Granted Patent
Utility
US 4,585,213 · App. 06/638,426
Well derrick
Inventors:
Grady M. Slagle, Jr., Raymond J. Swaim
Patented Case
View Patent ↗
Granted: Apr 29, 1986
Filed: Aug 7, 1984
Inventors
Grady M. Slagle, Jr.
Raymond J. Swaim
Assignee (at issue)
Armco 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.