BENDIX PP-DC PARK CONTROL VALVE User manual

1
®
SD-03-3619
Bendix®PP-DC™Park Control Valve
FIGURE 1 - PP-DC™PARK CONTROLVALVE
SUPPLY 12
EXHAUST
SUPPLY 11
BUTTON
EXHAUST
SUPPLY 11
BUTTON
COVER
DELIVERY
21
DESCRIPTION
The Bendix®PP-DC™park control valve is a push-pull,
manually operable on/off valve. It is dash board-mounted
andprovidesin-cabcontroloftruckorbusparkingbrakes.
Thevalve ispressuresensitive–itautomaticallymovesfrom
the applied to the exhaust position if total system pressure
drops below 20 to 30 psi. Also, manually pulling the button
will apply the parking brakes.
The PP-DC™valve body is made of non-metallic, non-
corrosivematerial,andthecoveris availableintwomounting
variations (see Figure 1). The valve is designed to accept
1/4" P.T. fittings or push-to-connect fittings that use SAE
J844Dnon-metallicairbrake tubing.
Ports:
Port EmbossedI.D.
Primary Reservoir Supply Supply 11
Secondary Reservoir Supply Supply 12
Delivery Delivery21
Exhaust Exhaust3
Operatingpressure:150psimax.
Operatingtemperature:-40°to 200°F
Basicvalveweight:Approximately.8lbs.
OPERATION
GENERAL
ThePP-DC™valvereceivesitssupplyofair fromtheprimary
servicereservoirorthesecondaryservicereservoir,whichever
isatthehigherpressure.When the button is pushed in, the
valve delivers air to the spring brake chambers (usually
through a spring brake valve such as the Bendix®SR-1™
valve and a relay or quick release valve). The air releases
thespringbrakesfor normal vehicle operation.
Toapplytheparkingbrakes,thebuttonispulledout,which
exhausts the PP-DC™valve delivery and releases air from
thespringbrakechambers.
Iftotalsystempressuredropsbelow20to30psi,thevalve
will automatically “pop out,” which removes the hold-off air
in the chambers and applies the spring brakes.
PARKING BRAKES RELEASED
Toreleasetheparkingbrakes,thepush-pullbutton ispushed
in. The PP-DC™valve plunger moves, closing the exhaust
portwiththe exhaust sealandallowingthe plunger o-ringto
move past the guide spool. Supply air then travels out the
deliveryporttoreleasethebrakes.
Note that Figure 3 shows the primary service reservoir
supplying the PP-DC™valve. The double check valve
diaphragmhassealedthesecondaryreservoirsupplyport
and allows air to pass from the primary reservoir into the
PP-DC™valve.

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FIGURE 2 - TYPICAL4 X 2 TRUCK SCHEMATIC WITH PP-DC™PARK CONTROL VALVE
SR-1™SPRING
BRAKE VALVE
SUPPLY (PRIMARY
RESERVOIR)
PP-DC™VALVE
EXH. ANTI-CMPD.
LINE
SERVICE
RELAYVALVE QR-1C™
VALVE
DEL.
SUPPLY (SECONDARY
RESERVOIR)
Ifprimaryservicereservoirpressure dropsbelowsecondary
servicereservoirpressure,thedoublecheckvalvereactsas
shown in Figure 4. It seals the primary service reservoir
supplyportand supplies thePP-DC™valvewith airfromthe
secondaryservicereservoir.Asisshown,thepush-pullbutton
remainsinandthespringbrakesremainreleased.
PARKING BRAKES APPLIED
Figure 5 shows the PP-DC™valve in the parking-brakes-
applied position. This will occur if the driver manually pulls
outthepush-pullbuttonoriftotalsystem pressure drops to
below 20 to 30 psi.
When the button “pops out,” the exhaust seal moves to
opentheexhaustportto atmosphere, allowing deliveryline
pressure to exhaust. The plunger o-ring moves to seal off
supply pressure. Spring brake hold-off air is exhausted
throughthespring brake relayvalve.
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.
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 bein operation, 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. Useonlythe proper toolsandobserve
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 certaintodraintheair pressurefrom
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.

