Bendix Sd 01 3131 Users Manual

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SD-01-3131

®

BENDIX® 720CC TWIN CYLINDER COMPRESSOR FOR
INTERNATIONAL® MAXXFORCE® BIG BORE ENGINES
Cylinder
Head

Safety
Valve

Cooling
Plate
Valve Plate
Assembly
Crankcase
Right Side
View

Mounting
Face

Rear
Flange

Locating
Pins

FIGURE 1 - BENDIX® 720CC TWIN CYLINDER COMPRESSOR

PRODUCT
This Bendix® 720cc twin cylinder compressor is a “discharge
line unloader” DLU-style compressor. The compressor
pumps continuously, unlike some compressor designs
which use an "unloader" mechanism in the compressor
head to switch from a pumping mode to a non-pumping
mode. With a DLU-style compressor, the control of air
delivery to the vehicle’s air system is managed by using a
separate discharge line unloader valve mounted in parallel
with a turbo cut-off-style air dryer (see Figure 6).

DESCRIPTION
The function of the air compressor is to provide and
maintain air, under pressure, to operate devices in air brake
systems. The Bendix 720cc compressor is a twin cylinder
reciprocating compressor with a rated displacement of 31.6
cubic feet per minute at 1250 RPM.
The compressor consists of an integral water-cooled
cylinder head assembly and water-cooled crankcase.

The cylinder head assembly is made up of an aluminum
cylinder head, an aluminum cooling plate, and a cast
iron valve plate assembly. It uses two sealing gaskets.
The cylinder head contains air and water ports. A cooling
plate is located between the cylinder head and valve plate
assemblies and assists in cooling.
The valve plate assembly consists of brazed cast iron
plates which have valve openings and passages for air and
engine coolant to flow into, and out of, the cylinder head and
crankcase water jacket. The compressor discharge valves
720cc COMPRESSOR
BENDIX
P/N

B

A

NAV
B
P/N
BENDIX PRODUCT - ASSY IN FRANCE

C

A

Bendix Part Number .  .  .  .  .  .  .A
Customer Part Number .  .  .  .  . B
Compressor Serial Number  .  . C
FIGURE 2 - NAMEPLATES
MAXXFORCE® is a trademark of International Engine Intellectual Property Company, LLC.

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.
▲ 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
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. 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, 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 Bendix®
Wingman® Advanced™-equipped vehicle.

▲ You should consult the vehicle manufacturer's operating and service manuals, and any related literature,
in conjunction with the Guidelines above.

2

Compressor to
engine block
mounting face

Oil drain locations

Safety
Valve
Cylinder
Head
Cooling
Plate

Piston

Valve Plate
Assembly

Mounting
Face

Nameplate

Crankcase

Connecting
Rod
Crankshaft

Drive Gear

FIGURE 3 - BENDIX® 720CC TWIN CYLINDER COMPRESSOR

are part of the valve plate assembly. The inlet reed valve/
gasket is installed between the valve plate assembly and
the top of the crankcase.
The cast iron crankcase has a water jacket to assist in the
cooling of the cylinder bore. The crankcase has an open
side with a machined face and locating pins. This open face
is bolted directly to the side of the engine block. Refer to
Figure 3.
The compressor gear engages the engine drive gear.
In addition, the crankcase houses the piston assembly,
connecting rod, crankshaft and related bearings. O-rings
are located in the countersunk holes (one each side) on
the crankcase deck to prevent coolant leakage between
the crankcase and valve plate coolant passage.

The Bendix® 720cc compressor is equipped with a safety
valve to protect the compressor head in the event of, for
example, a discharge line blockage downstream of the
compressor. Excessive air pressure will cause the safety
valve to unseat, release air pressure, and give an audible
alert to the operator. The safety valve is installed in the
cylinder head safety valve port, directly connected to the
cylinder head discharge port.
A nameplate is attached to a flat cast face on the side of
the crankcase. It is stamped with information identifying the
compressor model, customer piece number, compressor
assembly part number and serial number. See Figure 2.

3

Air
Discharge
Port

Air Inlet
Port

Discharge
Valve
Closed

Air
Discharge
Port

Cooling
Plate

Air Inlet
Port

Discharge
Valve
Open

Cooling
Plate
Valve
Plate

Valve
Plate

Inlet
Valve
Closed
Inlet
Valve
Open
Piston Moving Down
Piston Moving Up
FIGURE 4 - OPERATION - INTAKE

FIGURE 5 - OPERATION - COMPRESSION

OPERATION

AIR COMPRESSION (LOADED)

The compressor is driven by the vehicle's engine, and
functions continuously while the engine is in operation.
Actual compression of air is controlled by a downstream
component ­– like a discharge line unloader valve, or an air
dryer without turbo cut-off valve – operating in conjunction
RES
with a governor.

When the piston reaches the bottom of the stroke, (a
position known as Bottom Dead Center, or BDC), the inlet
reed valve closes. Air above the piston is trapped by the
closed inlet reed valve and is compressed as the piston
moves upwards. When air in the cylinder bore reaches
a pressure greater than that of the system pressure, the
discharge reed valves open and allow air to flow into the
discharge line and air brake system. See Figure 5.

C

AIR INTAKE (LOADED)

UNL

S

Just as the piston begins the down stroke, (a position known
UNL
as Top Dead Center, or
D TDC), the vacuum created in the
cylinder bore above the piston causes the inlet reed valve to
flex open. Atmospheric air flows through the open inlet valve
and fills the cylinder bore above the piston. See Figure 4.

DLU Valve

S
D

Air Dryer

C
S
UNL

D

S
21

Governor
Compressor

22

Front Service
Reservoir

Rear Service
Reservoir

FIGURE 6 - TYPICAL BENDIX® 720CC (DLU-STYLE) TWIN CYLINDER COMPRESSOR AIR CHARGING SYSTEM
4

Inlet
Port

Discharge Port

Coolant Port
(In or Out)

Head
Bolt (8)

Safety
Valve Port

Coolant Port
(In or Out)
CYLINDER HEAD PORT IDENTIFICATION
The cylinder head connection ports are
identified with “cast in” numerals as follows:
AIR IN .  .  .  .  .  .  .  .  .  .  .  .  .  .0
Compressed AIR OUT  .  .  .  .  . 2
Coolant IN  .  .  .  .  .  .  .  .  .  .  . 9
Coolant OUT  .  .  .  .  .  .  .  .  .  . 9

Oil
Supply

FIGURE 7 - BENDIX® 720CC TWIN CYLINDER COMPRESSOR PORT IDENTIFICATION

NON-COMPRESSION OF AIR (UNLOADED)

LUBRICATION

COMPRESSOR AND AIR DRYER SYSTEM
(REFER TO FIGURE 6)

The vehicle's engine provides a continuous supply of oil
to the compressor. Oil is routed from the engine to the
compressor's oil inlet. Note: There is no external oil supply
line; the oil delivery is located at the engine to compressor
mounting face. (See Figure 7.) This pressurized oil flows
to the precision front sleeve main bearing, and — via an oil
passage in the crankshaft — routes pressurized oil to the
connecting rod bearings and the rear journal associated
with the end cover. Spray lubrication of the cylinder bore
and connecting rod wrist pin bushing is obtained as oil is
forced out around the crankshaft journals by engine oil
pressure. Oil then falls to the bottom of the compressor
crankcase and is returned to the engine through the
opening at the compressor mounting flange.

Air delivery to the vehicle’s air system is controlled either
by the governor and the air dryer, or with a separate
discharge line unloader valve. The governor is plumbed
to the component (e.g. air dryer or DLU valve) in order to
control when the air is delivered to the vehicles air system.
When air pressure in the supply reservoir reaches the cutout setting of the governor, the governor delivers system air
to the discharge line unloader style (DLU) air dryer’s control
port. This allows the discharge air from the compressor to
flow out the exhaust port of the air dryer.
Note: The Bendix® 720cc compressor is a discharge
line unloader-style (DLU-style) unit. This means that the
compressor functions in a continuous pumping mode;
regardless of whether the brake system requires air. It
requires a downstream device (e.g. turbo cut-off-style air
dryer and discharge line unloader valve) to unload the
system when air requirements have been met as described
in the previous paragraph.

COOLING
The Bendix 720cc twin cylinder compressor is cooled both
by air flowing through the engine compartment as it passes
the compressor's cast-in cooling fins, and by the flow of
engine coolant through the cylinder head assembly and
the water jacket around the cylinder bore of the crankcase.
Coolant supplied by the engine cooling system passes
through connecting lines into the cylinder head, cooling
plate, valve plate assembly, and into the crankcase water
jacket. It returns through the same components — out of
the coolant outlet port of the cylinder head — and returns
to the engine. Figure 7 illustrates the approved coolant
flow connections. Proper cooling is important in minimizing
discharge air temperatures – see the tabulated technical
data on page 13 of this manual for specific requirements.

5

AIR INDUCTION

LUBRICATION INSPECTION

The Bendix 720cc twin cylinder compressor is only
permitted to be naturally aspirated – use of an engine
turbocharger as an air source is not allowed.

The compressor utilizes an internal oil feed design. Check
the exterior of the compressor (e.g. around the mounting
face) for the presence of oil seepage, and refer to the
troubleshooting section for appropriate tests and corrective
action. Refer to the tabulated technical data in the back of
this manual for oil pressure minimum values.

®

PREVENTIVE MAINTENANCE
Regularly scheduled maintenance is the single most
important factor in maintaining the air brake charging
system. Refer to Table A: Maintenance Schedule and
Usage Guidelines in the troubleshooting section (page
A-3) for a guide to various considerations that must be
given to maintenance of the compressor and other related
charging system components.
Important Note: Review the Bendix Warranty Policy
before performing any intrusive maintenance procedures.
An extended warranty may be voided if intrusive
maintenance is performed during this period.

EVERY 6 MONTHS, 1800 OPERATING HOURS,
OR AFTER EACH 50,000 MILES — WHICHEVER
OCCURS FIRST — PERFORM THE FOLLOWING
INSPECTIONS AND TESTS.
AIR INDUCTION INSPECTION	
A supply of clean air is one of the single most important
factors in compressor preventive maintenance. Since
the air supply for the 720cc twin cylinder compressor and
engine is the engine air cleaner, periodic maintenance of
the engine air filter is necessary.
Inspect the compressor air induction system each time
engine air cleaner maintenance is performed.
1. 	Inspect the intake hose adapters for physical damage.
Make certain to check the adapters at both ends of the
intake hose or tubing.
2. 	Inspect the intake hose clamps and tighten them if
needed.
3.	 Inspect the intake hose or line for signs of drying,
cracking, chafing and ruptures and replace if necessary.
4. 	Inspect the compressor’s cast inlet tube for physical
damage.

