BENDIX AR-2 ANTILOCK RELAY VALVE User manual

1
®
SD-13-4796
FIGURE1-AR-2™ANTILOCKRELAYVALVEASSEMBLY
DESCRIPTION
The AR-2™antilock relay is a specialized air brake valve
developed for use on antilock equipped tractors only. It is
essentiallyaBP-R1™“bobtail”brakeproportioningrelayvalve
(Bendix Service Data Sheet SD-03-1067) with a modified
cover that permits direct attachment of a Bendix®antilock
controller such as the EC-15™. When combined with an
antilockcontroller theresulting assemblyis referredto asa
antilock controller relay assembly. For example when the
AR-2™valve is combined with the EC-15™electronic
controller,the resultingassemblyis referredtoasaCR-16™
controllerrelay assembly.
While it is intended for use on antilock equipped tractors,
theAR-2™valve functions solely as an air brake relay and
contains no electronics of its own.
TheAR-2™valvereplacesthestandardrelay valveusedto
controltherearaxleservicebrakesandperformsthestandard
relayfunction duringtractor-trailer operation.Duringtractor
bobtailoperation,theAR-2™valvereducesbrake application
pressuretothe lighterrearaxle(s) brakestoimprovevehicle
controllability and minimize rear axle(s) wheel skid before
antilockisrequired.TheAR-2™valveprovidesaddedvehicle
brakingcontrol andreduces thenumber oftimes antilockis
actuallyneeded.
Like the standard relay valve it replaces, theAR-2™valve
anditsattached antilockcontrollerisnormally mountednear
theservice brakesitserves.Amounting bracket,furnished
with the valve, permits either frame or cross member
mounting.AllairconnectionsontheAR-2™valveareidentified
with cast, embossed letters for ease of identification and
installation.The letteridentification andairline connections
areshownbelowforreference.
Bendix®AR-2™AntiLock Relay Valve
ANTILOCK CONTROLLER
MOUNTING HOLES(4)
DELIVERY
SUPPLY
DELIVERY
MOUNTING
BRACKET
CONTROL
SERVICE

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FIGURE2-SECTIONALVIEWAR-2™ANTILOCKRELAY VALVE
CONTROL PORT
PROPORTIONING
PISTON INLET/EXHAUSTVALVE
AR-2™VALVE
AIRCONNECTION EMBOSSEDIDENT.
Supply(toreservoir) SUP
Delivery (to brake chamber) DEL
Service (to brake valve rear service delivery) SER
Control (to delivery of trailer supply valve) CON
TheAR-2™valve is part of the R-12™family of relay valves
whichincludestheR-12™,R-14™,BP-R1™,andAR-1™valves.
The internal components of the relay portion of all of these
valvesareinterchangeablewiththeR-12™valveandtherefore
thesame basiccomponentsareusedto serviceall ofthem.
The AR-2™valve incorporates various crack pressures to
accommodate specific applications, the standard is 4 psi.
OPERATION
GENERAL
Because the AR-2™valve is actually a relay valve, the
followingdescription ofoperation referstoits functionin the
vehicle’sairbrakesystemanddoesnotaddresstheseparate
antilockcomponents and theiroperation. Fora description
of antilock operation refer to the appropriate Service Data
Sheetcoveringthe electroniccontrollerused withtheAR-2™
valve (ie; SD-13-4785 covering the EC-15™electronic
controller). Other useful information regarding antilock
system components used in conjunction with the AR-2™
valveis containedin publicationsSD-13-4793 coveringthe
M-21™antilock modulator and SD-13-4754 covering the
WS-20™wheelspeed sensor.
INITIALCHARGING
During the initial build up of tractor system air pressure,
reservoir air flows into the supply port and through internal
body and cover passages to the blend back piston. When
sufficientairpressure isapplied tothe blend backpiston, it
moves against the resistance of its spring until it comes to
rest against the service piston.
