Issued Patents 1989
Showing 1–2 of 2 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4889195 | Drill bit direct drive for deep well drilling tools | Heinrich Daenicke | 1989-12-26 |
| 4854401 | Drill bit direct drive for deep well drilling tools | Heinrich Daenicke | 1989-08-08 |