Formulation of Preventive Maintenance Schedule for Dragline System

Abstract—Dragline system is a high capacity, capital intensive and specialized mining equipment in Open Cast Mines that are used to extract coal by removing overburden. It consists of six sub-systems namely Drag, Hoist, Swing, Power Drive, Propel &others. It is essential that all the subsystems remain in operating state for maximum possible time duration for efficient working of the dragline system. A typical dragline can move about 3 crore cubic metres of overburden a year [2] and equates to generate approximately 1 lac revenue per hr. Existing reliability for subsystem drag and hoist are 0.4742 (47.42%) and 0.5931 (59.31%) respectively. This paper outlines determination of improvement potential of reliability of drag and hoist. Mean Time Between Failure (MTBF) is calculated for failure component of drag and hoist. An entire dragline needs to be stopped for execution of any preventive maintenance action. Age replacement policy is suggested for critical failure component. Minimum MTBF is for spare link which is 3.31 months whereas MTBF for drag rope and O ring is 3.42months and 3.63 months respectively. It is suggested to replace drag rope and o ring at 3.31 month along with spare link that shall cause net saving potential of 9.5 lacs / year