Granted Patent
Utility
US 4,550,889 · App. 06/397,383
Traffic control system for single track railroad
Inventor:
David G. Emmel
Patented Case
View Patent ↗
Granted: Nov 5, 1985
Filed: Jul 12, 1982
Inventor
David G. Emmel
Assignee (at issue)
American Standard Inc.
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.