During rigging, increasing the angle of the sling legs away from vertical causes the force in each sling to do what?

During rigging, increasing the angle of the sling legs away from vertical causes the force in each sling to do what?

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

Answer: (D)

When two sling legs share a load, the upward support comes from the vertical components of each leg’s tension. If the legs are vertical, each sling carries half the weight. As you move the legs away from vertical, the vertical component per leg is T cos theta, so to keep the same load W the relationship 2 T cos theta = W must hold. Solving gives T = W / (2 cos theta). Since cos theta decreases as the angle increases, the required tension in each sling rises. Therefore, increasing the angle away from vertical causes the force in each sling to increase.

When two sling legs share a load, the upward support comes from the vertical components of each leg’s tension. If the legs are vertical, each sling carries half the weight. As you move the legs away from vertical, the vertical component per leg is T cos theta, so to keep the same load W the relationship 2 T cos theta = W must hold. Solving gives T = W / (2 cos theta). Since cos theta decreases as the angle increases, the required tension in each sling rises. Therefore, increasing the angle away from vertical causes the force in each sling to increase.