Sling Angle & Tension Calculator
Calculation Results
Load Angle Factor (LAF):
Tension Per Sling:
Understanding Sling Angles and Tension
In rigging and lifting operations, the angle at which a sling is attached to a load significantly affects the amount of tension placed on that sling. As the angle between the sling and the horizontal decreases, the tension on each individual leg increases. This is known as the Load Angle Factor.
The Physics of Rigging Angles
When you lift a load vertically (90 degrees from horizontal), each sling carries exactly its share of the weight. However, as the slings spread out to reach attachment points, they must fight both gravity (vertical force) and the horizontal tension pulling inward. This combined force means a sling might be required to hold much more than the actual weight of the load.
Load Angle Factor (LAF) Table
| Angle (Horizontal) | Load Angle Factor | Tension Increase |
|---|---|---|
| 90° | 1.000 | 0% |
| 60° | 1.155 | ~15% |
| 45° | 1.414 | ~41% |
| 30° | 2.000 | 100% (Double weight) |
The Calculation Formula
To calculate the tension on a specific sling leg, use the following formula:
Real-World Example
Imagine you are lifting a 5,000 kg generator using 2 slings at a 45-degree horizontal angle.
- Divide weight by number of slings: 5,000 / 2 = 2,500 kg per leg (vertical share).
- Identify the Load Factor for 45°: 1.414.
- Calculate tension: 2,500 kg × 1.414 = 3,535 kg.
Even though the generator only weighs 5,000 kg, each sling must be rated for at least 3,535 kg because of the angle. Failure to account for this is a leading cause of rigging accidents.