An apparatus for gripping a down hole tubular for support and rotation, or a string of such tubulars, includes a body element adapted to be rotated at high torques either by a top head drive or a rotary table of an earth drilling machine. Gripping elements are mounted in a central cavity of the body...http://www.google.com.au/patents/US5297833?utm_source=gb-gplus-sharePatent US5297833 - Apparatus for gripping a down hole tubular for support and rotation
