DEVICE FOR CLAMPING DRILL PIPES Russian patent published in 1994 - IPC

FIELD: drilling equipment. SUBSTANCE: device drive has additional driven rims installed in additional ring supports of body whose landing holes are made with vertical relative concentricity. Driven rims have bore with double eccentricity and recesses receiving plates for radial relative displacement for value of warranted gap between their installing projections and slot in side wall of driven rim. Slip inserts with vertical slots are fixed between plate side surfaces. Located in slots are rolling bearings. Placed between cylindrical surface of recess and plates are rollers. When drive is actuated, the driven rims turns over and plates clamp the drill pipe. EFFECT: higher efficiency. 4 dwg