Granted Patent
Utility
US 4,500,069 · App. 06/346,175
Hydraulic directional control valve
Inventors:
Ralph R. Barber, Eckart F. Schultze
Patented Case
View Patent ↗
Granted: Feb 19, 1985
Filed: Feb 5, 1982
Inventors
Ralph R. Barber
Eckart F. Schultze
Assignee (at issue)
Duff-Norton 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.