Granted Patent
Utility
US 4,273,186 · App. 05/960,170
Well safety valve system
Inventors:
Joseph L. Pearce, John H. Yonker, Thomas M. Deaton
Patented Case
View Patent ↗
Granted: Jun 16, 1981
Filed: Nov 13, 1978
Inventors
Joseph L. Pearce
John H. Yonker
Thomas M. Deaton
Assignee (at issue)
Otis Engineering 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.