BENDIX R-6 RELAY VALVE User manual

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®
Bendix®R-6™Relay Valve
SD-03-1060
SERVICE
PORT RELAYPISTON
DELIVERY
PORTS(4)
R-6™RELAY
VALVE INSERT
RETURN
SPRING
FIGURE 1 FIGURE 2
DESCRIPTION
The relay valve in an air brake system functions as a relay
stationtospeedup theapplicationandrelease ofthebrakes.
The valve is normally mounted at the rear of the vehicle in
proximityto the chamberit serves. Thevalve operates asa
remotecontrolled brakevalvethatdeliversorreleasesairto
the chamber in response to the control air delivered to it
from the foot brake valve or other source. The R-6™relay
valve is a piston operated valve. For ease of servicing, an
“insert”or“cartridge” type inlet/exhaust valve is employed.
Thisfeaturepermitsserviceoftheinlet/exhaustvalvewithout
lineremoval. TheR-6™relay valvemay bemounted directly
to or remotely from the reservoir which provides its supply
pressure. Standard porting consists of one (1) service port
andfour (4)deliveryports. Therearetwo (2)supply ports in
the reservoir mounted valve and one (1) supply port in the
remotemountvalve.
OPERATION
APPLYING
Air pressure delivered to the service port enters the small
cavity above the piston and moves the piston down. The
exhaustseatmoves down with the pistonandseats on the
inner or exhaust portion of the inlet/exhaust valve, sealing
offtheexhaust passage.Atthe sametime,the outeror inlet
portionoftheinlet/exhaustvalvemovesoffitsseat,permitting
supplyairtoflowfrom thereservoir,pasttheopeninletvalve
andintothechambers.
BALANCED
Theairpressurebeingdelivered bytheopeninletvalve also
iseffective on the bottomarea of the relaypiston. When air
pressurebeneath thepiston equalsthe serviceair pressure
above, the piston lifts slightly and the inlet spring returns
the inlet valve to its seat. The exhaust remains closed as
the service line pressure balances the delivery pressure.
(NOTE:Somevalvesareequippedwithapistonreturnspring
which will assist the lifting of the piston). As delivered air
pressureischangedthevalve reactsinstantly tothechange
holdingthebrake application at thatlevel.
EXHAUST
SUPPLY
PORT
SUPPLY PORT
(RESERVOIR
MOUNT TYPE)

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TYPICALRELAYVALVEPIPINGSINGLECIRCUITSYSTEM
COMPRESSOR GOVERNOR
SUPPLY
RESERVOIR SERVICE
RESERVOIR
BRAKE
VALVE RELAY
VALVE
BRAKE
CHAMBERS
RELEASING
Whenair pressure is releasedfromthe service portandair
pressure in the cavity above the relay piston is exhausted,
air pressure beneath piston lifts the relay piston and the
exhaustseat moves awayfromthe exhaust valve,opening
theexhaustpassage.Withthe exhaust passage open, the
air pressure in the chambers is then permitted to exhaust
throughtheexhaust port, releasing thebrakes.
PREVENTIVE MAINTENANCE
Important: Review the Bendix Warranty Policy before
performinganyintrusivemaintenanceprocedures.Awarranty
maybe voidedifintrusive maintenanceis performedduring
thewarranty period.
No two vehicles operate under identical conditions, as a
result, maintenance intervals may vary. Experience is a
valuableguideindeterminingthebestmaintenanceinterval
for air brake system components.At a minimum, the valve
shouldbeinspectedevery6monthsor1500operatinghours,
whichevercomesfirst,forproperoperation.Shouldthevalve
notmeetthe elements of theoperational tests noted in this
document,furtherinvestigation andserviceofthevalvemay
berequired.
OPERATING AND LEAKAGE TEST
1. Fully charge air brake system and adjust brakes.
2. Make several brake applications and check for prompt
applicationand release atallappropriate wheels.
3. Withbrake valve in released position, coat theexhaust
portwithsoapsolutionandcheckforinletvalveandvalve
guide o-ring leakage; 1" bubble in 5 seconds leakage
permitted.
4. Makeandholdabrakevalveapplication;coattheexhaust
portwith soapsolution andcheck forleakage; 1"bubble
in 3 seconds leakage permitted.
Ifleakage isdetected, replacingtheinlet/exhaustvalvemay
correctthe problem. Ifleakagestill occurs,leakagemay be
causedbyrelay piston o-ring orexhaustvalve seat.
5. Makeand holda brakevalveapplication;coatoutsideof
valvebody in area wherecover joins the bodyfor cover
o-ring leakage No leakage permitted. If the valve does
not function as described above, or if leakage is
excessive,itisrecommendedthat thevalve bereplaced
with a new or remanufactured unit, or repaired with
genuineBendix parts available atBendixoutlets.
REMOVING AND INSTALLING
REMOVING
Block and hold vehicle by means other than air brakes.
Drainair brake systemreservoirs.
Ifentire valve is tobe removed, identify airlinesto facilitate
installation.
Disconnectair linesfromvalve*.
Removemountingbolts,thenvalve.
*Itisgenerallynotnecessarytoremoveentirevalvetoservice
theinlet/exhaustvalve. Theinlet/exhaustvalve insertcanbe
removed by removing the two exhaust cover cap screws
andcover. Insert thenmaybe pulled out.
CAUTION: DRAIN RESERVOIRS BEFORE REMOVING
INSERT.Use careso as not todamage inlet/exhaust valve
orguide o-ring.

