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2-14
uses the vacuum created in the
engine
inlet
manifold
to boost force
applied
at the master
cylinder
push
rod in
an exact
and controlled
manner.
The
assembly
is
mounted between
the brake pedal and the master
cylinder, with the
push rod from the
rear of the unit
connected
to the
brake pedal, and a push rod from the
front of the unit abuts the master
cylinder piston.
The force which assists the pedal
GROUP
2-BRAKES
FIG. 16- Brake Booster.
effort is
obtained by admitting
atmospheric
pressure
to one
side of
both diaphragms which
are
suspended
in a
vacuum. The difference in pres-
sure
moves
the
diaphragms
and this
movement
is
used in a controlled
manner to
augment
the driver's pedal
effort.
In the
case of
a vacuum failure, the
valve and rod
assembly of
the servo
and the master
cylinder
push
rod act
as a single push
rod.·
The brakes will,
.
therefore, work
in the
conventional
EJ
IN-CAR ADJUSTMENTS
AND REPAIRS
BRAKE SHOE ADJUSTMENTS
-
EXCEPT T A:XI
The car should
be
in a raised pos-
ition with the wheels off the floor.
The
hydraulic
service brakes are
self-adjusting and
require a
manual
adjustment
only
after
the
brake
shoes have been
relined, replaced, or
when the length
of the adjusting
screw has been changed while
perfor-
ming
some other service
operation.
The
brake drums should be at
normal room
temperature
when ad-
justing the brake shoes. If the shoes
are
adjusted when the drums are hot
and expanded, the shoes may drag
when
the
.
drums are cool and con-
tracted.
1. After the
shoes
have been
in-
stalled
or the adjusting screw has
been
turned, install the drum. Be
sure
that all excess grease, oil, and
other foreign material are wiped off
the
backing plate and drum.
Before installing the brake drum
on the front wheel spindle, wipe the
spindle completely free of grease.
Install the drum carefully so that the
grease
seal
retainers within the hub
will not be damaged.
2. Remove the adjusting hole
manner, but more
effort
will be
required on the brake
pedal.
PARKING BRAKE
An independent hand operated
parking brake control actuates the
rear wheel brake
shoes
through a
cable linkage, the operating cable is
routed from the parking brake con-
trol assembly to the equalizer. The
rear brake cables connect the equali-
zer assembly to
the
parking brake
lever at each rear secondary shoe.
cover
from
the backing plate. Work-
ing from the backing plate
side,
turn
the adjusting screw upward to expand
the shoes (Fig. 17). Expand the shoes
until a drag is felt when
the
drum
is
rotated.
3. Remove the drum. Mark
the-
tooth on the star-wheel where the
adjusting lever contacts
it.
While
holding the adjusting lever out of en-
gagement with the adjusting
screw,
back off the adjusting screw
i
of a
turn
with the
fingers. If
finger
move-
ment will not
tum
the
screw, free
it
up; otherwise, the self-adjusting
lever
will not turn the
screw.
Lubricate the
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