How does the angle between sling legs affect the effective load capacity of a two-leg sling?

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Multiple Choice

How does the angle between sling legs affect the effective load capacity of a two-leg sling?

The main idea is that the load each leg must carry grows as the legs spread away from vertical. If the two legs are symmetric and each makes an angle theta with the vertical, the vertical components of the tensions add to the total load, so 2 times the leg tension times cos theta equals the load: 2 T cos theta = W. This gives T = W / (2 cos theta). As theta increases (the legs angle more from vertical), cos theta decreases, so the tension in each leg increases for the same load. Since each leg has a maximum allowable tension, the overall safe load the sling can lift becomes smaller as the angle grows. That’s why keeping the sling angles as small as practical yields higher capacity. This also clarifies why other choices aren’t correct: capacity doesn’t increase with angle, and the angle does matter—both vertical and horizontal components influence the tension. The horizontal angle between legs affects the same balance when legs are symmetric, so saying only the vertical angle matters or that horizontal angle has no effect isn’t accurate.

The main idea is that the load each leg must carry grows as the legs spread away from vertical. If the two legs are symmetric and each makes an angle theta with the vertical, the vertical components of the tensions add to the total load, so 2 times the leg tension times cos theta equals the load: 2 T cos theta = W. This gives T = W / (2 cos theta). As theta increases (the legs angle more from vertical), cos theta decreases, so the tension in each leg increases for the same load. Since each leg has a maximum allowable tension, the overall safe load the sling can lift becomes smaller as the angle grows. That’s why keeping the sling angles as small as practical yields higher capacity.

This also clarifies why other choices aren’t correct: capacity doesn’t increase with angle, and the angle does matter—both vertical and horizontal components influence the tension. The horizontal angle between legs affects the same balance when legs are symmetric, so saying only the vertical angle matters or that horizontal angle has no effect isn’t accurate.

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