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INSTALLING
Cleanair lines connectingto valve.
Inspect all lines and/or hoses for damage and replace as
necessary.
Installvalve and tightenmounting bolts.
Connectair lines to valve(Plugany unused ports).
Testvalve as outlinedin “Operating andLeakageTests.”
DISASSEMBLY
NOTE: Priortodisassembly,marklocationofcover tobody
to facilitate assembly.
1. Remove cover cap screws (1). Remove cover (2) with
relaypiston (4) and spring(6)(if so equipped).
2. Removerelay piston(4) fromcover.
3. Removepiston o-ring (3)from piston (4)and cover seal
o-ringfrom body.
4. Removeexhaust covercap screws,(19) exhaustcover,
andremove inlet/exhaustvalve insert(8) frombody(7).
5. Remove exhaust seat (5) from relay piston (4) and
exhaustcheck valve(18).(Remove onlyifnewpartsare
to be installed).
INLET/EXHAUSTVALVE INSERTDISASSEMBLY
NOTE: Ifcompleteinlet/exhaustvalveisreplaced,disregard
steps 6 to 9.
6. Depressand holdvalveguide downagainstvalvespring
tensionand removeretainer (16).
7. Remove valve insert seal o-ring (13), valve guide (14),
spring(12),andvalveretainer(11).
8. Removethe inlet/exhaust valve(9) fromitsbody (10).
9. Removeinner o-ring(15)from valveguide(14).
CLEANING AND INSPECTION
Washall metal partsinmineral spirits; wipeall rubber parts
dry. Inspect all parts for signs of wear and/or deterioration.
Inspect springs for cracks, distortion or corrosion.
Inspect inlet seat and exhaust seat for nicks and burrs and
replace as necessary. It is recommended that all rubber
partsbereplaced, and that any partshowingsigns of wear
ordeterioration bereplaced.
ASSEMBLY
NOTE: All torques specified in this manual are assembly
torques and can be expected to fall off after
assembly. Do not retorque after initial assembly
torques fall. (For assembly, hand wrenches are
recommended)
1. Priorto assembly, lightlylubricatethe relaypiston guide
post,o-rings,coverboreandinletbodywithDowCorning
Silicone 55-M Pneumatic grease (Bendix Pc. No.
291126).
INLET/EXHAUSTVALVEASSEMBLY
NOTE: If newinlet/exhaustvalve assembly insert isused,
disregard Steps 2 to 6.
2. Installinlet/exhaustvalve(9)overvalvebody(10),smooth
surfaceup.
3. Positionvalve retainer(11)overinletvalvebody(10)and
valve.
4. Installinletvalvespring(12)overinletbody(10)andinstall
o-ring(15) inthe innergroovein thevalve guide(14).
5. Depress and hold guide down against inlet spring and
installretainer ring(16) (A9/16"twelve pointsocket can
be used to push the retainer ring down until it snaps in
thegroove inthe inletvalvebody).
6. Installvalve insertseato-ring (13).
COMPLETEVALVEASSEMBLY
7. Install insert (8) in valve body (7), install exhaust cover
(17) and secure with 10-24 screws (19) torque to
approximately20-30inchpounds.
8. Installexhaust checkdiaphragm (18)into exhaustcover
(17).
9. Installcover sealo-ring.
10. Install relay piston o-ring (3) on relay piston (4), then
positionrelaypiston in cover.
11. If valve utilizes relay piston spring (6) position spring
overguide inbody.
12. Position cover/relaypiston assemblyin correctrelative
positionwith body;ifequipped withpiston returnspring,
make sure exhaust seat is centered inside spring.
13. Installcovercapscrews.Torquetoapproximately80-120
inchpounds.
14. Test valveas outlinedin “Operatingand leakageTests”
section.
WARNING! PLEASE READ AND FOLLOW
THESE INSTRUCTIONS TO AVOID
PERSONAL INJURYOR 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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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
enginebe inoperation, EXTREME CAUTIONshould
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. Useonly theproper toolsand 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,makecertain to draintheair 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
recommendedprocedures, deactivate theelectrical
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 cer-
tain all components and systems are restored to
their proper operating condition.

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COVER
CAP SCREW (4)
PISTON O-RING
RELAY PISTON
EXHAUST SEAT
RETURN SPRING
BODY
R-6 INSERT
INLET & EXHAUST VALVE
INLET & EXHAUST
VALVE BODY
VALVE RETAINER
SPRING
GUIDE SEAL O-RING
VALVE GUIDE
O-RING
RETAINER RING
EXHAUST COVER
EXHAUST CHECK
CAP SCREW

6BW1432 © 2004 Bendix Commercial Vehicle Systems LLC. All rights reserved. 3/2004 Printed in U.S.A.