Granted Patent
Utility
US 4,278,107 · App. 06/137,690
Automatic vacuum relief valve for hopper cars
Inventors:
Richard H. Dugge, Arnold Schlobohm
Patented Case
View Patent ↗
Granted: Jul 14, 1981
Filed: Apr 7, 1980
Inventors
Richard H. Dugge
Arnold Schlobohm
Assignee (at issue)
ACF Industries Incorporated
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.