Granted Patent
Utility
US 4,809,733 · App. 07/041,269
Fail-safe gate valve with separated actuators
Inventor:
Herman H. Hawkins
Patented Case
View Patent ↗
Granted: Mar 7, 1989
Filed: Apr 22, 1987
Inventor
Herman H. Hawkins
Assignee (at issue)
National Oilwell, Inc.
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.