Patents by Inventor Donald C. Campbell

Donald C. Campbell has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Ramp-operated mechanical gate systems
    Patent number: 4521992
    Abstract: A ramp-operated mechanical gate system, including vertically-swinging gate, sliding gate and side-swinging gate embodiments which utilize collapsible ramps to supply energy to open a gate so that the gate is opened automatically when the collapsible ramp is depressed by an approaching vehicle and is closed automatically when the vehicle drives through the gate and the ramp is no longer depressed.
    Type: Grant
    Filed: October 31, 1983
    Date of Patent: June 11, 1985
    Inventor: Donald C. Campbell