Endurance of steel wire ropes under fluctuating tension and twist: influence of the rope lay
1 Problem
Especially in the proximity of the rope termination, haulage ropes of jig-back ropeways are submitted during a ride to:
- pulsating tensile force due to change of gravity pull of the rope and downhill pull of the vehicle;
- alternating bending due to rope oscillations;
- pulsating twist caused by the differences of tensile Ioad; a free hanging rope has the tendency to twist on the top and to tighten below.
While the first two causes of stresses are, to a large extent, independent of the rope lay of the rope, the pulsating twist is more pronounced in the case of Lang's lay ropes than in that of regular lay ropes since the latter show more torsional rigidity.
The question is therefore constantly repeated whether it would not be more appropriate to take regular lay ropes for jig-back ropeways with big differences in elevation instead of the Lang's lay ropes which are currently used. The same loadings - and therefore also a similar problem - may occur with ropes of shaft installations showing big hoisting heights. (The twist tightening respectively untwisting effected on the haulage rope by the guiding parts is not a subject of this study.)
Author(s): G. Oplatka, M. Roth
Especially in the proximity of the rope termination, haulage ropes of jig-back ropeways are submitted during a ride to:
- pulsating tensile force due to change of gravity pull of the rope and downhill pull of the vehicle;
- alternating bending due to rope oscillations;
- pulsating twist caused by the differences of tensile Ioad; a free hanging rope has the tendency to twist on the top and to tighten below.
While the first two causes of stresses are, to a large extent, independent of the rope lay of the rope, the pulsating twist is more pronounced in the case of Lang's lay ropes than in that of regular lay ropes since the latter show more torsional rigidity.
The question is therefore constantly repeated whether it would not be more appropriate to take regular lay ropes for jig-back ropeways with big differences in elevation instead of the Lang's lay ropes which are currently used. The same loadings - and therefore also a similar problem - may occur with ropes of shaft installations showing big hoisting heights. (The twist tightening respectively untwisting effected on the haulage rope by the guiding parts is not a subject of this study.)
Author(s): G. Oplatka, M. Roth