Granted Patent
Utility
US 5,022,798 · App. 07/535,841
Thrust-responsive two-speed drill and method of operation
Inventor:
Richard E. Eckman
Patented Case
View Patent ↗
Granted: Jun 11, 1991
Filed: Jun 11, 1990
Inventor
Richard E. Eckman
Assignee (at issue)
Dresser Industries, 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.