If the horizontal sling angle decreases, what happens to the rated capacity?

If the horizontal sling angle decreases, what happens to the rated capacity?

• A. Increases
• B. Decreases
• C. Remains the same
• D. Cannot be determined

Answer: (B)

When a load is supported by two sling legs, the weight is shared between the legs, and how much each leg must carry depends on the angle the legs make with the horizontal. If the horizontal angle gets smaller, the legs are more spread out and closer to horizontal, so each leg must carry more tension to hold the same weight. Since the sling has a maximum safe tension, increasing that tension means the safe, or rated, load must be reduced. In practical terms, the smaller the horizontal sling angle, the lower the rated capacity. A quick way to see it: for a weight supported by two legs at angle φ to the horizontal, the vertical support is 2 T sin φ, so T = W/(2 sin φ). As φ decreases, sin φ decreases, T rises, and the maximum W you can lift safely goes down.

When a load is supported by two sling legs, the weight is shared between the legs, and how much each leg must carry depends on the angle the legs make with the horizontal. If the horizontal angle gets smaller, the legs are more spread out and closer to horizontal, so each leg must carry more tension to hold the same weight. Since the sling has a maximum safe tension, increasing that tension means the safe, or rated, load must be reduced. In practical terms, the smaller the horizontal sling angle, the lower the rated capacity.

A quick way to see it: for a weight supported by two legs at angle φ to the horizontal, the vertical support is 2 T sin φ, so T = W/(2 sin φ). As φ decreases, sin φ decreases, T rises, and the maximum W you can lift safely goes down.