Endurance of wire ropes in traction applications
In traction elevators wire ropes are degraded through multiple effects. Besides special groove geometries, which increase the contact pressure between the rope and the traction sheave, creep and slip effects are inevitable in traction applications. The rope endurance is thereby significantly reduced. To date the calculation factors applied for the dimensioning of elevator ropes according to EN 81-1  have been derived from unspecified field data of elevators built before 1980, regarding only rope constructions with fibre core. Due to this fact it is crucial to assess the impact of the latest technological changes in elevator and rope design and accomplish a systematic analysis of the specific rope deterioration mechanisms. Since the rope deterioration in traction elevators can not be simulated with regular bending machines a comprehensive research project was initiated at the Institute of Mechanical Handling and Logistics (IFT) in 2003. Financed by the Federal Ministry of Economics and Technology an extensive test program running over a period of almost five years was conducted with participation and support of different elevator and rope manufacturers. Utilising a traction test bench at the IFT, specially built for this project to reproduce rope deterioration in elevators, different rope constructions were tested in combination with varying traction sheave groove shapes. The results of the project can be used for an updated rope dimensioning in the elevator standard. The paper will present the results and analysis from these extensive tests.
Author: O.R. Berner