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| US4412590 | 23 Ene 1981 | 1 Nov 1983 | Reed Rock Bit Company | Rock bit internal lubricant pump |
| US4516640 | 8 Dic 1983 | 14 May 1985 | Santrade Ltd. | Rotary drill bit |
| US4540055 | 10 Jun 1983 | 10 Sep 1985 | Drumco | Drill bit assembly having improved operational life |
| US4541494 | 19 Oct 1982 | 17 Sep 1985 | Drumco | Drill bit assembly |
| US4805709 | 30 Jul 1987 | 21 Feb 1989 | DRUMCO | Drill bit and drill assembly |
| US4981182 | 26 Ene 1990 | 1 Ene 1991 | Dresser Industries, Inc. | Sealed rotary blast hole drill bit utilizing air pressure for seal protection |
| US5012876 | 1 Feb 1990 | 7 May 1991 | Dresser Industries, Inc. | Rotary drill bit providing separation of liquid from gas |
| US5441120 | 31 Ago 1994 | 15 Ago 1995 | Dresser Industries, Inc. | Roller cone rock bit having a sealing system with double elastomer seals |
| US5513711 | 31 Ago 1994 | 7 May 1996 | | Sealed and lubricated rotary cone drill bit having improved seal protection |
| US5513715 | 31 Ago 1994 | 7 May 1996 | Dresser Industries, Inc. | Flat seal for a roller cone rock bit |
| US5636700 | 3 Ene 1995 | 10 Jun 1997 | Dresser Industries, Inc. | Roller cone rock bit having improved cutter gauge face surface compacts and a method of construction |
