Issued Patents All Time
Showing 1–6 of 6 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 6634832 | Apparatus for transporting particulate materials from a lower level to a higher level | — | 2003-10-21 |
| 6428245 | Method of and apparatus for transporting particulate materials from a lower level to a higher level | — | 2002-08-06 |
| 4950034 | Shaft excavation method | — | 1990-08-21 |
| 4832143 | Rotary drilling device | Oscar Kaalstad | 1989-05-23 |
| 4790397 | Rotary drilling device | Oscar Kaalstad | 1988-12-13 |
| 4549614 | Drilling device | Oscar Kaalstad | 1985-10-29 |