BENDIX TP-3 Mounting instructions

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®
SD-03-3652
Bendix®TP-3®Tractor Protection Valve
Figure 1 - Bendix®TP-3®Tractor Protection Valve
DESCRIPTION
The Bendix®TP‑3®tractor protection valve is used in
combination with the Bendix®PP‑3™trailer supply valve
on pre‑121 tractors, and the Bendix®PP‑7™trailer supply
valve – or the Bendix® MV‑3®dash control valve – on
post‑121 tractors. It contains a passage for trailer supply
air and a service line shut off valve. It is normally mounted
behind the cab, with the delivery line from the trailer
supply valve connected into the tractor emergency port
and a delivery line from the brake valve connected to the
tractor service port. The trailer supply and service hoses
are mounted in their respective ports in the TP‑3 valve.
See Figure 2.
OPERATION
Air from the trailer supply valve passes through the
emergency ports of the TP‑3 valve to supply the trailer air
system and simultaneously exerts pressure on the end of
the plunger. The TP‑3 valve requires approximately 45 psi
to open the inlet valve. Whenever the pressure from the
trailer supply valve drops below 45 psi, the TP‑3 valve will
close the service line shut‑off valve.
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 Bendix TP‑3 valve should be inspected every 6 months
or 1500 operating hours, whichever comes rst, for proper
operation. Should the TP‑3 valve not meet the elements
of the operational tests noted in this document, further
investigation and service of the valve may be required.
Tractor
Emergency
Port
Trailer
Service
Port
Trailer
Emergency
Port
Tractor
Service
Port
Plunger
O‑Ring (Top)
Inlet Valve
Diaphragm Seat
Retaining Ring
Diaphragm
Seat O‑Ring
Plunger O‑Ring
(Bottom)
Valve Retainer
Plunger
Cap Screw
Washer
Diaphragm
Diaphragm
Seat
Valve
Spring
Valve Retaining
Ring
Exterior View Cross Section
Plunger Seat

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OPERATING AND LEAKAGE CHECKS
1. Block and/or hold the vehicle by a means other than the
air brakes during these tests. Place the trailer supply
valve in the emergency position and disconnect the
trailer supply and service couplings.
2. With the tractor reservoirs charged to at least 100 psi,
make and hold a full service brake application. Leakage
at either tractor hose coupling should not exceed a one
(1) inch bubble in ve seconds (100 SCCM).
3. Connect the trailer supply or emergency line hose
coupling and place the trailer supply valve in the run
position. Leakage at the service coupling should not
exceed a one (1) inch bubble in ve seconds (100
SCCM).
4. Connect the service coupling and make and hold a full
service brake application: Leakage at the diaphragm
end of the Bendix®TP‑3®valve shall not exceed a
one (1) inch bubble in three seconds (175 SCCM).
NOTE: If the TP‑3 valve does not function as
described, or if leakage is excessive, it is recommended
that it be replaced or repaired using genuine Bendix
service replacement parts.
REMOVAL
Remove the trailer hose assemblies from the TP‑3 valve.
Disconnect the tractor service and supply lines and remove
the TP‑3 valve.
INSTALLATION
When installing the TP‑3 valve, refer to Figure 2, and the
following explanation, for proper connections.
1. The delivery line from the Bendix®MV‑3®dash control
valve is connected to the tractor emergency port of the
TP‑3 valve.
2. The delivery line from the brake valve (or double‑check
valve) is connected to the tractor service port of the
TP‑3 valve.
3. Trailer hose assemblies are installed in the trailer
emergency and trailer service ports of the TP‑3 valve.
GENERAL SAFETY GUIDELINES
WARNING! PLEASE READ AND
FOLLOW THESE INSTRUCTIONS
TO AVOID PERSONAL INJURY OR DEATH:
When working on or around a vehicle, the following
guidelines should be observed AT ALL TIMES:
▲Park the vehicle on a level surface, apply the parking
brakes and always block the wheels. Always wear personal
protection equipment.
▲Stop the engine and remove the 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.
▲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.
▲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, a Bendix®
DRM™dryer reservoir module, or a Bendix® AD-9si®air
dryer, be sure to drain the purge reservoir.
▲
Following the vehicle manufacturer’s recommended
procedures, deactivate the electrical system in a manner
that safely removes all electrical power from the vehicle
.
▲Never exceed manufacturer’s recommended pressures.
▲Never connect or disconnect a hose or line containing
pressure; it may whip and/or cause hazardous airborne
dust and dirt particles. Wear eye protection. Slowly open
connections with care, and verify that no pressure is
present. Never remove a component or plug unless you are
certain all system pressure has been depleted.
▲Use only genuine Bendix®brand replacement parts,
components and kits. Replacement hardware, tubing, hose,
fittings, wiring, etc. must be of equivalent size, type and
strength as original equipment and be designed specifically
for such applications and systems.
▲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.
▲Prior to returning the vehicle to service, make certain all
components and systems are restored to their proper
operating condition.
▲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.
▲The power MUST be temporarily disconnected from the
radar sensor whenever any tests USING A DYNAMOMETER
are conducted on a vehicle equipped with a Bendix®
Wingman®system.
▲You should consult the vehicle manufacturer's operating
and service manuals, and any related literature, in
conjunction with the Guidelines above.

