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TM 10-3930-643-20
INTRODUCTION. (cont)
1-19.
Brake System. The vehicle is equipped with an air over hydraulic brake
system. The brake system can be divided in two sections; the air system and the
brake system. For illustrations refer to specific maintenance tasks.
a.
Brake System.
(1) Brake rotors and calipers. Each wheel has a single brake
consisting of a caliper with 4 apply pistons, two on each side of
the
unit
brake
rotor, with a pad assembly.
When-the brake pedal is released, the brake rotor
will create a slapping effect on the pads, pushing the caliper pistons
back.
This effect is caused by the way the brake rotor is machined.
(2) Service brake pressure converters (S/N 2001 and above).
The service
brake pressure converters convert air pressure into hydraulic pressure.
(3) Power clusters (S/N 2000 and below).
The power clusters convert air
pressure to hydraulic pressure.
( 4 ) S e r v i c e b r a k e r e s e r v o i r . T h e r e s e r v o i r s t o r e s t h e h y d r a u l i c o il
needed to operate the system. S/N 2000 and below have one reservoir. S/N 2001
and above have two reservoirs. A breather assembly is located on the top cover
of each reservoir.
(5) Parking/emergency brake.
The parking brake is spring actuated and
air released.
(6) Parking brake drums and shoes. The air cylinder spring rod is
attached to a cam within the brake. It forces the two shoes and
l i n i n g s o ut
against the brake drum.
The shoes and linings have a spring return to
reposition them when the brake is released.
When no pressure is present in the
air cylinder, the spring takes over and moves the spring rod, keeping the brake
applied.
b.
Air System. The air system consists of the following components.
(1) Air compressor. The air compressor draws fresh air from the air
c l e a n e r.
A regulating governor, mounted on the rear of the
a ir
compressor,
senses air pressure and starts and stops air compression automatically.
( 2 ) A i r c l e a n e r.
Filters air before it is drawn into the air compressor.
( 3 ) A i r t a n k s.
A i r t a n k s p r o v i d e a r e s e r v o i r f o r t h e s t o r a g e of
compressed air.
( 4 ) A i r c y l i n d e r.
A spring loaded air cylinder is used to operate the
parking brake.
The air cylinder spring rod is attached to a cam within the
brake.
( 5 ) T r e a d l e v a l v e s . T h e t r e a d l e v a l v e s r e g u l a t e t h e a m o u n t o f a ir
directed to the power clusters/pressure converters to apply the brakes.
1-16
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