COMPRESSOR COOLING INSPECTION
Inspect the compressor discharge port, inlet cavity and
discharge line for evidence of restrictions and carbon
buildup. If more than 1/16" of carbon is found, thoroughly
clean or replace the affected parts. In some case, carbon
buildup indicates inadequate cooling. Closely inspect the
compressor cooling system. Check all compressor coolant
lines for kinks and restrictions to flow. Minimum coolant line
size is 3/8" Inside Diameter (I.D.) Check coolant lines for
internal clogging from rust scale. If coolant lines appear
suspicious, check the coolant flow and compare to the
tabulated technical data present in the back of this manual.
6

OIL PASSING INSPECTION
All reciprocating compressors pass a minimal amount of
oil. Air dyers will remove the majority of oil before it can
enter the air brake system. For particularly oil sensitive
systems, the Bendix® PuraGuard® system can be used in
conjunction with a Bendix® air dryer.
If compressor oil passing is suspected, refer to the
troubleshooting section (starting on page A-1) for the
symptoms and corrective action to be taken. In addition,
Bendix has developed the “Bendix® Air System Inspection
Cup” — or Bendix® BASIC™ kit — to help substantiate
suspected excessive oil passing. The steps to be followed
when using the BASIC kit are presented in APPENDIX B.

COMPRESSOR DRIVE INSPECTION
Check for noisy compressor operation, which could indicate
excessive drive component wear. Adjust and/or replace
as necessary. Check all compressor mounting bolts and
retighten evenly if necessary. Check for leakage. Repair
or replace parts as necessary.

CHARGING SYSTEM UNLOADING & GOVERNOR
TEST
Note: The Bendix 720cc DLU-style twin cylinder
compressor does not contain components to unload
the compressor. Therefore, the compressor pumps
continuously. In most systems that utilize an air dryer, the
governor and DLU-style air dryer are used to unload the
system (e.g. air is not being delivered to the brake system
reservoirs). When system unloading occurs, air from the
compressor will typically flow out the exhaust port of the
air dryer. Refer to Figure 6.
Test and inspect the unloading system (e.g. air dryer and
governor) for proper operation and pressure settings.

1. 	 Make certain the unloader system lines (illustrated in
Figure 6) are connected and leak free.
2.	 Cycle the charging system between the loaded and
unloaded mode several times. This can be achieved by
applying the brakes to bleed down the system pressure.
Make certain that the governor cuts-in (charging
system resumes compressing air) at a minimum of
105 psi. Governor cut-out (charging system stops
delivering air to the brake system reservoirs) should be
approximately 15 - 20 psi greater than cut-in pressure.
Adjust or replace the governor as required.

3. 	 Note that the charging system cycles to the loaded and
unloaded conditions promptly. If prompt action is not
noted, repair or replace the governor and/or repair the
air dryer purge valve assembly.

IMPORTANT NOTE
Replacement air governors must have a minimum cut-in
pressure of 100 psi. The cut-in pressure is the lowest system
pressure registered in the gauges before the compressor
resumes compressing air.

SERVICE TESTS
GENERAL
The compressor operating and leakage tests listed below
need not be performed on a regular basis. These tests
should be performed when it is suspected that leakage is
substantially affecting compressor build-up performance, or
when it is suspected that the charging system is “cycling”
between the loaded (pumping) and unloaded (charging
system stops delivering air to the brake system reservoirs)
modes due to unloader system leakage.

IN SERVICE OPERATING TESTS
Compressor Performance: Build-up Test
This test is performed with the vehicle parked and the
engine operating at maximum recommended governed
speed. Fully charge the air system to governor cut-out (air
dryer purges). Pump the service brake pedal to lower the
system air pressure below 80 psi using the dash gauges.
As the air pressure builds back up, measure the time from
when the dash gauge passes 85 psi to the time it passes
100 psi. The time should not exceed 40 seconds. If the
vehicle exceeds 40 seconds, test for (and fix) any air leaks
and then re-test the compressor performance. If the vehicle
does not pass the test the second time, use the Advanced
Troubleshooting Guide for Air Brake Compressors, starting
on page A-1 of this document, to assist your investigation
of the cause(s).
Note: All new vehicles are certified using the FMVSS
121 test (paragraph S5.1.1) by the vehicle manufacturer,
however the above test is a useful guide for in-service
vehicles.

Optional Comparative Performance Check
It may be useful to also conduct the above test with the
engine running at high idle (instead of maximum governed
speed), and record the time required to raise the system
pressure a selected range (for example: from 90 to 120 psi,
or from 100 to 120 psi, etc.) in the vehicle’s maintenance
files. Subsequent build-up times throughout the vehicle’s
service life can then be compared to the first one recorded.
(Note: the 40 second guide in the test above does not
apply to this build-up time.) If the performance degrades
significantly over time, use the Advanced Troubleshooting
Guide for Air Brake Compressors, starting on page A-1 of
this document, to assist investigation of the cause(s).
Note: When comparing build-up times, be sure to make
an allowance for any air system modifications which would
cause longer times, such as adding air components or
reservoirs. Always check for air system leakage.

LEAKAGE TESTS
See the standard Air Brake System and Accessory Leakage
test on Page A-14, Test 2.
Note: Leakage in the air supply system (components
before the supply reservoir - such as the governor, air dryer,
reservoir drain cocks, safety valve, and check valves) will
not be registered on the vehicle dash gauges and must
be tested separately. Refer to the various maintenance
manuals for individual component leakage tests and the
Bendix “Test and Checklist” published in the Bendix Air
Brake System Handbook (BW5057) and on the back of
the Bendix Dual Circuit Brake System Troubleshooting
Card (BW1396).

CYLINDER HEAD
Check the cylinder head gaskets for air leakage.

1. 	 With the engine running, lower the air system pressure
to 60 psi and apply a soap solution around the cylinder
head. Check the gaskets between the cylinder head
and the valve plate assembly, as well as the inlet reed
valve/gasket between the valve plate assembly and
crankcase for air leakage.
2. 	 No leakage is permitted. If leakage is detected, replace
the compressor or repair the cylinder head using the
maintenance kit available from an authorized Bendix
parts outlet.

7

INLET & DISCHARGE VALVES
In order to test the inlet and discharge valves, it is necessary
to have shop air pressure and an assortment of fittings. A
soap solution is also required.

1. 	 With the engine shut off, drain ALL air pressure from the
vehicle.
2. 	 Disconnect the inlet and discharge lines.
3. 	 Apply 120-130 psi shop air pressure to the discharge port
and then apply and release air pressure to the inlet port.
Soap the inlet port and note that leakage at the inlet port
does not exceed 200 sccm.
If excessive leakage is noted in Test 3, replace or repair
the compressor using genuine Bendix® replacements or
maintenance kits available from any authorized Bendix parts
outlet.
While it is possible to test for inlet and discharge leakage, it
may not be practical to do so. Inlet and discharge valve leakage
can generally be detected by longer compressor build-up and
recovery times. Compare current compressor build-up times
with the last several recorded times. Make certain to test for
air system leakage, as described under “In-Service Operating
Tests”, before making a determination that performance has
been lost.

COMPRESSOR REMOVAL & DISASSEMBLY
GENERAL
The following disassembly and assembly procedure is
presented for reference purposes and pre-supposes that
a rebuild or repair of the compressor is being undertaken.
Several maintenance kits are available and the instructions
provided with these parts and kits should be followed in lieu
of the instructions presented here.

MAINTENANCE KITS & SERVICE PARTS
BENDIX® 720CC TWIN CYLINDER COMPRESSOR
Compressor Seal Kit (Major)  .  .  .  .  .  .  .  .  .  .  . K026808
Compressor Seal Kit (Minor)  .  .  .  .  .  .  .  .  .  .  . K051352
Discharge Safety Valve Kit  .  .  .  .  .  .  .  .  .  .  .  . K026809
Compressor to Engine 	
Supplied by the
Mounting Face Sealant  .  .  .  .  .  .  .  . engine manufacturer

REMOVAL
In many instances it may not be necessary to remove the
compressor from the vehicle when installing the various
maintenance kits and service parts. The maintenance
technician must assess the installation and determine the
correct course of action. These instructions are general
and are intended to be a guide. In some cases additional
preparations and precautions are necessary. In all cases follow
8

the instructions contained in the vehicle maintenance
manual in lieu of the instructions, precautions and
procedures presented in this manual.

1. 	Block the wheels of the vehicle and drain the air
pressure from all the reservoirs in the system.
2. 	Drain the engine cooling system and the cylinder
head of the compressor. Identify and disconnect all
air, water and oil lines leading to the compressor.
3. 	Remove as much road dirt and grease from the
exterior of the compressor as possible.
4. 	 Remove the discharge fitting, if applicable, and note
their position on the compressor to aid in reassembly.
5. 	Remove any supporting bracketing attached to
the compressor and note their positions on the
compressor to aid in reassembly.
6. 	Remove the six mounting bolts that retain the
compressor to the side of the engine block. Note
the position of the six mounting bolts. Two of the six
bolts are shorter and must be installed in their original
locations. Remove the compressor from the vehicle.
7. 	Inspect drive gear and associated drive parts for
visible wear or damage. If the compressor drive
gear is worn or damaged, the compressor must be
replaced. Refer to the engine manufacturer's service
manual to address the associated engine drive parts.
8. 	 If the compressor is being replaced, stop here and
proceed to “Installing the Compressor” at the end
of the assembly procedure. (Note: Replacement
compressors come with the drive gear preassembled on the compressor.)

PREPARATION FOR DISASSEMBLY
Place a clean rag over the openings that expose the
gear and crankshaft / connecting rod assembly. Refer
to Figure 3. No contamination is permitted in these
areas.
Remove the balance of road dirt and grease from the
exterior of the compressor with a cleaning solvent. If the
rear end cover is being removed from the compressor,
mark it, along with the two cap screws, in relation to
the crankcase. It is also recommended to mark the
relationship of the cylinder head, cooling plate, valve
plate assembly and crankcase.
A convenient method to indicate the above relationships
is to use a metal scribe to mark the parts with numbers or
lines. Do not use marking methods, such as chalk, that
can be wiped off or obliterated during rebuilding.
Prior to disassembly make certain that the appropriate
kits are available. Refer to Figure 8 during the entire
disassembly and assembly procedure. The serviceable
items are identified by "Item" numbers 1 through 11.

3

4
1

2

Cylinder Head

5

Cooling
Plate

6
Valve Plate
Assembly
7

Crankcase
Alignment Pins
(x2) - one at
each end

8
Crankcase

10

9

Cap
Screws
(x2)

Compressor
Drive Gear
Crankcase
Side Cover

End Cover
11

Crankcase Side
Cover Cap
Screws (x6)

Safety Valve Kit Pc. No. K026809 consists of the
following:
Item

1
2

Qty.

Description

1
1

Sealing Ring
Bendix® ST-4™ Safety Valve

Compressor Seal Kit (Minor) Pc. No. K051352
consists of the following:
Item

Qty.

9
10

1
1

Description

Cover
End Cover O-ring

Compressor Seal Kit (Major) Pc. No. K026808
consists of the following:
Item

Qty.

3
4
5

8
2
1

Cap Screws (long)
Cap Screws (short)
Head Gasket

Description

6
7
8
9
10
11

1
1
2
1
1
1

Cooling Plate Gasket
Inlet Reed Valve/Gasket
Crankcase O-ring
Cover
End Cover O-ring
Side Cover Gasket

FIGURE 8 – BENDIX® 720CC TWIN CYLINDER COMPRESSOR EXPLODED VIEW
9

These items are also referenced in the following procedures
and are denoted by the numbers in parenthesis.

