Abstract text

A valve assembly includes a check valve element in an output chamber. The check valve element opens to permit forward flow of fluid under pressure in the output chamber from an input port to an output port. The check valve element closes to block back flow of fluid under pressure in the output chamber from the output port toward the input port. The back flow of fluid under pressure exerts a closing force upon the check valve element from within the output chamber. A counter force generating element, or pilot element, communicates with the valve element, to selectively open the valve, even in the presence of back flow pressure. The counter force generating element may apply a counter force to the check valve element, which urges the valve element toward the opened condition. The counter force may be less than the closing force, so the check valve element remains closed.