DOWN-HOLE GEAR TO FORM DIRECTED CRACKS Russian patent published in 2002 - IPC

FIELD: mining industry. SUBSTANCE: invention can be used to form cracks in holes in order to separate blocks from rock mass, to mine crystalline raw materials and construction stone. Down-hole gear has tube, sealing piece of elastic material and distance ring placed in sequence on end of tube, system injecting liquid into tube, unit rotating tube relative to sealing piece. Conical thread is cut on end of tube, outer circumference of distance ring is sharpened, has slit and face holes where rods are put to form screw pair together with tube. EFFECT: enhanced efficiency and operational reliability of down-hole gear. 3 cl, 4 dwg