CYLINDER HEAD, COOLING PLATE & VALVE
PLATE ASSEMBLY
1. 	 Remove the sealing ring (2) and discharge safety valve
(1) from the compressor cylinder head.
2. 	 Remove the two short hex head screws (4) and eight
long hex head screws (3) from the compressor cylinder
head.
3. 	 Gently tap the cylinder head, cooling plate and valve
plate assembly with a soft mallet to break the gasket
seal between the valve plate assembly and the
crankcase. Lift the cylinder head — with cooling plate
and valve plate assembly — off the crankcase.
4. 	 Remove the metal inlet reed valve gasket(7).
5.	 Remove the two crankcase o-rings (8) from the deck
(top) of the crankcase. The o-rings are located in
countersunk holes, one on each side of the cylinder
bores.
6. 	Gently tap the removed cylinder head, cooling plate
and valve plate assembly with a soft mallet to break
the gasket seals. Then separate the cylinder head from
the cooling plate and valve plate assembly and remove
and discard the two head gaskets (5) and (6).

CRANKCASE FRONT COVER
1. 	 Remove the cover (9) from the front of the crankcase.
Use a sharp, flat head screw driver or a scraper. Place
the edge under the lip along the outside diameter of
the cover. Pry the cover from the cast surface until the
cover can be removed. Refer to Figure 10.

CRANKCASE SIDE COVER
1.	 Remove the six cap screws that secure the crankcase
side cover to the crankcase.
2.	 Gently tap the crankcase side cover with a soft mallet
to break the gasket seal between the crankcase side
cover and the crankcase. Remove the crankcase side
cover and the gasket (11).

M10x1.5
Cap
Screws
(Larger)
M8x1.25
Cap
Screws
(Smaller)

FIGURE 9 - REAR END COVER ATTACHMENT BOLTS

2.	 Remove the two end cover cap screws that secure the
rear end cover to the crankcase.
3. 	Remove the rear end cover from the crankcase.
Remove and discard the o-ring (10) from the end cover.

CLEANING OF PARTS
GENERAL
All parts should be cleaned in a good commercial grade of
solvent and dried prior to inspection.

CRANKCASE
1.	 Carefully remove all sealant gasket material adhering
to the machined face of the crankcase. See Figure
3. Make certain not to scratch or mar the mounting
surface. Note: Keep the crankcase opening covered
to prevent any of the sealant material from entering.

REAR END COVER
1. 	Note: There are two cap screws used to retain the
end cover to the crankcase. There a two longer cap
screws (not shown in Figure 9) that are used to retain
the auxiliary drive unit (e.g. hydraulic pump) via the end
cover and torqued into the crankcase. If the auxiliary
drive unit has already been removed, these two cap
screws are no longer present on the end cover. Refer
to Figure 8 to see location of the cap screws in the end
cover.

9

FIGURE 10 - FRONT COVER
10

Repeat this process on the engine mounting face as
well. Follow the instructions contained in the vehicle
maintenance manual in lieu of the instructions and
procedures presented in this manual.
2.	 Carefully remove all gasket material adhering to the
deck (top) of the crankcase. Remove any carbon
deposits from the deck of the crankcase. Make certain
not to scratch or mar the gasket surfaces.

CYLINDER HEAD, COOLING PLATE & VALVE
PLATE ASSEMBLY
1. 	Carefully remove all gasket material adhering to the
cylinder head, cooling plate and valve plate assembly.
Make certain not to scratch or mar the gasket surfaces.
Pay particular attention to the gasket surfaces of the
cylinder head and cooling plate.
2. 	 Remove carbon deposits from the discharge and inlet
cavities of the cylinder head, cooling plate and valve
plate assembly. They must be open and clear in the
components. Make certain not to damage the parts.
3. 	 Remove rust and scale from the cooling cavities and
passages in the cylinder head, cooling plate and valve
plate assembly and use shop air to clear debris from
the passages.
4. 	 Check the threads in all cylinder head ports for galling
(e.g. abrasion, chafing). Minor thread chasing (damage)
is permitted. 	
	

INSPECTION OF PARTS
CYLINDER HEAD, COOLING PLATE AND VALVE
PLATE ASSEMBLY
1. 	Carefully inspect the head gasket surfaces on the
cylinder head for deep gouges and nicks. Also, inspect
the cylinder head for any cracks or port thread damage.
If detected, the compressor must be replaced. If large
amounts of carbon build-up are present in the discharge
cavity, such that it restricts the air flow through the
cylinder head, the compressor should be replaced.
2. 	Carefully inspect both sides of the gasket surfaces
on the cooling plate for deep gouges and nicks.
Also, inspect the cooling plate for any cracks or other
damage. If damage is found, the compressor must be
replaced.
3. 	Carefully inspect the valve plate assembly gasket
surfaces (both sides) for deep gouges and nicks. Pay
particular attention to the gasket surface. An inlet
reed valve gasket (7) is used between the valve plate
assembly and crankcase. These gasket surfaces
must be smooth and free of all but the most minor
scratches. If excessive marring or gouging is detected,
the compressor must be replaced. If large amounts of
carbon build-up are present on the two main surfaces, in

the two discharge valve holes or between the discharge
valve and the discharge seat, the compressor should
be replaced.

REAR END COVER
Check for cracks and external damage. Check the
crankshaft rear bearing diameter in the rear end cover for
excessive wear, flat spots or galling. Check the hydraulic
pump attachment pilot and threaded holes for damage.
Minor thread chasing is permitted, but do not re-cut the
threads. If any of these conditions are found, replace the
compressor.

CRANKCASE
Check the cylinder head gasket surface on the deck (top)
of the crankcase for nicks, gouges, and marring. A metal
gasket is used to seal the cylinder head to the crankcase.
This surface must be smooth and free of all but the most
minor scratching. If excessive marring or gouging is
detected, the compressor must be replaced.
Check the condition of the two countersunk holes on the
deck of the crankcase that retain the o-rings (8) and prevent
coolant leakage between the valve plate assembly and the
crankcase. The surface in contact with the o-ring should be
smooth and free of any scratches and gouges that could
cause leakage around the o-rings.

ASSEMBLY
General Note: All torques specified in this manual are
assembly torques and typically can be expected to fall off
after assembly is accomplished. Do not re-torque after
initial assembly torques fall unless instructed otherwise.
A compiled listing of torque specifications is presented on
page 13.

INCH POUNDS TO FOOT POUNDS
To convert inch pounds (in-lbs) to foot pounds (ft-lbs) of
torque, divide inch-pounds by 12.
Example: 12 in-lbs = 1 ft-lbs
	

12

FOOT POUNDS TO INCH POUNDS
To convert foot pounds to inch pounds of torque, multiply
foot pounds by 12.
Example: 1 ft-lbs x 12 = 12 in-lbs

11

CRANKCASE FRONT COVER
1. 	Position the new cover (9) over the hole in the front
of the crankcase. Using a rubber mallet, drive the
cover into the hole in the front of the crankcase until
the outside diameter of the cover is flush with the cast
surface.

CRANKCASE SIDE COVER
1.	 Position the gasket (11) on the crankcase side cover.
Install the crankcase side cover on the side of the
crankcase using the six (6) cap screws previously
removed. “Snug” all six cap screws then torque to
97–115 in-lbs (11–13 Nm). When torquing the bolts, it is
best to start with the two mid bolts then use a crossing
pattern with the four remaining bolts.

REAR END COVER
1. 	 Install the o-ring (10) on the rear end cover.
2. 	 Orient the rear end cover to the crankcase using the
reference marks made during disassembly. Carefully
install the rear end cover in the crankcase. Make certain
not to damage the crankshaft bearing surface.
3. 	 Install the two end cover cap screws. Refer to Figure
9 to ensure that the two cap screws are installed in
the proper crankcase bolt holes. “Snug” the screws,
then tighten to between 195 and 212 in-lbs (22-24
Nm).

CYLINDER HEAD, COOLING PLATE & VALVE
PLATE ASSEMBLY
1.	 Install the two crankcase o-rings (8) into the countersunk
holes on the deck of the crankcase.
2.	 Note the position of the two protruding crankcase
alignment pins on the deck (top) of the crankcase.
Install the metal inlet reed valve gasket (7) over the
alignment pins on the crankcase; being careful not to
disturb the crankcase o-rings (8).
3. 	Position the valve plate assembly on the crankcase
so that the alignment pins in the crankcase fit into the
corresponding holes in the valve plate assembly.
4. 	Position the embossed metal head gasket (5) over
the alignment bushings protruding from the top of
the cooling plate. Position the embossed metal head
gasket (6) over the alignment bushings on the opposite
side of the cooling plate. When properly positioned, the
outline of the two embossed gaskets match the outline
of the cooling plate, and the machined sealing surfaces
on the cooling plate, will be covered by the embossed
metal gasket material. Important: The two gaskets are
different and must be installed on the proper side of the
cooling plate for the compressor to function properly.
See Figure 8 for proper head gasket positions.

12

5. 	Install the cooling plate with the pre-installed head
gaskets (5 and 6) onto the valve plate assembly.
Align the alignment bushings on the cooling plate over
the oversized countersunk holes of the valve plate
assembly. Again, when properly installed, the outline of
the cooling plate matches the outline of the valve plate
assembly.
6. 	 Position and install the cylinder head over the alignment
bushings protruding from the cooling plate. When
properly installed, the outline of the cylinder head
assembly will match the outline of the cooling plate and
valve plate assembly.
	

Note: To assist with correct installation, the alignment
bushings in the cooling plate only fit into two of the four
corner head bolt holes on the valve plate assembly and
the cylinder head.

7.	 Install the eight long hex head cap screws (3) into the
cylinder head. Note: A light film of oil should be
applied to the threads of these cap screws prior to
installing. Oil should not be applied to any of the
other hardware.
8.	 Install the two short hex head cap screws (4) into the
cylinder head. Important: The two short hex head
cap screws (4) must be installed in hole positions
designated as sequence “3” and “8” in Figure 11.
9. 	 To ensure the cylinder head cap screws are properly
torqued, the following three step procedure must be
adhered to. Each cap screw must be tightened a total
of three times. Referencing Figure 11, tighten each
screw—in numerical order—to the torque identified in
Step 1. Once all have been tightened follow the same
procedure for Steps 2 and 3.
10.	Install the washer (1) and safety valve (2) in the side
(discharge) port identified by the number '2' on the
cylinder head (3) as shown in Figure 11, then tighten
to a torque not to exceed 66 foot pounds (90 Nm).

INSTALLING THE COMPRESSOR
1. 	Apply a liquid gasket sealant to the compressor /
engine mounting interface (Refer to Figure 3 for
compressor mounting face). Follow the “engine or
vehicle manufacturer's guidelines for the proper liquid
gasket sealant material and application procedure.
2.	 Secure the compressor on the engine mounting
interface using the six mounting bolts. NOTE: There
are two short bolts and four long bolts. Be sure to use
the proper length bolt for the crankcase bolt holes. Run
each of the bolts down finger tight, making sure not to
smear the liquid gasket material on the sealing surface.
Once the bolts are all finger tight, tighten the mounting
bolts per the engine manufacturer's recommended
torquing sequence and torque requirements.

