BENDIX AD-SP, SC-PR User Manual
®
SD-08-2415
Bendix® AD-SP™ System Purge Air Dryer & SC-PR
Single Check Protection Valve
“SPIN OFF”
DESICCANT
CARTRIDGE
MOUNTING
HOLES (3)
CONTROL
PORT
HEATER &
THERMOSTAT
CONNECTOR
TURBO
CUTOFF VALVE
EXHAUST PORT
MOUNTING
HOLES (3)
SUPPLY
PORT
™
DELIVERY PORT
EXHAUST PORT
FIGURE 1 - AD-SP™ SYSTEM PURGE AIR DRYER
DESCRIPTION
The function of the AD-SP™ System Purge Air Dryer is to
collect and remove 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. Daily manual draining of the reservoirs is eliminated.
The system purge designation is used because the
AD-SP™ air dryer uses a small portion of system air pressure
from the supply and front axle service reservoirs to perform
the purge or regenerative function. An SC-PR™ single check
protection valve or a valve that performs the same function
is always used in conjunction with the AD-SP™ air dryer to
protect the service system.
The AD-SP™ air dryer consists of two major component
groups, a spin off desiccant cartridge assembly and a die
cast aluminum body assembly. The desiccant cartridge is
self contained and serviced as a complete assembly . The
AD-SP™ air dryer aluminum body contains the following
serviceable components or assemblies; the turbocharger
cut-off valve, heater and thermostat assembly , delivery check
valve assembly and combined purge and relief valve
assembly. In addition, the non-serviceable purge control
valve is located in the body. All service and replacement
can be accomplished from the exterior of the dryer without
removal from the vehicle. The spin-on desiccant cartridge
is removed and installed using a “strap wrench.”
The AD-SP™ air dryer has three female pipe thread air
connections identified as follows:
Air Connection Port ID Function/Connection
CON 4...................... Control Port (purge valve control
& turbo cut-off).
SUP 11 .................... Supply Port (air in).
DEL 2 ...................... Delivery Port (air out).
1
COMPRESSOR
GOVERNOR
AD-SP
AIR
DRYER
™
REAR AXLE
™
SC-PR
SUPPLY
VALVE
FRONT AXLE
DELIVERY PORT
(TO FRONT SERVICE
RESERVOIR)
EMBOSSED PORT
IDENTIFICATION “2 DEL”
FIGURE 2 - AD-SP™ AIR DRYER SYSTEM DRAWING WITH EXTERIOR AND TOP VIEW OF SC-PR™ VALVE.
OPERATION
SUPPLY PORT
(FROM SUPPLY
RESERVOIR)
EMBOSSED PORT
IDENTIFICATION
“1 SUP”
After exiting the end cover , the air flows into the desiccant
cartridge where an oil separator, located between the outer
GENERAL
The AD-SP™ air dryer alternates between two operational
modes or “cycles” during operation: the Charge Cycle and
the Purge Cycle. The following description of operation is
separated into these “cycles” of operation.
and inner shells of the cartridge, removes water in liquid
form as well as liquid oil and solid contaminants.
After exiting the oil separator , air enters the space between
the desiccant drying bed and the outer cartridge shell and
flows down through the column of desiccant. Flowing through
the desiccant column, air becomes progressively dryer as
CHARGE CYCLE (refer to Figure 3)
When the compressor is loaded (compressing air)
compressed air, along with oil, oil vapor, water and water
vapor flows through the compressor discharge line to the
supply port of the air dryer body.
Air entering the supply port immediately encounters the
“turbo cut-off” valve. With no air pressure in the control port,
the turbo cut-off piston moves the valve away from its seat
in the body allowing the supply air to enter the body . As air
travels through the end cover assembly , its direction of flow
changes several times, reducing the temperature, causing
contaminants to condense and drop to the bottom or sump
of the air dryer body.
water vapor adheres to the desiccant material in a process
known as “ADSORPTION.” Using the adsorption process,
the desiccant cartridge typically removes 95% of the water
vapor from the pressurized air.
