BENDIX PP-7 TRAILER SUPPLY VALVE User manual

1
®
Bendix®PP-7™Trailer Supply Valve
SD-03-3617
EXHAUST
LOCK
WASHER
1/8 P.T.
SUPPLY
NUT & THREAD
CAPSCREW
(18) PLUNGER
RETURN
SPRING
SPIROL
PIN(1)
(12) O-RING
BUTTON (2)
THIN NUT
(17) PLUNGER
HEX LOCK NUT (15)
FUNCTION AND DESCRIPTION
ThePP-7™trailer supplyvalve providesin cabcontrolforthe
tractor protection system and functions in conjunction with
thepark controlvalve.Itisresponsibleforsynchronizing the
tractorandtrailer parking andemergencybrakes.
It is essentially a combination of two non-modulating, on-
off control valves in a single, compact package.
Each of the four pipe tapped ports of the PP-7™valve are
identifiedwithcast in,raisedletters. Thesupplyand control
portshave 1/8 inch N.P.T.F.drysealpipethreads while the
delivery and exhaust ports have 1/4 inch N.P.T.F. dry seal
pipethreads.
GENERALOPERATION
ThePP-7trailer supplyvalveis apanelmounted, push-pull
operatedcontrolvalve. Thebuttonof thePP-7™valvemust
be manually depressed, but will automatically pop out and
exhaust if supply air is below 40 p.s.i. Fifty p.s.i. or greater
supply air pressure is required for the button to remain in
LOCK
WASHER
CAPSCREW
(13) INLET &
EXHAUST
VALVE
1/4P.T.DELIVERY
(9) O-RING
1/8 P.T. CONTROL
O-RING (19)
BODY
INLET & EXHAUST
(16)VALVE
RETAINING RING (10)
SEALINGRING(3)
O-RING RETAINER (11)
INLET & EXHAUST (14)
VALVESPRING
SPRING(7)
LOWERBODY
PISTON (6)
O-RING (8)
O-RING (5)
ENDPLATE(4)
FIGURE 1 - EXTERIOR
FIGURE2 -SECTIONAL

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DoubleCheck
Valve
#1 Service
Reservoir
PP-7™
Control
Valve
Modulator
Park
Control
DS-1
Supply
Reservoir
TP-3™TractorProtection
#2 Service
Reservoir
LQ-3™Valve
E-7™
Dual
BrakeValve
LP-3™Low
Pressure Indicator
SB-3
SR-1™Spring
Brake Valve
R-8™
RELAY
VALVE
SB-3
SB-3 SB-3
TRACTOR DUAL AIR BRAKE SYSTEM
FIGURE3- PIPINGDIAGRAM
FIGURE 4 - PP-7™TRAILER SUPPLY VALVE LESS THAN 50 PSI SYSTEM PRESSURE
PP-7™VALVE LESS THAN 50 PSI
SYSTEM PRESSURE
#1 Service
Reservoir
#2 Service
Reservoir
Double
Check
Valve
Park
Control
Valve
To
Parking
Brakes
Supply
Port
Plunger
Inlet&Exhaust
ExhaustVent ControlInlet
andExhaust
Exhaust
Port
Control
Piston
ToTractor
Protection
ControlPort

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after it is depressed and it will remain in until supply air
pressure falls below 40 P.S.I. or until the valve is manually
actuated.
OPERATION - LESS THAN 50 P.S.I. SYSTEM
PRESSURE
With less than 50 P.S.I. system air pressure, the button of
thePP-7™valve willbeoutandtheparkcontrolvalvewillnot
deliver air to the control port of the PP-7™valve. In this
conditionsupplyaircannotflow pastthe closedplungerinlet
and the plunger exhaust valve is off its seat. With no air
pressure on the control port, the control inlet is seated and
the exhaust passage through the control piston is open.
OPERATION - ABOVE 50 P.S.I. SYSTEM AIR
PRESSURE
Whensystemairpressureisgreaterthan50P.S.I.,thebutton
of the PP-7™valve can be depressed and will stay in. If the
vehicleisin therunning condition,thepark controlvalvewill
be delivering system air pressure to the control port of the
PP-7™valve.(See Note.)
With the button of the PP-7™valve depressed, the plunger
inletwillbeopenandtheexhaustvalvewillbeseated,sealing
theexhaustvent. Supplyairis permittedtoflow through the
body to the control inlet and exhaust valve. With the park
control valve delivering full system pressure to the control
portof thePP-7™valve,thecontrolpiston movesintocontact
withthecontrol valve,closingthe exhaustpassagethrough
the piston and opening the inlet. Opening the control inlet
permits supply air to flow out the delivery port of the PP-7™
valve.(SeeNote.)
NOTE: If the vehicle is parked and system air pressure is
above 50 P.S.I., the park control valve will not be
deliveringair tothePP-7™valvecontrolportandthe
controlinletvalve will beclosed.Inthis case noair
will be flowing from the delivery port of the PP-7™
valve.
OPERATION - MANUAL OR AUTOMATIC
EMERGENCY
MANUAL
In order to disconnect the tractor and trailer, the button of
thePP-7™valveis pulledbythe operator. Pullingthebutton
closes the plunger inlet and unseats the exhaust valve.Air
that was flowing out the delivery port returns to the PP-7™
valveand isexhaustedfromtheventinthemidsectionofthe
PP-7™valve.
NOTE: If the parking brakes were applied prior to pulling
the PP-7™valve button, no delivery air would be
present to exhaust. Delivery air would have been
exhaustedwhentheparkingbrakes were applied.
See“OperationParkApplication.”
AUTOMATIC
Intheeventoftrailerbreakawayorasuddencompletefailure
of the trailer supply line, the button of the PP-7™valve will
pop out when air pressure in the supply line falls below 40
P.S.I.
FIGURE5 -PP-7™TRAILERSUPPLYVALVESYSTEM FULLYCHARGED
PP-7™VALVE SYSTEM FULLY CHARGED
#1 Service
Reservoir
#2 Service
Reservoir
Double
Check
Valve
Park
Control
Valve
To
Parking
Brakes
Supply
Port
Plunger
Inlet&Exhaust
ExhaustVent ControlInlet
andExhaust
Exhaust
Port
Control
Piston
ToTractor
Protection
ControlPort