3. 	 Install any supporting brackets on the compressor in
the same position(s) noted and marked during removal.

4

1

4. 	 Inspect all air and coolant lines and fittings before
reconnecting them to the compressor. Make certain
o-ring seals are in good or new condition, the threads
are clean, and the fittings are free of corrosion. Replace
as necessary.

5

3

9
8

5. 	 Install the discharge and coolant fittings, if applicable, in
the same position on the compressor noted and marked
during disassembly. See the Torque Specifications for
various fitting sizes and types of thread at the rear of
this manual. Tighten all hose clamps.
6. 	Before returning the vehicle to service, perform
the Operation and Leakage Tests specified in this
manual. Pay particular attention to all lines and hoses
disconnected during the maintenance and check for air,
oil, and coolant leaks at compressor connections and
the compressor engine interface. Also check for noisy
operation.

BENDIX® 720CC TWIN CYLINDER
COMPRESSOR SPECIFICATIONS

2

6

7

10

Sequence - Numerical order 1 through 10
Step

Torque (in-lbs)

Torque (Nm)

1

177

20

2

221

25

3

221 + 180° turn

25 + 180° turn

FIGURE 11 - CYLINDER HEAD BOLT TORQUE SEQUENCE

Typical weight........................................ 67 lbs. (30.5 kg.)
Number of cylinders ....................................................... 2
Bore Diameter ..................................... 3.622 in. (92 mm)

TORQUE SPECIFICATIONS

Stroke .................................................. 2.126 in. (54 mm)

Assembly Torques

Calculated displacement at 1250 RPM ............. 31.6 CFM

M8 x 1.25-6g Cylinder Head Bolts... 221 in-lbs + 180° turn
(25 Nm + 180° turn)

Flow Capacity @ 1800 RPM & 120 psi ........... 30.3 CFM
Flow Capacity @ 3000 RPM & 120 psi ............. 45.3 CFM
Approximate horsepower required:
Loaded 1800 RPM at 120 psig .......................... 9.1 hp	
Loaded 1800 RPM at 0 psig (DLU) .................. 4.4 hp	
Minimum coolant flow
at maximum RPM ........................ 2.64 GPM (10 LPM)
Maximum coolant temperature...................... 203°F (95°C)
Maximum inlet air temperature .................... 122°F (50°C)
Maximum system pressure......................................150 psi
Minimum oil pressure required ................................ 10 psi

M10 x 1.5 End Cover Bolts..........................195–213 in-lbs
(22 – 24 Nm)
M6 x 1 Crankcase Side Cover Bolts..............97–115 in-lbs
(11–13 Nm)
M26 x 1.5 Safety Valve ................................... 59–66 ft-lbs
(80–90 Nm)
M26 x 1.5 Discharge Port Fittings......................... 66 ft-lbs
(90 Nm) Maximum
M16 x 1.5-6H Water Port Fittings...................... 33.2 ft-lbs
(45 Nm) Maximum

13

Notes

14

Appendix A
Advanced Troubleshooting Guide for Air Brake Compressors
The guide consists of an introduction to air brake charging system components, a table
showing recommended vehicle maintenance schedules, and a troubleshooting symptom
and remedy section with tests to diagnose most charging system problems.

INDEX
	Symptom	

Page Number

Air

	Symptom	

Page Number

Coolant

Air brake charging system:
	 Slow build (9.0)......................................A-9-10
	 Doesn’t build air (10.0).............................. A-11
Air dryer:
	 Doesn’t purge (14.0)................................. A-12
	 Safety valve releases air (12.0)................ A-12
Compressor:
	 Constantly cycles (15.0)........................... A-12
	 Leaks air (16.0)......................................... A-13
	 Safety valve releases air (11.0)................ A-11
	 Noisy (18.0) ............................................. A-13
Reservoir:
	 Safety valve releases air (13.0)................ A-12

Compressor leaks coolant (17.0)....................A-13

Test Procedures

Maintenance & Usage Guidelines

(1) Oil Leakage at Head Gasket ......A-14
(2) System Leakage ........................A-14
(3) Compressor Discharge and
Air Dryer Inlet Temperature............A-15

Engine
Oil consumption (6.0) .......................................A-9
Oil
Oil Test Card results (1.0)..................................A-4
Oil is present:
	 On the outside of the compressor (2.0).......A-5
	 At the air dryer purge/exhaust
		 or surrounding area (3.0).........................A-5	
	 In the supply reservoir (4.0)..................... A-6-8
	 At the valves (5.0)........................................A-8
	 At air dryer cartridge (7.0)............................A-9
	 In the ping tank or compressor
		 discharge aftercooler (8.0).......................A-9

Maintenance Schedule and
Usage Guidelines (Table A)...... A-3

(4) Governor Malfunction .................A-14
(5) Governor Control Line ................A-15
(6) Compressor Unloader ................A-15
BASIC™ Test Information......... A-16-18

A-1

Introduction to the Air Brake Charging System
Powered by the vehicle engine, the air compressor
builds the air pressure for the air brake system. The air
compressor is typically cooled by the engine coolant system
and lubricated by the engine oil supply.
This Bendix ® 720cc compressor is a “discharge line
unloader” (DLU-style) compressor, meaning that the
compressor pumps continuously, unlike some compressor
designs which use an “unloader” mechanism in the
compressor head to switch from a pumping mode to a
non-pumping mode. Instead, the control of air delivery to
the vehicle’s air system is managed by using a separate
discharge line unloader valve mounted in parallel with the
compressor, a turbo cut-off style of the air dryer, and a
governor (see figure below). The discharge line unloader
(DLU) valve and governor control the brake system
air pressure between a preset maximum and minimum
pressure level by monitoring the pressure in the service (or
“supply”) reservoir. When the air pressure becomes greater
than that of the preset “cut-out”, the governor controls the
discharge line unloader valve such that the air from the
compressor flows through the exhaust of the discharge
line unloader valve and to atmosphere (i.e. preventing air
delivery to the reservoirs) and also causes the air dryer to
purge. As the service reservoir air pressure drops to the
“cut-in” setting of the governor, the governor returns the
discharge line unloader valve back to building air mode
and the air dryer to air drying mode.
As the atmospheric air is compressed, all the water vapor
originally in the air is carried along into the air system, as
well as a small amount of the lubricating oil as vapor.
The duty cycle is the ratio of time the compressor
RES
spends building air to the total engine running
time. Air
C
UNL
S
compressors are designed to build air (run “loaded”) up to
25% of the time. Higher duty cycles cause conditions that
affect air brake charging system performance which may
UNL
require additional maintenance.
Factors that add to the
D
duty cycle are: air suspension; additional air accessories;

S

use of an undersized compressor; frequent stops; and
excessive leakage from fittings, connections, lines,
chambers or valves, etc.
The discharge line allows the air, water‑vapor and
oil‑vapor mixture to cool between the compressor and air
dryer. The typical size of a vehicle's discharge line, (see
column 2 of Table A on page A-3) assumes a compressor
with a normal (less than 25%) duty cycle, operating in
a temperate climate. See Bendix and/or other air dryer
manufacturer guidelines as needed.
When the temperature of the compressed air that enters
the air dryer is within the normal range, the air dryer can
remove most of the charging system oil. If the temperature
of the compressed air is above the normal range, oil — as
oil-vapor — is able to pass through the air dryer and into the
air system. Larger diameter discharge lines, and/or longer
discharge line lengths, can help reduce the temperature.
The discharge line must maintain a constant slope down
from the compressor to the air dryer inlet fitting to avoid low
points where ice may form and block the flow. If, instead,
ice blockages occur at the air dryer inlet, insulation may be
added here; or if the inlet fitting is a typical 90 degree fitting,
it may be changed to a straight — or 45 degree — fitting.
For more information on how to help prevent discharge
line freeze-ups, see Bendix Bulletins TCH-008-021 and
TCH‑008‑022 (see pages A-19-21). Shorter discharge
line lengths or insulation may be required in cold climates.
The air dryer contains a filter that collects oil droplets, and
a desiccant bed that removes almost all of the remaining
water vapor. The compressed air is then passed to the air
brake service (supply) reservoir. The oil droplets and the
water collected are automatically purged when the governor
reaches its “cut-out” setting.
For vehicles with accessories that are sensitive to small
amounts of oil, we recommended installation of a Bendix®
PuraGuard® system filter, designed to minimize the amount
of oil present.

D

The Air Brake Charging System supplies the compressed air for the braking system as well
as other air accessories for the vehicle. The system usually consists of an air compressor, governor,
discharge line, air dryer, and service reservoir.
DLU Valve

Air Dryer

C
S
UNL

D

S
21

Governor
Compressor

A-2

22

Front Service
Reservoir

Rear Service
Reservoir

Table A: Maintenance Schedule and Usage Guidelines

Regularly scheduled maintenance is the single most important factor in maintaining the air brake charging system.
Column 1
Column 2
					
			Typical	
Discharge	
			
Compressors	
Line	
No. of
			Spec'd	
	
Axles
				
	
I.D.
Length

Vehicle Used for:
Low Air Use

Compressor with less than 15% duty
cycle

e.g. Line haul single trailer
w/o air suspension, air over
hydraulic brakes.

1/2 in.
5
or
less

e.g. Line haul single trailer
with air suspension, RV,
school bus.

5
or
less

5/8 in.

E for Engine
Application
Matrix for

High Air Use

1/2 in.

9 ft.
9 ft.

Every 3
Years

For oil carry-over
control4 suggested
upgrades:

5/8 in.

Recommended
Every
Month Max of
every 90
days

12 ft.

360cc Single
Cylinder and
720cc Two

8
or
less

Cylinder
Compressors
for

1/2 in.

12 ft.

For oil carry-over
control4 suggested
upgrades:

5/8 in.

Every 2
Years

15 ft.

International

Every
Month

Maxxforce®
Compressor with up to 25% duty cycle

e.g. City transit bus, refuse,
bulk unloaders, low boys,
urban region coach, central
tire inflation.

Big Bore
Engines

3/4 in.

12
or
less

Footnotes:
1.	 With increased air demand the air dryer cartridge needs to be replaced
more often.
2.	 Use the drain valves to slowly drain all reservoirs to zero psi.
3.	 Allow the oil/water mixture to fully settle before measuring oil quantity.
4.	 To counter above normal temperatures at the air dryer inlet, (and resultant
oil-vapor passing upstream in the air system) replace the discharge line
with one of a larger diameter and/or longer length. This helps reduce the
air's temperature. If sufficient cooling occurs, the oil-vapor condenses
and can be removed by the air dryer. Discharge line upgrades are not
covered under warranty. Note: To help prevent discharge line freezeups, shorter discharge line lengths or insulation may be required in
cold climates. (See Bendix Bulletins TCH‑008‑021 and TCH-008-022,
included in Appendix B, for more information.)