Dry air exits the bottom of the desiccant cartridge through
its center opening and returns to the air dryer body
assembly. As air flows through the supply cavity it is also
conducted, via internal passages, to the non-serviceable
purge control mechanism contained in the body . The purge
control mechanism (not shown) is able to monitor supply
air pressure. The air then flows through the delivery check
valve assembly and out the delivery port to the first (supply)
reservoir of the air system. As air moves p ast the delivery
check valve, on its way to the delivery port, it is also
conducted to the purge control mechanism. The purge
control mechanism is able to monitor air brake system
pressure as well as supply air pressure.
2
SUPPLY
PORT
GOVERNOR
COMPRESSOR
FIGURE 3 - AD-SP
OIL
SEPARATOR
CONTROL
PORT
TURBO
CUTOFF
ENGINE
TURBO
™
AIR DRYER CHARGE CYCLE
PURGE
PISTON
EXHAUST
PORT
DESICCANT
PURGE
ORIFICE
DELIVERY
PORT
PURGE /
RELIEF
VALVE
DELIVERY
CHECK
SC-PR
VALVE
REAR
RESERVOIR
™
FRONT
RESERVOIR
The air dryer will remain in the charge cycle until the air
brake system pressure builds to the governor cutout setting.
To protect against over pressurization of the AD-SP™ air
dryer, the purge valve incorporates an integral relief valve
feature. In the event that the compressor unloader
OIL
SEPARATOR
CONTROL
PORT
SUPPLY
PORT
MALFUNCTIONING
GOVERNOR
COMPRESSOR
TURBO
CUTOFF
PURGE
PISTON
ENGINE
TURBO
mechanism or governor malfunctions, at approximately 200
psi supply air pressure the AD-SP™ air dryer purge valve
will open (without control pressure), and vent excess air
pressure to atmosphere (refer to Figure 4).
DESICCANT
PURGE
EXHAUST
PORT
ORIFICE
DELIVERY
PURGE /
RELIEF
VALVE
PORT
DELIVERY
CHECK
SC-PR
VALVE
REAR
RESERVOIR
™
FRONT
RESERVOIR
FIGURE 4 - AD-SP™ AIR DRYER RELIEF VALVE OPERATION
3
OIL
SEPARATOR
CONTROL
PORT
DESICCANT
PURGE
ORIFICE
DELIVERY
PORT
DELIVERY
CHECK
REAR
RESERVOIR
TURBO
CUTOFF
GOVERNOR
PURGE
PISTON
ENGINE
TURBO
COMPRESSOR
FIGURE 5 - AD-SP™ AIR DRYER PURGE CYCLE
PURGE CYCLE (refer to Figure 5)
When air brake system pressure reaches the cutout setting
of the governor, typically 120 p si, the compressor unloads
(air compression is stopped) and the purge cycle of the air
dryer begins. When the governor unloads the compressor,
it pressurizes the compressor unloader mechanism and
the line connecting the governor unloader port to the control
port of the AD-SP™ air dryer body. Air entering the control
port is simultaneously directed to the turbo cut-off valve
and the purge valve control piston.
The initial purge cycle consists of two simultaneous
occurrences; the closing of the turbo cut-off valve and the
opening of the purge valve. Each is discussed below under
a separate subheading.
TURBO CUT-OFF VALVE (refer to Figure 5)
The primary function of the turbo cut-off valve is to prevent
loss of engine turbocharger air pressure through the
AD-SP™ air dryer in systems where the compressor intake
is connected to the engine turbocharger. The turbo cut-of f
valve also eliminates the “puffing” of air out the open air
dryer exhaust when a naturally aspirated, single cylinder
compressor is equipped with an inlet check valve.
