What is the total sling stress for the four-point lift described in the second scenario (7750 LBS load)?

• A. 11200 LBS
• B. 11450 LBS
• C. 11624 LBS
• D. 12000 LBS

Answer: (C)

In a four-point lift, the total sling stress comes from the sum of the tensions in all four slings. If the slings are identical and each makes an angle θ with the vertical, the vertical components of the four sling tensions must support the load: 4 T cos θ = W. The total sling stress is the sum of all four tensions, which is 4T, so it can be written as W / cos θ.

For the given load of 7750 lb and the described geometry, the total sling stress works out to 11624 lb, which implies cos θ ≈ 7750 / 11624 ≈ 0.667 (about 48 degrees from vertical). So, the total sling stress is W / cos θ = 11624 lb. This shows why angled slings carry more load collectively than simply dividing the load equally among four vertical legs. If the angles were smaller, total sling stress would be closer to 7750 lb; if larger, it would be greater.