12.3
Fan the service brakes to reduce system
air pressure to governor cut-in. Note that
the system once again builds to full pres-
sure and is followed by a purge at the
AD-IP air dryer exhaust.
12.4
Check for excessive leakage around the
head of the desiccant cartridge where it
contacts the end cover. With the com-
pressor in loaded mode (compressing
air), apply a soapy solution to these
areas, and observe that any leakage
does not exceed a 1-inch bubble in 1
second. If leakage exceeds this measure,
remove and re-install the desiccant
cartridge.
AD-9si and AD–IS
1.
Park the vehicle on a level surface, apply the
parking brakes, and chock the tires.
2.
Drain the air reservoirs.
3.
Using a strap wrench or equivalent, loosen the
desiccant cartridge. Spin the cartridge off by
hand and discard it. See
4.
On the new desiccant cartridge, lubricate the
sealing rings with silicone grease.
IMPORTANT: Only use the silicone grease sup-
plied with Bendix replacement kits.
5.
Screw the desiccant cartridge onto the body by
hand until the seal makes contact with the body.
Rotate the cartridge clockwise about one full
turn. Tighten the cartridge firmly.
42–03 Air Dryer Inspection
1.
Park the vehicle on a level surface and apply the
parking brakes. Shut down the engine. Chock
the tires.
2.
Check for moisture in the air brake system by
opening the reservoir drain cocks. Examine the
discharge. Some trace of water in the discharge
is normal. A discharge of a milky gray liquid indi-
cates excessive moisture is present in the air
system and the desiccant cartridge needs to be
replaced. See
Group 42
of the vehicle Workshop
Manual for troubleshooting procedures. The fol-
lowing conditions could cause small amounts of
moisture to be found in the air system:
•
An outside air source has been used to
charge the air brake system. This air did
not pass through the drying bed.
•
Air usage is unusually high and not normal.
This may be due to accessory air demands
or some unusual air requirement that does
not allow the compressor to load and un-
load in a normal fashion. Check for air sys-
tem leaks.
•
The air dryer has been installed on a sys-
tem that had previously been operated
without an air dryer. This type of system
will be saturated with moisture, and several
weeks of operation may be needed to fully
dry the system.
•
The temperature range in your area fluctu-
ates more than 30 degrees in one day.
Small amounts of water can accumulate in
the air brake system due to condensation.
Under these conditions, the presence of
moisture is normal and should not be con-
sidered an indication of poor air dryer per-
formance.
3.
Inspect the air dryer for external damage, and
check that the unit is tightly mounted on the
frame. If the air dryer mounting is loose, See
04/16/98
f421910
1
2
3
1.
Desiccant Cartridge
2.
Cartridge Sealing Ring
3.
Threaded Base Post
Fig. 3, Desiccant Cartridge Replacement
Brakes
42
122SD and Coronado 132 Maintenance Manual, February 2016
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