Issued Patents All Time
Showing 1–2 of 2 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4826195 | Auxiliary towing apparatus for tractor trucks and the like | Douglas R. Hagge, C. V. Johnston | 1989-05-02 |
| 4640528 | Torsion-absorbing highway semitrailer | Douglas R. Hagge, Clifford V. Johnston | 1987-02-03 |