Reliability-based maintenance scheduling of powered supports in Tabas mechanized coal mine

In this paper, the reliability of powered supports has been discussed utilizing the gathered failure data and failure interval data from Tabas coal mine in two years. The data sets were investigated using statistical procedures and in two levels: the existence of trend and serial correlation. The results show that the powered supports follow the Gamma reliability function. The reliability of the machine decreases to almost zero after 520 operation hours and after 80 hours the probability of failure of powered supports increases to 60 percent.Powered Support’s failure rate shows an improving behavior and therefore decreasing failure rate. In the beginning of the process the failure rate is 0.021 failures per hour, which after a sudden decrease reaches the rate of 0.012, thence forward on a gently decreasing rate and after 100 hours gets to the rate of 0.01.Regarding the maintenance policy and to protect the machine’s operation continuity Preventive maintenance strategy can be chosen. The reliability of the discussed machine can be maintained on a descent level by inspecting and controlling over the parts in short term intervals. With regard to reliability plots of powered supports operation, preventive reliability-based maintenance time intervals for 80% reliability levels for powered supports is 15 hours.