RAM measure of hydraulic powered roof supports in underground longwall coal mines

Abstract

Mining operations in underground coal mines, particularly those using the longwall method, require continuous progress and the avoidance of interruptions, as any stoppage can lead to roof collapse. Given the mechanization of coal mining and the underground extraction of this mineral, the use of powered supports is essential to prevent roof collapse. To maintain continuity in mining operations, increase production, and simultaneously control and reduce costs caused by downtime and failures of roof support systems, it is necessary to assess their reliability. This paper aims to analyze the reliability, maintainability, and availability (RAM) of powered support equipment. To achieve this, the hydraulic powered support system was selected for data collection and analysis. The results indicate that the time between failures (TBF) and time to repair (TTR) data of the subsystems followed a renewal process, except for the TBF data of the hydraulic subsystem, which followed a non-homogeneous Poisson process (NHPP). The reliability of the subsystems decreased to 85% after 25 hours. The maintainability analysis showed that most failures of the powered roof supports are repaired within 1 hour. Furthermore, the powered support systems operate under desirable conditions with 99.58% availability. However, in order to create an efficient and easy-to-manage maintenance schedule, it was suggested that preventive maintenance activities be performed at the end of each working day.