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®
Bendix® PP-7™ Trailer Supply Valve
NUT & THREAD
1/8 P.T.
SUPPLY
EXHAUST
SD-03-3617
FUNCTION AND DESCRIPTION
The PP-7™ trailer supply valve provides in cab control for the
tractor protection system and functions in conjunction with
the park control valve. It is responsible for synchronizing the
tractor and trailer parking and emergency brakes.
It is essentially a combination of two non-modulating, onoff control valves in a single, compact package.
Each of the four pipe tapped ports of the PP-7™ valve are
identified with cast in, raised letters. The supply and control
ports have 1/8 inch N.P.T.F . dry seal pipe threads while the
delivery and exhaust ports have 1/4 inch N.P.T .F. dry seal
pipe threads.
LOCK
WASHER
CAP SCREW
FIGURE 1 - EXTERIOR
(17) PLUNGER
(18) PLUNGER
RETURN
SPRING
HEX LOCK NUT (15)
(12) O-RING
(13) INLET &
EXHAUST
VALVE
1/4 P.T. DELIVERY
(9) O-RING
1/8 P.T. CONTROL
LOCK
WASHER
CAP SCREW
GENERAL OPERA TION
The PP-7 trailer supply valve is a panel mounted, push-pull
operated control valve. The button of the PP-7™ valve must
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
BUTTON (2)
SPIROL
PIN (1)
THIN NUT
O-RING (19)
BODY
INLET & EXHAUST
(16) VALVE
RETAINING RING (10)
SEALING RING (3)
O-RING RETAINER (11)
INLET & EXHAUST (14)
VALVE SPRING
SPRING (7)
LOWER BODY
PISTON (6)
O-RING (8)
O-RING (5)
FIGURE 2 - SECTIONAL
END PLATE (4)
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PP-7
Control
Valve
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TRACTOR DUAL AIR BRAKE SYSTEM
™
TP-3
Tractor Protection
DS-1
Park
Control
LQ-3
Modulator
FIGURE 3 - PIPING DIAGRAM
™
Valve
Double Check
Supply
Reservoir
™
E-7
Dual
Brake Valve
Valve
#1 Service
Reservoir
SR-1™ Spring
Brake Valve
LP-3™ Low
Pressure Indicator
#2 Service
Reservoir
SB-3
R-8
™
SB-3
RELAY
VALVE
SB-3 SB-3
PP-7™ VALVE LESS THAN 50 PSI
SYSTEM PRESSURE
To
Parking
Brakes
Double
Check
Valve
FIGURE 4 - PP-7
™
TRAILER SUPPL Y V ALVE LESS THAN 50 PSI SYSTEM PRESSURE
Park
Control
Valve
#1 Service
Reservoir
#2 Service
Reservoir
Inlet & Exhaust
Exhaust Vent
To Tractor
Protection
Control Port
Supply
Port
Plunger
Control Inlet
and Exhaust
Exhaust
Port
Control
Piston
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PP-7™ VALVE SYSTEM FULLY CHARGED
Park
Control
Valve
To
Parking
Brakes
#1 Service
Reservoir
Double
Check
Valve
FIGURE 5 - PP-7™ TRAILER SUPPL Y V AL VE SYSTEM FULL Y CHARGED
#2 Service
Reservoir
Plunger
Inlet & Exhaust
Exhaust Vent
To Tractor
Protection
Control Port
Supply
Port
Control Inlet
and Exhaust
Exhaust
Port
Control
Piston
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
the PP-7™ valve will be out and the park control valve will not
deliver air to the control port of the PP-7™ valve. In this
condition supply air cannot flow past the closed plunger inlet
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
When system air pressure is greater than 50 P .S.I., the button
of the PP-7™ valve can be depressed and will stay in. If the
vehicle is in the running condition, the park control valve will
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
inlet will be open and the exhaust valve will be seated, sealing
the exhaust vent. Supply air is permitted to flow through the
body to the control inlet and exhaust valve. With the park
control valve delivering full system pressure to the control
port of the PP-7™ valve, the control piston moves into contact
with the control valve, closing the exhaust passage through
the piston and opening the inlet. Opening the control inlet
permits supply air to flow out the delivery port of the PP-7
valve. (See Note.)
NOTE: If the vehicle is parked and system air pressure is
above 50 P.S.I., the park control valve will not be
delivering air to the PP-7™ valve control port and the
control inlet valve will be closed. In this case no air
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
the PP-7™ valve is pulled by the operator. Pulling the button
closes the plunger inlet and unseats the exhaust valve. Air
that was flowing out the delivery port returns to the PP-7
valve and is exhausted from the vent in the midsection of the
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
exhausted when the parking brakes were applied.
See “Operation Park Application.”
AUTOMA TIC
In the event of trailer breakaway or a sudden complete failure
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.
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PP-7™ VALVE MANUAL EMERGENCY
Park
Control
Valve
To
Parking
Brakes
#1 Service
Reservoir
Double
Check
Valve
FIGURE 6 - PP-7™ TRAILER SUPPLY VAL VE MANUAL EMERGENCY
#2 Service
Reservoir
Inlet & Exhaust
To Tractor
Protection
Control Port
PP-7™ VALVE PARK APPLICATION
Supply
Port
Plunger
Exhaust Vent
Control
Piston
Control Inlet
and Exhaust
Exhaust
Port
Park
Control
Valve
To
Parking
Brakes
#1 Service
Reservoir
To Tractor
Double
Check
Valve
FIGURE 7 - PP-7™ TRAILER SUPPLY V AL VE PARK APPLICA TION
#2 Service
Reservoir
Protection
OPERATION - AUTOMATIC EXHAUST (NO
OVER RIDE)
If the driver holds the button of the PP-7™ valve in after supply
air pressure has dropped below the 40 P .S.I. automatic pop
out pressure, the control piston will move into the exhaust
position when control port pressure falls below 20 P .S.I.
