| # | Country | Total Patents | |
|---|---|---|---|
| #1 | United States | 60 | |
| #2 | Canada | 25 | |
| #3 | France | 5 | |
| #4 | United Kingdom | 3 | |
| #5 | Germany | 2 | |
| #6 | Austria | 1 |
| # | Industry | |
|---|---|---|
| #1 | Mechanical elements | |
| #2 | Machines | |
| #3 | Machine tools | |
| #4 | Furniture and games | |
| #5 | Materials and metallurgy | |
| #6 | Engines, pumps and turbines |
| # | Technology | |
|---|---|---|
| #1 | Pistons and sealings | |
| #2 | Unspecified technologies | |
| #3 | Metal-working | |
| #4 | Unspecified technologies | |
| #5 | Toys | |
| #6 | Metal tempering | |
| #7 | Cyclically operating valves | |
| #8 | Venting or aerating devices | |
| #9 | Accessories for machine tools | |
| #10 | Grinding or polishing devices |
| # | Name | Total Patents |
|---|---|---|
| #1 | Engelhardt Carl F | 19 |
| #2 | William Wuerfel | 13 |
| #3 | Wilkening Frederick W | 11 |
| #4 | Wuerfel William | 9 |
| #5 | Braendel Helmuth G | 8 |
| #6 | Robertson Delmar D | 7 |
| #7 | Hsia-Si Pien | 6 |
| #8 | Derham Philip A | 5 |
| #9 | Briggs George L | 4 |
| #10 | Loeb William S | 4 |
| Publication | Filing date | Title |
|---|---|---|
| US3295857A | Piston ring assembly | |
| US3202430A | Piston ring assembly | |
| US2967746A | Piston ring | |
| US2965423A | Piston ring assembly | |
| US3000678A | Piston ring | |
| GB867305A | Flexible unit for toys and the like | |
| US2854301A | Piston ring expander and method of forming same | |
| US2845748A | Plastic toy and flexible plastic unit for toys and other articles | |
| US2858644A | Pop-up toy | |
| US2877072A | Piston-ring construction | |
| US3005286A | Toy | |
| GB739682A | Piston ring assembly and method of installing thereof | |
| US2777740A | Piston-ring construction | |
| US2826468A | Piston ring assembly and method of installing thereof | |
| GB730305A | Composite piston ring and components thereof | |
| US2713527A | Piston ring | |
| US2671705A | Oil-control piston ring | |
| US2670256A | Piston ring | |
| US2771329A | Composite piston ring | |
| US2635933A | Piston ring construction |