Subaru SVX 1992 Manual page 836

4-4 [M3B1]
BRAKES
B : OPERATION
1 . BRAKE BOOSTER "OFF"
The plunger valve comes in contact with the poppet
valve so that atmospheric air passing through the filter
and silencer is shut out by the atmospheric valve (of the
poppet valve).
The plunger valve is moved to the key at the right by the
return spring so that the poppet valve is held at the
right. Since the vacuum valve of the valve body and the
poppet valve are kept away from each other, passage A
is linked with passage B and the constant-pressure
chamber is also linked with the variable-pressure cham-
ber . At this point, pressure differential does not occur
between the two chambers ; the diaphragm plate is
moved back to the right by return spring tension .
Variable pressure chamber
I
~~ Passage A
Plunger valve
/ -Valve body
Poppet valve
0 00 0 0
0
q o 0 0 o
r
` +- Filter
/ L Valve return spring
Passage B
key
Diaphragm plate
i
Constant-pressure chamber
Return spring
- C4-501
Fig . 7
2. BRAKE BOOSTER "ON"
When the brake pedal is depressed, the operating rod
pushes the plunger valve so that the poppet valve
comes in contact with the vacuum valve of the valve
body. This shuts off the circuit between passages A and
B, as well as the circuit between the constant- and
variable-pressure chambers .
Further movement of the plunger valve moves the
atmospheric valve away from it so that atmospheric air
is directed to the variable-pressure chamber via pas-
sage B. This produces a pressure differential between
the constant- and variable-pressure chambers .
As a result, the diaphragm and its plate are moved to
the left as a single unit .
The power applied to the diaphragm plate by the
pressure differential is then transmitted to the reaction
disc via a hub, as well as to the push rod, and produces
a booster output.
Fig. 8
6