Granted Patent
Utility
US 6,286,791 · App. 09/521,338
Railroad spring wing frog with hold-open and shock dampening elements
Inventors:
Keith Young, Stephen R. Kuhn
Patented Case
View Patent ↗
Granted: Sep 11, 2001
Filed: Mar 9, 2000
Inventors
Keith Young
Stephen R. Kuhn
Assignee (at issue)
ABC-NACO 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.