When lever 1 turns clockwise (opening of the radiator dampers), screw 2 pushes rod 3 which runs up against valve member 4. The right end of valve member 4 closes the internal passage of rod 3 and its left end opens valve 5. After this, fluid flows from port 6 to port 7. When lever 1 returns to its initial position (closing of the radiator dampers), fluid is admitted from port 7 to the internal passage of rod 3 and drains back to the tank through port 8. Check valve 9 allows surplus fluid from port 7 to flow to port 8 when valve 4 is closed.
$3925$LHP,FC$