Page 1
®
Bendix® AR-2™ AntiLock Relay Valve
ANTILOCK CONTROLLER
MOUNTING HOLES(4)
MOUNTING
BRACKET
SD-13-4796
SERVICE
SUPPLY
DELIVERY
FIGURE 1 - AR-2™ ANTILOCK RELAY VALVE ASSEMBLY
DESCRIPTION
The Bendix® AR‑2™ antilock relay is a specialized air brake
valve developed for use on antilock equipped tractors only.
It is essentially a BP‑R1® “bobtail” brake proportioning relay
valve (Bendix Service Data Sheet SD‑03‑1067) with a
modied cover that permits direct attachment of a Bendix®
antilock controller such as the EC‑15™. When combined
with an antilock controller the resulting assembly is referred
to as a antilock controller relay assembly. For example
when the AR‑2™ valve is combined with the EC‑15™
electronic controller, the resulting assembly is referred to
as a CR‑16™ controller relay assembly.
While it is intended for use on antilock equipped tractors,
the AR‑2™ valve functions solely as an air brake relay and
contains no electronics of its own.
CONTROL
DELIVERY
The AR‑2™ valve replaces the standard relay valve used
to control the rear axle service brakes and performs the
standard relay function during tractor‑trailer operation.
During tractor bobtail operation, the AR‑2™ valve reduces
brake application pressure to the lighter rear axle(s) brakes
to improve vehicle controllability and minimize rear axle(s)
wheel skid before antilock is required. The AR‑2™ valve
provides added vehicle braking control and reduces the
number of times antilock is actually needed.
Like the standard relay valve it replaces, the AR‑2™ valve
and its attached antilock controller is normally mounted
near the service brakes it serves. A mounting bracket,
furnished with the valve, permits either frame or cross
member mounting. All air connections on the AR‑2™ valve
are identied with cast, embossed letters for ease of
identication and installation.
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BLEND BACK
PISTON
SPRING
CONTROL PORT
EXHAUST
INLET/EXHAUST VALVE
PROPORTIONING
PISTON
SUPPLY PORT
EXHAUST
FIGURE 2 - SECTIONAL VIEW BENDIX® AR-2™ ANTILOCK RELAY VALVE
SERVICE PORT
SERVICE PISTON
RELAY PISTON
SPRING (NOT IN ALL
MODELS)
INLET/EXHAUST VALVE
DELIVERY PORT
The letter identication and air hose connections are shown
below for reference.
Bendix® AR-2™ VALVE
AIR CONNECTION EMBOSSED IDENT.
Supply (to reservoir) SUP
Delivery (to brake chamber) DEL
Service (to brake valve rear service delivery) SER
Control (to delivery of trailer supply valve) CON
The AR‑2™ valve is part of the R‑12® family of relay valves
which includes the R‑12®, R‑14®, BP‑R1®, and AR‑1™
valves. The internal components of the relay portion of all
of these valves are interchangeable with the R‑12® valve
and therefore the same basic components are used to
service all of them.
The AR‑2™ valve incorporates various crack pressures to
accommodate specic applications, the standard is 4 psi.
OPERATION
GENERAL
Because the AR‑2™ valve is actually a relay valve, the
following description of operation refers to its function in
the vehicle’s air brake system and does not address the
separate antilock components and their operation. For a
description of antilock operation, refer to the appropriate
Service Data Sheet covering the electronic controller used
with the AR‑2™ valve (SD‑13‑4785 covering the EC‑15™
electronic controller). Other useful information regarding
antilock system components used in conjunction with the
AR‑2™ valve are contained in publications: SD‑13‑4793
(Bendix® M‑21™ antilock modulator); SD‑13‑4870 (Bendix®
M‑32™ and M‑32QR™ antilock modulators); SD‑13‑4860
(Bendix® WS‑24™ wheel speed sensors); and SD‑13‑4754
(Bendix® WS‑20™ wheel speed sensors).
INITIAL CHARGING
During the initial build up of tractor system air pressure,
reservoir air ows into the supply port and through internal
body and cover passages to the blend back piston. When
sufcient air pressure is applied to the blend back piston,
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 the AR‑2™ valve control port. Air entering the AR‑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 exhaust passage. Continued movement of the
proportioning piston opens the inlet seat. With the tractor
and trailer air system fully charged the vehicle may be
operated.
