Granted Patent
Utility
US 5,697,457 · App. 08/759,321
No load derrick for drilling rig
Inventor:
Carl F. Back
Patented Case
View Patent ↗
Granted: Dec 16, 1997
Filed: Dec 2, 1996
Inventor
Carl F. Back
Assignee (at issue)
Laibe Supply Corporation
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.