Caterpillar Inc.

Joseph T Phillips

Robert A Lapke

Randall A Harlow

Joseph F Duffy

James R Carlberg

Steven P Seaney

Rita R Waller

A check valve normally blocks fluid flow from a bore to a passage and includes a spring normally holding a ball in sealing engagement with a valve seat to form a primary metal-to-metal hard seal. Another spring normally holds a poppet in engagement with another valve seat causing an annular protuberance formed on the poppet to sealingly engage a resilient seal to provide a more positive secondary soft seat seal. The poppet is unseated from the valve seat by a stem of a piston prior to the ball being unseated from the valve seat by a guide stem of the poppet so that the soft seal is opened at essentially zero flow conditions.

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Dunlap, IL, United States of America

Joseph T Phillips