Activating the trailer supply valve (dash control with red
octagonal button), simultaneously charges the trailer and
theAR-2™valve control port. Air entering theAR-2™valve
control causes the proportioning piston to move toward its
stop in the cover. The integral inlet and exhaust valve is
carried along with the piston until it seats and seals the
exhaustpassage.Continuedmovementoftheproportioning
piston opens the inlet seat. With the tractor and trailer air
systemfullycharged thevehicle maybeoperated.
SPRING (NOT IN ALL
MODELS)
RELAYPISTON
SERVICEPISTON
SERVICEPORT
SPRING
BLENDBACK
PISTON
EXHAUST
INLET/EXHAUSTVALVE
SUPPLY PORT
EXHAUST
DELIVERYPORT

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FIGURE3-TRACTORSERVICEBRAKESAPPLYING-TRACTORTRAILERCOMBINATION
SERVICE BRAKES APPLYING - TRACTOR/TRAILER
COMBINATION
Brake application air enters the AR-2™valve service port
and is conducted through the service piston then through
thecenter ofboth theblend backand proportioningpistons
totheinletand exhaustvalve.Flowingaroundtheinlet valve,
applicationair movesthrough apassage inthe coverto the
top of the service relay piston. In response to air pressure,
therelay pistonmoves intocontactwith theexhaust portion
of its inlet and exhaust valve. With the exhaust passage
sealed,continued movementof thepiston unseatsthe inlet
portion of the inlet and exhaust valve, allowing supply air
fromthe reservoirto flowout theAR-2™valvedelivery ports
to the brake chambers.
SERVICE BRAKES HOLDING - TRACTOR/TRAILER
COMBINATION
The air pressure being delivered to the brake chambers is
alsopresentbeneath therelay piston.
When the air pressure above and below relay piston is
equal, the piston moves slightly allowing the inlet valve to
return to its seat. The exhaust valve remains closed. With
boththe inletand exhaustvalvesclosed,airpressure inthe
brake chambers is held stable and neither increases nor
decreases.
SERVICE BRAKES RELEASING - TRACTOR/TRAILER
COMBINATION
Whenthebrake applicationis released,air fromabovethe
relay piston, flows back through the proportioning, blend
back and service pistons to the foot brake valve and is
exhausted. As air pressure is reduced above the relay
piston, pressure beneath it lifts the piston away from the
exhaustvalve andopenstheexhaustpassage. Airfromthe
servicebrakechambersreturnstotheAR-2™valveandflows
out the open exhaust.
SERVICEAPPLICATION - BOBTAIL TRACTOR
Whenthetrailersupplyvalve(dashcontrolwithredoctagonal
button)is activatedtodisconnectthetrailer, airintheAR-2™
valve control port and trailer supply line is exhausted to
atmosphere. During bobtail tractor operation, service
applicationair enterstheAR-2™valveserviceport andasit
passes through the blend back piston air exerts a force on
thefulleffectivediameterofthepiston. Theblendbackpiston
remains stationary at application pressures below
approximately 80 psi because of opposing reservoir air
actingon thelarge diameter.Applicationair flowingthrough
the blend back piston also exerts a force on the small
diameter of the proportioning piston while simultaneously
TRAILER
SUPPLY
VALVE
INLET-OPEN
EXHAUST-CLOSED
REARAXLE
SERVICE
CHAMBER
RELAYPISTON
SERVICE
BRAKE
VALVE
ANTILOCK
CONTROLLER
INLET-OPEN
EXHAUST-CLOSED
M-21™MODULATOR

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FIGURE4-TRACTORSERVICEBRAKES HOLDING - TRACTORTRAILER COMBINATION
flowing through the center of it on its way to the inlet and
exhaustvalve.
Oncepast theinletand exhaustvalve, serviceair pressure
exertsaforceon thelargerdiameterendof theproportioning
piston, which opposes the air pressure and spring force
exerted on the other end. The proportioning piston inlet
valveremainsopenuntilapreset,initialapplication pressure
has reached the relay piston assuring that the foundation
brake shoes are brought into contact with the drum. As
service pressure begins to exceed the preset initial
application, the proportioning piston will have moved
sufficiently to close its inlet valve without opening the
exhaust.
