Granted Patent
Utility
US 4,640,309 · App. 06/766,668
Pilot operated poppet valve with speed control
Inventors:
Robert K. Hoffman, Mark A. Kavanaugh, David C. Franson
Patented Case
View Patent ↗
Granted: Feb 3, 1987
Filed: Aug 15, 1985
Inventors
Robert K. Hoffman
Mark A. Kavanaugh
David C. Franson
Assignee (at issue)
Parker-Hannifin Corporation
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.