Granted Patent
Utility
US 4,574,888 · App. 06/637,385
Method and apparatus for removing stuck portions of a drill string
Inventor:
Wayne V. Vogen
Patented Case
View Patent ↗
Granted: Mar 11, 1986
Filed: Aug 2, 1984
Inventor
Wayne V. Vogen
Assignee (at issue)
URS 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.