Tree Work
Lift Angle Force Multiplier
When you lift with two sling legs, the angle between them changes the tension in each leg. A 60° spread doubles the load per leg vs a vertical lift. Enter the load and angle from horizontal.
Force per sling leg (lb)
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- Angle multiplier
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- Total system stress
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- Required sling WLL each (lb)
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FAQ
What is sling angle? +
The angle each sling leg makes from horizontal. A 90° (vertical) lift puts half the load on each leg. As the angle drops toward 0° (legs more horizontal), tension multiplies dramatically.
Crosby angle multipliers? +
90° = 1.000, 60° = 1.155, 45° = 1.414, 30° = 2.000. At 30°, each leg carries the entire load weight. Below 30° is generally unsafe with normal slings.
When does this matter most? +
Choker rigging and basket hitches around odd-shaped pieces where you cannot get a steep sling angle. Always pick the WLL based on the actual angle you will use, not the rated capacity at 90°.