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TRAILER
SUPPLY
VALVE
INLET-OPEN
EXHAUST-CLOSED
ANTILOCK
CONTROLLER
SERVICE
BRAKE
VALVE
RELAY PISTON
INLET-OPEN
EXHAUST-CLOSED
BENDIX® M-21™
MODULATOR
REAR AXLE
SERVICE
CHAMBER
FIGURE 3 - TRACTOR SERVICE BRAKES APPLYING - TRACTOR TRAILER COMBINATION
SERVICE BRAKES APPLYING - TRACTOR/TRAILER
COMBINATION
Brake application air enters the Bendix® AR‑2™ valve service
port and is conducted through the service piston then
through the center of both the blend back and proportioning
pistons to the inlet and exhaust valve. Flowing around the
inlet valve, application air moves through a passage in the
cover to the top of the service relay piston. In response
to air pressure, the relay piston moves into contact with
the exhaust portion of its inlet and exhaust valve. With the
exhaust passage sealed, continued movement of the piston
unseats the inlet portion of the inlet and exhaust valve,
allowing supply air from the reservoir to ow out the AR‑2™
valve delivery ports to the brake chambers.
SERVICE BRAKES RELEASING - TRACTOR/TRAILER
COMBINATION
When the brake application is released, air from above the
relay piston ows 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
exhaust valve and opens the exhaust passage. Air from
the service brake chambers returns to the AR‑2™ valve and
ows out the open exhaust.
SERVICE APPLICATION - BOBTAIL TRACTOR
When the trailer supply valve (dash control with red
octagonal button) is activated to disconnect the trailer, air
in the AR‑2™ valve control port and trailer supply line is
SERVICE BRAKES HOLDING - TRACTOR/TRAILER
COMBINATION
The air pressure being delivered to the brake chambers
is also present beneath the relay piston. When the air
pressure above and below the relay piston is equal, the
piston moves slightly allowing the inlet valve to return to
its seat. The exhaust valve remains closed. With both
the inlet and exhaust valves closed, air pressure in the
brake chambers is held stable and neither increases nor
decreases.
exhausted to atmosphere. During bobtail tractor operation,
service application air enters the AR‑2™ valve service
port and as it passes through the blend back piston, air
exerts a force on the full effective diameter of the piston.
The blend back piston remains stationary at application
pressures below approximately 80 psi because of opposing
reservoir air acting on the large diameter. Application air
owing through the blend back piston also exerts a force
on the small diameter of the proportioning piston while
simultaneously owing through the center of it on its way
to the inlet and exhaust valve.
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ANTILOCK
CONTROLLER
TRAILER
SUPPLY
VALVE
INLET-OPEN
EXHAUST-CLOSED
REAR AXLE
SERVICE
CHAMBER
FIGURE 4 - TRACTOR SERVICE BRAKES HOLDING - TRACTOR TRAILER COMBINATION
SERVICE
BRAKE
VALVE
RELAY PISTON
INLET-CLOSED
EXHAUST-CLOSED
BENDIX® M-21™
MODULATOR
Once past the inlet and exhaust valve, service air
pressure exerts a force on the larger diameter end of the
proportioning piston, which opposes the air pressure and
spring force exerted on the other end. The proportioning
piston inlet valve remains open until a preset, initial
application 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 sufciently to close its inlet valve without opening
the exhaust.
The inlet remains closed, preventing additional air delivery
to the relay piston and a subsequent increase in brake
chamber pressure, until service application pressure
exceeds approximately 30 psi. Service applications above
this pressure will result in a proportioned increase of the
preset initial brake application to the tractor’s rear brakes.
Proportioning occurs due to the difference in effective area
on each end of the proportioning piston. Tractor rear axle
brake proportioning will occur for all service applications
between approximately 30 and 80 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
When the brake application is released, all air pressure
from between the closed proportioning piston inlet valve
and the Bendix® AR‑2™ valve service port returns to the
brake valve and is exhausted. Air from above the relay
piston ows back to the proportioning piston, causing it to
move. As it moves, the proportioning piston unseats the
exhaust valve allowing air from above the relay piston to
escape to atmosphere.
