Bendix AD-IS User Manual
®
Bendix® AD-IS® Air Dryer and Reservoir System
RES
GOVERNOR
RESERVOIR (2)
21
PRI
DELIVERY TO
PRIMARY
RESERVOIR
PURGE VALVE
PRESSURE
22
SEC
DELIVERY TO
SECONDARY
RESERVOIR
PROTECTION
VALVES (4)
SAFETY VALVE
DESICCANT
CARTRIDGE
SD-08-2418
MOUNTING
HOLES - 4
PURGE
RESERVOIR
UNL
GOVERNOR
UNLOADER (2)
FIGURE 1 - AD-IS® AIR DRYER AND RESERVOIR SYSTEM
GOVERNOR
EXH
GOVERNOR
EXHAUST
AD-IS® AIR DRYER
PART NUMBER
STAMPED HERE
1
IN
SUPPLY FROM
COMPRESSOR
DESCRIPTION
The function of the Integrated Solution Air Dryer (AD-IS®)
and Reservoir System is to provide heavy vehicles with an
integrated vehicle air dryer, purge reservoir , governor and a
number of the charging valve components in a module.
These have been designed as an integrated air supply
system.
The AD-IS® air dryer and reservoir system collects and
removes air system contaminants in solid, liquid and vapor
form before they enter the brake system. It provides clean,
dry air to the components of the brake system which
increases the life of the system and reduces maintenance
costs. The necessity for daily manual draining of the
reservoirs is eliminated.
MOUNTING
BOLTS (3)
HEATER /
THERMOSTAT
AUXILIARY
PRESSURE PROTECTION
VALVES (4)
Air
Connection Function/Connection QTY
Port ID
DELIVERY PORTS
23
AUX2
AUXILIARY
DELIVERY PORTS
(2)
24
AUX1
(4)
1
IN
Inlet Port (air in). 1
21
PRI
Delivery Port out (to Primary reservoir) 1
22
SEC
Delivery Port out (to Secondary reservoir) 1
24
AUX 1
Auxiliary Delivery Port (air out). 4
23
AUX 2
Auxiliary Delivery Port (air out). 1
UNL Unloader Control Air (D-2A™ Governor) 2
RES Common Reservoir Pressure
(D-2A™ Governor) 2
EXH Governor Exhaust 1
TABLE 1 - PORT DESIGNATIONS
1
GOVERNOR
UNLOADER
PORT
DESICCANT
BED
DELIVERY
CHECK
VALVE
(OPEN)
PURGE
CONTROL
CHANNEL
OIL
SEPARATOR
PRESSURE PROTECTION
VALVES
A
Note 1:
The AD-IS
®
air dryer and reservoir system
purge piston has a purge control channel
drain. This allows any condensation in this
area to flow past a diaphragm in the top of the
purge piston and out through a channel in
the middle of the central bolt of the purge
assembly to be drained. During the purge
cycle this drain is closed.
PURGE
ORIFICE
PURGE
RESERVOIR
INLET
PORT
(IN)
TURBO CUT-
OFF VALVE
(OPEN)
PURGE
VALVE
(CLOSED)
SEE
NOTE 1
ENGINE
TURBO
COMPRESSOR
B
SAFETY
VALVE
PRIMARY
PORT
(PRI)
SECONDARY
PORT
(SEC)
PRIMARY
RESERVOIR
C
AUXILIARY PORTS
(TO ACCESSORIES)
FIGURE 2 - AD-IS® AIR DRYER AND RESERVOIR SYSTEM CHARGE CYCLE
D
PURGE
RESERVOIR
DRAIN VALVE
SECONDARY
RESERVOIR
DIAGRAM SHOWS PRESSURE
PROTECTION VA LVES A & B OPEN,
C & D CLOSED.
The function of the pressure protection valves is to protect
each reservoir from a pressure loss in the other reservoir or
a pressure loss in an air accessory . Each of the pressure
protection valves in the AD-IS® air dryer and reservoir system
may have different pressure settings, but these are factory
set and must not be changed or adjusted.
The air dryer and reservoir system consists of a “spin on”
desiccant cartridge secured to a base assembly . The base
assembly contains a delivery check valve assembly , safety
valve, heater and thermostat assembly , pressure protection
valves, threaded air connections and the purge valve
assembly.
