Issued Patents All Time
Showing 1–3 of 3 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 6742608 | Rotary mine drilling bit for making blast holes | — | 2004-06-01 |
| 4623028 | Seal assembly for drill bits | Percy W. Schumacher | 1986-11-18 |
| 4444281 | Combination drag and roller cutter drill bit | Percy W. Schumacher, Kenneth W. Jones, Paul E. Pastusek | 1984-04-24 |