Reducing the air pressure above the relay piston causes
pressure beneath it to lift the piston away from the exhaust
valve. Air from the service brake chambers returns to the
AR‑2™ valve and ows out the open exhaust.
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ANTILOCK
CONTROLLER
TRAILER
SUPPLY
VALVE
INLET-OPEN
EXHAUST-OPEN/CLOSED
REAR AXLE SERVICE
FIGURE 5 - TRACTOR SERVICE BRAKES RELEASING - TRACTOR TRAILER COMBINATION
PREVENTIVE MAINTENANCE
SERVICE
BRAKE
VALVE
INLET-CLOSED
EXHAUST-OPEN
BENDIX® M-21™
MODULATOR
CHAMBER
GENERAL
Perform the tests and inspections presented at the
prescribed intervals. If the Bendix® AR‑2™ valve fails to
function as described, or leakage is excessive, it should
be repaired or replaced with a new or genuine Bendix
remanufactured unit, available at any authorized parts
outlet.
EVERY 3 MONTHS, 25,000 MILES OR 900 OPERATING
HOURS
1. Remove any accumulated contaminates and visually
inspect the exterior for excessive corrosion and physical
damage.
2. Inspect all air lines connected to the AR‑2™ valve
for signs of wear or physical damage. Replace as
necessary.
3. Test air line ttings for excessive leakage and tighten
or replace as necessary.
4. Perform the Leakage Test described in this manual.
EVERY YEAR, 100,000 MILES, OR 3,600 OPERATING
HOURS
1. Perform the Operation and Leakage Tests described
in this manual.
TRACTOR
TRAILER
COMBINATION
BOBTAIL
TRACTOR
PRESSURE
BRAKE CHAMBER
0 PSI
FIGURE 6 - AR‑2™ VALVE BRAKE PRESSURE DELIVERY
BRAKE VALVE DELIVERY PRESSURE (AR-2™
VALVE SERVICE PORT)
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.
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ANTILOCK
CONTROLLER
TRAILER
SUPPLY
VALVE
PROPORTIONING
PISTON
INLET-CLOSED
EXHAUST-CLOSED
FIGURE 7 - SERVICE APPLICATION HOLDING - BOBTAIL TRACTOR
SERVICE
BRAKE
VALVE
BLEND BACK
PISTON
RELAY PISTON
INLET-CLOSED
EXHAUST-CLOSED
BENDIX® M-21™
MODULATOR
REAR AXLE SERVICE
CHAMBER
TRAILER
SUPPLY
VALVE
ANTILOCK
CONTROLLER
SERVICE
BRAKE
VALVE
BENDIX® M-21™
MODULATOR
REAR AXLE SERVICE
CHAMBER
FIGURE 8 - TRACTOR SERVICE BRAKES RELEASING - BOBTAIL TRACTOR
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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 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 a
Bendix® 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® brand replacement parts,
components and kits. Replacement hardware,
tubing, hose, ttings, etc. must be of equivalent
size, type and strength as original equipment and
be designed specically 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 specically 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 Automatic 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.
OPERATION & LEAKAGE TESTS
Operation
To properly test the function of the Bendix® AR‑2™ valve,
a pair of test 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. Connect the tractor service and emergency “glad
hands” (hose couplings) to dummy connectors, or
alternatively, to a trailer. Build the tractor system air
pressure to governor cut‑out and make 4 to 5 full brake
applications. Check the air ttings at the AR‑2™ valve
for leakage. Tighten as needed.
3. With the trailer supply valve (dash control with a red
octagonal button) and system park control (dash control
with a 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 Bendix® M‑21™ antilock modulator
between the AR‑2™ valve and the brake chamber for
proper operation. If a “sluggish” response is noted at
all wheels, inspect for a kinked or obstructed air line
leading to or from the AR‑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 chamber for proper operation. If
an incomplete release is noted at all wheels, inspect
for a kinked or obstructed air line leading to or from the
AR‑2™ valve.
4. Check the AR‑2™ valve’s differential pressure by
applying 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 the measured
differential with the pressure specied for the AR‑2™
valve part number. NOTE: For AR‑2™ valves not
incorporating a relay piston return spring the measured
differential should be approximately 4 psi. When a
spring is in use, the differential will be higher.
5. Make and hold a full (100 psi or greater) brake
application and note that full pressure is delivered to
the brake chambers.
