Issued Patents All Time
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 5248007 | Electronic control system for stair climbing vehicle | Douglas J. Littlejohn, John H. Hessler, Havard L. Staggs, Chi-Foun Kuen | 1993-09-28 |
| 5123495 | Wheelchair stair climbing control system | Douglas J. Littlejohn, John H. Hessler | 1992-06-23 |
| 5033000 | Variable keyed power distribution and control system for motorized wheelchair | Douglas J. Littlejohn, Havard L. Staggs | 1991-07-16 |
| 4915184 | Cushioning mechanism for stair-climbing wheelchair | — | 1990-04-10 |
| 4674584 | Stair-climbing wheelchair with stair step sensing means | — | 1987-06-23 |
| 4671369 | Stair-climbing wheelchair with means for cushioning vertical movements thereof | Patrick J. Tiffin | 1987-06-09 |