Granted Patent
Utility
US 4,294,284 · App. 06/093,612
Fail-safe, non-pressure locking gate valve
Inventor:
David P. Herd
Patented Case
View Patent ↗
Granted: Oct 13, 1981
Filed: Nov 13, 1979
Inventor
David P. Herd
Assignee (at issue)
SMITH INTERNATIONAL, 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.