BENDIX® TR-2™ INVERSION VALVE MAINTENANCE KIT

1/4-in.
P.T.
Supply

Cap Nut
Mounting
Nut

1
Lock Washer

Valve Spring

3
Valve
Body
5/8-in.

Description

Qty.

1

Sealing Ring

1

3

Inlet and Exhaust Valve

1

7

O-ring

1

11

Exhaust Diaphragm

1

13

O-ring

1

15

Tube of Lubricant

1

1/4-in. P.T.
Delivery (x2)
Valve Body

1/4-in.
P.T.
Control
(3)

Kit Contents, Bendix Part Number 281138
Item No.

13

Piston
Piston
Springs
7

Cover
Plate
11

Retaining
Ring
Slotted
Screw

Washer

15

Figure 1 – Maintenance Kit Contents

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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 ▲ Never connect or disconnect a hose or line
containing pressure; it may whip and/or cause
parking brakes, and always block the wheels.
hazardous airborne dust and dirt particles. Wear
Always wear personal protection equipment.
eye protection. Slowly open connections with
▲ Stop the engine and remove the ignition key
care, and verify that no pressure is present. Never
when working under or around the vehicle.
remove a component or plug unless you are
When working in the engine compartment,
certain all system pressure has been depleted.
the engine should be shut off and the ignition
key should be removed. Where circumstances ▲ Use only genuine Bendix ® brand replacement
parts, components, and kits. Replacement
require that the engine be in operation, EXTREME
hardware, tubing, hose, fittings, wiring, etc.
CAUTION should be used to prevent personal
must be of equivalent size, type, and strength as
injury resulting from contact with moving,
original equipment and be designed specifically
rotating, leaking, heated, or electrically charged
for such applications and systems.
components.
▲ Do not attempt to install, remove, disassemble, ▲ Components with stripped threads or damaged
parts should be replaced rather than repaired.
or assemble a component until you have read,
Do not attempt repairs requiring machining or
and thoroughly understand, the recommended
welding unless specifically stated and approved
procedures. Use only the proper tools and
by the vehicle and component manufacturer.
observe all precautions pertaining to use of those
tools.
▲ Prior to returning the vehicle to service, make
certain all components and systems are restored
▲ If the work is being performed on the vehicle’s
to their proper operating condition.
air brake system, or any auxiliary pressurized air
systems, make certain to drain the air pressure ▲ For vehicles with Automatic Traction Control
from all reservoirs before beginning ANY work
(ATC), the ATC function must be disabled (ATC
on the vehicle. If the vehicle is equipped with
indicator lamp should be ON) prior to performing
®
®
®
a Bendix AD-IS air dryer system, a Bendix
any vehicle maintenance where one or more
DRM™ dryer reservoir module, a Bendix® AD-9si®,
wheels on a drive axle are lifted off the ground
AD-HF®, or AD-HFi® air dryer, be sure to drain the
and moving.
purge reservoir.
▲ The power MUST be temporarily disconnected
▲ F o l l o w i n g t h e v e h i c l e m a n u f a c t u r e r ’s
from the radar sensor whenever any tests USING
recommended procedures, deactivate the
A DYNAMOMETER are conducted on a vehicle
electrical system in a manner that safely removes
equipped with a Bendix® Wingman® system.
all electrical power from the vehicle.
▲ Never exceed manufacturer’s recommended
pressures.
▲ 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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REMOVAL

OPERATING AND LEAKAGE TESTS

1. Block and hold the vehicle on a level surface by means
other than the air brakes.
2. Drain the air pressure from all reservoirs.
3. Mark the air lines and their connections to the Bendix®
TR-2™ valve and disconnect them.
4. Loosen and remove the mounting nut and washer.

It is recommended that the operating and leakage tests be
performed prior to installation on the vehicle.
1. Connect a 120 psi air source to the supply port and
one of the three control ports. (The other control ports
should be plugged.) An accurate test gauge should be
teed into each air line and a means of controlling the
air pressure provided. A small volume with a gauge
should be connected to one of the two delivery ports.
The other delivery port should be plugged.
2. With 120 psi supply pressure and 0 psi at the control
port, the gauge at the delivery port should read 120 psi
also. Leakage at the exhaust port and at the control
port should not exceed a 1-in. bubble in five seconds.
No leakage is permitted around the cap nut.
3. Slowly increase air pressure to the control port. When
the air pressure at the control port reaches 80 psi, the
air pressure at the delivery port should exhaust to 0
psi. Leakage at the exhaust port should not exceed a
1-in. bubble in five seconds.
4. When air pressure is exhausted from the control port,
120 psi should register on the gauge at the delivery port.

DISASSEMBLY

1. Remove the cap nut and remove and discard the
sealing ring (1).
2. Remove and retain the valve spring.
3. Remove and discard the inlet and exhaust valve (3).
4. Remove and retain the slotted screw and washer.
5. Remove and discard the exhaust diaphragm (11).
6. While applying pressure to the cover plate, remove the
retaining ring and slowly allow the piston springs to relax.
NOTE: Caution should be used in removing the retaining
ring since the piston springs exert a force which must be
relaxed.
7. Remove and retain the cover plate and both piston
springs.
8. Remove the piston from the valve body.
9. Remove the o-rings (7 and 13) from the piston.

INSTALLATION

1. Mount the TR-2 using the lock washer and mounting nut.
2. Reconnect the air lines to the proper parts of the TR-2
valve as marked during their removal.

ASSEMBLY

Prior to assembly, lubricate the o-rings and bearing
surfaces with silicone lubricant (15), Bendix Part Number
291126.
1. Install the sealing ring (1) on the cap nut.
2. Install the o-rings (13 and 7) on the piston.
3. Install the inlet and exhaust valve (3) and the valve
spring in the valve body.
4. Install the cap nut in the valve body and torque to
75-175 in-lbs (8-20 N•m).
5. Install the piston in the valve body.
6. Install the inner and outer piston springs in the piston.
7. Install the flat side of cover plate against the springs
and using thumb pressure, push the cover plate into the
valve body. See the cautionary note in Disassembly,
Step 6.
8. Install the retaining ring, making certain it is well seated
in its groove in the valve body before releasing the thumb
pressure.
9. Install the diaphragm (11) and washer and secure with
the screw. Torque the screw to 15-25 in-lbs (2-3 N•m).

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owned by, or licensed to, Bendix Commercial Vehicle Systems LLC.

S-0268 Rev 002 © 6/2025 Bendix Commercial Vehicle Systems LLC, a member of Knorr-Bremse • All Rights Reserved

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