Issued Patents All Time
Showing 1–2 of 2 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 |
| 4790390 | Valveless down-the-hole drill | — | 1988-12-13 |