Bendix®
BASIC™ test
acceptable
range:
3 oil units
per month.
See
Appendix
A.
For the
BASIC™
Test Kit:
Order
Bendix
P/N
5013711

Bendix®

Compressor with up to 25% duty cycle

e.g. Double/triple trailer,
open highway coach, (most)
pick-up & delivery, yard or
terminal jockey, off-highway,
construction, loggers, concrete
mixer, dump truck, fire truck.

6 ft.

For oil carry-over
control4 suggested
upgrades:

See Appendix

Compressor with up to 25% duty cycle

Column 3
Column 4
Column 5
Recom-	 Recom-	 Acceptable
mended	
mended	
Reservoir
Air Dryer	
Reservoir	
Oil Contents3
Cartridge	
Drain	
at Regular
Replacement1	Schedule2	 Drain Intervals

12 ft.

BASIC test
acceptable
range:
5 oil units
per month.
See
Appendix
A.

Every
Year

Note: Compressor and/or air dryer upgrades are recommended
in cases where duty cycle is greater than the normal range
(for the examples above).
For correct compressor upgrades consult Bendix.

* See Appendix E for the Application Matrix for Bendix®
360cc and 720cc air compressors.

A-3

Air Brake Charging System Troubleshooting
Look for:

How to use this guide:
Find the symptom(s) that you see, then move to the right
to find the possible causes (“What it may indicate”) and
remedies (“What you should do”).
Review the warranty policy before performing any intrusive
compressor maintenance. Unloader or cylinder head gasket
replacement and resealing of the bottom cover plate are
usually permitted under warranty. Follow all standard safety
procedures when performing any maintenance.

Normal - Charging system is working within
normal range.
Check - Charging system needs further
investigation.

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.
▲ 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
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. 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, 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 Bendix®
Wingman® Advanced™-equipped vehicle.

▲ You should consult the vehicle manufacturer's operating and service manuals, and any related literature,
in conjunction with the Guidelines above.

Symptom:	
1.0 Oil Test Card
Results

What it may indicate:	

What you should do: 	

Not a valid test.

Discontinue using this test.
Do not use this card test to diagnose compressor
"oil passing" issues. They are subjective
and error prone. Use only the Bendix® Air
System Inspection Cup (BASIC™) test and the
methods described in this guide for advanced
troubleshooting.
The Bendix® BASIC™ test is the definitive
method for judging excessive oil fouling/
oil passing. (See Appendix B, on page A-16
for a flowchart and expanded explanation of
the checklist used when conducting the BASIC
test.)


Bendix®
BASIC™ Test

A-4



Symptom:	

What it may indicate:	

What you should do:

2.0 Oil on the
Outside of the
Compressor

Engine and/or other accessories
leaking onto compressor.

Find the source and repair. Return the vehicle
to service.

2.1 Oil leaking at
compressor / engine
connections:

(a)	
Leak at the front or rear (fuel
pump, etc.) mounting flange.	

	
Repair or replace as necessary. If the
mounting bolt torques are low, replace the
gasket.	

(b)	Leak at air inlet fitting.	

	
Replace the fitting gasket. Inspect inlet
hose and replace as necessary.

(c)	Leak at air discharge fitting.

	
Replace gasket or fitting as necessary to
ensure good seal.	

(d)	Loose/broken oil line fittings.

	
Inspect and repair as necessary.	

(a)	Excessive leak at head gasket.	

	
Go to Test 1 on page A-14.	

(b)	
Leak at bottom cover plate.
	

	
Reseal bottom cover plate using RTV
silicone sealant.

(c)	
Leak at internal rear flange
gasket.
	
(d)	
Leak through crankcase.

	
Replace compressor.

2.2 Oil leaking
from compressor:

(e)	(If unable to tell source of leak.)

	
Replace compressor.
	
Clean compressor and check periodically.




(a)	

Head
gaskets and
rear flange
gasket
locations.



(c)	

3.0 Oil at air dryer
purge/exhaust or
surrounding area
	

Air brake charging system functioning
normally.
	

	
Air dryers remove water and oil from the air
brake charging system.
	 Check that regular maintenance is being
performed. Return the vehicle to service.
An optional kit (Bendix piece number
5011327 for the Bendix® AD-IS® or AD‑IP®
air dryers, or 5003838 for the Bendix® AD‑9®
air dryer) is available to redirect the air dryer
exhaust.

A-5

Symptom:	

What it may indicate:	

4.0 Oil in Supply or
Maintenance
Service Reservoir
(a)	If air brake charging system
(air dryer installed)
®
maintenance has not been
(If a maintained Bendix
®
performed. That is, reservoir(s)
PuraGuard system
®
have not been drained per the
filter or Bendix
PuraGuard® QC oil
schedule in Table A on page
coalescing
A-3, Column 4 and/or the air
filter is installed, call
dryer maintenance has not been
1‑800‑AIR‑BRAKE
performed as in Column 3.
(1‑800‑247-2725, option
2) and speak to a Tech
Team member.)

(b)	If the vehicle maintenance has
been performed as recommended
in Table A on page A-3, some oil in
the reservoirs is normal.
(a)

See Table A, on page
A-3, for maintenance
schedule information.
Drain all air tanks (reservoirs)
into the Bendix® BASIC™ test
cup. (Bendix kit P/N 5013711).

What you should do: 	

	
Drain all air tanks and check vehicle at next
service interval using the Bendix BASIC
test. See Table A on page A-3, column 3
and 4, for recommended service schedule.
	

	
Drain all air tanks into Bendix BASIC test
cup (Bendix Air System Inspection Cup).
If less than one unit of reservoir contents
is found, the vehicle can be returned to
service. Note: If more than one oil unit
of water (or a cloudy emulsion mixture)
is present, change the vehicle's air dryer,
check for air system leakage (Test 2, on
page A-14), stop inspection and check
again at the next service interval.
	 See the BASIC test kit for full details.
	 If less than one "oil unit" of water (or water/
cloudy emulsion mixture) is present, use the
BASIC cup chart on the label of the cup to
determine if the amount of oil found is within
the acceptable level.
	 If within the normal range, return the
vehicle to service. For vehicles with
accessories that are sensitive to small
amounts of oil, consider a Bendix ®
PuraGuard® QC oil coalescing filter.
	 If outside the normal range go to Symptom
4.0(c).
	 Also see the Table A on page A-3, column
3 for recommended air dryer cartridge
replacement schedule.

Duty cycle too high
(c)	Air brake system leakage.	

	
Go to Test 2 on page A-14.

(d)	Compressor may be undersized for
the application.

	
See Table A, column 1, on page A-3 for
recommended compressor sizes.
	 	 If the compressor is "too small" for
the vehicle's role (for example, where a
vehicle's use has changed or service conditions exceed the original vehicle or engine
OE spec's) then upgrade the compressor.
Note: The costs incurred (e.g. installing
a larger capacity compressor, etc.) are
not covered under original compressor
warranty.
	 	 If the compressor is correct for the
vehicle, go to Symptom 4.0 (e).

The duty cycle is the ratio of time the compressor spends
building air to total engine running time. Air compressors
are designed to build air (to "run loaded") up to 25% of the
time. Higher duty cycles cause conditions that affect air
brake charging system performance which may require
additional maintenance. Factors that add to the duty cycle
are: air suspension, additional air accessories, use of an
undersized compressor, frequent stops, excessive leakage
from fittings, connections, lines, chambers or valves, etc.

A-6

Symptom:	
4.0 Oil in Supply
or Service
Reservoir*
(air dryer installed)
(continued)

What it may indicate:	

What you should do:

Temperature
(e)	Air compressor discharge and/or
air dryer inlet temperature too
high.
(f)	 Insufficient coolant flow.

	
Inspect coolant line. Replace as necessary.
Inside Diameter (I.D.) is 1/2".	
	
Inspect the coolant lines for kinks and
restrictions and fittings for restrictions.	
Replace as necessary.

(f)

(e)

	
Check temperature as outlined in Test 3 on
page A-14. If temperatures are normal go
to 4.0(h).

	
Verify coolant lines go from engine block to
compressor and back to the water pump.
Repair as necessary.

(g)

Testing the temperature
at the discharge fitting.

Inspecting the coolant hoses.

(g)	Restricted discharge line.

	
If discharge line is restricted or more than
1/16" carbon build-up is found, replace the
discharge line. See Table A, column 2, on
page A-3 for recommended size. Replace
as necessary.
	
The discharge line must maintain a
constant slope down from the compressor
to the air dryer inlet fitting to avoid low points
where ice may form and block the flow.
If, instead, ice blockages occur at the air
dryer inlet, insulation may be added here,
or if the inlet fitting is a typical 90 degree
fitting, it may be changed to a straight or
45 degree fitting. For more information on
how to help prevent discharge line freezeups, see Bendix Bulletins TCH‑008‑021
and TCH‑008‑022 (Appendix B). Shorter
discharge line lengths or insulation may be
required in cold climates.

(g)

Kinked discharge line shown.

Other
(h)	Restricted air inlet (not enough air
to compressor).
(h)

Partly
collapsed
inlet line
shown.

	
Check compressor air inlet line for restrictions, brittleness, soft or sagging hose
conditions etc. Repair as necessary. Inlet
line size is 3/4 ID. Maximum restriction
requirement for compressors is 25 inches
of water.
	
Check the engine air filter and service if
necessary (if possible, check the air filter
usage indicator).

*If a maintained Bendix® PuraGuard® system filter or Bendix® PuraGuard® QC oil coalescing
filter is installed, call 1‑800‑AIR‑BRAKE (1‑800‑247-2725, option 2) and speak to a Tech Team
member.
A-7

Symptom:	
4.0 Oil in Supply
or Service
Reservoir*
(air dryer installed)
(continued)

What it may indicate:	

What you should do: 	

Other (cont.)
(i)	Poorly filtered inlet air (poor air
quality to compressor).

	
Check for leaking, damaged or defective
compressor air inlet components (e.g.
induction line, fittings, gaskets, filter bodies,
etc.). Repair inlet components as needed.
Note: Dirt ingestion will damage compressor
and is not covered under warranty.

Inspect the
engine air
cleaner.

(j)	 Governor malfunction or setting.

	
Go to Test 4 on page A-15.

(k)	Compressor malfunction.

	
If you found excessive oil present in the
service reservoir in step 4.0 (b) above and
you did not find any issues in steps 4.0 (c)
through 4.0 (j) above, the compressor may
be passing oil.
	 Replace compressor. If still under warranty,
follow normal warranty process. Note: After
replacing a compressor, residual oil may
take a considerable period of time to be
flushed from the air brake system.

Crankcase Flooding
Consider installing a compressor bottom drain kit
(where available) in cases of chronic oil passing where
all other operating conditions have been investigated.
Bendix compressors are designed to have a 'dry'
sump and the presence of excess oil in the crankcase
can lead to oil carryover.

*If a maintained Bendix® PuraGuard® system filter or Bendix® PuraGuard® QC oil coalescing
filter is installed, call 1‑800‑AIR‑BRAKE (1‑800‑247-2725, option 2) and speak to a Tech Team
member.

5.0 Oil present
at valves (e.g. at
exhaust, or seen
during servicing).

Air brake system valves are required
to tolerate a light coating of oil.