Theinlet remains closed,preventing additionalair delivery
to the relay piston and a subsequent increase in brake
chamber pressure, until service application pressure
exceedsapproximately30 psi. Serviceapplications above
this pressure will result in a proportioned increase of the
preset initial brake application to the tractor’s rear brakes.
Proportioningoccurs duetothedifferencein effectivearea
on each end of the proportioning piston. Tractor rear axle
brake proportioning will occur for all service applications
betweenapproximately 30and80 psi.
Service applications of more than 80 psi cause the blend
back piston to begin to move. Service air pressure acting
on the full diameter of the blend back piston over comes
the resistance of reservoir pressure acting on the large
diameter of the other side. Above 80 psi the ratio between
control and delivered air pressure is reduced and “blends
back” from a proportioned delivery to a full 1 to 1 delivery.
Complete “blend back” to a 1 for 1 delivery is achieved
when a full brake application is made.
SERVICE BRAKES RELEASING - BOBTAIL TRACTOR
Whenthebrake applicationisreleased, allairpressurefrom
betweenthe closedproportioning pistoninlet valveand the
AR-2™valve service port returns to the brake valve and is
exhausted. Air from above the relay piston, flows back to
theproportioning pistoncausingit tomove.As itmoves,the
proportioningpiston unseatsthe exhaustvalve allowingair
fromabove the relaypiston toescape toatmosphere.
Reducing the air pressure above the relay piston, causes
pressurebeneathit tolift thepiston away fromthe exhaust
valve. Air from the service brake chambers returns to the
AR-2™valveand flowsout theopen exhaust.
TRAILER
SUPPLY
VALVE
INLET-CLOSED
EXHAUST-CLOSED
REARAXLE
SERVICE
CHAMBER
RELAYPISTON
SERVICE
BRAKE
VALVE
ANTILOCK
CONTROLLER
INLET-OPEN
EXHAUST-CLOSED
M-21™MODULATOR

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FIGURE5- TRACTORSERVICEBRAKES RELEASING -TRACTORTRAILER COMBINATION
FIGURE6 - AR-2™VALVE BRAKE PRESSURE DELIVERY
PREVENTIVE MAINTENANCE
GENERAL
Perform the tests and inspections presented at the
prescribed intervals. If theAR-2™valve fails to function as
described,or leakageis excessive,itshouldberepairedor
replaced with a new or genuine Bendix remanufactured
unit,available atanyauthorized partsoutlet.
EVERY 3 MONTHS, 25,000 MILES OR 900 OPERATING
HOURS
1. Remove any accumulated contaminates and visually
inspecttheexteriorforexcessivecorrosion andphysical
damage.
2. Inspect all air lines connected to the AR-2™valve for
signsofwearorphysicaldamage.Replaceasnecessary.
3. Testair linefittings forexcessive leakageand tightenor
replace as necessary.
4. Perform the Leakage Test described in this manual.
EVERY YEAR, 100,000 MILES, OR 3,600 OPERATING
HOURS
1. Performthe OperationandLeakageTestsdescribed in
this manual.
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.
