Granted Patent
Utility
US 4,497,497 · App. 06/623,010
Oil ring assembly with annular expander spring
Inventors:
Jerome L. Berti, Paul J. Patchen
Patented Case
View Patent ↗
Granted: Feb 5, 1985
Filed: Jun 21, 1984
Inventors
Jerome L. Berti
Paul J. Patchen
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.