2
The removable purge valve assembly incorporates the purge
valve mechanism and a turbocharger cut-off feature that is
designed to prevent loss of engine “turbo” boost pressure
during the purge cycle of the AD-IS® air dryer and reservoir
system. For ease of maintenance, all replaceable
assemblies can be serviced without removal of the air dryer
and reservoir system from its mounting on the vehicle. Refer
to Preventive Maintenance section.
GOVERNOR
UNLOADER
PORT
INLET
PORT
(IN)
DELIVERY
CHECK
VALVE
(CLOSED)
PURGE
CONTROL
CHANNEL
TURBO CUT-
OFF VALVE
(CLOSED)
EXHAUST
PURGE
VALVE
(OPEN)
ENGINE
TURBO
COMPRESSOR
SAFETY
VALVE
PRESSURE PROTECTION
A
PRIMARY
PORT
(PRI)
SECONDARY
PORT
(SEC)
DESICCANT
BED
OIL
SEPARATOR
VALVES
PURGE
ORIFICE
D
CB
AUXILIARY PORTS
(TO ACCESSORIES)
PRIMARY
RESERVOIR
PURGE
RESERVOIR
PURGE
RESERVOIR
DRAIN VALVE
SECONDARY
RESERVOIR
GOVERNOR SIGNALS AIR
COMPRESSOR TO SUSPEND
COMPRESSED AIR SUPPLY
TO AD-IS
®
AIR DRYER
DIAGRAM SHOWS ALL PRESSURE PROTECTION V ALVES
OPEN.
FIGURE 3 - AD-IS® AIR DRYER AND RESERVOIR SYSTEM PURGE CYCLE
AD-IS® AIR DRYER AND RESERVOIR SYSTEM
OPERATION: GENERAL
The AD-IS® air dryer and reservoir system is designed to
receive compressed air from the vehicle air compressor,
clean and dry the air, deliver air to the vehicle’s primary
reservoir, secondary reservoir and accessories, and control
the compressor/dryer charge cycle.
(Refer to Figure 2)
Charge Cycle and the Purge Cycle. The following
descriptions are separated into these “cycles” of operation.
CHARGE CYCLE (Refer to Figure 2)
When the compressor is loaded (compressing air)
compressed air flows through the compressor discharge
line to the inlet (1/IN) port of the air dryer body. The
compressed air often includes contaminates such as oil,
AIR DRYER AND RESERVOIR SYSTEM
OPERATION: GENERAL
The AD-IS® air dryerand reservoir system alternates between
oil vapor, water and water vapor .
Traveling through the discharge line and into the air dryer ,
the temperature of the compressed air falls, causing some
two operational modes or “cycles” during operation: the
3
of the contaminants to condense and drop to the bottom of
the air dryer and reservoir system purge valve assembly,
ready to be expelled at the next purge cycle. The air then
flows into the desiccant cartridge, where it flows through an
oil separator which removes liquid oil and solid contaminants.
Air then flows into the desiccant drying bed and becomes
progressively drier as water vapor adheres to the desiccant
material in a process known as “ADSORPTION.”
Dry air exits the desiccant cartridge through the center of
the base assembly. The air then flows to the delivery check
valve and also through an orifice into the purge reservoir.
The delivery check valve opens, supplying air to the pressure
protection valves (A) through (D) simultaneously , the safety
valve, and also to the reservoir port of the attached governor.
The purge reservoir fills, storing air that will be used to
reactivate the desiccant during the purge cycle. This air is
available to supply downstream components during the
charge mode.
When the air pressure reaches approximately 106 psi, the
four pressure protection valves will open and air will be
supplied to the primary reservoir, secondary reservoir and
accessories. If the pressure protection valves are preset to
different values the valves will open in order of lowest setting
to highest setting when charging a flat system.
The air dryer and reservoir system will remain in the charge
cycle until the air brake system pressure builds to the
governor cut-out setting of approximately 130 p.s.i.
PURGE CYCLE (Refer to Figure 3.)
When air brake system pressure reaches the cut-out setting
of the governor, the governor unloads the compressor and
the purge cycle of the air dryer and reservoir system begins.
The governor unloads the compressor by allowing air
pressure to fill the line leading to the compressor unloader
mechanism - causing the delivery of compressed air to
the AD-IS® air dryer and reservoir system to be suspended.
Similarly, the governor also supplies air pressure to the
AD-IS® air dryer and reservoir system purge control channel.
