Issued Patents All Time
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 5203614 | Tunneling machine having liquid balance low flow slurry system | Richard J. Robbins, David T. Cass | 1993-04-20 |
| 4646853 | Shaft boring machine and method | David B. Sugden, David T. Cass, Nicholas A. Hynd | 1987-03-03 |