Screw lift
CA 2005666 C · Owner: Lindberg, Ulf · Inventors: Lindberg, Ulf
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
In a screw lift the lift cage (4) is carried by a drive nut (10) rotatably provided on an essentially upright screw (2) the, lift cage carrying a bearing means (8) and a drive means (6) for the nut. The screw (2) is supported by several supporting braces (14) attached thereto along the length thereof. The nut (10) has the shape of a spiral having turns, the pitch and axial thickness (a) of which are adapted to the distance (b) between the braces (14) and the dimension (c) of these in the length direction of the screw so as to enable the nut to pass freely past the braces by these passing between the turns of the nut during the passage.
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
- Filed December 15, 1989 and granted February 23, 1999. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended December 15, 2009.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by December 15, 2011.
- 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.