Governor unloader pressure causes the turbo cut-off valve
piston to move and close. With the turbo cut-off valve piston
seated (closed position), air in the discharge line and
AD-SP™ air dryer inlet port is prevented from entering the
air dryer.
SUPPLY
RESERVOIR
FRONT
RESERVOIR
EXHAUST
PORT
PURGE /
RELIEF
VALVE
SC-PR
VALVE
™
PURGE PISTON
The AD-SP™ air dryer purge piston also moves in response
to governor unloader pressure, causing the purge valve to
open to atmosphere. Contaminants in the body sump are
instantly expelled when the purge valve opens. Air which
was flowing through the desiccant cartridge immediately
changes direction and begins to flow back toward the open
purge valve. Oil and solid contaminants collected by the oil
separator are removed by air flowing from the desiccant
drying bed to the open purge valve.
DESICCANT RE-ACTIVATION (DRYING THE
DESICCANT)
The initial decompression of the air dryer assembly lasts
only a few seconds and is evidenced by an audible burst of
air at the AD-SP™ air dryer exhaust. The initial
decompression of the air dryer assembly is “sensed” by
the purge control mechanism and is used by the purge
mechanism as a signal that desiccant re-activation should
begin. The purge control mechanism “remembers” the
highest pressure attained in the air system, the cutout
pressure of the governor.
The actual re-activation of the desiccant drying bed begins
as the purge mechanism allows dry air to flow from the
delivery port (air brake system) back into the AD-SP™ air
dryer body and through the desiccant cartridge. The delivery
check valve assembly prevents air pressure in the brake
system from returning to the air dryer and flowing out the
open purge valve. The delivery check valve forces system
4
air to flow through the purge mechanism. Dry air for the
brake system enters the purge control mechanism through
an air channel located in the delivery port, before the delivery
single check valve. It flows through the mechanism and
exits a 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.
Dry, brake system air will continue to flow through the
desiccant bed until the purge mechanism senses that the
brake system pressure has dropped between 8 - 14 psi
below what it “remembered” as being high (governor cut
out). For example: If governor cutout pressure was 120 psi
the purge mechanism will use air from the supply and front
axle reservoirs until it detects that pressure has dropped to
between 1 12 - 106 psi. System pressure will be reduced in
the supply and secondary (front axle) reservoirs only . The
primary or rear axle service reservoir will retain governor
cutout pressure (in the example, 120 psi). The purge cycle
and re-activation of the desiccant drying bed along with the
resulting pressure reduction takes place in approximately
15 - 20 seconds.
CHARGING
BELOW 100 PSI
SUPPLY
PORT
CHARGING
ABOVE 100 PSI
SUPPLY
PORT
DIAPHRAGM
DELIVERY
PORT
SINGLE
CHECK
VALVE
DIAPHRAGM
DELIVERY
PORT
Once the purge cycle is complete, the purge control
mechanism closes and no further reduction of system
pressure should occur. The air dryer is ready for the next
charge cycle to begin.
The purge valve will remain open and the turbo cut-off valve
closed after the purge cycle is complete and neither will
change position until air brake system pressure is reduced
to governor cut-in pressure and the Charge Cycle begins.
SC-PR™ VALVE DESCRIPTION
The SC-PR™ single check protection valve, combines a
single check valve and a pressure protection valve in a single
assembly . Its primary use is in conjunction with the Bendix
AD-SP™ air dryer and is installed in the front axle
(secondary) service reservoir in place of a standard single
check valve.
The SC-PR™ valve allows the AD-SP™ air dryer to draw air
pressure from the front axle service reservoir during the purge
cycle. It also protects the air pressure in the front axle
service reservoir, in the event of a compressor, supply, or
rear axle reservoir failure, or malfunction of the AD-SP™ air
dryer purge control mechanism.
The SC-PR™ valve is intended for direct mounting to the
service reservoir. Both SC-PR™ valve air connections are
1/2 inch pipe thread and each is identified with cast,
embossed letters for ease of identification and installation.
