Granted Patent
Utility
US 4,187,546 · App. 05/777,724
Computer-controlled oil drilling rig having drawworks motor and brake control arrangement
Inventors:
James P. Heffernan, Loren B. Sheldon, James R. Tomashek, Donald H. Ward
Patented Case
View Patent ↗
Granted: Feb 5, 1980
Filed: Mar 15, 1977
Inventors
James P. Heffernan
Loren B. Sheldon
James R. Tomashek
Donald H. Ward
Assignee (at issue)
BJ-Hughes 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.