Wire rope endurance on multi-rope friction winders
ln installations where wire ropes are used in parallel great care must be taken to ensure that the load is distributed evenly. An example of such an application is a multi-rope friction winder. However, because of different rope stiffnesses and different diameters of the friction wheels (the actual difference in diameters may be quite small and caused by wear of the sheave groove inserts) the loads may vary considerably. While in service, load variations between the ropes may be as big as 100% - in practice that means one rope may carry no load whilst another carries twice the normal service load. During the periodic inspections of multi-rope friction winders the tension in the rope is measured and if necessary the groove of the friction wheel is modified to balance the loads. Subsequent service shows that the rope subjected to overloading has a much better endurance than the one that was previously slack and unworked. This paper describes this kind of installation and presents a model to predict the difference in service endurance. The model gives good agreement between theory and practice.
Author(s): Tytko, A.A.