Granted Patent
Utility
US 4,271,850 · App. 06/134,745
Concave safety door with sealing and latching features
Inventor:
William Ryczek
Patented Case
View Patent ↗
Granted: Jun 9, 1981
Filed: Mar 27, 1980
Inventor
William Ryczek
Assignee (at issue)
Allis-Chalmers Corporation
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.