Granted Patent
Utility
US 4,643,395 · App. 06/800,250
Valve with protected seats
Inventor:
John B. Williams, Jr.
Patented Case
View Patent ↗
Granted: Feb 17, 1987
Filed: Nov 21, 1985
Inventor
John B. Williams, Jr.
Assignee (at issue)
Joy Manufacturing Company
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.