	
A small amount of oil does not affect SAE
J2024** compliant valves.
	
Check that regular maintenance is being
performed and that the amount of oil in the
air tanks (reservoirs) is within the acceptable range shown on the Bendix® BASIC™
test cup (see also column 5 of Table A on
page A-3). Return the vehicle to service.
For oil-sensitive systems, see page A-16.

** 	SAE J2024 outlines the tests all air brake system
pneumatic components need to be able to pass,
including minimum levels of tolerance to contamination.

Genuine
Bendix®
valves are
all SAE
J2024
compliant.

A-8

Symptom:	

What it may indicate:	

What you should do:

6.0 Excessive oil
consumption in
engine.

A problem with engine or other engine
accessory.

	
See engine service manual.

7.0 Oil present
at air dryer
cartridge during
maintenance.

Air brake charging system is functioning
normally.

The engine
service
manual
has more
information.

Oil shown
leaking
from an
air dryer
cartridge.

	
Air dryers remove water and oil from
the air brake charging system. A small
amount of oil is normal. Check that regular
maintenance is being performed and that
the amount of oil in the air tanks (reservoirs)
is within the acceptable range shown by the
Bendix® BASIC™ test (see also column 5
of Table A on page A-3). Replace the air
dryer cartridge as needed and return the
vehicle to service.

8.0 Oil in ping tank
or compressor
discharge
aftercooler.

Air brake charging system is functioning
normally.

	
Follow vehicle OE maintenance
recommendation for these components.

9.0 Air brake
charging system
seems slow to
build pressure.

(a)	Air brake charging system
functioning normally.

	
Using dash gauges, verify that the
compressor builds air system pressure
from 85–100 psi in 40 seconds or less with
engine at full governed rpm. Return the
vehicle to service.

		
(b)	Air brake system leakage.

(d) is not applicable for the
compressor featured in this SD
sheet —- information is shown
for reference only.

	
Go to Test 2 on page A-14.

(c)	Compressor may be undersized for
the application.

	
See Table A, column 1, on page A-3 for
some typical compressor applications. If the
compressor is "too small" for the vehicle's
role, for example, where a vehicle's use has
changed, then upgrade the compressor.
Note: The costs incurred (e.g. installing
a larger capacity compressor, etc.) are
not covered under original compressor
warranty.

(d)	Compressor unloader mechanism
malfunction.	

	
Go to Test 6 on page A-15.

(e)	Damaged compressor head
gasket. 	

	
An air leak at the head gasket may indicate a downstream restriction such as a
freeze‑up or carbon blockage and/or could
indicate a defective or missing safety valve.
Find blockage (go to 9.0(f) for details) and
then replace the compressor. Do not reuse the safety valve without testing. See
Symptom 12.0(a).

A-9

Symptom:	

What it may indicate:	

What you should do: 	

9.0 Air brake
charging system
seems slow to
build pressure.
(continued)

(f)	 Restricted discharge line.

	
If the discharge line is restricted:
	 	 By more than 1/16" carbon build-up,
replace the discharge line (see Table A,
column 2, on page A-3 for recommended
size) and go to Test 3 on page A-14.
	 	 By other restrictions (e.g. kinks).
Replace the discharge line. See Table A,
column 2, on page A-3 for recommended
size. Re-test for air build. Return vehicle to
service or, if problem persists, go to 9.0(a).

(f)

Dash gauges.

Kinked discharge line shown.

Engine Oil Quality
Inadequate oil change intervals, the formulation of the
oil and/or the quality of oil filter used can all lead to poor
oil quality. These can increase the rate at which carbon
builds up in the discharge line. Bendix recommends oil
soot (solids) be maintained at less than 3%.

(g)

(g)	Restricted air inlet (not enough air
to compressor).

	
The discharge line must maintain a
constant slope down from the compressor
to the air dryer inlet fitting to avoid low points
where ice may form and block the flow.
If, instead, ice blockages occur at the air
dryer inlet, insulation may be added here,
or if the inlet fitting is a typical 90 degree
fitting, it may be changed to a straight or
45 degree fitting. For more information on
how to help prevent discharge line freezeups, see Bendix Bulletins TCH-008-021
and TCH‑008‑022 (Appendix B). Shorter
discharge line lengths or insulation may be
required in cold climates.

	
Check compressor air inlet line for restrictions, brittleness, soft or sagging hose conditions etc. Repair as necessary. Refer to
vehicle manufacturer’s guidelines for inlet
line size.
	
Check the engine air filter and service if
necessary (if possible, check the air filter
usage indicator).

Partly collapsed
inlet line shown.

A-10

(h)	Poorly filtered inlet air (poor air
quality to compressor).

	
Check for leaking, damaged or defective
compressor air inlet components (e.g.
induction line, fittings, gaskets, filter bodies,
etc.). Repair inlet components as needed.
Note: Dirt ingestion will damage compressor
and is not covered under warranty.

(i)	Compressor	malfunction.

	
Replace the compressor only after making
certain that none of the preceding conditions,
9.0 (a) through 9.0 (h), exist.

Symptom:	
10.0 Air charging
system doesn’t
build air.

What it may indicate:	

What you should do:

(a)	Governor malfunction*.	

	
Go to Test 4 on page A-15.

(b) Restricted discharge line.

	
See 9.0(f).

(c)	Air dryer heater malfunction:
exhaust port frozen open.

	
Replace air dryer heater.

(d) Compressor malfunction.

	
Replace the compressor only after making
certain the preceding conditions do not
exist.

* Note: For the Bendix® DuraFlo 596™ air compressor, not only
the governor, but also the SV‑1™ synchro valve used would
need to be tested. See Bulletin TCH-001-048.

11.0 Compressor
safety valve
releases air
(Compressor
builds too much
air).

(a)	Restricted discharge line.	



Damaged
discharge
line shown.

	
If the discharge line is restricted:
	 	 By more than 1/16" carbon build-up,
replace the discharge line (see Table A,
column 2, on page A-3 for recommended
size) and go to Test 3 on page A-14.
	 	 By other restrictions (e.g. kinks).
Replace the discharge line. See Table A,
column 2, on page A-3 for recommended
size.
	
The discharge line must maintain a
constant slope down from the compressor
to the air dryer inlet fitting to avoid low points
where ice may form and block the flow.
If, instead, ice blockages occur at the air
dryer inlet, insulation may be added here,
or if the inlet fitting is a typical 90 degree
fitting, it may be changed to a straight or
45 degree fitting. For more information on
how to help prevent discharge line freezeups, see Bendix Bulletins TCH-008‑021
and TCH‑008‑022 (Appendix B). Shorter
discharge line lengths or insulation may be
required in cold climates.

(b)	Downstream air brake system check
valves or lines may be blocked or
damaged. 	

	
Inspect air lines and verify check valves are
operating properly.

(c)	Air dryer lines incorrectly installed.

	
Ensure discharge line is installed into the
inlet of the air dryer and delivery is routed
to the service reservoir.

(d)	Compressor safety valve
malfunction.	

	
Verify relief pressure is 250 psi. Replace if
defective.	

(e)	Compressor unloader mechanism
malfunction.	

	
Go to Test 6 on page A-15.

(f)	 Governor malfunction.

	
Go to Test 4 on page A-15.

A-11

Symptom:	
12.0 Air dryer
safety valve
releases air.	
Air dryer
safety valve





Technician removes
governor.

13.0 Reservoir
safety valve
releases air.

14.0 Air dryer
doesn’t purge.
(Never hear
exhaust from air
dryer.)

15.0 Compressor
constantly cycles
(compressor
remains unloaded
for a very short
time.)
(b) is not applicable for the
compressor featured in this SD
sheet —- information is shown
for reference only.

A-12

What it may indicate:	

What you should do: 	

(a)	Restriction between air dryer and
reservoir.

	
Inspect delivery lines to reservoir for
restrictions and repair as needed.	

(b)	Air dryer safety valve
malfunction.	

	
Verify relief pressure is at vehicle or
component manufacturer specifications.
Replace if defective.	

(c)	Air dryer maintenance not
performed.	

	
See Maintenance Schedule and Usage
Guidelines (Table A, column 3, on page
A-3).	

(d)	Air dryer malfunction.	

	
Verify operation of air dryer. Follow vehicle
OEM maintenance recommendations and
component Service Data information.

(e)	Improper governor control line
installation to the reservoir.

	
Go to Test 5 on page A-15.	

(f)	 Governor malfunction.

	
Go to Test 4 on page A-15.

(a)	Reservoir safety valve
malfunction.	

	
Verify relief pressure is at vehicle or
component manufacturer's specifications
(typically 150 psi). Replace if defective.	

(b)	Governor malfunction.

	
Go to Test 4 on page A-15.

(c)	Compressor unloader mechanism
malfunction.	

	
Go to Test 6 on page A-15.

(a)	Air dryer malfunction.	

	
Verify operation of air dryer. Follow vehicle
OEM maintenance recommendations.

(b)	Governor malfunction.	

	
Go to Test 4 on page A-15.

(c)	Air brake system leakage.	

	
Go to Test 2 on page A-14.

(d)	Improper governor control line
installation to the reservoir.

	
Go to Test 5 on page A-15.	

(a)	A i r b r a k e c h a r g i n g s y s t e m
maintenance not performed.	

	
Available reservoir capacity may be
reduced by build-up of water, etc. Drain
and perform routine maintenance per Table
A, columns 3 & 4, on page A-3.

(b)	Compressor unloader mechanism
malfunction.	

	
Go to Test 6 on page A-15.

(c)	Air dryer purge valve or delivery
check valve malfunction.

	
Verify operation of air dryer. Follow vehicle
OEM maintenance recommendations and
component Service Data information.

(d)	Air brake system leakage.

	
Go to Test 2 on page A-14.

Symptom:	
16.0 Compressor
leaks air
(b) is not applicable for the
compressor featured in this SD
sheet —- information is shown
for reference only.

What you should do:

(a)	Compressor leaks air at connections
or ports.	

	
Check for leaking, damaged or defective
compressor fittings, gaskets, etc. Repair
or replace as necessary.

(b)	Compressor unloader mechanism
malfunction.	

	
Go to Test 6 on page A-15.

(c)	Damaged compressor head
gasket(s).

	
An air leak at the head gasket(s) may
indicate a downstream restriction such as a
freeze-up or carbon blockage and/or could
indicate a defective or missing safety valve.
Find blockage (go to 9.0(f) for details) and
then replace the compressor. Do not reuse the safety valve without testing. See
Symptom 12.0(a).




What it may indicate:	

Head
gasket
locations

Testing for leaks with
soap solution.

17.0 Compressor
leaks coolant

(a)	Improperly installed plugs or coolant
line fittings.	

(b)	Damaged compressor head
gasket.	

18.0 Noisy
compressor
(Multi-cylinder
compressors only)

	
Inspect for loose or over-torqued fittings.
Reseal and tighten loose fittings and plugs
as necessary. If overtorqued fittings and
plugs have cracked ports in the head,
replace the compressor.
	
