| # | Country | Total Patents | |
|---|---|---|---|
| #1 | Australia | 1 | |
| #2 | Bulgaria | 1 | |
| #3 | Canada | 1 | |
| #4 | Germany | 1 | |
| #5 | EPO (European Patent Office) | 1 | |
| #6 | Finland | 1 | |
| #7 | Hungary | 1 | |
| #8 | Japan | 1 | |
| #9 | Republic of Korea | 1 | |
| #10 | Norway | 1 | |
| #11 | Russian Federation | 1 | |
| #12 | United States | 1 | |
| #13 | WIPO (World Intellectual Property Organization) | 1 |
| # | Industry | |
|---|---|---|
| #1 | Civil engineering |
| # | Technology | |
|---|---|---|
| #1 | Earth drilling |
| # | Name | Total Patents |
|---|---|---|
| #1 | Dahn Rolf | 13 |
| Publication | Filing date | Title |
|---|---|---|
| DE4016965A1 | Drilling head for tunnel boring - has central channel with nozzles directed to front and rear |