The letter identifications and connections to the air system
are shown below for reference.
GOVERNOR
™
AD-SP
AIR
DRYER
COMPRESSOR
FIGURE 6 - SC-PR™ VALVE CHARGE POSITION*
®
SUPPLY
RESERVOIR
SC-PR™ VALVE
REAR AXLE
RESERVOIR
FRONT AXLE RES.
Air Connection Identification System Connection
Supply .................... 1 SUP ....................... Connected to Supply (wet)
Reservoir
Delivery................. 2 DEL ......................... Nipple Mounted to Front
Axle Service Reservoir
SC-PR™ VALVE OPERATION
CHARGING
During initial air system build up, air flows from the supply
reservoir to the supply port of the SC-PR™ valve. Air entering
the SC-PR™ valve supply port is present beneath the
pressure protection diaphragm and simultaneously flows
through the single check valve portion into the front axle
service reservoir. With supply air pressure less than 100
psi, the pressure protection diaphragm, which functions as
a valve, remains seated on its inlet due to spring force above.
*Cutaway views are functionally correct, but do not represent current form of SC-PR™ valve.
5
When supply pressure reaches 100 psi, the diaphragm moves
away from its seat and air entering the supply port flows through
the pressure protection valve portion, as well as the single
check valve portion, and into the front axle service reservoir.
NORMAL PURGE
The pressure protection valve remains open as long as
supply pressure remains above 95 psi.
PURGING
When the AD-SP™ air dryer begins its purge cycle, air from
the supply and front axle service reservoirs flows back to
the air dryer to re-activate the desiccant. Air flowing from
the front axle service reservoir to the supply reservoir must
pass through the SC-PR
because the single check valve portion is closed to flow in
that direction.
Since an AD-SP™ air dryer purge cycle begins at governor
cutout (120 psi minimum) and only reduces reservoir air
pressure 8 - 14 psi, the SC-PR™ pressure protection valve
will normally remain open. If a malfunction occurs that
causes the supply reservoir to lose pressure, air from the
front axle service reservoir will flow back to the supply
reservoir until the pressure beneath the SC-PR™ pressure
protection valve diaphragm falls to approximately 95 psi.
With 95 psi or less beneath the diaphragm, spring force
moves the diaphragm into contact with the inlet seat and
air flow to the supply reservoir ceases. The supply reservoir
will continue to lose pressure, however 95 psi will be retained
in the front axle service reservoir for braking.
™
pressure protection valve portion
SUPPLY
PORT
PROTECTION
FUNCTION
SUPPLY
PORT
GOVERNOR
AD-SP
DRYER
AIR
DIAPHRAGM
DELIVERY
PORT
SINGLE
CHECK
VALVE
DIAPHRAGM
DELIVERY
PORT
REAR AXLE
™
RESERVOIR
Any malfunction occurring between the compressor and
SC-PR™ valve that causes pressure to drop below 95 psi
will result in the SC-PR™ pressure protection valve closing
and protecting the front axle service reservoir.
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 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
reservoirs, drain cocks, or drain valves and checking for
presence of water. If moisture is present, the desiccant
cartridge may require replacement; however, the following
conditions can also cause water accumulation and
should be considered before replacing the desiccant:
FRONT AXLE RES.
COMPRESSOR
FIGURE 7 - SC-PR™ SINGLE CHECK PROTECTION VALVE
PURGE POSITION*
SUPPLY
RESERVOIR
SC-PR™ VALVE
A. An outside air source has been used to charge the
system. This air does 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 Appendix A, Table A and
the column entitled Vehicle V ocation.
C. The air dryer has been installed in a system that
has been previously used without an air dryer. The
system will be saturated with moisture and several
weeks of operation may be required to dry it out.
6
*Cutaway views are functionally correct, but do not represent current form of SC-PR™ valve.