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FIGURE4 - SPRINGBRAKES RELEASED(SECONDARYRESERVOIRSUPPLY)
SECONDARY
SERVICERESERVOIR
PRIMARYSERVICE
RESERVOIR EXHAUST
EXHAUST
SEAL
FIGURE3 -SPRING BRAKESRELEASED(PRIMARYRESERVOIRSUPPLY)
SUPPLY
PLUNGER O-RING BUTTON
PLUNGER
GUIDE SPOOL
DELIVERY
SECONDARY
SERVICERESERVOIR
PRIMARYSERVICE
RESERVOIR EXHAUST
EXHAUST
SEAL
SUPPLY
PLUNGER O-RING BUTTON
PLUNGER
GUIDE SPOOL
DELIVERY

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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
lampshouldbe ON) prior toperforming any vehicle
maintenance where one or more wheels on a drive
axle are lifted off the ground and moving.
PREVENTIVE MAINTENANCE
Important: Review the Bendix Warranty Policy before
performinganyintrusivemaintenanceprocedures.Awarranty
maybevoidedif intrusive maintenanceisperformedduring
thewarrantyperiod.
No two vehicles operate under identical conditions, as a
result, maintenance intervals may vary. Experience is a
valuableguidein determiningthebestmaintenanceinterval
for air brake system components. At a minimum, the
PP-DC™valveshouldbeinspectedevery 6 monthsor1500
operatinghours, whichevercomesfirst,forproperoperation.
Should the PP-DC™valve not meet the elements of the
operationaltestsnotedinthisdocument,furtherinvestigation
andserviceof the valvemayberequired.
SERVICECHECKS
1. Remove any accumulated contaminants. Visually
inspectthevalve’sexteriorforexcessivewearorphysical
damage.Repair/replaceas necessary.
2. Inspect all air lines connected to the valve for signs of
wearorphysical damage.Repair/replaceas necessary.
3. Testairlinefittingsforexcessiveleakage.Repair/replace
as necessary.
LEAKAGE AND OPERATIONAL TESTS
To perform the following tests, connect two separate 120
psi air sources to the PP-DC™valve supply ports. Tee an
accuratetestgaugeintothesupply lines, and provide for a
means to control supply line pressure. Connect a small
volumewithagaugetothedelivery port.
LEAKAGETEST
1. Supplythe valve with120psifromthe primary reservoir
supply port. With the button out, coat the exhaust port
and the plunger stem with a soap solution. Leakage
should not exceed a 1" bubble in 5 seconds. There
shouldbenoleakagefromthesecondaryreservoirsupply
port.
2. With the button out, supply the valve with 120 psi from
thesecondaryreservoir supplyport.Thereshouldbeno
leakagefromtheprimaryreservoir supply port.
FIGURE5 - PARKING BRAKESAPPLIED
SECONDARY
SERVICERESERVOIR
PRIMARYSERVICE
RESERVOIR EXHAUST
EXHAUST
SEAL
SUPPLY
PLUNGER O-RING BUTTON
PLUNGER
GUIDE SPOOL
DELIVERY

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BODY
INDEXTABS
GUIDE
SPOOL
PLUNGER
STEM
FIGURE 6 - EXPLODED VIEW
COVER
CHECKVALVESEAT
BUTTON
SCREW
1
4
27
8
3
9
5
6
PLUNGER

