If two slings lift a load and the legs form a wider angle with vertical, the load in each sling will do what?

• A. Decreases
• B. Stays the same
• C. Increases
• D. Varies with angle

Answer: (C)

When two slings share a lift, the tension in each sling depends on how far the legs are from vertical. The vertical components of the two sling tensions must add up to the load, so 2T cos(theta) = W, where theta is the angle between a sling leg and the vertical. Solve for T: T = W / (2 cos(theta)). As the angle with vertical increases (legs form a wider angle), cos(theta) decreases, so T must increase to keep the same load. So the load carried in each sling increases with a wider angle. For example, with the same weight, a small angle gives about half the weight per sling; a larger angle requires much more tension in each sling.