	
An air leak at the head gasket may indicate
a downstream restriction such as a freezeup or carbon blockage and/or could indicate
a defective or missing safety valve. Find
blockage (go to 9.0(f) for details) and then
replace the compressor. Do not re-use the
safety valve without testing. See Symptom
12.0(a).

(c)	Porous compressor head casting.

	
If casting porosity is detected, replace the
compressor.	

(a)	Damaged compressor.	

	
Replace the compressor.	

Other Miscellaneous Areas to Consider
This guide attempts to cover most compressor system problems. Here are some
rare sources of problems not covered in
this guide:
• Turbocharger leakage. Lubricating
oil from leaking turbocharger seals can
enter the air compressor intake and give
misleading symptoms.

• Where a compressor does not have
a safety valve installed, if a partial or
complete discharge line blockage has
occurred, damage can occur to the connecting rod bearings. Damage of this kind
may not be detected and could lead to
compressor problems at a later date.

A-13

Tests
Test 1: Excessive Oil Leakage at the
Head Gasket
Exterior leaks at the head gasket are not a sign that oil is being passed into
the air charging system. Oil weepage at the head gasket does not prevent
the compressor from building air.

Look
for

Weepage

Observe the amount of weepage from the head gasket.
If the oil is only around the cylinder head area, it is acceptable (return the vehicle
to service), but, if the oil weepage extends down to the nameplate area of the
compressor, the gasket can be replaced.

Test 2: Air Brake System and Accessory Leakage
Inspect for air leaks when working on a vehicle and
repair them promptly.
Park the vehicle on level ground and chock wheels.
Build system pressure to governor cut‑out and allow
the pressure to stabilize for one minute.
Step 1: Observe the dash gauges for two additional
minutes without the service brakes applied.
Step 2: Apply the service brakes and allow the
pressure to stabilize. Continue holding for two
minutes (you may use a block of wood to hold the

pedal in position.) Observe the dash gauges.
If you see any noticeable decrease of the dash air
gauge readings (e.g. more than four psi, plus two psi
for each additional trailer) during either two minute
test, repair the leaks and repeat this test to confirm
that they have been repaired.
Air leaks can also be found in the charging system,
parking brakes, and/or other components - inspect
and repair as necessary.

Test 3: Air Compressor Discharge
Temperature and Air Dryer Inlet
Temperature*
Caution: The temperatures used in this test
are not normal vehicle conditions.
Above normal temperatures can cause oil (as
vapor) to pass through the air dryer into the
air brake system.
This test is run with the engine at normal operating
temperature, with engine at max. rpm. If available,
a dyno may be used.
1.	 Allow the compressor to build the air system
pressure to governor cut-in.
2.	 Pump the brakes to bring the dash gauge
pressure to 90 psi.
3.	 Allow the compressor to build pressure from
95 to 105 psi gauge pressure and maintain
this pressure range by cycling the brakes for
five (5) minutes.

T1

T2

Discharge Line
A-14

(* Note that only vehicles that have passed Test 2
would be candidates for this test.)
4.	 Then, while maintaining max rpm and
pressure range, measure and record the
surface temperature of the fittings:
	 	at the compressor discharge port. (T1).
	 	at the air dryer inlet fitting. (T2).
	
Use a touch probe thermocouple for measuring
the temperature.
5.	 See table below.
6.	 Re-test before returning the vehicle to service.
	

T1	T2	

	

	 Compressor	 Air Dryer	
Action
	Discharge	
Inlet	
	Fitting	 Fitting		

	 under 	
under	
	 360°F	
200°F	
			
	
	 under	
over	
	 360°F	
200°F	
			
			
			
			
	 over	
__	
	 360°F		
			

Temperatures are within	
normal range for this test, check	
other symptoms. Go to 4.0 (h).	
This could indicate a discharge
line problem (e.g. restriction).
Call 1-800-AIR-BRAKE
(1-800-247-2725, option 2)
and speak with our Tech Team.
Compressor is running hot.
Check coolant 4(f) and/or	
discharge line 4(g).	

		

Tests (continued)
Test 4: Governor Malfunction
1.	 Inspect control lines to and from the governor
for restrictions (e.g. collapsed or kinked).
Repair as necessary.
2.	 Using a calibrated external gauge in the supply

reservoir, service reservoir, or reservoir port
of the Bendix® D-2® governor, verify cut-in
and cut-out pressures are within vehicle OEM
specification.
3.	 If the governor is malfunctioning, replace it.

Test 5: Governor Control Line
1.	 Ensure that the governor control line from the
reservoir is located at or near the top of the reservoir. (This line, if located near the bottom of
the reservoir, can become blocked or restricted
by the reservoir contents e.g. water or ice.) 	

2.	 Perform proper reservoir drain intervals and air
dryer cartridge maintenance per Maintenance
Schedule and Usage Guidelines (Table A on
page A-3).
3.	 Return the vehicle to service.

Test 6: Compressor Unloader Leakage
Bendix ® Compressors: Park vehicle, chock
wheels, and follow all standard safety procedures.
Remove the governor and install a fitting to the
unloader port. Add a section of air hose (min
1 ft long for a 1/2" diameter line) and a gauge
to the fitting followed by a shut-off valve and an
air source (shop air or small air tank). Open the

shut-off and charge the unloader port by allowing
air pressure to enter the hose and unload the
compressor. Shut off the air supply and observe
the gauge. A steady reading indicates no leakage
at the unloader port, but a falling reading shows
that the unloader mechanism is leaking and needs
to be serviced.

Note: This Test is not applicable for the compressor
featured in this SD sheet —- information is shown for
reference only.

A-15

Appendix B: Information about the BASIC™ Test Kit (Bendix P/N 5013711)

Bendix® Air System Inspection Cup (BASIC™)
Test Information

Drain contents of ALL air
tanks into Bendix® Basic™ cup

* If the number of days since the air tanks were drained is unknown
- use the 30 day line.
** Note: Typical air dryer cartridge replacement schedule is every 3 yrs/
300K miles for low air use vehicles and every year/100K miles for high
air use vehicles.

Replace the Compressor. If under warranty, follow standard
procedures.
If, after a compressor was already replaced, the vehicle fails the
BASIC test again, do not replace the compressor**** - use the
Advanced Troubleshooting Guide to investigate the cause(s).

*** To get an accurate reading for the amount of oil collected during
a 30 day period, ask the customer not to drain the air tanks before
returning. (Note that 30-90 days is the recommended air tank drain
schedule for vehicles equipped with a Bendix air dryer that is properly
maintained.) If, in cold weather conditions, the 30 day air tank drain
schedule is longer than the customer's usual draining interval, the
customer must determine, based on their experience with the vehicle,
whether to participate now, or wait for warmer weather. See the cold
weather tips in Bulletins TCH‑008-021 and TCH-008-022 (included on
pages A-19-21 of this document).
****Note: After replacing a compressor, residual oil may take a
considerable period of time to be flushed from the air brake system.

A-16

Appendix B continued: Information about the BASIC™Test Kit (Bendix P/N 5013711)
Filling in the Checklist for the Bendix® Air System Inspection Cup (BASIC™) Test
Note: Follow all standard safety precautions. For vehicles using a desiccant air dryer.

The Service Writer fills out these fields with information gained from the customer
Number of Days Since Air Tanks Were Last Drained: ________ Date: ___________Vehicle #: ____________
Engine SN __________________________ Vehicle Used for: _______________Typical Load:________ (lbs.)
No. of Axles: ____ (tractor) ____ (trailer) No. of Lift Axles: ____ Technician’s Name: ____________________
Checklist for Technician

The Service Writer
also checks off any
complaints that the
customer makes to
help the Technician
in investigating.

Have you confirmed complaint?


Customer’s Complaint	
(Please check all that apply)

“Relay valve  leaks oil /  malfunctions”	
 no  yes*
“Dash valve  leaks oil /  malfunctions”	
 no  yes*
 “Air dryer leaks oil”	
 no  yes*
 “Governor malfunction”	
 no  yes*
 “Oil in gladhands” 	
 no  yes*
how much oil did you find? ________________________________
 “Oil on ground or vehicle exterior” 	
 no  yes*
amount described: ______________________________________
 “Short air dryer cartridge life”
replaces every: ______________  miles,  kms, or  months
 “Oil in air tanks” amount described:_______________________
We will measure amount currently found when we get to step B of the test.

 “Excessive engine oil loss” amount described: ______________
Is the engine leaking oil? 	
 no  yes*
Is the compressor leaking oil? 	
 no  yes*
 Other complaint: _____________________________________
 No customer complaint.

BASIC™ test starts here:

STEP A - Select one:

 This is a low air use vehicle: Line haul (single trailer) with 5 or less axles, or
 This is a high air use vehicle: Garbage truck, transit bus, bulk unloader, or line
haul with more than 5 axles.
Then go to Step B.

STEP B - Measure the Charging System Contents
1.	 Park and chock vehicle on level ground. Drain the air system by
pumping the service brakes.
2.	 Completely drain ALL the air tanks into a single BASIC™cup.
3.	 If there is less than one unit of contents total, end the test now and
return the vehicle to service. Vehicle passes.
4.	 If more than one oil unit of water (or a cloudy emulsion mixture)
is found:
		 (a)	 Change the vehicle’s air dryer cartridge
Oil
				 - see Footnote 1,				
Units
	 (b)	 Conduct the 4 minute leakage test (Step D),
		(c)	STOP the inspection, and check the vehicle
				 again after 30 days - see Footnote 2. STOP
+ CK.

The Technician
checks boxes
for any of the
complaints that
can be confirmed.

* Note: A confirmed complaint
above does NOT mean that
the compressor must be
replaced.
The full BASIC™ test below will
investigate the facts.

The Technician selects the air use
category for the vehicle. This decides
which of the two acceptance lines on
the cup will be used for the test below.

For an accurate test, the
contents of all the air tanks on
the vehicle should be used.
Note for returning vehicles that are being
retested after a water/cloudy emulsion
mixture was found last time and the air
dryer cartridge replaced: If more than
one oil unit of water or a cloudy emulsion
mixture is found again, stop the BASIC test
and consult the air dryer's Service Data sheet
troubleshooting section.

Otherwise, go to Step C.
Footnote 1: Note: Typical air dryer cartridge replacement schedule is every 3 yrs/ 300K miles for low air use vehicles and every year/100K miles for
high air use vehicles.
Footnote 2: To get an accurate reading for the amount of oil collected during a 30 day period, ask the customer not to drain the air tanks before
returning. (Note that 30-90 days is the recommended air tank drain schedule for vehicles equipped with a Bendix air dryer that are properly maintained.)
If, in cold weather conditions, the 30 day air tank drain schedule is longer than the customer's usual draining interval, the customer must determine,
based on its experience with the vehicle, whether to participate now, or wait for warmer weather. See the cold weather tips in Bulletins TCH-008-021
and TCH‑008-022 (included in Appendix B of the advanced troubleshooting guide).
A-17

Appendix B continued: Information about the BASIC™Test Kit (Bendix P/N 5013711)
®

Filling in the Checklist for the Bendix Air System Inspection Cup (BASIC™) Test
Note: Follow all standard safety precautions. For vehicles using a desiccant air dryer.

