OVERSHOT Russian patent published in 2001 - IPC

FIELD: mining, particularly, equipment for fishing in well; applicable in removal of members of pipe strings ending in upper part in flange, box or tool joint. SUBSTANCE: overshot includes hollow body with side windows. Spring and collet are installed in body. Collet lugs on lower ends are provided with catching projections which are conjugated with collet lugs over spherical surface. Eternal surface of lug lower ends and body internal surface under side windows are conical. Value of axial motion of collet is limited by height of body conical surface under side windows. EFFECT: reliable design of overshot with required load lifting capacity. 2 cl, 4 dwg