Manhole cover
US5378078A · kind A · utility
22Cited by
2References
6Claims
0Family size
Inventors
Key dates
| Filing date | Oct 15, 1992 |
| Grant date | Jan 3, 1995 |
| Priority date | — |
| Expiry date | Oct 15, 2012 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE02D29/14
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
The improved manhole cover of this invention provides a strong yet lightweight access cover structure made from a series of radially staggered ply layers bonded above and below a homogenous frusto-conical core portion with resin, each ply layer made from an array of radially staggered unidirectional fiber tape.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.