Technical description



Köysien venymäominaisuudet

From Rod to Rope

Teräsköyden valinta

Teräsköyden rakenne

Strand Lay

In a strand construction with several layers of wire of the same diameter the different layers cross each other (cross lay). In an strand construction with unequal wire diameters the layers of wires lie parallel to each other (equal or parellel lay).

In equal laid strands the steel area increases compared to cross lay strands. Other advantages of  parallel laid strands are the improved fatigue and wear resistance resulting from the same wire lay length and strand angle.  

Teräsköysi - tekninen määritelmä
Cross lay

The Core

The strands in a rope are laid around a core of either fibre, steel or solid plastic.

Where the strands are laid over a fibre core  FC is used, e.g. 6x19-FC.

Ropes with steel cores should be chosen if the rope is exposed to high working temperature, hard strains, high work rate, hard pressures on drums and blocks etc. The steel core gives better support for the strands, which result in the rope retaining its shape better and giving a better distribution of the stresses in the individual wires. 

If the steel core of the rope consists of a single strand the term -WSC is used, e.g. 6x19-WSC.

If the steel core of the rope consists of a steel wire rope the term -IWRC is used, e.g. 6x19-IWRC.

Some steel wire ropes can have a plastic encapsulated core which provides increased stability to the rope and also reduces the wear and corrosion in and around the core, e.g. Dyform 8 PI.

Teräsköysi - tekninen määritelmä

Rope Lay

Ordinary hand lay
The direction of the lay of the outer layer of wires in the strands is opposite to the direction of lay of the strands in the rope. Ordinary lay is more resistant to kinking and untwisting, and less likely to fail as a result of crushing and distortion.

Lang's lay
The direction of lay of the outer layer of wires in the strands are in the same  direction of lay of the strands in the rope. The advantage of using Lang's lay is that the rope offers a better wearing surface when in use, and therefore can be expected, in many cases to last longer. Lang's lay ropes produce relatively high torque values under working conditions and must not be used on applications where one end of the rope is free to rotate or where problems from rope turn are likely to occur.

Right hand lay
The strands are twisted to the right around the core. Right hand lay is the most common lay direction in a rope.

Left hand lay
The strands are twisted to the left around the core.

Teräsköysi - tekninen määritelmä
Ordinary right hand lay (sZ)





Special Wire Ropes

Demands for longer operation life and higher breaking loads have contributed to the development of  "special wire ropes". These are to be used in demanding and tough environments when the ropes are used intensively.
The special wire ropes are often manufactured with high tensile wires and the strands are in many cases compacted to give a larger steel area and consequently a higher breaking load.  This results in an increased working load for a specific rope diameter. Compacting of the rope also results in longer life and therefore a lower life cost.

Some areas of use demand wire ropes with better stability and extra low inner friction. For that purpose ropes are manufactured with a plastic coated steel core.

Special wire ropes can be double parallel which means that both wires and strands lay parallel to each other. This prevents wire cross over which can lead to wire indentations. Special wire ropes have a few things in common: less outer and inner friction, narrow tolerances, more flexible, more rounded and a larger contact surface against sheaves and drums. This results in a longer life in tough working conditions.

Teräsköysi - tekninen määritelmä

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