Method and apparatus for operating a hoist
CA 2074203 C · Owner: Harnischfeger Corporation · Inventors: Hipp, William A.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A hoist having an alternating current induction motor for rotating the drum of the hoist and an adjustable frequency power supply connected to the motor has a first control connected to the adjustable frequency power supply for directing the power supply to provide power to the motor at a first voltage level at the initiation of a raising operation. A second control is also connected to the adjustable frequency power supply for directing the power supply to provide power to the motor at the initiation of a lowering operation at a second voltage level which is lower than the first voltage level. The voltage level supplied to the hoist at the initiation of a raising operation may comprise a …
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 July 20, 1992 and granted May 13, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended July 20, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by July 20, 2014.
- 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.