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Figure 2 - System Schematic
Trailer Service Line
Trailer Emergency Line
Front
Reservoir
Brake
Valve
Rear
Reservoir
Double
Check
Valve
Compressor
Bendix®MV‑3®
Control Valve
DISASSEMBLY
(See Figure 1)
1. Remove the diaphragm seat retaining ring while holding
the diaphragm seat in the body.
2. While still holding the diaphragm seat in the body,
remove the date code ring.
3. Allow the seat to rise until the valve spring force is no
longer present.
4. Remove the diaphragm seat assembly, valve spring,
and plunger assembly.
5. Remove the diaphragm seat o‑ring, cap screw,
diaphragm washer, and diaphragm.
6. Remove the valve retainer ring, valve retainer, inlet
valve, and both plunger o‑rings –top and bottom – from
the plunger.
CLEANING AND INSPECTION
1. Clean all metal parts in mineral spirits and dry them
completely.
2. Inspect all parts for excessive wear or deterioration.
Inspect valve seats for nicks or burrs. Check the valve
spring for cracks or corrosion.
Bendix® TP‑3®
Tractor
Protection
Valve
Air
Dryer
3. Inspect the bores of the valve housing for deep scufng
or gouges.
Replace all parts that were discarded, and any parts not
found to be serviceable during inspection, using only
genuine Bendix®replacement parts.
ASSEMBLY
Before assembling the Bendix®TP‑3® tractor protection
valve, lubricate all o‑rings, o‑ring grooves, body bores, and
rubbing surfaces with Bendix silicone lubricant (Piece No.
291126) or equivalent.
NOTE: When using pipe thread sealant during assembly
and installation, take particular care to prevent the
sealant from entering the valve itself. Apply the
sealant beginning with the second thread back
from the end.
1. Install the inlet valve on the plunger.
2. Position and force the valve retainer down over the inlet
valve.
3. Install the retainer ring beneath the inlet valve retainer.

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4. Install both plunger o‑rings– top and bottom– in their
proper grooves.
5. Place the plunger and valve assembly in the valve body.
6. Install the cap head screw, diaphragm washer with the
cup side up, and diaphragm into the diaphragm seat.
7. Place the inlet valve spring into the plunger.
8. Install the diaphragm seat o‑ring in the body.
9. Position the diaphragm seat assembly over the spring
and plunger assembly and force it into the body.
10. Replace the date code washer and install the retaining
ring making sure the retaining ring snaps fully into the
groove.
TESTING SERVICED BENDIX®TP-3®VALVES
Perform the operating and leakage checks as outlined in
previous section.
SD‑03‑3652 Rev. 008 © 2019 Bendix Commercial Vehicle Systems LLC, a member of the Knorr‑Bremse Group • 12/2019 • All Rights Reserved
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