Subaru SVX 1992 Manual page 837

BRAKES (M3B4] 4-4
3. BRAKE BOOSTER UNDER MEDIUM LOAD
The poppet valve comes in contact with the plunger .
valve and valve body when a force pushes the center of
the reaction disc (at the contact portion of the plunger
valve) via the operating rod and plunger valve . This
occurs when brake pedal depression is balanced with a
force pushing the plunger valve (via the push rod and
reaction disc) due to the reaction force of oil pressure
delivered from the master cylinder.
As a result, pressure differential is maintained between
the constant-pressure chamber and variable-pressure
chamber unless the pedal depression force is changed .
4 . BRAKE BOOSTER UNDER FULL-LOAD CONDI-
TIONS
When pedal depression increases to such an extent that
the variable-pressure chamber is maintained at atmos-
pheric pressure, the maximum pressure differential acts
on the diaphragm plate .
Further pedal depression does not act on the dia-
phragm plate but rather on the push rod .
Fig. 10
Fig . 9
7