TRAILER
SUPPLY
VALVE
INLET-CLOSED
EXHAUST-OPEN
REARAXLESERVICE
CHAMBER
SERVICE
BRAKE
VALVE
ANTILOCK
CONTROLLER
INLET-OPEN
EXHAUST-OPEN/CLOSED
M-21™MODULATOR
TRACTOR
TRAILER
COMBINATION
BOBTAIL
TRACTOR
BRAKE VALVE DELIVERY PRESSURE
(AR-2™VALVESERVICEPORT)
0 PSI
BRAKE CHAMBER
PRESSURE

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FIGURE7-SERVICEAPPLICATIONHOLDING-BOBTAILTRACTOR
FIGURE8 - TRACTOR SERVICEBRAKESRELEASING-BOBTAILTRACTOR
TRAILER
SUPPLY
VALVE
INLET-CLOSED
EXHAUST-CLOSED
REARAXLESERVICE
CHAMBER
SERVICE
BRAKE
VALVE
ANTILOCK
CONTROLLER
INLET-CLOSED
EXHAUST-CLOSED
M-21™MODULATOR
BLENDBACK
PISTON
PROPORTIONING
PISTON
RELAYPISTON
TRAILER
SUPPLY
VALVE
REARAXLESERVICE
CHAMBER
SERVICE
BRAKE
VALVE
ANTILOCK
CONTROLLER
M-21™MODULATOR

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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
enginebeinoperation,EXTREMECAUTIONshould
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. Useonlythepropertoolsandobserve
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™airdryersystemoradryerreservoirmodule,
be sure to drain the purge reservoir.
5. Following the vehicle manufacturer’s
recommendedprocedures,deactivatetheelectrical
systeminamannerthatsafelyremovesallelectrical
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
bedesignedspecificallyforsuchapplicationsand
systems.
9. Components with stripped threads or damaged
parts should be replaced rather than repaired. Do
notattemptrepairsrequiringmachiningorwelding
unless specifically stated and approved by the
vehicle and component manufacturer.
10. Prior to returning the vehicle to service, make
certainallcomponentsandsystemsarerestoredto
their proper operating condition.
OPERATION & LEAKAGE TESTS
Operating Test
To properlytestthe functionoftheAR-2™valve,a pairoftest
gauges or gauges of known accuracy must be used.
1. Install a “tee” at the AR-2™valve’s service port and at
one of the delivery ports, then install a gauge in each.
2. Connectthetractorserviceandemergency“glad hands”
(hosecouplings) todummyconnectors,oralternatively,
to a trailer. Build the tractor system air pressure to
governorcut-outandmake4to5fullbrake applications.
Check the air fittings at the AR-2™valve for leakage.
Tightenas needed.
3. Withthetrailersupplyvalve(dashcontrolw/redoctagonal
button)andsystem parkcontrol (dashcontrol w/yellow
diamond button) activated for tractor/trailer operation,
apply and release the brakes several times and check
for prompt application and release at each wheel. If
prompt reaction is noted at some, but not all wheels,
test the M-21™antilock modulator between the AR-2™
valve and the brake chamber for proper operation. If a
“sluggish”response is notedat allwheels, inspectfora
kinkedorobstructedairlineleading toorfrom theAR-2™
valve. If a complete release of the brakes is noted at
some, but not all wheels, test the M-21™antilock
modulator between the AR-2™valve and the brake
chamberforproper operation.If anincomplete release
isnoted atall wheels,inspect fora kinkedor obstructed
airline leadingto orfrom theAR-2™valve.
4. ChecktheAR-2™valve’sdifferentialpressurebyapplying
10 psi to the service port and noting the pressure
registered at the delivery port. Subtract delivery port
pressure from the 10 psi service pressure to obtain the
differential.Compare themeasured differentialwith the
pressure specified for the AR-2™valve part number.
NOTE:ForAR-2™valvesnotincorporatinga relaypiston
return spring the measured differential should be
approximately 4 psi. When a spring is in use, the
differentialwill behigher.
5. Makeandholdafull(100psiorgreater)brakeapplication
and note that full pressure is delivered to the brake
chambers.
6. Activatethe dashmountedtrailersupplyvalveforbobtail
tractor operation. Then make a slow brake application,
increasingthe pressureattheAR-2™valve serviceport
to20 psiwhile watchingthe reactionat thedelivery port
gauge.Notethatdeliverypressurerisestoapproximately
5to 10psi andremainsconstant whileservice pressure
continues to rise to 20 psi. Release the application.
