| # | Country | Total Patents | |
|---|---|---|---|
| #1 | Sweden | 5 | |
| #2 | Canada | 3 | |
| #3 | Denmark | 3 | |
| #4 | Belgium | 1 | |
| #5 | Switzerland | 1 | |
| #6 | Germany | 1 | |
| #7 | United Kingdom | 1 | |
| #8 | Norway | 1 |
| # | Industry | |
|---|---|---|
| #1 | Civil engineering |
| # | Technology | |
|---|---|---|
| #1 | Foundations and excavations |
| # | Name | Total Patents |
|---|---|---|
| #1 | Westheim Per T | 7 |
| #2 | Isaksen Roald | 4 |
| #3 | Tobiassen O | 2 |
| #4 | Haatveit Halvor | 2 |
| #5 | Nilsson Mats | 2 |
| #6 | Kirkaas Knut | 2 |
| #7 | Tobiassen Olav | 2 |
| #8 | Myhre Olav | 2 |
| #9 | Nilsson M | 2 |
| #10 | Myhre O | 2 |
| Publication | Filing date | Title |
|---|---|---|
| CA2054660A1 | Manhole cover locking system | |
| CA2052962A1 | Manhole cover frames or the like | |
| DK123791D0 | Exchanged fitting to a manhole frame | |
| DK44691D0 | Well cover frame device | |
| DK38991D0 | Arrangement for a frame for lids or covers for wells or the like | |
| DE1954133A1 | Frame of manhole covers for manholes | |
| CA877040A | Manhole frames |