Definitions
Wire Rope safety dedication
Working Load Limit (WLL)
The working load limit is the maximum load that must be applied to the product, even when the product is new and when the load is applied uniformly – straight line traction only. Avoid side loading. All catalog classifications are based on typical environmental conditions and unusual conditions, such as extremely high or low temperatures, chemical solutions or vapors, prolonged immersion in salt water, etc., should be taken into account. Never exceed the working load limit.
Test Load (Proof Load)
The term “proof test” designates a quality control test applied to the product for the sole purpose of detecting defects in material or workmanship. The proof test load (generally two times the working load limit) is the load that the product withstood without deformation when new and under laboratory test conditions. A constantly increasing force is applied in a direct line to the product at a uniform speed in a standard tensile testing machine. Test load testing does not mean that the working load limit should never be exceeded.
Breaking Strength / Maximum Strength
Do not use breaking strength as a criterion for service or design purposes. See Working Load Limit instead. Breaking strength is the average force at which the product, in the condition in which it would leave the factory, has been found to break by representative tests, when a constantly increasing force is applied in a direct line to the product at a uniform speed in a standard tensile testing machine. Proof testing at twice the working load limit does not apply to hand spliced slings. Remember: Breakdown Strengths, when published, were obtained under controlled laboratory conditions. The breaking strength listing does not mean that the working load limit should ever be exceeded.
Design factor (sometimes called safety factor)
An industry term is usually calculated by dividing the catalog Breaking Strength by the catalog workload limit and is usually expressed as a ratio. For example: 5 to 1.
Shock load
A load resulting from a rapid change of motion, such as impact, shaking, or swinging a static load. The sudden release of tension is another form of shock loading. Shock loads are generally significantly greater than static loads. Any shock loading must be considered when selecting the item for use in a system. Avoid shock loads as they may exceed the working load limit.