A percussion device
CA 2033848 C · Owner: Erlach, Josef · Inventors: Erlach, Josef
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The percussion device which can be used as a hammer drill has a drive piston for driving an overhung percussion piston which is mounted between two air cushions. Depending on the percussion travel of the percussion piston, the percussion air cushion is reversed so that a respective partial quantity is passed around the percussion piston to the opposite side by a central bypass. A no-load bypass is also provided to vent the recoil air cushion to the percussion cushion for a no-load condition. A third bypass bridges the drive piston in the top dead center position to communicate an annular chamber to the rear of the drive piston with the percussion cushion.
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 January 9, 1991 and granted August 15, 2000. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended January 9, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by January 9, 2013.
- 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.