The AD-IS® air dryer and reservoir system purge piston
moves down in response to this air pressure, causing the
purge valve to open to the atmosphere and 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 purge valve base are expelled immediately when the
purge valve opens. Also, air which was flowing through the
desiccant cartridge changes direction and begins to flow
toward the open purge valve. Oil and solid contaminants
collected by the oil separator are removed by air flowing
from the purge reservoir through the desiccant drying 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 the AD-IS
air dryer and reservoir system
exhaust.
The actual reactivation of the desiccant drying bed begins
as dry air from the purge reservoir flows through the purge
orifice into the desiccant bed. Pressurized air from the
purge reservoir expands after passing through the purge
orifice; its pressure is lowered and its volume increased.
The flow of dry air through the drying bed reactivates the
desiccant material by removing the water vapor adhering to
it. Approximately 30 seconds are required for the entire
contents of the purge reservoir of a standard AD-IS
®
air dryer
and reservoir system to flow through the desiccant drying
bed.
The delivery check valve assembly prevents air pressure in
the brake system from returning to the air dryer and reservoir
system during the purge cycle. After the purge cycle is
complete, the air dryer and reservoir system is ready for
the next charge cycle to begin.
TURBO CUT-OFF FEATURE (Refer to Figure 3.)
The primary function of the turbo cut-off valve is to prevent
loss of engine turbocharger air pressure through the
AD-IS® air dryer and reservoir system when the dryer is 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) 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® air dryer and reservoir system inlet port cannot enter
the air dryer and reservoir system. In this manner the turbo
cut-off effectively maintains turbo charger boost pressure
to the engine.
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. Purge valve maintenance is permissible
during the warranty period only when using a genuine Bendix
purge valve kit.
Because no two vehicles operate under identical conditions,
maintenance and 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 cartridge
4
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. Refer to Bendix Specification
BW-100-A, Appendix D to determine if any changes
are necessary .
C. Location of the air dryer and reservoir system is too
close to the air compressor. Refer to Bendix
Specification BW-100-A, Appendix B for discharge
line lengths.
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: A small amount of oil in the system is normal and
should not be considered as a reason to replace the
desiccant cartridge. Some oil at the dryer exhaust is normal.
2. Visually check for physical damage such as chaffed or
broken air and electrical lines and broken or missing
parts.
®
3. Check the AD-IS
air dryer 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.
4. Perform the Operation & Leakage Tests listed in this
publication.
WARNING!
This air dryer and reservoir system is intended to
remove moisture and other contaminants normally
found in the air brake system. Do not inject alcohol,
anti-freeze, or other de-icing substances into or
upstream of the air dryer and reservoir system. Alcohol
is removed by the dryer, but reduces the effectiveness
of the device to dry air. Use of these or other subst ances
can damage the air dryer and reservoir system and
may void the warranty.
HEATER & THERMOSTAT
CONNECTOR
FIGURE 4 - AD-IS® AIR DRYER AND RESERVOIR SYSTEM
HEATER AND THERMOSTAT CONNECTOR
OPERATION & LEAKAGE TESTS (ALSO SEE
VIDEO BW2327)
1. Check all lines and fittings leading to and from the air
dryer and reservoir system for leakage and integrity.
Repair any leaks found.
2. Build up system pressure to governor cut-out and note
that the AD-IS
with an audible escape of air. Watch the system
pressure and note the pressure fall-off for a ten minute
period. If pressure drop exceeds, for a single vehicle - 1
psi/minute from either service reservoir; or for tractor trailer
- 3 psi/minute from either service reservoir , inspect the
vehicle air systems for sources of leakage and repair
them. Refer to section entitled Troubleshooting,
Symptoms 1 and 4.
3. Caution: Be sure to wear safety glasses in case of
a purge blast. Check for excessive leakage around
the purge valve with the compressor in the loaded mode
(compressing air). Apply a soap solution to the purge
valve exhaust port and observe that leakage does not
exceed a 1" bubble in 1 second. If the leakage exceeds
the maximum specified, refer to section entitled
Troubleshooting, Symptom 4.
4. Build up system pressure to governor cut-out and note
that the AD-IS
with an audible burst of air, followed immediately by
approximately 30 seconds of air flowing out of the purge
valve. "Fan" the service brakes to reduce system air
pressure to governor cut-in. Note that the system once
again builds to full pressure and is followed by an
AD-IS® air dryer and reservoir system purge. If system
does not follow this pattern, refer to section entitled
Troubleshooting, Symptoms 5 and 6.
5. Check the operation of the end cover heater and
thermostat assembly during cold weather operation as
follows:
®
air dryer and reservoir system purges
®
air dryer and reservoir system purges
5
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