Granted Patent
Utility
US 4,291,449 · App. 06/117,650
Method of making a stem seat for a piston and cylinder type thermal device
Inventor:
Warren G. Williamson
Patented Case
View Patent ↗
Granted: Sep 29, 1981
Filed: Feb 1, 1980
Inventor
Warren G. Williamson
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.