Granted Patent
Utility
US 4,294,278 · App. 06/110,712
Pressure modulating valve
Inventor:
William W. Blake
Patented Case
View Patent ↗
Granted: Oct 13, 1981
Filed: Dec 14, 1979
Inventor
William W. Blake
Assignee (at issue)
Caterpillar Tractor Co.
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.