Issued Patents All Time
Showing 1–3 of 3 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4802539 | Polycrystalline diamond bearing system for a roller cone rock bit | David R. Hall | 1989-02-07 |
| 4738322 | Polycrystalline diamond bearing system for a roller cone rock bit | David R. Hall | 1988-04-19 |
| 4577705 | Bellows lubricant pressurizer for sealed bearing rock bits | — | 1986-03-25 |