manufacture and supply of hammers for coal crusher of coal handling plant, otps, obra, sonebhadra ( u.p. ) manufacture and supply of hammers for coal crusher of coal handling plant, otps, obra, sonebhadra ( u.p. ) , toothed ring hammer ( for tsl make crusher 7c & 7d ) mat- manganese steel grade -iv ( is:276 / 1978 with latest amendment ) , finished weight of each hammer = 24 kg ( approx. ) hardness = 229 bhn tolerance: as per class ii of is-4897 / 1976 ( with latest amendment ) ( 1set = 76 nos ) , dimension: as per drawing / sample , crusher hammer ( for russian make crusher ) . mat- manganese steel ( duly heat treated ) grade -iv ( is:276 / 1978 with latest amendment ) , finished weight of each hammer = 61 kg ( ±100g ) ( 1set = 99 nos ) , hardness: 210 to 229 bhn tolerance: as per is-4897 class ii dimension: as per drawing / sample