Granted Patent
Utility
US 4,189,073 · App. 05/772,694
Spring element for use in sliding gate valve
Inventor:
Joseph Lothmann
Patented Case
View Patent ↗
Granted: Feb 19, 1980
Filed: Feb 28, 1977
Inventor
Joseph Lothmann
Assignee (at issue)
United States Steel 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.