Adjustable manhole cover
US4197031A · kind A · utility
Inventor
Key dates
| Filing date | Sep 12, 1978 |
| Grant date | Apr 8, 1980 |
| Priority date | — |
| Expiry date | Sep 12, 1998 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE02D29/1409
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A vertically adjustable manhole cover assembly having a fixed annular support member, and a vertically adjustable annular member supported therein. The support member is provided with sets of graduated supports symmetrically mounted on its inner surface, and the adjustable member has sets of complementary graduated teeth on its outer surface which interact with the supports to rigidly support the adjustable member at a plurality of vertical levels. Grooves are also provided on the inside surface of the support member for accepting, and interlocking with, the teeth to prevent relative rotation of the annular members. The graduated teeth of the sets may include subsets of graduated steps.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.