If you adjust the spreader to a smaller angle, what happens to the tension on the load?

If you adjust the spreader to a smaller angle, what happens to the tension on the load?

• A. Tension increases
• B. Tension decreases
• C. Tension stays the same
• D. Tension becomes unpredictable

Answer: (A)

When a load is supported by two lines from a spreader, how much each line must pull depends on the angle of the lines relative to the spreader bar (the horizontal). If the angle is small, the lines are more horizontal and contribute less vertical support. The vertical component of each line’s tension is T sin φ, where φ is the angle with the horizontal. The load W must equal the sum of these vertical components: 2 T sin φ = W, so T = W / (2 sin φ). As φ gets smaller, sin φ gets smaller, causing T to increase. In short, reducing the spreader angle makes the tension on the load higher.

When a load is supported by two lines from a spreader, how much each line must pull depends on the angle of the lines relative to the spreader bar (the horizontal). If the angle is small, the lines are more horizontal and contribute less vertical support. The vertical component of each line’s tension is T sin φ, where φ is the angle with the horizontal. The load W must equal the sum of these vertical components: 2 T sin φ = W, so T = W / (2 sin φ). As φ gets smaller, sin φ gets smaller, causing T to increase. In short, reducing the spreader angle makes the tension on the load higher.