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OPERATION - AUTOMATIC EXHAUST (NO
OVER RIDE)
IfthedriverholdsthebuttonofthePP-7™valveinaftersupply
airpressurehas droppedbelowthe 40P.S.I.automaticpop
out pressure, the control piston will move into the exhaust
positionwhencontrolport pressure fallsbelow20 P.S.I.
OPERATION - PARK APPLICATION
During a parking brake application, the park control valve
removesairpressurefromthecontrolportofthePP-7™valve.
Thebuttonof thePP-7™valveremains in.
Withair pressureremovedfromthecontrolportofthePP-7™
valve, the control piston moves away from the control inlet
and exhaust valve. The inlet valve seats and the exhaust
passagethroughthecontrolpistonisopen.Airatthedelivery
port of the PP-7™valve is exhausted at the exhaust port of
thePP-7™valve.
FIGURE6 -PP-7™TRAILERSUPPLYVALVE MANUALEMERGENCY
FIGURE7 -PP-7™TRAILERSUPPLYVALVE PARKAPPLICATION
#1 Service
Reservoir
#2 Service
Reservoir
Double
Check
Valve
Park
Control
Valve
To
Parking
Brakes
Supply
Port
Plunger
Inlet&Exhaust
ExhaustVent ControlInlet
andExhaust
Exhaust
Port
Control
Piston
PP-7™VALVE MANUAL EMERGENCY
PP-7™VALVE PARK APPLICATION
ToTractor
Protection
ControlPort
#1 Service
Reservoir
#2 Service
Reservoir
Double
Check
Valve
Park
Control
Valve
To
Parking
Brakes
Supply
Port
Plunger
Inlet&Exhaust
ExhaustVent ControlInlet
andExhaust
Exhaust
Port
Control
Piston
ToTractor
Protection
ControlPort