6. Activate the dash mounted trailer supply valve for
bobtail tractor operation. Then make a slow brake
application, increasing the pressure at the AR‑2™ valve
service port to 20 psi while watching the reaction at the
delivery port gauge. Note that delivery pressure rises to
approximately 5 to 10 psi and remains constant while
service pressure continues to rise to 20 psi. Release
the application.
7. Make another brake application and slowly increase
the pressure at the AR‑2™ valve service port to between
60 and 70 psi while observing the gauge installed at
the delivery port. Note that when service port pressure
rises to between 20 and 30 psi, delivery pressure begins
to rise above the initial pressure noted in step 6. The
rise of delivery pressure should be at a proportioned
rate of approximately 3 to 1. For example: Each 3
psi increase at the service port results in a delivery
pressure increase of 1 psi. At 70 psi service port
pressure, brake chamber pressure should be 15 to 25
psi.
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DASH CONTROL VALVES
TRACTOR PROTECTION
BRAKE VALVE
FIGURE 9 - TYPICAL BENDIX® CR-16™ AIR BRAKE SYSTEM
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
or greater) brake application, the Bendix® AR‑2™ valve
MAY begin to cycle between an apply and exhaust
mode. This condition is normal while the AR‑2™ valve
is transitioning from the proportioning mode to the
full delivery mode and will only occur if the service
application is SLOWLY increased as described.
Cycling will not occur or can be stopped by increasing
or decreasing service port pressure.
9. Remove the test gauges from the AR‑2™ valve.
10. If the AR‑2™ valve fails to perform as described it
should 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 the cover and one in the body).
The leakage noted should not exceed a 1" bubble in
less than 3 seconds at either exhaust port.
2. Make and hold a full brake application and apply a
soap solution to both exhaust ports and around the
8
BENDIX® M-21™
MODULATORS
BENDIX®
AR-2™ WITH
CONTROLLER
cover where it joins the body. The leakage noted should
not exceed a 1" bubble in less than 3 seconds at any
exhaust port with no leakage detected between the
cover and body.
VALVE REMOVAL
1. Park the vehicle on a level surface and block the wheels
and/or hold the vehicle by means other than the air
brakes.
2. Drain the air pressure from all vehicle reservoirs.
3. Identify, mark or label all air lines and wiring cables and
their respective connections on the valve or antilock
controller to facilitate ease of installation.
4. Disconnect all air lines and wiring.
5. Remove the AR‑2™ valve and controller assembly from
the vehicle.
VALVE INSTALLATION
1. Install all air line ttings and plugs making certain thread
sealing material does not enter the valve.
2. Install the assembled valve on the vehicle.
3. Reconnect all air lines and wiring cables to the valve
and controller assembly using the identication made
during VALVE REMOVAL step 3.
4. After installing the valve and controller assembly, test
all air ttings for excessive leakage and tighten as
needed.
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1
20
22
2
24
26
30
28
21
23
5
6
3
7
32
34
25
36
35
33
31
29
27
8
4
37
38
39
19
18
17
40
9
16
15
14
13
12
11
10
FIGURE 10 - BENDIX® AR-2™ ANTILOCK RELAY VALVE
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Page 10
DISASSEMBLY
GENERAL
The following disassembly and assembly procedure is
presented for reference purposes only and presuppos‑
es 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 presented here. Refer to gure 10 throughout the
disassembly and assembly procedure. CAUTION: The
Bendix® AR‑2™ valve may be lightly clamped in a bench
vise during disassembly, however, over clamping will
cause dam age to the valve and result in leakage and/or
malfunc tion. If a vise is to be used, position the valve so
that the jaws bear on the supply ports on opposing sides
of the valve’s body.
1. Remove all air ttings and plugs from the AR‑2™ valve.
2. Mark the relationship of the antilock electronic controller
(2) and valve cover (4) to the body (9). Note the position
of the mounting bracket (6) and mark the relationship
of the bracket to the valve body (9), cover (4), and
antilock controller (2). Remove and retain the four cap
screws and lock washers (1) that secure the controller
to the cover (4), then carefully remove the electronic
controller without damaging its gasket (3).
3. While holding the exhaust cover (11), remove the
retaining ring (10) that secures it to the body (9).
4. Remove the exhaust cover (11) along with both o‑rings
(12 & 13).