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3. Withthe buttonin,coatthe exhaustportandthe plunger
stemwithasoapsolution.Leakageatbothareas should
not exceed a 1" bubble in 3 seconds.
OPERATIONAL TEST
1. With the button out, supply either supply port with 120
psi of air. Then push the button in.Air pressure should
risein thedeliveryvolumeequivalentto supplypressure.
2. Pullthe button out. Deliverypressureshouldexhaustto
0 psi.
3. Build each supply source to 120 psi. Decrease supply
pressureatthesecondaryservice reservoir supply port
ata rate of 10 psi per second. Primary supply pressure
and delivery pressure should not drop below 100 psi.
Repeatthetest for decreasingprimaryservicereservoir
pressure.
4. Build each supply source to 120 psi. Then decrease
bothsupplypressurestobelow 20 to 30 psi.Thebutton
should automatically “pop” out when pressure drops
withinthatrange.
If the PP-DC™valve fails to function as described, or if
leakage is excessive, repair the valve or replace it at the
nearest authorized Bendix Commercial Vehicle Systems
parts outlet.
REMOVAL
1. Identify and mark or label all air lines and their
connectionsonthe valve.
2. RemovethePP-DC™valvefromthevehicleandsavethe
mountinghardware.
INSTALLATION
1. Installthe PP-DC™valveinitslocationonthedashboard.
Using the mounting hardware saved in “REMOVAL,”
securethevalveto the vehicle.
2. Reconnectallairlinestothevalveusingtheidentification
madein“REMOVAL.”
3. Perform“OPERATIONALANDLEAKAGETESTS”before
placingthevehiclebackinservice.
DISASSEMBLY
The following disassembly and assembly procedures are
forreferenceonly.Alwayshavetheappropriatemaintenance
kitonhandanduseitsinstructionsinlieuofthosepresented
here.RefertoFigure 6 throughout theprocedure.
1. Turn the button counterclockwise to remove it from the
plungerstem.
2. Remove the four screws that secure the cover to the
body,andremovethe cover.
3. Pull the plunger stem to remove the plunger and the
guidespoolfromthebody.
4. Removeplunger spring(6)anddiscard.
5. If necessary, use a screwdriver to carefully remove the
checkvalveseatfromthebody. Be sure not to damage
the check valve seat or the body.
6. Removeand discardcheckvalveseato-rings(7)and(8).
7. Turn the body upside down and gently tap it on a flat
surface to remove check valve(9). Discard the check
valve.
8. Removethe guide spool fromtheplunger.Removeand
discardo-ring(1)fromtheguide spool.
9. Remove and discard o-rings(2), (3) and (5) from the
plunger.Alsoremove and discard exhaustseal(4).
CLEANING & INSPECTION
1. Wash all metal parts in mineral spirits and thoroughly
dry.
2. Inspectallre-usablepartsforexcessivewearordamage.
Inspect the body for gouges or deep scuffing. Replace
keynumbers1-9 (and anypartsnotdetermined usable)
withgenuineBendixreplacements.
ASSEMBLY
Beforeassembly,lubricateallo-rings,o-ringgrooves,rubbing
surfaces and bores with Bendix silicone lubricant (Pc. No.
291126)orequivalent.
1. Placecheck valve(9) into its seatinthebodywithits flat
surfacefacingupward. Ifnecessary, reachintothebody
tomake sure the valve is seated evenlyin the bore.
2. Install o-rings(7) and (8) on the check valve seat and
installthe checkvalveseatintothebody.Makesurethe
seat is fully seated-its surface should be even with the
body’ssurface.
3. Installplungerspring(6)intothebody.Makesureitstands
uprightand isseatedproperlyinthe bodybore.(Itshould
surroundtheprotrusion or “lip”atthebottomof thebody
bore.)
4. Install o-rings(2), (3), (5) and exhaust seal(4) onto the
plunger. Then install the plunger into the body. Line up
the plunger’s index tabs with the spaces in the body
boreforeaseofinstallation.
5. Install o-ring(1) onto the guide spool. Then install the
guide spool over the plunger and into the body. Press
the guide spool into place firmly.
6. Place the cover onto the body and secure with its four
screws. Torque to 35 in. lbs.
7. Thread the button clockwise onto the plunger stem. It
should take approximately 3 full button revolutions to
install it on the plunger. The protrusions on the side of
theplungershould lineupwith thebuttongrooves.Push
onthebuttonanumberof timestomakesuretheplunger
movesfreelythroughoutitsrange of motion.
NOTE: BEFORE PLACING THE VEHICLE BACK INTO
SERVICE, PERFORM THE “LEAKAGE AND
OPERATIONALTESTS”INTHIS MANUAL.
BW1739 © 2007 Bendix Commercial Vehicle Systems LLC. All rights reserved. 6/2007 Printed in U.S.A.