Granted Patent
Utility
US 4,502,508 · App. 06/477,551
Spool valve for connecting an output to one of two inputs
Inventor:
Graham G. Lester
Patented Case
View Patent ↗
Granted: Mar 5, 1985
Filed: Mar 21, 1983
Inventor
Graham G. Lester
Assignee (at issue)
Smiths Industries Public Limited Company
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.