PNEUMATIC TOOL FOR ACTION ON INLET PART OF BOREHOLE Russian patent published in 1994 - IPC

FIELD: geology. SUBSTANCE: body of pneumatic tool has shut-off valve, air supply branch pipe, valve unit. Shut-off valve is mounted for movement along body, it controls volume of pneumatic chamber. Valve unit is manufactured in the form of seat and cast ball shut-off element. Seat of valve unit is placed in body beneath shut-off valve and above holes for discharge of compressed air. Lower part of body has container for cast ball shut-off elements. Shut-off valve closes with inrush of ball shut-off element through seat of valve unit limiting flow acting on inlet part of borehole. EFFECT: enhanced reliability and safety. 2 dwg