FIELD: mining industry.
SUBSTANCE: device has pipe casing with end elements, made of longitudinal metallic lines, which are mounted in overlapping manner and rigidly fixed at ends. Pipe casing is filled with plastic substance, on one end of it a plug is mounted, and onto its other end a ring is placed with outer thread. Onto which a barrel is screwe having central aperture with thread, wherein a screw is screwed having handles.
EFFECT: higher effectiveness.
7 cl, 5 dwg
