Issued Patents 1989
Showing 1–3 of 3 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4880065 | Air motor operated rotary earth drilling tool | William J. McDonald, Curtis E. Leitko, Jr., Gerard T. Pittard, William C. Maurer | 1989-11-14 |
| 4858704 | Guided earth boring tool | William J. McDonald, Gerard T. Pittard, William C. Maurer, William Christian Herben | 1989-08-22 |
| 4834193 | Earth boring apparatus and method with control valve | Curtis E. Leitko, Jr., Douglas W. Lee, Gerald A. Stangl | 1989-05-30 |