Granted Patent
Utility
US 4,643,228 · App. 06/585,823
Convertible high or low pressure pilot valve
Inventor:
Larry K. Spencer
Patented Case
View Patent ↗
Granted: Feb 17, 1987
Filed: Mar 2, 1984
Inventor
Larry K. Spencer
Assignee (at issue)
SIGMA ENTERPRISES, 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.