legs is assumed to hang from only 2; the conservative tension divides over 2 legsASME B30.9
- Equal-share reference the equal-share value is reference only; do not use it unless an engineer qualifies a true equal-share liftASME B30.9
- Angle the load factor 1/sin(angle from horizontal) grows fast as the angle flattens (1.155 at 60 deg, 2.0 at 30 deg)first principles