Granted Patent
Utility
US 5,146,939 · App. 07/626,303
Valve bushing cleaning device and method of cleaning valve bushings
Inventors:
Alvin J. Matthews, Thomas M. Hartzell, Ronald M. Markos, Richard H. Gumbert
Patented Case
View Patent ↗
Granted: Sep 15, 1992
Filed: Dec 12, 1990
Inventors
Alvin J. Matthews
Thomas M. Hartzell
Ronald M. Markos
Richard H. Gumbert
Assignee (at issue)
Westinghouse Air Brake Co.
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.