In the position shown of valve spool 1, rarified air, admitted from the receiver through pipeline 2, fills the lower space of membrane chamber 4 and passes into chamber a of the valve from where it is directed to the upper space of membrane chamber 4. When valve spool 1 is shifted downward, chamber d of the valve, connected to the atmosphere, is also connected to pipeline 3. Atmospheric pressure bends membrane 6 downward, pulling cable 5 and thereby opening the bucket.
$4283$CHP,MH$