Bendix Commercial Vehicle Systems AD-IS EVERFLOW ASSEMBLY - Manual (Page 4)

4
the turbo cut-off valve to close off the supply of air from
the compressor (this will be further discussed in the Turbo
Cut-off Feature section). Water and contaminants which
have collected in the dryer are expelled immediately when
the purge valve opens. Also, air which was fl owing through
the desiccant cartridge changes direction and begins to
fl ow toward the open purge valve.
Liquids and other contaminants collected by the liquid
separator are removed by air fl owing from the purge
reservoir through the desiccant bed to the open purge valve.
The initial purge and desiccant cartridge decompression
lasts only a few seconds and is evidenced by an audible
burst of air at one of the AD-IS
® EverFlow ™ assembly’s
purge exhaust. The actual reactivation of the desiccant
bed begins as dry air from the purge reservoir fl ows through
the purge orifi ce into the desiccant bed. Pressurized air
from the purge reservoir expands after passing through
the purge orifi ce.
The fl ow of dry air through the drying bed removes water
vapor from the desiccant material. The purge lasts 30
seconds. The delivery check valve assembly prevents air
pressure in the brake system from returning to the purging
air dryer during the purge cycle. After the purge cycle is
complete, the air dryer is ready for the next charge cycle
to begin.
TURBO CUT-OFF FEATURE
The primary function of the turbo cut-off valve is to prevent
loss of engine turbocharger air pressure through the AD-IS
®
EverFlow ™ assembly when both dryers are in the unloaded
mode. At the onset of the purge cycle, the downward travel
of the purge piston is stopped when the turbo cut-off valve
(tapered portion of purge piston with a soft seat) contacts its
mating metal seat in the purge valve housing. With the turbo
cut-off valve seated (closed position), air in the compressor
discharge line and AD-IS
® EverFlow ™ assembly inlet port
cannot pass through the air dryer. In this manner the turbo
cut-off effectively maintains turbo charger boost pressure to
the engine. Delivery pressure in excess of 175 PSIG can
cause the purge valve to cycle rapidly between load
and purge mode. All AD-IS
® EverFlow ™ Assemblies
require a soft seat purge valve.
HIGH VOLUME MODE
If the GOV port of the electronic module indicates that the
compressor has been charging for longer than 30 seconds,
the dryers will alternatively purge every 30 seconds. This
is an indication of high volume through the dryer. When
the governor signal indicates the charge cycle is complete,
the assembly returns to normal brake cycling.
PREVENTIVE MAINTENANCE
Important: Review the warranty policy before performing
any intrusive maintenance procedures. An extended
warranty may be voided if intrusive maintenance is
performed during this period. Because no two vehicles
operate under identical conditions, maintenance intervals
will vary. Experience is a valuable guide in determining the
best maintenance interval for any one particular operation.
Every 900 operating hours, or 25,000 miles or three (3)
months:
1. Check for moisture in the air brake system by opening
reservoir drain valves and checking for presence of
water. If moisture is present, the desiccant cartridges
may require replacement; however, the following
conditions can also cause water accumulation and
should be considered before replacing the desiccant:
A. An outside air source has been used to charge the
system. This air did not pass through the drying bed.
B. Air usage is exceptionally high and not normal for a
highway vehicle. This may be due to accessory air
demands or some unusual air requirement that does not
allow the compressor to load and unload (compressing
and non-compressing cycle) in a normal fashion. Check
for high air system leakage. If the vehicle vocation
has changed it may be necessary to upgrade the
compressor size.
C. Discharge line length too short. The minimum line
length from the compressor to the dryer should be:
6' & 1/2" ID On low duty cycle applications (0-20%)
10' & 5/8" ID On high duty cycle applications (20-40%)
D. In areas where more than a 30 degree range of
temperature occurs in one day, small amounts of water
can temporarily accumulate in the air brake system due
to condensation. Under these conditions, the presence
of small amounts of moisture is normal.
Note:
1. Replace both desiccant cartridges at one time. Failure
to change both could cause one dryer to pass wet air
and the other dryer pass dry air. This would lead to a
wet brake system.
2. A small amount of oil in the system is normal and should
not be considered as a reason to replace the desiccant
cartridges. Oil at the dryer purge exhaust is normal.
3. Visually check for physical damage such as chaffed or
broken air and electrical lines and broken or missing
parts.
4. Check the AD-IS ® EverFlow ™ assembly and purge
reservoir bolts for tightness. See Figure 1. Re-torque
the three air dryer bolts to 360-420 inch pounds and the
four purge reservoir bolts to 300-360 inch pounds.
5. Perform the Operation & Leakage Tests listed in this
publication.
6. The assembly will not operate without electrical power.
Ensure electrical power is at the assembly during
vehicle operation.