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| US3930739 | 18 avr. 1974 | 6 janv. 1976 | | Manhole frame with adjustment screws |
| US3945746 | 27 janv. 1975 | 23 mars 1976 | Maryland Grading and Fabricating Company, Inc. | Grating structure for roadway storm drain inlets and the like |
| US4149816 | 6 févr. 1978 | 17 avr. 1979 | | Metal shaft cover frame |
| US4273467 | 25 juin 1979 | 16 juin 1981 | Cremo Supply Ltd. | Adjustable manhole cover support |
| US4844402 | 1 juil. 1988 | 4 juil. 1989 | | Form for a mortar cap |
| US4925337 | 28 sept. 1988 | 15 mai 1990 | Von Roll, AG | Manhole covering |
| US5299637 | 25 août 1992 | 5 avr. 1994 | | Concrete well |
| US6371687 | 7 févr. 2000 | 16 avr. 2002 | | Method and apparatus for leveling manhole cover frames |
| US6527476 | 2 déc. 1999 | 4 mars 2003 | Tycom (US) Inc. | Non-sinking manhole assembly for below ground liquid storage tanks |
| US6811350 | 7 oct. 2003 | 2 nov. 2004 | | Method and apparatus for adjusting the height and inclination of roadway and greenway appurtenances |
| US6997639 | 27 oct. 2004 | 14 févr. 2006 | | Method and apparatus for adjusting the height and inclination of roadway and greenway appurtenances |
| USD280126 | 20 juin 1983 | 13 août 1985 | Central States Concrete Products, Inc. | Precast drain inlet |
