Glossary

Minimum Breaking Load (MBL) is the lowest load at which a product is expected to fail (break) when tested to the applicable standard, based on the manufacturer’s rating. It represents a strength threshold, not a recommended working load, and it is typically used as the basis for establishing the Working Load Limit (WLL) by applying a required design factor (for example, WLL = MBL ÷ design factor, when that approach is specified).

MBL is commonly stated for wire rope, chain, slings, synthetic rope, and rigging hardware, and it assumes proper configuration and test conditions. The actual breaking load in a specific test may be higher than the minimum value, but ratings and safety calculations are built around the minimum to ensure consistency. Because configuration and loading conditions matter, MBL can be reduced effectively by factors such as knots, sharp bends (D/d), termination efficiency, wear, corrosion, temperature, shock loading, side loading, or improper thread engagement—which is why WLL and application rules must be followed even if the published MBL looks high.

AKA: Minimum Breaking Strength (MBS), Breaking Load Limit (BLL)