Brake System; Description And Operation - Ford Comet 1964 Shop Manual

PART
Section Page
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BRAKE SYSTEM
1 Description and Operation 2-6
2 In-Car Adjustments and Repairs
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2-9
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2-2
3 Removal and Installation 2-13
4 Major Repair Operations
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2-16
DESCRIPTION AND OPERATION
REAR BRAKE FRONT BRAKE
FIG. 1
-Self Adjusting Brake Assemblies
HYDRAULIC SELF ADJUSTING rearward and only when the second- the drum. Therefore, the adjuster
BRAKE SYSTEM
ary shoe is free to move toward the
does not operate.
The hydraulic brake system em-
ploys single anchor, internal expand-
ing and self-adjusting brake assem-
blies. A vacuum booster is available
as optional equipment on all cars
equipped with an automatic trans-
mission.
The master cylinder converts phys-
ical force from the brake pedal and
booster into hydraulic pressure
against the pistons in the wheel cylin-
ders. The wheel cylinder pistons in
turn convert hydraulic pressure back
into physical force at the brake
shoes.
The self-adjusting brake mecha-
nism consists of a cable, cable guide,
adjusting lever, and adjuster spring
(Fig. 1 ) . The cable is hooked over
the anchor pin at the top and is
connected to the lever at the bottom.
The cable is connected to the sec-
ondary brake shoe by means of the
cable guide. The adjuster spring is
hooked to the primary brake shoe
and to the lever. The automatic ad-
juster operates only when the brakes
are applied while the car is moving
drum beyond a predetermined point.
With the car moving rearward and
the brakes applied, the "wrap-
around" action of the shoes follow-
ing the drum forces the upper end
of the primary shoe against the
anchor pin. The action of the wheel
cylinder moves the upper end of the
secondary shoe away from the an-
chor pin. The movement of the sec-
ondary shoe causes the cable to pull
the adjusting lever upward and
against the end of a tooth on the
adjusting screw star-wheel. The up-
ward travel of the lever increases as
lining wear increases. When the 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 level downward causing the
star-wheel to turn and expand the
shoes. The star-wheel is turned one
tooth at a time as the linings pro-
gressively 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 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 are non-adjustable.
BOOSTER SYSTEM
The diaphragm type booster is a
self-contained vacuum hydraulic
power braking unit mounted on the
engine side of the dash panel. It is
of the vacuum suspended type which
utilizes engine intake manifold vac-
uum and atmospheric pressure for its
power. It consists of three basic
elements combined into a single unit
(Fig. 2 ) .
The three basic elements are:
1. A vacuum power chamber
which consists of a front and a rear
shell, a power diaphragm, a hydraulic
pu'sh-rod and a vacuum diaphragm
return spring.
2. A mechanically actuated control
valve integral with the vacuum power
diaphragm controls the degree of