Importance

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Abstract

A check valve system controls the flow of fluid between a spool valve and a hydraulic actuator and includes a pilot operated check valve that is controlled by a lock-out valve. The check valve has a poppet that engages and disengages a first valve seat in response to a pressure in a control chamber. The lock-out valve has an inlet connected to the control chamber, an outlet connected to an opening in the bore of the spool valve, and an second valve seat between the inlet and the outlet. A valve member that selectively engages and disengages the second valve seat and spool of the spool valve applies force to the valve member which responds by moving into engagement with the second valve seat. Thus in one position, the spool valve maintains the lock-out valve closed which traps pressure in the control chamber which tend to keep the check valve closed.

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First Claim