A roller cone drill bit in which the orientations of the teeth are varied within a single row, and/or between the heel row of one cone and the heel row of another cone, to prevent tracking....http://www.google.es/patents/US6401839?utm_source=gb-gplus-sharePatente US6401839 - Roller cone bits, methods, and systems with anti-tracking variation in tooth orientation
Roller cone bits, methods, and systems with anti-tracking variation in tooth ...
