ISO 1721:1974 Preview
Rock drilling -- Extension drill-steel equipment for percussive long-hole drilling -- Reverse-buttress-threaded equipments 1 1/16 and 1 1/4 in (27 and 32 mm)
This standard was last reviewed and confirmed in 2017. Therefore this version remains current.
Specifies the basic dimensions for equipment. Gives a list of components; tabulates together with figures: shank adapters for central flushing, hexagon type and lug-shank type; extension rods; coupling sleeves; four-wing bits; reverse-buttress threads; hollow hexagonal bars for extension rods; hexagonal drill-steels.
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