Cross-over relief valve assembly for use in bi-directional circuit

A cross-over relief valve assembly adapted for use in conjunction with first and second fluid conduits, communicating between a source of pressurized fluid and a fluid pressure operated device, either of said first and second fluid conduits being operable to communicate relatively high pressure, and the other communicating relatively low pressure;

• said cross-over relief valve assembly comprising a housing defining a first port adapted for fluid communication with said first fluid conduit, and a second port adapted for fluid communication with said second fluid conduit;
• said housing further defining a poppet seat, disposed between said first and second ports, and a poppet member;
• said housing and said poppet member cooperating to define a spring chamber, and a biasing spring disposed in said spring chamber and being operable to bias said poppet member toward sealing engagement with said poppet seat to prevent substantial fluid flow between said first and second ports;
• characterized by:
• (a) said poppet member defining a shuttle cavity and a shuttle passage providing fluid communication from said shuttle cavity to said spring chamber;
• (b) said poppet member further defining a first shuttle seat at a first end of said shuttle cavity, and a first fluid passage in fluid communication with said first port, and a second shuttle seat at a second end of said shuttle cavity, and a second fluid passage in fluid communication with said second port;
• and
• (c) a shuttle valve assembly operably associated with said shuttle cavity and with said first and second shuttle seats, whereby the fluid pressure in whichever of said first and second ports is at lower pressure is communicated to said spring chamber and adds to the force of said biasing spring.