Granted Patent
Utility
US 4,764,221 · App. 06/928,090
Silo cleaning process
Inventors:
Wesley D. Hartwigsen, Alan D. Johnson, Jeffrey C. Beckham, Kenneth L. White
Patented Case
View Patent ↗
Granted: Aug 16, 1988
Filed: Nov 7, 1986
Inventors
Wesley D. Hartwigsen
Alan D. Johnson
Jeffrey C. Beckham
Kenneth L. White
Assignee (at issue)
Shell Mining Company
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.