Patents by Inventor John D. Grabenhofer

John D. Grabenhofer 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).

  • Means for measuring the plasticity of coal
    Patent number: 4074561
    Abstract: A device for measuring the plastic characteristics of coal includes a bath of molten metal and a crucible with a coal sample therein positioned within said bath. A drive motor is connected through a hysteresis brake to a stir rod positioned in the coal sample. As the coal sample plasticizes due to heat from the molten metal, a calibrated disc connected to the stir rod will be driven by the motor. Optical sensing means including a phototransistor and a light source positioned on opposite sides of the calibrated disc are connected to a counter which is used to record stir rod movement within a given time reference.
    Type: Grant
    Filed: November 15, 1976
    Date of Patent: February 21, 1978
    Assignee: Fuel Research & Instrument Co.
    Inventors: Willis H. Brockschmidt, Robert W. Brockschmidt, John D. Grabenhofer