Caterpillar Inc.

Gary J Shane

George G Codina

Eldon D Oestmann

An apparatus for determining the spool position of a directional valve is disclosed. A longitudinal valve housing has opposed ends and a plurality of fluid ports, and a spool moves reciprocatingly within the valve housing. A first spring disposed adjacent an end of the spool extends and retracts with the reciprocating movement of the spool. A first oscillator circuit is coupled to the first spring and is adapted to produce a first position signal in response to the inductance of the first spring. Finally, a logic device determines the incremental linear position of the spool relative to the housing in response to the frequency of the first position signal.

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Edelstein, IL, United States of America

Gary J Shane