Issued Patents 1989
Showing 1–3 of 3 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4844179 | Drill string stabilizer | Rory McCrae Tulloch, William M. Stewart | 1989-07-04 |
| 4807708 | Directional drilling of a drill string | Roger John Catherall, William M. Stewart, Randall Pounds | 1989-02-28 |
| 4796704 | Drop ball sub-assembly for a down-hole device | William M. Stewart, Rory McCrae Tulloch | 1989-01-10 |