Granted Patent
Utility
US 4,815,701 · App. 07/187,806
Spring and seat assembly for ball valves
Inventor:
Ralph S. Stone
Patented Case
View Patent ↗
Granted: Mar 28, 1989
Filed: Apr 29, 1988
Inventor
Ralph S. Stone
Assignee (at issue)
Cooper Industries Holdings
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.