7. Make another brake application and slowly increase
thepressure attheAR-2™valveserviceportto between
60and 70psi whileobserving thegauge installedatthe
deliveryport. Notethatwhen serviceportpressure rises
to between 20 and 30 psi, delivery pressure begins to
rise above the initial pressure noted in step 6. The rise
ofdelivery pressure shouldbe ata proportionedrate of
approximately 3to1. Forexample:Each3psiincrease
attheservice portresultsin adeliverypressureincrease
of1 psi.At70 psiserviceportpressure, brakechamber
pressure should be 15 to 25 psi.
8. Make a full brake application and note that both test
gauges register the same pressure. IMPORTANT: If
during testing the service port pressure is SLOWLY
increased from approximately 70 psi to a full (100 psi
orgreater)brakeapplication,theAR-2™valveMAYbegin
to cycle between an apply and exhaust mode. This

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FIGURE 9- TYPICALCR-16™AIRBRAKE SYSTEM
conditionisnormal whiletheAR-2™valveistransitioning
from the proportioning mode to the full delivery mode
andwill onlyoccur iftheserviceapplicationis SLOWLY
increasedas described.Cycling willnotoccurorcan be
stopped by increasing or decreasing service port
pressure.
9. Removethe testgauges fromtheAR-2™valve.
10. IftheAR-2™valvefailsto performas describeditshould
be replaced or repaired using genuine Bendix
replacement parts or kits.
LEAKAGE TESTS
1. Build the air system pressure to governor cut-out. With
the dash mounted trailer supply valve activated for
tractor/trailer operation, apply a soap solution to both
exhaust ports (one in cover and one in body). The
leakage noted should not exceed a 1” bubble in less
than 3 seconds at either exhaust port.
2. Makeand holda fullbrakeapplicationandapply asoap
solution to both exhaust ports and around the cover
where it joins the body. The leakage noted should not
exceeda1”bubblein lessthan3secondsatanyexhaust
port with no leakage detected between the cover and
body.
VALVEREMOVAL
1. Parkthe vehicleona levelsurfaceandblockthe wheels
and/or hold the vehicle by means other than the air
brakes.
2. Drainthe airpressure fromallvehiclereservoirs.
3. Identify,mark orlabel allair linesand wiringcablesand
their respective connections on the valve or antilock
controller to facilitate ease of installation.
4. Disconnect all air lines and wiring.
5. RemovetheAR-2™valveandcontroller assemblyfrom
thevehicle.
VALVE INSTALLATION
1. Install allairline fittingsandplugsmakingcertain thread
sealingmaterial doesnot enterthe valve.
2. Install theassembledvalve onthe vehicle.
3. Reconnect all air lines and wiring cables to the valve
and controller assembly using the identification made
during VALVE REMOVALstep 3.
4. Afterinstallingthe valveandcontroller assembly, testall
airfittings forexcessiveleakageandtighten asneeded.
DASHCONTROLVALVES
BRAKEVALVE M-21™
MODULATORS
TRACTOR
PROTECTION
AR-2™WITH
CONTROLLER

9
FIGURE10-AR-2™ANTILOCKRELAYVALVE
1
2
330
32
34
36
35 33 31
7
6
5
29 27
25
24
26
28
4
19
17
40
18
39
38
37
8
20
22
21
23
15
13
11
14
12
10
16
9

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DISASSEMBLY
GENERAL
The following disassembly and assembly procedure is
presented for reference purposes only and presupposes
that the appropriate maintenance kit is on hand at the time
of disassembly. The instructions provided with the
maintenance kit should always be used in lieu of those
presentedhere.Refertofigure10throughoutthedisassembly
andassembly procedure.CAUTION:TheAR-2™valvemay
be lightly clamped in a bench vise during disassembly,
however,overclampingwill causedamageto thevalveand
resultin leakage and/ormalfunction. Ifa viseisto beused,
positionthevalve sothat thejawsbear onthe supplyports
onopposing sidesofthevalve’s body.
