Bendix Commercial Vehicle Systems AD-4 AIR DRYER 10/04 - Manual (Page 9)

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the end cover. Remove and discard the three sealing
rings. One sealing ring is located in the groove on the
sealing plate and the other two are in grooves in the end
cover.
2. Remove 1/4" cap screw from the bottom of the purge
valve and remove the diaphragm washer, exhaust
diaphragm and purge valve. Discard the exhaust
diaphragm and purge valve. Remove purge piston. Note:
Hold piston down when removing cap screw due to spring
tension.
3. Remove and discard the check valve assembly in the
recess at the delivery port of the end cover.
4. Remove the safety valve from the end cover (only if it has
been determined that it needs replacement during service
checks).
5. To remove the thermostat see the appropriate section in
this manual (only if it has been determined that it needs
replacement during service checks).
6. Remove purge piston and spring from the top side of the
cover.
7. Remove o-ring from the purge piston and discard the
o-ring.
8. Remove the four 1/4" cap screws and lockwashers that
secure the sealing plate to the desiccant cartridge.
Separate the sealing plate from the desiccant cartridge
and discard the sealing ring at the base of the cartridge.
CLEANING & INSPECTION
1. Using mineral spirits or an equivalent solvent, clean and
thoroughly dry all metal parts.
2. Inspect the interior and exterior of all metal parts that
will be reused for severe corrosion, pitting and cracks.
Superficial corrosion and or pitting on the exterior portion
of the upper and lower body halves is acceptable.
3. Inspect the bores of both the end cover for deep scuffing
or gouges.
4. Make certain that all purge valve housing and end cover
passages are open and free of obstructions.
5. Inspect the pipe threads in the end cover. Make certain
they are clean and free of thread sealant.
6. Inspect the purge valve housing bore and seat for
excessive wear and scuffing.
7. Inspect the purge valve piston seat for excessive wear.
8. Inspect all air line fittings for corrosion. Clean all old
thread sealant from the pipe threads.
9. All o-rings removed should be discarded and replaced
with new o-rings provided in appropriate kit(s).
Any component exhibiting a condition described in step 1
to 8 should be replaced.
ASSEMBLY
Prior to assembly, coat all o-rings, o-ring grooves, and bores
with a generous amount of barium base lubricant.
Important Note: The single exception to prelubrication
is the sealing ring between the desiccant cartridge and
sealing plate. Refer to step number 8 for proper
installation of this sealing ring. Refer to Figure 6 during
assembly unless otherwise advised.
1. Place return spring into cavity in the center of top side of
end cover.
2. Install the purge piston o-ring on the purge piston and
place the purge piston inside the return spring installed
in Step 2.
3. Turn end cover over on a flat clean surface (making sure
purge piston and return spring remain in proper position.)
Compress the return spring by pushing down on the end
cover and align square shank of purge piston into mating
hole in the end cover.
4. Place the diaphragm washer, diaphragm, and purge valve
onto the 1/4" cap screw.
5. Install the 1/4" cap screw with parts on it into exhaust
cover and torque to 60-80 inch pounds.
6. Install safety valve (if removed) and torque to 120-400
inch pounds, making sure that the exhaust hole is
pointed downward when the dryer is installed.
7. Install thermostat (if removed). Refer to instructions
pertaining to thermostat installation under section
Thermostat Assembly.
8. Place sealing ring on bottom of desiccant cartridge. The
desiccant cartridge, sealing ring and sealing plate should
be wiped and free of lubricant prior to this assembly
procedure. Attach cartridge to plate (smooth side of plate
opposite cartridge) with four 1/4" socket head cap screws
and lockwashers. Torque to 80-100 inch pounds.
9. Install the two sealing rings in the recesses of the end
cover.
10. Install the check valve assembly into the end cover
making sure the tang on the check valve assembly fits
into the mating recess in the end cover.
11. Place desiccant cartridge and sealing plate assembly
onto end cover. (Taking care not to displace sealing rings.)
The large hole in the sealing plate must line up with the
check valve and spiral pins in the sealing plate must
enter corresponding holes in the end cover.
12. Install the outer sealing ring on the sealing plate. Place
the outer housing over the desiccant cartridge (lining up
marks made on the outer housing and end cover prior to
disassembly) and retain with eight 3/8" hex head bolts,
special washers, and lock nuts. Refer to Figure 8 for
torque pattern. Torque to 270-385 inch pounds. Note: If