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BRAKES
Fig. 45
5.2 Brakes applied condition (Fig. 45) :
When the pedal is depressed, the operating rod
is pushed in. The piston moves away from the
valve rubber cup, opening the air valve (Y),
thereby communicating atmospheric air to
chamber 4 and to chamber 2. Fig. 45. This
results in presence of air in chambers 2 & 4.
During this time the vacuum valve (X) is closed
and vacuum is retained in chambers 1 & 3
resulting in a pressure difference from those
in chambers 2 & 4. This pressure difference
results in net force acting towards the front
housing side resulting in transfer of force to
the master cylinder through the push rod.