A rotary drill bit having a drill bit body and at least one trunnion projecting from the drill bit body and a rotary cutter supported on at least one radial roller bearing on the trunnion. The rolling elements of the bearing are guided on at least one axial end facing the drill bit body in an outer bearing...http://www.google.es/patents/US4256193?utm_source=gb-gplus-sharePatente US4256193 - Rotary drill bit with rotary cutter