Supply
Port
Plunger
Inlet & Exhaust
Exhaust Vent
Control Port
Control
Piston
Control Inlet
and Exhaust
Exhaust
Port
OPERATION - PARK APPLICATION
During a parking brake application, the park control valve
removes air pressure from the control port of the PP-7™ valve.
The button of the PP-7™ valve remains in.
With air pressure removed from the control port of the PP-7
valve, the control piston moves away from the control inlet
and exhaust valve. The inlet valve seats and the exhaust
passage through the control piston is open. Air at the delivery
port of the PP-7™ valve is exhausted at the exhaust port of
the PP-7™ valve.
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PREVENTIVE MAINTENANCE
Important: Review the Bendix Warranty Policy before
performing any intrusive maintenance procedures. A warranty
may be voided if intrusive maintenance is performed during
the warranty period.
No two vehicles operate under identical conditions, as a
result, maintenance intervals may vary. Experience is a
valuable guide in determining the best maintenance interval
for air brake system components. At a minimum, the PP-7
valve should be inspected every 6 months or 1500 operating
hours, whichever comes first, for proper operation. Should
™
the PP-7
valve not meet the elements of the operational
tests noted in this document, further investigation and service
of the valve may be required.
OPERATING AND LEAKAGE CHECKS
T o perform the following test, an accurate vehicle test gauge
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. Apply a soap solution to the exhaust vent and the plunger
stem of the PP-7™ valve to check for leakage. Leakage
should not exceed a 1 inch bubble in 5 seconds at either
point.
4. Depress the control button of the PP-7™ valve and apply
a soap solution to the exhaust vent and the exhaust
port. Leakage should not exceed a 1" bubble in 5 seconds
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
pressure on the test gauge. The pressure registered on
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 the tractor air system at governor cut-out pressure,
shut off the engine and note the dash gauge pressure.
Quickly disconnect the test gauge and hose coupling
from the tractor-trailer supply line coupling. Leakage from
the tractor-trailer supply line should cease immediately
and button of the PP-7™ valve should be out. Dash gauge
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 at what pressure (descending) the button
of the PP-7™ valve pops out and exhausts the
tractor-trailer supply line. This should occur between
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20-45 P.S.I. air system pressure.
If the PP-7™ trailer supply valve fails to function as described
or if leakage is excessive, it is recommended that it be
returned to the nearest Bendix authorized outlet for a factory
remanufactured valve. If this is not possible, the valve should
be repaired using only genuine Bendix replacement parts,
in which case the following should prove helpful.
NOTE: Maintenance piece number 287367 kit is available
for the PP-7™ trailer supply valve, which contains
all the necessary parts to completely repair it, from
any authorized Bendix outlet.
REMOV AL
1. Chock the vehicle wheels and drain all air system
reservoirs completely .
2. Disconnect all air lines leading to and from the PP-7
valve and mark them for proper reconnection.
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
remove the valve.
DISASSEMBL Y
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)
between the upper and lower body halves.
4. Remove the end plate (4) and o-ring (5) from the lower
body and discard the o-ring.
5. Remove the control piston (6) and piston return spring
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(7).
6. Remove the large (8) and small diameter o-rings (9) from
the piston and discard them.
7. Remove the internal truarc retaining ring (10) from the
lower body .
8. Remove the o-ring retainer (11) and remove and discard
the o-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) from the plunger inlet exhaust valve and washer.
1 1. Remove the plunger inlet exhaust valve (16) and washer.
12.Remove the plunger (17) and plunger return spring (18)
from the body .
13.Remove and discard the plunger o-ring (19).
CLEANING AND 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. It is recommended that all non-metallic parts and springs
be replaced, using only genuine Bendix replacements.
ASSEMBLY
GENERAL
Prior to assembly all internal bores and all non-metallic parts
should be coated with a film of silicone lubricant, Bendix
piece number 291 126.
1. Install the control inlet exhaust valve (13) and return
spring (14) in the lower body .
2. Install the o-ring (12) in the body, then the o-ring retainer
(1 1) and the truarc retainer (10).
3. Install the end plate o-ring (5) in the oval groove in the
lower body .
4. Install the plunger o-ring (19) and place the plunger return
spring (18) and plunger (17) in the upper body .
5. Depress the plunger until the threaded portion extends
sufficiently to install the plunger inlet and exhaust valve
(16), the valve washer and special hex nut (15). T orque
the special hex nut to 30-40 inch pounds.
6. Install the square cut seal ring (3) in the upper body .
7. Install the large (8) and small diameter o-rings (9) on the
control piston (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.
1 1. T orque 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
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.
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 an 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® 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.
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T est the rebuilt unit using the operation and leakage checks
outlined in this manual.
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BW1579 © 2004 Bendix Commercial Vehicle Systems LLC. All rights reserved. 3/2004 Printed in U.S.A.
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