Issued Patents All Time
Showing 1–3 of 3 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4557631 | Off-center rock bolt anchor and method | David C. Donan, Jr. | 1985-12-10 |
| 4188158 | Mine roof bolt hole seal | David C. Donan, Jr. | 1980-02-12 |
| 4183699 | Washer/gasket for mine roof bolt assembly | David C. Donan, Jr. | 1980-01-15 |