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Expired Canadian patentCanada

Trench shoring assembly

CA 1106339 A · Owner: Griswold, James L. · Inventors: Griswold, James L.

CIPO record

Overview

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Its claims, description and drawings are in the Canadian Patents Database.

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Abstract From the Canadian patent

This invention relates to a trench shoring assembly which includes a pair of spaced-apart side walls for vertical disposition within a trench. Spreader pipes and spreader collars interconnect the side walls and allow limited pivotal movement between the side walls. Each side wall includes outer and inner metal plates connected to a horizontally extending hollow top beam which extends longitudinally along the top of the side wall two intermediate beams parallel the hollow metal beam and a bottom beam. A hardwood insert is disposed within the top beam to prevent the collapse of the hollow metal beam. A number of hollow beams extend perpendicularly to the horizontal beams. The members extend …

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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

  • Granted August 4, 1981. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended August 4, 1998.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledFebruary 2, 1977
GrantedAugust 4, 1981
Term endedAugust 4, 1998
Patent numberCA 1106339 A
Classification (IPC)E04G25/02

Timeline

Timeline From CIPO dates

1978198119841987199019931996Application filedFeb 2, 1977Patent grantedAug 4, 1981Term endedAug 4, 1998

Sources & verification

Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.