Technical terms

Break load (BL)

Also called “breaking load”. Maximum force under direct tension that a rope can be subjected to before it breaks. The break load is indicated in daN or kN.

Break elongation

Maximum elongation before the rope breaks. Break elongation is indicated in %.

Break length

Also called “strength to weight ratio”. Refers to the length of a fibre, rope, etc. at which its own weight is equal to the break load. In other words, when the rope would break under its own weight. This allows a comparison of break load and weight to be made between various ropes and rope diameters.

cN / daN / kN

Newton (N) is the unit of force 1 cN = 0.00102kg 1 daN = 1.0197kg 1 kN = 101.97kg


Creep indicates the time and temperature dependent deformation or lengthening under load. As synthetic materials are made of large, in the case of thermoplastics and elastomers, entangled molecule chains, these glide or disentangle under external load by which irreversible elongation occurs. This means that such ropes increase in length and will not return to the original length even when the load is removed (such as with HMPE ropes).


dtex is the expression of weight in grams for filaments, yarns or twines of 10,000m length (g/10,000m). The higher the dtex number, the thicker the filament, yarn or twine.

Elastic modulus

The relationship between tenacity and elongation. The lower the elongation under load, the higher the elastic modulus.


Elongation indicates by how much the rope will stretch under load. Unit of elongation is indicated in %.

Safe Working Load (SWL)

The usual working load of a rope in use. The working load is determined depending on the type of application. In most applications, 1/5th the break load is customary.

Specific tensile load

Refers to the maximum tensile force that can be subjected to a filament, yarn or twine before it comes to a break. It enables a direct comparison to be made between filaments, yarns and twines of varying fineness. The unit of measurement is cN/dtex.

Working Load Limit (WLL)

The maximum weight / strength a fibre rope can be subjected to in general use.