chp mechanical maintenance stage i stage ii , mandatory job , roller screen overhauling , crusher overhauling , conveyer overhauling ( conveyer-3a/b , 5a/b , ;bc-12a/b , 16a/b , 17a/b ) , replacement of drive pulley of conveyor including apron feeder , replacement of gearbox of stg . -i , 3a/b , 5a/b , 6a/b , boom , intermidiate . slew drive of s/r ) , compressor overhauling of stg . -i , paddle feeder drive end ( travell gearbox side ) track wheel bearing replacement , stg . -i , dust extraction system overhauling & allied job , hydraulic pipeline area major cleaning of conveyor hydraulic drive , stg . -ii , track hopper , wagon tippler , bunker floor grattings major repairing , hydraulic system flushing & allied jobs during any major hydraulic pump and motor failure-stg . -ii , conveyor belt replacement ( above 25 mtr . )