Limit switch weight apparatus for crane hoist drives
CA 2119300 C · Owner: Plass, Thomas E. · Inventors: Plass, Thomas E.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Disclosed is a crane hoist system having a hoist drum (33), a drum drive motor (37) and control and power circuit limit switches (47, 49). The improvement involves a first trip bar (75) coupled to the power circuit limit switch (49) and a second trip bar (57) coupled to the control circuit limit switch (47). The bars (75, 57) are vertically aligned and both are pivot mounted at their corresponding ends (79 87). The second, trip bar (57) is mounted for movement independently of the first trip bar (75). If the control circuit limit switch (47) fails to function as the second bar (57) is moved a suitable distance upwardly, such bar (57) contacts and lifts the first bar (75) which in turn, …
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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 March 17, 1994 and granted March 25, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended March 17, 2014.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 17, 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.