D. A single check valve, or a device with a check valve
feature, may have been installed to the inlet port of
the supply tank or in the delivery line between the
air dryer and the supply tank. This will prevent regeneration of the air dryer desiccant cartridge and
lead to moisture accumulation in the air reservoirs.
E. Location of the air dryer is too close to the air com-
pressor. Refer to Locating AD-SP™ Air Dryer On
Vehicle section and Appendix A, Table A, column 2
for discharge line length.
F. In areas where more than a 30 degree range of tem-
perature 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
and should not be considered as an indication that
the dryer is not preforming properly .
Note: A small amount of oil in the system is normal and
should not be considered as a reason to replace the
desiccant cartridge; oil-stained desiccant can function
adequately.
2. Visually check for physical damage to the AD-SP™ air
dryer such as dented desiccant cartridge, chaffed or
broken air and electrical lines and broken or missing
parts. Check the SC-PR™ valve also.
3. Check mounting bolts for tightness. Re-torque to 50 ft.
pounds.
4. Perform the Operation & Leakage Tests listed in this
publication.
Every 3600 operating hours, or 100,000 miles or twelve
(12) months:
1. T est the AD-SP™ air dryer turbo cut-off and purge valves
for leakage. Disconnect the supply , control and delivery
lines from the AD-SP™ air dryer. Perform the test s below
in the order they are presented.
A. Apply 120 psi shop air pressure to the control port
and a soap solution to the supply port. If leakage
exceeds a 1” bubble in 5 seconds, repair the turbo
cut-off piston and valve before proceeding to step 2.
B. With 120 psi shop air pressure applied to the con-
trol port, apply a soap solution to the purge exhaust
port. If leakage exceeds a 1” bubble in 5 seconds,
repair the purge piston and valve before proceeding
to step 2.
C. With 120 psi shop air pressure applied to the con-
trol and supply port, apply a soap solution to the
purge exhaust port. If leakage exceeds a 1” bubble
in 5 seconds, repair the turbo cut-off piston and valve
before proceeding to step 2.
D. With a plug installed in the delivery port, 0 psi in the
control port, and 120 psi applied to the supply port,
apply a soap solution to the purge exhaust port. If
leakage exceeds a 1” bubble in 5 seconds, repair
the purge piston and valve before proceeding to
step 2.
2. Perform the Operation & Leakage Tests shown in this
publication.
Every 10,800 hours; or 350,000 miles or 36 months:
1. Replace the air dryer desiccant cartridge.
Note: The desiccant change interval may vary from vehicle
to vehicle. Although typical desiccant cartridge life is three
years, many will perform adequately for a longer period of
time. In order to take maximum advantage of desiccant life
and assure that replacement occurs only when necessary ,
it is important that Operation & Leakage T ests be performed.
2. Perform the Operation & Leakage Tests shown in this
publication.
WARNING!
This air dryer 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. Alcohol
is removed by the dryer, but reduces the effectiveness
of the device to dry air. Use of other substances can
damage the air dryer and may void the warranty.
OPERATION & LEAKAGE TESTS (ALSO SEE
VIDEO BW2327)
1. Check for excessive leakage around the purge valve.
With the compressor in 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 5 second. If the leakage exceeds the maximum
specified, service the purge valve assembly .
2. Check for leakage around the desiccant cartridge. With
the compressor in loaded mode (compressing air), apply
a soap solution around the desiccant cartridge seal and
observe that no leakage occurs. If leakage is noted,
tighten the cartridge using a strap wrench and re-test for
leakage.
3. While observing the dash gauge(s), build up system
pressure at approximately 1,800 engine/compressor rpm
to governor cut-out. Note the pressure on the dash
gauge(s) at the moment governor cutout occurs and that
the AD-SP™ air dryer purges with an audible escape of
air. Observe the dash gauge(s) pressure for two minutes
after the purge cycle begins. The front axle service
(secondary) reservoir pressure should not drop more than
8-14 psi below the governor cutout pressure noted and
the rear axle (primary) reservoir pressure should not drop
more than 2 psi. Perform this test 3 times to positively
confirm the values.
