Granted Patent
Utility
US 4,589,503 · App. 06/788,668
Top drive drilling apparatus with improved wrench assembly
Inventors:
Horace A. Johnson, Roger D. Smith
Patented Case
View Patent ↗
Granted: May 20, 1986
Filed: Oct 17, 1985
Inventors
Horace A. Johnson
Roger D. Smith
Assignee (at issue)
Hughes Tool Company LLC
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.