Granted Patent
Utility
US 4,890,645 · App. 07/333,873
Rotary shear seal hydraulic valve
Inventor:
Roger Andersen
Patented Case
View Patent ↗
Granted: Jan 2, 1990
Filed: Apr 3, 1989
Inventor
Roger Andersen
Assignee (at issue)
Baroid Technology, 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.