Rock drilling; Extension drill-steel equipment for percussive long-hole drilling; Rope-threaded equipments 1 1/2 to 2 in (38 to 51 mm)
Описание (англ.):
Specifies the basic dimensions for equipment. Gives a list of components; tabulates together with figures: extension rods; wrench flats; coupling sleeves; drill-bits; four-wing bits; left-hand rope threads; round drill-steels.