Patents Represented by Attorney Al Riddles

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  • Fluid measurement of dielectric property change in hydraulic fluid
    Patent number: 5994906
    Abstract: The identification of and compensation for changes in the dielectric properties of a hydraulic fluid in hydraulic apparatus is achieved by continuously sampling a hydraulic fluid in a resonant chamber with a central conductor that is both inductively and capacitively coupled to an oscillator. The output frequency changes of the oscillator is an indicator of changes of the dielectric properties of the hydraulic fluid and their magnitude. The invention is of particular value in hydraulic cylinder piston position determining systems.
    Type: Grant
    Filed: February 13, 1997
    Date of Patent: November 30, 1999
    Assignee: Caterpillar Inc.
    Inventors: Dennis E. Morgan, Eric J. Hangartner, Jerry Collum