Ford Thunderbird 1964 - Booster System; Booster in Applied Position; Booster in Holding Position

PART
2-2
BRAKE
SYSTEM
2-7
lever
can
move
upward far
enough,
it
passes over the end of
the tooth
and
engages
the tooth. When
the
brakes are
released,
the
adjusting
spring
pulls
the lever downward
causing
the
star
wheel
to
turn
and
expand
the shoes. The star wheel is
turned
one
tooth at
a time
as
the
linings
progressively
wear.
With the
car
moving
forward and
the
brakes
applied,
the
secondary
shoe
is against the
anchor
pin
and
the
primary
shoe is moved
toward
the
drum.
Therefore,
the
adjuster
does
not
operate.
The
rear brake
assembly
is
basi
cally
the
same
as
the
front
brake.
The
conventional
parking
brake
lever, link,
and
spring
are
used in
the rear
brake.
The
anchor
pins
on all
brakes
are
fixed and
non-adjustable.
BOOSTER
SYSTEM
The
power brake booster is
in
stalled on
the
engine side of
the
dash panel and
is connected to the
brake pedal
through a lever
assem
bly
and
push rod link.
The booster
consists
of a
vacuum
chamber,
atmospheric
valve,
con
trol
valve plunger
assembly,
dia
phragm
and
an
atmospheric
cham
ber.
Atmospheric pressure
is
present
at
all times
in
the atmospheric
chamber at
the front
side of
the
atmospheric valve.
The
air
intake
to
the
atmospheric chamber is pro
tected
by
an
air
filter. The atmos
pheric
chamber
is
separated
from
the
vacuum
chamber
by
the bellows
assembly
within the
vacuum cham
ber.
Vacuum
is
present
at all times
in
that
area
of the
vacuum chamber
forward of
the
diaphragm.
Vacuum
is
supplied
through a
hose
from the
intake
manifold to
the
vacuum
mani
fold
and
check valve
on
the booster
body.
With this
integral
check
valve
and
vacuum
chamber,
it is
possible
to
obtain
several
power
assisted
brake
applications
with
the
engine
shut
off.
This
arrangement makes
a
vacuum
reservoir
unnecessary.
Either
vacuum
from the
forward
side
of
the
diaphragm or air
from
the
bellows
(atmospheric
chamber)
can
be
connected
to
the
rear
side of
the
diaphragm
through
porting
in
the
control
valve hub
and
the
plunger
assembly.
VACUUM
SOURCE
CHECK
VALVE
ATMOSPHERIC
SOURCE'
VACUUM
PORT
CLOSED
BRAKE
PEDAL
VACUUM
ATMOSPHERIC PRESSURE
FIG.
2-Booster
in
Applied Position
APPLYING
POSITION
As
the brake pedal
is
depressed,
the
valve
operating
rod
and
valve
plunger
assembly
move forward
compressing
the plunger
return
spring
(Fig. 2).
The
initial move
ment
of
the plunger
closes
the port
ing
from the vacuum chamber
pre
venting
further
evacuation of
the
area back of
the diaphragm.
Fur
ther
movement
of the plunger forces
the atmospheric valve
off
its
seat
so
that
atmospheric
pressure from
the
bellows
can enter the hub
porting
that leads
to the rear side
of
the
diaphragm.
With
vacuum on the
front
side
of the
diaphragm and
atmospheric
pressure on the back
side
of
the
diaphragm,
a
force is
developed
to
H1205-A
move
the
diaphragm,
push
rod
and
master
cylinder piston
forward to
close
the
compensating
port
and
force hydraulic
fluid under
pressure
through
the
residual
pressure
check
valve and
brake tubes
to the
wheel
brakes. As
hydraulic pressure is
de
veloped in the hydraulic
system,
a
reaction counter-force acts
against
the
reaction
lever
and
ring
assem
bly.
This
reaction
lever
and
ring
assembly
is designed to
transmit
the
reaction
forces
back
through
the
actuating
control valve
assembly
to
the
brake
pedal
and provide the
driver
with a resistance
that
is
in
proportion
to the brake
hydraulic
apply
forces.
This
is
the
means of
providing
the
proper
"driver
feel"
to the power
brake
unit.
VACUUM SOURCE
--iHr^r
ATMOSPHERIC
SOURCE
VACUUM
PORT
OPEN
P]
VACUUM
f^?]
ATMOSPHERIC
PRESSURE
FIG.
3-Booster
in
Holding
Position
BRAKE
PEDAL
H1206-A