Issued Patents 1989
Showing 1–2 of 2 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4865489 | Mine roof anchor having adjustable resin retaining washer | Eugene H. Stewart, Glen S. Grissinger | 1989-09-12 |
| 4861198 | Expansion assembly for mine roof bolts | — | 1989-08-29 |