Measurement of lay length in stranded ropes

One condition for the correct functioning of a wire rope is that its lay length lies within the tolerances specified by the manufacturer. In a rope with a lay length that is outside these tolerances, the load distribution between wire layers may be incorrect, as shown in figure 1 (Heller, 1989). Upon dynamic loading of such ropes, premature wire breaks may occur for two main reasons:

•  in slackened layers on the outside of the rope wire breaks are caused by excessive deformation 

• inside layers may be overstressed and longitudinal tension in the wires may become too high.

Author(s): Oplatka, G. Schwitter, R.