5. Remove the valve spring (14), valve retainer (15), and
the valve assembly (16) from the body (9).
6. Remove and retain the two cap screws and lock washers
(5) that secure the bracket (6) to the cover (4). Remove
and retain the two bolts with lock washers (7), and nuts
(8) that secure the cover (4) and mounting bracket to
the valve body (9). Then remove the remaining two cap
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 and retain the relay piston (17) and relay piston
spring (if present) from the body (9). NOTE: The relay
piston spring is not used in all AR‑2™ valves.
9. Remove the o‑ring (18) from the relay piston (17).
10. Remove the retaining ring (20) from the cover (4), then
remove the exhaust piston (21).
11. Remove the exhaust piston o‑ring (22).
12. Remove the service piston (23) from the cover (4).
13. Remove the spring (24) and spring cage (25) from the
cover (4).
14. Remove the blend back piston (26) from the valve cover
(4), then remove both o‑rings (27 & 28).
15. Remove the proportioning piston (30) from the valve
cover (4), then remove both o‑rings (29 & 31).
16. While holding the inlet valve seat (34) in place, remove
the retaining ring (36) from the proportioning piston
(30).
17. Remove the inlet valve seat (34), the inlet valve (33),
and the valve spring (32) from the proportioning piston
(30), then remove the o‑ring (35) from the valve seat
(34).
18. Remove the exhaust diaphragm screw (37), washer
(38) and exhaust diaphragm (39) from the cover (4).
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.
Supercial 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 scufng 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. Wash all non‑metallic components in a soap and water
solution making certain to rinse and dry thoroughly.
Inspect each non‑metallic component for cracks, wear
or distortion. Replace the entire valve if these 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 ttings for corrosion and replace
as necessary. Make certain to remove all old thread
sealant before reuse.
ASSEMBLY
1. Prior to assembly, lubricate all o‑rings, seals, and
pistons, as well as body and cover bores, using the
lubricant provided with the Bendix maintenance kit.
2. Install the o‑ring (35) on the inlet valve seat (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.
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Page 11
5. Carefully insert the assembled valve (33) and seat (34)
into the proportioning piston (30), making certain that
the coils of the valve spring (32) rest on the four tabs
of the valve (33). While holding the seat (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 the proportioning 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. Carefully insert the assembled proportioning and blend
back pistons (30 & 26) into the cover (4).
9. Install the spring cage (25) in the blend back piston (26)
so that its at 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. Insert the service piston (23) in the cover (4) so that 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 the gure and make certain that the exhaust piston
(21) is installed with its concave surface away from the
service piston (23).
13. While holding the exhaust piston (21) in the cover (4),
install the retaining ring (20), making certain it is fully
seated in its groove.
14. Install the exhaust diaphragm (39) using its screw (37)
and washer (38) to retain it. Torque the screw to 8‑15
pound inches.
15. 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).
16. Install the inlet and exhaust valve return spring (14) in
the body (9).
17. Install the large and small diameter o‑rings (13 & 12)
in the cover (11), then install the exhaust cover in the
body (9) taking care not to damage the o‑rings. Hold
the exhaust cover in place.
18. 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.
19. If the Bendix® AR‑2™ valve was equipped with a relay
piston return spring, install the spring in the body, large
diameter rst.
O-RING IDENTIFICATION CHART
O.D.
W
I.D.
KEY NO. 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"
20. 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).
21. Install the o‑ring (18) on the relay piston (17), then install
the piston in the body (9).
22. After noting the relationship marks made prior to
disassembly, install the cover (4) on the body (9).
Secure the cover to the body using the two shortest cap
screws and lock washers (7). Make certain the sealing
rings (19 & 40) remain in place. Torque the cap screws
to 120‑150 pound inches.
23. 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
mounting bracket (6) to the body (9) and cover (4) using
the two longest cap screws and lock washers (7) and
nuts (8) and torque the cap screws to 120‑150 pound
inches.
24. Install all air line ttings and plugs making certain thread
sealing material does not enter the valve.
25. Install the AR‑2™ valve on the vehicle and perform
the Operation and Leakage Tests before returning the
vehicle to service.
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BW1672 © 2011 Bendix Commercial Vehicle Systems LLC. All rights reserved. 8/11. Printed in the United States.
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