1. Removeall airfittings andplugs fromtheAR-2™valve.
2. Markthe relationshipofthe antilockelectroniccontroller
(2)and valvecover (4)tothe body(9). Notetheposition
ofthe mountingbracket (6)and marktherelationshipof
thebracket tothe valvebody(9),cover(4), andantilock
controller (2). Remove and retain the four cap screws
and lock washers (1) that secure the controller to the
cover(4), thencarefullyremove theelectroniccontroller
without damaging its gasket (3).
3. Whileholdingtheexhaustcover(11),removetheretaining
ring (10) that secures it to the body (9).
4. Removethe exhaustcover(11)along withbotho-rings
(12 & 13).
5. Remove the valve spring (14), valve retainer (15), and
the valve assembly (16) from the body (9).
6. Remove andretainthetwocapscrewsandlockwashers
(5)that securethebracket(6)to thecover (4).Remove
andretain the twobolts withlock washers(7),and nuts
(8) that secure the cover (4) and mounting bracket to
thevalve body(9). Thenremove theremaining twocap
screws (7) that secure the cover (4) to the body (9).
7. Separate the cover (4) and mounting bracket (6) from
the body (9), then remove the large and small sealing
rings (19 & 40).
8. Remove andretainthe relaypiston(17)andrelaypiston
spring (if present) from the body (9). NOTE: The relay
piston spring is not used in allAR-2™valves.
9. Removethe o-ring(18) fromthe relaypiston (17).
10. Remove the retaining ring (20) from the cover (4), then
removethe exhaustpiston (21).
11. Removetheexhaustpistono-ring(22).
12. Removethe servicepiston(23) fromthecover (4).
13. Remove the spring (24) and spring cage (25) from the
cover (4).
14.Remove theblendback piston(26)fromthevalvecover
(4),then removeboth o-rings(27 &28).
15. Removetheproportioningpiston(30)fromthevalvecover
(4),then removeboth o-rings(29 &31).
16. While holding theinlet valve seat(34) inplace, remove
theretainingring(36)fromtheproportioningpiston(30).
17.Remove the inlet valve seat (34), the inlet valve (33),
and the valve spring (32) from the proportioning piston
(30),thenremovetheo-ring(35)fromthevalveseat(34).
18. Removetheexhaustdiaphragmscrew (37),washer(38)
and exhaust diaphragm (39) from the cover (4).
CLEANING & INSPECTION
1. Using mineralspiritsor anequivalentsolvent, cleanand
thoroughlydryall metalparts.
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 body (9) and cover (4) is acceptable.
Replace the entire valve if the interior of the body or
cover exhibit signs of corrosion or pitting.
3. Inspect the bores of both the body (9) and cover (4) for
deep scuffing or gouges. Replace the entire valve if
either are found.
4. Make certain all air channels and exhaust passages in
the valve cover (4) are clear and free of obstruction.
5. Inspect the pipe threads in the body (9). Make certain
they are clean and free of thread sealant.
6. Washallnon-metallic componentsina soapandwater
solution making certain to rinse and dry thoroughly.
Inspect each non-metallic component for cracks, wear
ordistortion. Replacetheentire valveifthese conditions
are found.
7. If the valve was equipped with a relay piston spring,
inspect it for signs of corrosion, pitting and cracks.
Replace as necessary.
8. Inspect all air line fittings for corrosion and replace as
necessary.Makecertaintoremoveall oldthreadsealant
before reuse.
ASSEMBLY
1. Priortoassembly,lubricateallo-rings,seals,andpistons,
as well as body and cover bores, using the lubricant
providedwith theBendixmaintenancekit.
2. Installthe o-ring(35)ontheinlet valveseat (34).
3. Insert the inlet and exhaust valve spring (32), LARGE
END FIRST, into the proportioning piston (30).
4. Install the inlet and exhaust valve (33) inside the inlet
valve seat (34) making certain that the four tabs are
within the bore of the seat.

