Bendix® GSAT® (Global Scalable Air Treatment) Core Module Park Brake
Silencer Kit for Daimler® Truck North America (DTNA)
KIT COMPONENTS
See Figure 1. The following components are in the Bendix®
GSAT® (Global Scalable Air Treatment) core module park
brake silencer kit for Daimler® Truck North America (DTNA):
Item No.

Component

Quantity

1

Silencer Cover

1

2

Silencer Mesh

1

Bendix Kit Part Number: K279102K57

NOTE: If two (2) core module park brake silencers are to
be replaced, (for example, replacing both silencers on a
towing vehicles), two (2) silencer kits will be required.

NOTE: Image shown with core module removed from vehicle. For
most vehicles, it is not necessary to remove the core module in order
to replace the silencer.
Figure 1 – GSAT Core Module Park Brake Silencer Kit

VEHICLE PREPARATION
1. Park the vehicle on a level surface and chock the wheels.
2. Turn the ignition switch OFF.
3. Drain all reservoirs to 0 psi (0 kpa).
4. Clean the exterior of the air dryer body, cartridge, core
module, and core module silencer(s) to remove any
dirt and debris.

Always depressurize the air dryer and all other
reservoirs on the vehicle to 0 psi (0 kpa) before servicing
the air dryer. Failure to drain the air pressure from the
air dryers and all other reservoirs may result in property
damage, serious injuries, and/or death.

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, a Bendix ® AD-9si ®, AD-HF®,
or AD-HFi ® 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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DISASSEMBLY

ASSEMBLY

1. To service the silencers, first remove the silencer cover by
bending the locking tab outward, away from the air dryer
housing, and rotate the cover ¼ turn in a counterclockwise
direction. Remove the silencer cover by pulling it away
from the core module. Discard the cover. See Figure 2.

1. Place the bound mesh material into the exhaust cavity
of the core module, ensuring it is fully seated.

2. With the cover removed, the mesh material can be
removed by firmly gripping and pulling the material out
of the core module exhaust cavity. Discard the mesh
material.
3. Clean the surface area of the park brake exhaust cavity
with a clean cloth. Be careful not to allow dirt or other
contaminants to fall into the exhaust cavity.

2. To install the exhaust cover, align the locking tabs with
the core module housing backer plate slots. Push the
locking tabs inward, towards the core module and rotate
¼ turn clockwise until the locking tab engages.
3. Before placing the vehicle back into service, perform the
Operational Test.

OPERATIONAL TEST
Before placing the vehicle in service, perform the following
tests.
1. Close all of the reservoir drain cocks.

Figure 2 – Locking Tab Location

Cleaning and Inspection
1. Using a clean rag, wipe the core module silencer body
bores clean, taking care to not knock contamination into
the bores.
2. Inspect for physical damage to the core module and take
note of broken or missing parts.
3. Inspect the visible parts of the core module for severe
corrosion, pitting, and cracks. Superficial corrosion
and/or pitting on the exterior portion is acceptable.
4. Inspect the silencer bores for deep scuffing, gouges,
nicks, or damage that would prevent proper operation.
NOTE: If any of the conditions in Steps 2 to 4 are noted, repair
the damage if possible. If the damage cannot be repaired,
replace the GSAT Core Module. Refer to S-1707, Bendix®
GSAT® (Global Scalable Air Treatment) Core Module Kit for
Daimler® Trucks North America (DTNA), on B2Bendix.com.
5. Inspect all air line fittings for damage or corrosion.
Clean, repair, or replace corroded or damaged fittings
as necessary.

IMPORTANT
Failure to maintain and replace corroded fittings may
result in poor vehicle performance and may be a violation
of commercial vehicle regulations.
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2. Start the vehicle. With the engine at 1800 rpm, build
up system pressure to system cutout while observing
that both service reservoir dash gauges show a rise in
pressure from 0 psi (0 kpa) to system cutout. If either
gauge fails to display this condition, stop testing and
check the installation. Note that the GSAT system
regenerates/purges with an audible escape of air
when system cutout pressure is reached. Refer to
SD-24-250D, Bendix® GSAT® (Global Scalable Air
Treatment) System for Daimler® Truck North America
(DTNA), on B2Bendix.com for more information on
troubleshooting a GSAT system.
NOTE: The service reservoir pressures will drop slightly
during regeneration/purge.
3. Fan down the service brakes by repeatedly pressing
and releasing the service brakes to reduce system air
pressure to system cut-in. Note that the system – once
again – builds to full system pressure and is followed
by a regeneration/purge event at the GSAT air dryer
primary exhaust.
4. To verify proper park brake function, use the Hand Control
Unit (HCU) to release and apply the tractor park brakes
several times. The HCU and/or dash cluster should
illuminate, indicating a proper park state. Refer to the
applicable Operator's Manual for HCU statuses.
5. It is recommended that the following items be tested for
leakage to ensure the GSAT will not cycle excessively:
a. A
ir brake system (Refer to the Bendix® Air Brake
Handbook, BW5057, on B2Bendix.com)
b. Compressor unloader mechanism
c. GSAT core module pneumatic connections
d. D
rain cock and safety valve in first (supply) reservoir
(if equipped)
e. A
ll air connections leading to and from the first
(supply) reservoir (if equipped)

TECHNICAL ASSISTANCE
For additional assistance, the Bendix Tech Team can
be reached by email at [email protected] or by
phone at 1-800-AIR-BRAKE (1-800-247-2725), option 2.
Representatives are available Monday through Thursday,
8:00 a.m. – 6:00 p.m., and Friday, 8:00 a.m. – 5:00 p.m. ET.

24/7/365 ACCESS
FULL SERVICE AT YOUR FINGERTIPS

1-800-AIR-BRAKE (1-800-247-2725)
[email protected]

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identification and cross reference purposes. The trademarks are the property of their respective companies.
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are United States trademarks owned by, or licensed to, Bendix Commercial Vehicle Systems LLC.

S-1702 Rev 000 © 4/2025 Bendix Commercial Vehicle Systems LLC, a member of Knorr-Bremse • All Rights Reserved

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