Manhole extension
CA 1046326 A · Owner: Pelsue, Thurman A. · Inventors: Pelsue, Thurman A.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
IMPROVED MANHOLE EXTENSION", ABSTRACT OF THE INVENTION This invention relates to an improved manhole extension or shield of the type constituting the subject matter of my U. S. Patent No. 3,294,000 which improvement comprises providing at least one, and preferably both of the outwardly-facing channels with a circular fence projecting down into the casting bordering the mouth of the manhole so as to bridge any gap left between the latter and the annular flange from which it depends thus co-operating with said casting to retain the inflatable gasket.
Read the whole patent
Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Granted January 16, 1979. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended January 16, 1996.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.