Centrifugal backspin retarder and drive head for use therewith
CA 2322656 C · Owner: Weatherford Technology Holdings, Llc · Inventors: Hult, Vern Arthur; Blundell, Curtis Christopher
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A backspin retarder for a shaft comprises a brake mechanism including a stationary brake member and opposed brake members rotatable with the shaft and movable between braking position in which the movable brake members engage the stationary brake member and a non-braking position in which the movable brake members are removed from the stationary brake member and a brake control mechanism responsive to the direction of rotation of the shaft for disabling the brake mechanism when the shaft rotates in a forward direction and for enabling the brake mechanism when the shaft rotates in a reverse direction.
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 May 12, 1999 and granted July 2, 2002. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended May 12, 2019.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by May 12, 2021.
- 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.