7
RETAINING RING
CONTROL PORT
PISTON
CAP
O-RINGS
DESICCANT
CARTRIDGE
™
AIR
AD-SP
DRYER BODY
DELIVERY PORT
RETAINING RING
CONNECTOR
HEATER & THERMOSTAT
ASSEMBLY
FIGURE 8 - AD-SP™ SYSTEM PURGE AIR DRYER EXPLODED VIEW
A. If the pressure drop in the front axle reservoir ex-
O-RING
5. Check the operation of the heater and thermostat
ceeds 8-14 psi, check the air brake system for
excessive leakage and repair and re-test. If the excessive pressure drop persists, replace the AD-SP
™
air dryer.
B. If the pressure drop in the rear axle reservoir
exceeds 2 psi, check the air brake system for
excessive leakage and repair.
Build up system pressure to governor cut-out, wait 30
seconds for completion of the purge cycle, then "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-SP™ air dryer
purge.
4. Check the operation of the SC-PR™ single check
protection valve. Build system pressure to governor
cutout, wait 30 seconds for completion of the purge cycle,
then drain all air pressure from the supply reservoir while
observing the front axle reservoir dash gauge. Reservoir
pressure should decrease to approximately 95 psi and
stop. If front axle reservoir pressure continues to drop
replace the SC-PR™ valve. Do not attempt to adjust
the SC-PR™ valve. This valve is factory preset and mixadjustment can result in insufficient air pressure in the
front axle reservoir in the event of a line or component
failure. The rear axle reservoir pressure should remain
constant.
Note: If this test is performed in warm weather (above 30
deg. F) it may be necessary to remove the heater and
thermostat assembly and cool it in a freezer.
Using an ohmmeter, check the resistance between the
electrical pins in the connector. The resist ance should be
1.5 to 1.7 ohms for the 12 volt heater assembly and 6.0 to
6.9 ohms for the 24 volt heater assembly . If the resistance
is higher than the maximum stated, replace the heater and
thermostat assembly .
Warm the heater and thermostat assembly to over 90
degrees Fahrenheit and again check the resistance. The
resistance should exceed 1000 ohms. If the resistance
values obtained are within the stated limits, the thermostat
and heater assembly is operating properly . If the resistance
8
values obtained are outside the stated limits, replace the
heater and thermostat assembly .
SUPPLY PORT
PURGE VALVE
O-RING
PURGE PISTON
SPRING
EXHAUST COVER
RETAINING RING
assembly in the body during cold weather operation (if
possible) as follows:
A. Electric Power to the Heater and Thermostat
With the ignition or engine kill switch in the ON
position, check for voltage to the heater and
thermostat assembly using a voltmeter or test light.
Unplug the electrical connector at the air dryer and
place the test leads on each of the pins of the male
connector. If there is no voltage, look for a blown
fuse. broken wires, or corrosion in the vehicle wiring
harness. Check to see if a good ground path exists.
B. Thermostat and Heater Operation
Turn off the ignition switch and cool the body
assembly to below 40 degrees Fahrenheit.
REPAIRING THE AD-SP™ AIR DRYER GENERAL
If, after completing the routine operation and leakage tests,
it has been determined that one or more components of the
air dryer requires replacement or maintenance, refer to the
following list to find the appropriate kit(s). When repairing
or replacing components of the air dryer use only genuine
Bendix parts.
MAINTENANCE KITS A V AILABLE:
109495 ... 12 VOLT REPLACEMENT HEA TER AND THERMOSTAT
ASSEMBL Y KIT
109496 ... 24 VOLT REPLACEMENT HEA TER AND THERMOSTAT
ASSEMBL Y KIT
109993 ... TURBO CUT-OFF MAINTENANCE KIT
5008414 . DESICCANT CARTRIDGE REPLACEMENT
109995 ... PURGE & RELIEF VAL VE MAINTENANCE KIT
™
65677... The SC-PR
single check protection valve is
non-serviceable. Replace as an assembly .
