Granted Patent
Utility
US 4,425,941 · App. 06/273,220
Valve construction having multiple piston means and method of making the same
Inventor:
Marvin P. Weaver
Patented Case
View Patent ↗
Granted: Jan 17, 1984
Filed: Jun 12, 1981
Inventor
Marvin P. Weaver
Assignee (at issue)
ROBERTSHAW CONTROLS PRIVATE LIMITED
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.