Granted Patent
Utility
US 4,863,144 · App. 07/259,901
Plug valve
Inventors:
A. Kenneth Wilson, John V. Ballun
Patented Case
View Patent ↗
Granted: Sep 5, 1989
Filed: Oct 19, 1988
Inventors
A. Kenneth Wilson
John V. Ballun
Assignee (at issue)
AMSTED INDUSTRIES INCORPORATED
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.