11
5. Carefullyinsert theassembledvalve (33)and seat(34)
into the proportioning piston (30), making certain that
thecoilsof thevalvespring (32)reston thefourtabs of
thevalve(33).While holdingtheseat(34)in place,install
the retaining ring (36) to secure it in the piston (30).
Make certain the retaining ring is fully seated in its
groove.
6. Install both the large and small diameter o-rings (31 &
29)on theproportioning piston(30).
7. Install both the large and small diameter o-rings (27 &
28) on the blend back piston (26), then insert the small
diameter of the proportioning piston (30) into the small
diameter end of the blend back piston (26).
8. Carefullyinsert theassembled proportioningand blend
back pistons (30 & 26) into the cover (4).
9. Installthe springcage (25)in theblend backpiston (26)
so that it’s flat side rests against the blend back piston.
10. Install the spring (24) in the cage (25) so that its coils
are within the I.D. of the cage.
11. Inserttheservice piston(23) inthe cover(4) sothat the
coils of the spring (24) are contained within the piston
and the six protruding posts of the piston are visible
after the piston is in the cover.
12. Install the o-ring (22) on the exhaust piston (21) then
install the exhaust piston (21) in the cover (4). Refer to
thefigure andmake certainthat theexhaust piston(21)
is installed with its concave surface away from the
servicepiston (23).
14. While holding the exhaust piston (21) in the cover (4),
install the retaining ring (20), making certain it is fully
seated in its groove.
15.Install the exhaust diaphragm (39) using its screw (37)
and washer (38) to retain it. Torque the screw to 8-15
poundinches.
16. Install the valve retainer (15) on the inlet and exhaust
valve (16) so that the flange of the retainer (15)
surrounds the rubber portion of the valve. Install the
inlet and exhaust valve in the body (9).
17.Install the inlet and exhaust valve return spring (14) in
the body (9).
18. Install the largeand small diametero-rings (13& 12) in
thecover (11), theninstalltheexhaust coverinthe body
(9) taking care not to damage the o-rings. Hold the
exhaustcover inplace.
19. While depressing the exhaust cover (11), install the
retaining ring (10) in the body (9). Make certain the
retainer (10) is fully seated in its groove in the body.
20. IftheAR-2™valvewasequippedwitharelaypistonreturn
spring,installthe springinthebody,large diameterfirst.
21. Using lubricant to hold them in place, install the large
diameter sealing ring (19) on the cover (4) and the
small diameter sealing ring (40) on the body (9).
22. Installtheo-ring(18) ontherelaypiston (17),theninstall
the piston in the body (9).
23. After noting the relationship marks made prior to
disassembly,install thecover(4)onthebody(9).Secure
thecover tothe bodyusing thetwoshortestcapscrews
and lock washers (7). Make certain the sealing rings
(19 & 40) remain in place. Torque the cap screws to
120-150pound inches.
24. Secure the mounting bracket (6) to the cover (4) using
the cap screws and lock washers (5), and torque the
cap screws to 180-220 pound inches. Then secure the
mountingbracket (6)tothebody(9) andcover (4)using
the two longest cap screws and lock washers (7) and
nuts (8) and torque the cap screws to 120-150 pound
inches.
25. Installall airlinefittingsandplugsmaking certainthread
sealingmaterial doesnot enterthe valve.
26. Install the AR-2™valve on the vehicle and perform the
OperationandLeakageTestsbeforereturningthevehicle
toservice.
O.D.
W
I.D.
KEYNO. I.D. O.D. W
12 .862" 1.068" .103"
13 1.424" 1.630" .103"
19 3.487" 3.693" .103"
18 3.234" 3.512" .139"
22 1.356" 1.496" .070"
27 1.112" 1.318" .103"
28 .737" .943" .103"
29 .412" .552" .070"
31 .739" .879" .070"
35 .489" .629" .070"
O-RING IDENTIFICATION CHART

12 BW1672 © 2004 Bendix Commercial Vehicle Systems LLC All rights reserved. 6/2004 Printed in U.S.A.