Issued Patents 1989
Showing 1–3 of 3 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4867255 | Technique for steering a downhole hammer | Dmitry Feldman, Shiu S. Ng, Albert W. Chau, John E. Mercer | 1989-09-19 |
| 4856600 | Technique for providing an underground tunnel utilizing a powered boring device | Albert W. Chau, James A. Fikse, John E. Mercer | 1989-08-15 |
| 4821815 | Technique for providing an underground tunnel utilizing a powered boring device | Albert W. Chau, James A. Fikse, John E. Mercer | 1989-04-18 |