WARNING! PLEASE READ AND FOLLOW
THESE INSTRUCTIONS TO AVOID
PERSONAL INJURY OR DEATH:
When working on or around a vehicle, the following
general precautions should be observed at all times.
1. Park the vehicle on a level surface, apply the
parking brakes, and always block the wheels.
Always wear safety glasses.
2. Stop the engine and remove ignition key when
working under or around the vehicle. When
working in the engine compartment, the engine
should be shut off and the ignition key should be
removed. Where circumstances require that the
engine be in operation, EXTREME CAUTION should
be used to prevent personal injury resulting from
contact with moving, rotating, leaking, heated or
electrically charged components.
3. Do not attempt to install, remove, disassemble or
assemble a component until you have read and
thoroughly understand the recommended
procedures. Use only the proper tools and observe
all precautions pertaining to use of those tools.
4. If the work is being performed on the vehicle’s air
brake system, or any auxiliary pressurized air
systems, make certain to drain the air pressure from
all reservoirs before beginning ANY work on the
vehicle. If the vehicle is equipped with an AD-IS
air dryer system or a dryer reservoir module, be
sure to drain the purge reservoir.
5. Following the vehicle manufacturer’s
recommended procedures, deactivate the electrical
system in a manner that safely removes all
electrical power from the vehicle.
6. Never exceed manufacturer’s recommended
pressures.
7. Never connect or disconnect a hose or line
containing pressure; it may whip. Never remove a
component or plug unless you are certain all
system pressure has been depleted.
®
8. Use only genuine Bendix
replacement parts,
components and kits. Replacement hardware,
tubing, hose, fittings, etc. must be of equivalent
size, type and strength as original equipment and
be designed specifically for such applications and
systems.
9. Components with stripped threads or damaged
parts should be replaced rather than repaired. Do
not attempt repairs requiring machining or welding
unless specifically stated and approved by the
vehicle and component manufacturer.
10. Prior to returning the vehicle to service, make
certain all components and systems are restored to
their proper operating condition.
11. For vehicles with Antilock Traction Control (ATC),
the ATC function must be disabled (ATC indicator
lamp should be ON) prior to performing any vehicle
maintenance where one or more wheels on a
drive axle are lifted off the ground and moving.
AD-SP™ AIR DRYER REMOVAL
1. Park the vehicle on a level surface and prevent movement
by means other than the brakes.
2. Drain ALL reservoirs to 0 p.s.i. (0 kPa). - Caution:
Compressor discharge line may still contain
residual pressure.
3. Identify, mark and disconnect the supply, delivery and
control port air lines. Disconnect the wiring harness
connector from the heater and thermostat assembly
connector on the body assembly .
4. If so equipped, disconnect, remove and save the exhaust
line from the exhaust port of the air dryer.
5. Remove the three mounting bolts that secure the air
dryer to the vehicle and remove the air dryer.
Note: It is important to retain the three mounting bolts
since their length is specific to mounting the air dryer
without damage. If these bolts must be replaced, the
same length must be used.
6. Remove the AD-SP™ air dryer from its mounting brackets
on the vehicle.
DISASSEMBLY FOR PART REPLACEMENT
AND KIT INSTALLATION
1. The following disassembly and assembly procedures are
™
presented for reference purposes and assumes that the
appropriate AD-SP™ air dryer kits are on hand. The
instructions provided with these parts and kits should
be followed instead of the instructions presented here.
2. The replacement parts and maintenance kits that are
available do not require full disassembly and in most
cases do not require the removal of the AD-SP™ air dryer
from the vehicle.
3. If removal of the air dryer is necessary adhere to the
following caution:
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