Method and apparatus for forming a trench
CA 2131867 C · Owner: Abt, Inc. · Inventors: Stegall, Lannie L.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A trench forming assembly and removable form for forming a trench of predetermined shape is disclosed according to the present invention. The removable form includes an elongate form body having top, bottom and opposed side surfaces and first and second elongate form removal slots extending upwardly from the bottom surface of the form body. Preferably the removable form has a top surface defining a complex shape including at least a first upwardly extending ear portion which extends longitudinally along the top surface. At least a first form removal slot of this elongate form body extends into a portion of the first ear portion. Advantageously, the form body includes a pair of coplanar …
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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
- Filed September 12, 1994 and granted April 27, 1999. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended September 12, 2014.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by September 12, 2016.
- 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.