Upon a change in temperature of the medium being regulated, in which bellows 1 is placed, the bellows, filled with a liquid, is deformed by the change in volume of the liquid. This actuates the stem of valve spool 2. At this, fluid, delivered under pressure to the valve, is directed to one of the ends of cylinder 3 and moves piston 4. As the piston moves, radiator flap 5, turning about fixed axis A and having fork a that engages pin B of the piston rod, turns and changes the amount of air admitted to the radiator.
$4109$EHP,Rg$