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PREVENTIVE MAINTENANCE
Important: Review the Bendix Warranty Policy before
performinganyintrusivemaintenanceprocedures.Awarranty
maybevoided ifintrusive maintenanceisperformed during
thewarrantyperiod.
No two vehicles operate under identical conditions, as a
result, maintenance intervals may vary. Experience is a
valuableguide indeterminingthebestmaintenanceinterval
forairbrake systemcomponents.Ataminimum, thePP-7™
valveshouldbeinspectedevery6monthsor1500 operating
hours,whichevercomesfirst, for properoperation.Should
the PP-7™valve not meet the elements of the operational
testsnotedinthisdocument,furtherinvestigationandservice
ofthevalvemaybe required.
OPERATING AND LEAKAGE CHECKS
Toperformthefollowingtest,anaccuratevehicletestgauge
installed in a spare hose coupling is required. The vehicle
dash gauge(s) should be checked for accuracy against
the test gauge prior to making these tests.
1. Block or hold the vehicle by means other than the
service air brakes.
2. With the PP-7™trailer supply valve button out and the
parking control valve in the exhaust, or brakes applied
position, build the air system pressure to governor
cut-out.
3. Applyasoapsolutiontotheexhaustventandtheplunger
stemofthePP-7™valve to checkforleakage. Leakage
shouldnotexceeda1inchbubble in5 secondsateither
point.
4. DepressthecontrolbuttonofthePP-7™valveandapply
a soap solution to the exhaust vent and the exhaust
port.Leakageshouldnotexceeda1"bubblein5seconds
at either point.
5. Install the test gauge and coupling on the trailer supply
coupling (tractor emergency hose coupling) at the rear
of the tractor.
6. Place the tractor parking control valve in the “brakes
released” position and observe an immediate rise in
pressureonthe testgauge.The pressureregisteredon
the test gauge should equal dash gauge or system
pressure.
7. Apply a soap solution to the exhaust port of the PP-7™
valve. Leakage should not exceed a 1" bubble in 5
seconds.
8. With thetractor airsystematgovernorcut-out pressure,
shut off the engine and note the dash gauge pressure.
Quickly disconnect the test gauge and hose coupling
fromthetractor-trailersupplylinecoupling.Leakagefrom
thetractor-trailersupply line shouldceaseimmediately
andbuttonofthePP-7™valveshouldbeout.Dashgauge
air pressure after the performing of the preceding test
should be within approximately 10 P.S.I. of the initial
pressure.
9. Reconnect the test gauge to the tractor-trailer supply
line and depress the button of the PP-7™valve. Open
the drain cocks of No. 1 and No. 2 service reservoirs
slightly. Note atwhatpressure(descending) the button
of the PP-7™valve pops out and exhausts the
tractor-trailer supply line. This should occur between
20-45 P.S.I. air system pressure.
Ifthe PP-7™trailersupply valvefails tofunction asdescribed
or if leakage is excessive, it is recommended that it be
returnedto thenearest Bendixauthorized outletforafactory
remanufacturedvalve.Ifthisis notpossible,thevalveshould
be repaired using only genuine Bendix replacement parts,
inwhichcase thefollowingshould provehelpful.
NOTE: Maintenancepiecenumber 287367kitisavailable
for the PP-7™trailer supply valve, which contains
allthenecessary partstocompletelyrepair it,from
anyauthorizedBendixoutlet.
REMOVAL
1. Chock the vehicle wheels and drain all air system
reservoirscompletely.
2. Disconnect all air lines leading to and from the PP-7™
valveandmarkthemforproperreconnection.
3. Using a drift pin punch, remove the spirol pin (1) Fig. 2
which secures the button to the plunger. Remove the
button (2).
4. Using a 1-5/16 inch wrench, remove the special thin
nut which secures the PP-7™valve to the panel and
removethevalve.
DISASSEMBLY
1. Mark the upper and lower body halves to show their
relationship to each other.
2. Remove the two 1/4 inch-20 cap screws, that secure
the lower valve body to the upper valve body, using a
7/16 inch wrench. Separate the two body halves.
3. Remove and discard the square cut sealing ring (3)
betweentheupper and lowerbodyhalves.
4. Remove the end plate (4) and o-ring (5) from the lower
bodyanddiscard the o-ring.
5. Remove the control piston (6) and piston return spring
(7).
6. Removethelarge(8)andsmalldiametero-rings(9) from
the piston and discard them.
7. Remove the internal truarc retaining ring (10) from the
lower body.
8. Removetheo-ringretainer(11)andremoveanddiscard
theo-ring(12).
9. Remove the inlet exhaust valve (13) and return spring
(14).

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10. Using a 7/16 inch wrench remove the special hex nut
(15)fromthe plunger inletexhaustvalve and washer.
11. Removetheplungerinletexhaustvalve(16)andwasher.
12. Removethe plunger(17) andplunger returnspring (18)
from the body.
13. Removeand discardthe plungero-ring(19).
CLEANINGAND INSPECTION
1. Clean all metal parts in a good commercial solvent
making sure all ports, passages, and bores are clean
and open.
2. Dry the parts thoroughly and inspect the plunger and
piston bores for scratches and nicks.
3. Itisrecommendedthat allnon-metallicpartsandsprings
be replaced, using only genuine Bendix replacements.
ASSEMBLY
GENERAL
Priorto assemblyallinternalboresandallnon-metallicparts
should be coated with a film of silicone lubricant, Bendix
piece number 291126.
1. Install the control inlet exhaust valve (13) and return
spring (14) in the lower body.
2. Installtheo-ring(12) inthe body,thentheo-ringretainer
(11) andthetruarc retainer(10).
3. Install the end plate o-ring (5) in the oval groove in the
lower body.
4. Installtheplungero-ring(19)andplacetheplungerreturn
spring(18)and plunger(17)inthe upperbody.
5. Depress theplungeruntil the threadedportionextends
sufficientlytoinstall the plungerinletand exhaustvalve
(16),thevalve washer andspecialhex nut(15).Torque
the special hex nut to 30-40 inch pounds.
6. Install the square cut seal ring (3) in the upper body.
7. Installthelarge(8)andsmalldiameter o-rings(9)onthe
controlpiston(6).
8. Place the upper and lower bodies together taking care
to align the marks made during disassembly.
9. Install the control piston return spring (7) and control
piston in the lower body.
10. Install the end plate (4) on the lower body and secure it
with the two 1/4 inch-20 cap screws.
11. Torque the cap screws to 30-40 inch pounds.
12. Reinstall the rebuilt valve on the vehicle in the reverse
manner in which it was removed.
TESTING THE REBUILT VALVE
Test therebuilt unitusingthe operationandleakagechecks
outlined in this manual.
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
enginebe inoperation, EXTREMECAUTION 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. Useonly the propertools andobserve
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 certaintodrain theair 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, deactivatethe 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.
BW1579 © 2004 Bendix Commercial Vehicle Systems LLC. All rights reserved. 3/2004 Printed in U.S.A.