Issued Patents 1989
Showing 1–1 of 1 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4819746 | Reverse circulation down-the-hole hammer drill and bit therefor | John Christopher Brown, Patrick Purcell | 1989-04-11 |
Showing 1–1 of 1 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4819746 | Reverse circulation down-the-hole hammer drill and bit therefor | John Christopher Brown, Patrick Purcell | 1989-04-11 |