Issued Patents All Time
Showing 1–3 of 3 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| RE36002 | Transmission sleeve for a down hole hammer | John Elsby, Andrew Greathead | 1998-12-22 |
| 5154244 | Transmission sleeve for a down hole hammer | John Elsby, Andrew Greathead | 1992-10-13 |
| 5085285 | Compensating ring for a down hole hammer | John Elsby, John Urquhart Dewar, Andrew Greathead | 1992-02-04 |