Granted Patent
Utility
US 4,813,749 · App. 07/137,764
Pilot operated stepping directional valve and method for single line operation
Inventor:
Arthur L. Cilles
Patented Case
View Patent ↗
Granted: Mar 21, 1989
Filed: Dec 24, 1987
Inventor
Arthur L. Cilles
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.