Patents by Inventor Robert G. Hamm

Robert G. Hamm 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).

  • Mine roof warning indicator
    Patent number: 4217849
    Abstract: A mine warning device which comprises tensioned arms that abut the roof of an underground mine. The arms support a cone shaped shaft which is attached to a warning indicator. The indicator remains invisible within the body of the device when the rocks forming the roof are stable. Upon a shifting of the mine roof, which applies pressure to the arms of the device, the shaft is released and the warning cylinder falls into view. Preferably, the device attaches to bolts that hold plates to the mine roof and the warning indicator is fluorescent.
    Type: Grant
    Filed: December 21, 1978
    Date of Patent: August 19, 1980
    Inventors: Larry L. Brown, Robert G. Hamm
  • Mine roof warning indicator
    Patent number: D258499
    Type: Grant
    Filed: December 21, 1978
    Date of Patent: March 10, 1981
    Inventors: Larry L. Brown, Robert G. Hamm