Granted Patent
Utility
US 4,257,574 · App. 06/026,431
Spherical valve seal
Inventor:
Selim A. Chacour
Patented Case
View Patent ↗
Granted: Mar 24, 1981
Filed: Apr 2, 1979
Inventor
Selim A. Chacour
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.