Reduction in service life of wire ropes running over sheaves with angular offset

In many applications which use rope drives, such as crane drives, ropes inevitably run over a pulley with a fleet angle. Excessive fleet angles can cause serious damage to the wire ropes, pulleys and grooved drums. Even though this has been known for a long time, the negative impact of rope deflection has not yet been subject to a comprehensive quantification. The purpose of the study - funded by the German Research Foundation (DFG) – was a fundamental examination of the influence and effects of fleet angle on the service life of ropes running over pulleys. In the theoretical part of the study all the relevant factors influencing rope service life with a fleet angle were determined and analysed. Thus, it was possible to identify the key rope and rope drive parameters affecting the service life of ropes running over sheaves with a fleet angle. The project focused on systematic and reproducible fatigue bending tests. In the tests performed with fleet angle the rope service life and the development of wire breaks was analysed with 6 ordinary lay ropes and rope diameters d = 12 mm and d = 16 mm. As a result of these tests, the service life reduction of ordinary lay ropes with fleet angle was quantified in comparison with their service life without fleet angle.

Author(s): S. Schonherr and K.-H. Wehking