Granted Patent
Utility
US 4,247,972 · App. 06/006,847
Method of manufacturing a piston ring
Inventors:
John L. Hendrixon, Robert R. Rositch
Patented Case
View Patent ↗
Granted: Feb 3, 1981
Filed: Jan 26, 1979
Inventors
John L. Hendrixon
Robert R. Rositch
Assignee (at issue)
Sealed Power 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.