Reliability analysis of a dragline using fault tree analysis

Abstract

Draglines, as massive and expensive stripping machines, are highly utilized in open cast mining to remove overburden. Reliabilities and availabilities of draglines play a critical role to sustain the continuity of overburden stripping and, hence, coal productions. Thorough understanding of the system and its components is required in order to accomplish high levels of availability and it can be achieved with an in depth reliability analysis. This study presents component-based reliability analysis of a walking dragline being operated in an open cast coal mine in Turkey. The main objective of the study is to understand the effects of each component or subsystem of a dragline on its reliability which will further provide insight into optimized maintenance schedule. The results of the study revealed that the system is expected to fail in 37.9 hours, most probably due to a failure in the rotation component of the movement subsystem. Dragging rope is predicted to have the highest contribution to number of failures within a year, but the motors and generators will cause the longest downtime if failed. Reliability importance (RI) values were also found to be useful to decide which components need attention at certain time intervals.