1. Record days since air
tanks were last drained.

2. Record amount
of oil found:

The Technician uses the chart (label) on the BASIC™
test cup to help decide the action to take, based on
the amount of oil found. Use the lower acceptance
line for low air use vehicles, and upper line for high
air use vehicles (from Step A).

_________ days

_________ units

If number of days is:
30-60 days (high air
use) or
30-90 days (low air
use)


Otherwise . . .


(if the number of days is
unknown, or outside the
limits above)

STOP
if oil level is at or below System OK.
30‑day acceptance line  Return to service. TEST
Stop inspection.
if oil level is above 30‑day Test again
STOP
+ CK.
acceptance line 
after 30 days.
See Footnote 2.

Acceptance
Lines

An oil level of 4 units in a sixty-day period is within the
acceptance area (at or below the line) for both low and
high air use vehicles. Return the vehicle to service.

Sixty days since last air
tank draining

Park the vehicle on level ground and chock wheels. Build system pressure to governor cut-out
and allow the pressure to stabilize for one minute.
1: Observe the dash gauges for two additional minutes without the service brakes applied.
2: Apply service brakes for two minutes (allow pressure to stabilize) and observe the dash
gauges.
If you see any noticeable decrease of the dash air gauge readings, repair leaks. Repeat this
test to confirm that air leaks have been repaired and return vehicle to service. Please repeat
BASIC test at next service interval. Note: Air leaks can also be found in the charging system,
parking brakes, and/or other components - inspect and repair as necessary.
	 If no air leakage was detected, and if you are conducting
this test after completing Step C, go to Step E.

STEP E - If no air leakage was detected in Step D

Note: If the compressor is within warranty period,
please follow standard warranty procedures. Attach
the completed checklist to warranty claim.

A-18

Oil
Level

X

STEP D - Air Brake System Leakage Test

Replace the compressor.



if oil level is at or below System OK.
STOP
acceptance line for number
TEST
Return
to
service.
of days
if oil level is above
Go to Step D
acceptance line for number
of days 

BASIC Test Example

The Technician looks for the point where the number of
days since the air tanks were drained meets the oil level.
If it is at or below the (low or high use) acceptance line,
the vehicle has passed the test. If the point is above
the line then go to the leakage test.

3. Action to
take





STEP C - How to Use the BASIC™ Test

Decision point

Air leakage is the number one
cause of compressors having
to pump excessive amounts of
air, in turn run too hot and pass
oil vapor along into the system.
Here the Technician conducts a
four-minute test to see if leakage
is a problem with the vehicle
being tested.

The Technician only reaches
Step E if the amount of oil
found, or the amount of time
since the air tanks were last
drained exceeds the acceptance
level, AND the vehicle passes
the four-minute leakage test
(no noticeable leakage was
detected).

Appendix C

Technical Bulletin
Bulletin No:	TCH-008-021
Subject:

Effective Date:	 3-5-2010

Cancels:	PRO-08-21 dated 2-6-2008

Page: 1 of 2

Air Brake System - Cold Weather Operation Tips

As the cold weather approaches, operators and fleets alike begin to look to their vehicles with an eye toward
“winterization”, and particularly what can be done to guard against air system freeze-up. Here are some basic
“Tips” for operation in the cold weather.
Engine Idling
Avoid idling the engine for long periods of time! In addition to the fact that most engine manufacturers warn that
long idle times are detrimental to engine life, winter idling is a big factor in compressor discharge line freeze-up.
Discharge line freeze-ups account for a significant number of compressor failures each year. The discharge
line recommendations under “Discharge Lines” are important for all vehicles, but are especially so when some
periods of extended engine idling can not be avoided.
Discharge Lines
The discharge line should slope downward from the compressor discharge port without forming water traps,
kinks, or restrictions. Cross-overs from one side of the frame rail to the other, if required, should occur as close
as possible to the compressor.
								
Dryer Inlet Temperature
The dryer inlet air temperature should typically be within the range of no more than 160°F and no less than 45°F
above low ambient (surrounding) temperature to prevent freeze-ups. (For example, if low ambient is minus
40°F, the dryer inlet must be above 5°F.) Lower dryer inlet temperatures should be avoided to minimize the risk
of freeze-up upstream of the air dryer. Higher temperatures should also be avoided to minimize the risk of heat
damage to the air dryer seals and to avoid a loss of drying performance.
Compressor Line Size
The line size and length is established by the vehicle manufacturer and should not be altered without the vehicle
manufacturers approval. As a reference, the line length from the compressor to the air dryer should be less than
16 feet and the minimum line sizes should be as follows:	
Minimum
Length

Minimum
Application
I.D.

6 ft.

1/2 in.

Low Compressor Duty Cycle Applications (0-20%)

10 ft.

5/8 in.

High Compressor Duty Cycle Applications (20-40%)

Line Insulation
To guard against freez-ups in Low Duty Cycle applications, the discharge line can be insulated if it is greater
than 9 feet in length. The line can only be insulated back to 9 feet and a maximum of 3 feet. For example, if
the line is 10 feet, insulate the fitting and the last one foot of the line. If the line is 15 feet, insulate the fitting and
the last 3 feet of the line.

© 2010 Bendix Commercial Vehicle Systems LLC All rights reserved. 3/2010

A-19

Appendix C: Continued
Bulletin No.: TCH-008-021 		

Effective Date: 3/5/2010				

Page: 2 of 2

System Leakage
Check the air brake system for excessive air leakage using the Bendix “Dual System Air Brake Test and Check
List” (BW1279). Excessive system leakage causes the compressor to “pump” more air and also reduce the life
of the air dryer desiccant cartridge.
Reservoir Draining (System without an Air Dryer)
Routine reservoir draining is the most basic step in reducing the possibility of freeze-up. All reservoirs in a
brake system can accumulate water and other contamination and must be drained! The best practice is to
drain all reservoirs daily if the air brake system does not include an air dryer. When draining reservoirs; turn
the ENGINE OFF and drain ALL AIR from the reservoir, better still, open the drain cocks on all reservoirs and
leave them open over night to assure all contamination is drained (reference Service Data Sheet SD-04-400 for
Bendix Reservoirs). If automatic drain valves are installed, check their operation before the weather turns cold
(reference Service Data Sheet SD-03-2501 for Bendix® DV-2™ Automatic Drain Valves). It should be noted that,
while the need for daily reservoir draining is eliminated through the use of an automatic drain valve, periodic
manual draining is still required.
Reservoir Draining (System with an Air Dryer)
Daily reservoir draining should not be performed on systems with an air dryer. This practice will cause the dryer
to do excessive work (e.g. build pressure from 0 -130 psi instead of the normal 110-130 psi).
Alcohol Evaporator or Injector Systems
Bendix Commercial Vehicle Systems LLC discourages the use of alcohol in the air brake system as a means
of preventing system freeze-up in cold temperatures. Studies indicate that using alcohol and alcohol based
products sold for this purpose removes the lubrication from the components of the air braking system. In
addition, the materials used for the internal seals of the air system components may be adversely impacted
by the residue that some anti-freeze additives leave behind. Both are detrimental to air system component life
expectancy, causing premature wear. Because of this, Bendix® air system components warranty will be void if
analysis shows that alcohol was added to the air brake system.
Alcohol is not an acceptable substitute for having adequate air drying capacity. If the air dryer is maintained in
accordance with the manufacturer’s recommended practices and moisture is found to be present in the system
reservoirs, more drying capacity is required. Bendix has several viable options including extended purge air
dryers, extended purge tandem dryers in parallel with common control, and air dryers arranged to provide
continuous flow as with the Bendix® EverFlow® continuous flow air dryer module. To address concerns with
contaminants in trailer air brake systems, the Bendix® Cyclone DuraDrain® water separator and the Bendix®
System-Guard® trailer air dryer are available. Refer to Bendix Technical Bulletin TCH-008-042 “Alcohol in the
Air Brake System” for additional information.
Air Dryers
Make certain air brake system leakage is within the limits stated in BW1279. Check the operation and function
of the air dryer using the appropriate Service Data Sheet for the air dryer.
Air Dryer

Service Data Sheet

AD-2® air dryer

SD-08-2403

AD-4 air dryer

SD-08-2407

™

AD-9 air dryer

SD-08-2412

AD-IP® air dryer

SD-08-2414

AD-IS air dryer

SD-08-2418

AD-IS EverFlow air dryer

SD-08-2417

AD-SP® air dryer

SD-08-2415

®

®

®

®

Cyclone DuraDrain water separator

SD-08-2402

PuraGuard® QC system filter

SD-08-187B

Trailer System-Guard® air dryer

SD-08-2416

®

A-20

Bendix literature is
available to order or
download on Bendix.com

Appendix D

Technical Bulletin
Bulletin No.: TCH-008-022 		

Subject: Additional

Effective Date: 1/1/1994 				

Page: 1 of 1

Cold Weather Operation Tips for the Air Brake System

Last year we published Bulletin PRO-08-21 which provided some guidelines for “winterizing” a
vehicle air brake system. Here are some additional suggestions for making cold weather vehicle
operation just a little more bearable.
Thawing Frozen Air Lines
The old saying; “Prevention is the best medicine” truly applies here! Each year this activity accounts
for an untold amount of unnecessary labor and component replacement. Here are some Do’s and
Don’ts for prevention and thawing.
Do’s
1.	Do maintain freeze prevention devices to prevent road calls. Don’t let evaporators or injectors run
out of methanol alcohol or protection will be degraded. Check the air dryer for proper operation
and change the desiccant when needed.
2.	Do thaw out frozen air lines and valves by placing the vehicle in a warmed building. This is the
only method for thawing that will not cause damage to the air system or its components.
3.	 Do use dummy hose couplings on the tractor and trailer.
4.	 Do check for sections of air line that could form water traps. Look for “drooping” lines.
Don’ts
1.	 Do not apply an open flame to air lines and valves. Beyond causing damage to the internal
nonmetallic parts of valves and melting or burning non-metallic air lines. WARNING: THIS
PRACTICE IS UNSAFE AND CAN RESULT IN VEHICLE FIRE!
2.	 Do not introduce (pour) fluids into air brake lines or hose couplings (“glad hands”). Some fluids
used can cause immediate and severe damage to rubber components. Even methanol alcohol,
which is used in Alcohol Evaporators and Injectors, should not be poured into air lines. Fluids
poured into the system wash lubricants out of valves, collect in brake chambers and valves and
can cause malfunction. Loss of lubricant can affect valve operating characteristics, accelerate
wear and cause premature replacement.
3.	 Do not park a vehicle outside after thawing its air system indoors. Condensation will form in the
system and freeze again. Place the vehicle in operation when it is removed to the outdoors.
Supporting Air and Electrical Lines
Make certain tie wraps are replaced and support brackets are re-assembled if removed during routine
maintenance. These items prevent the weight of ice and snow accumulations from breaking or
disconnecting air lines and wires.
Automatic Drain Valves (System without Air Dryer)
As we stated last year, routine reservoir draining is the most basic step (although not completely
effective) in reducing the possibility of freeze-up. While automatic drain valves relieve the operator
of draining reservoirs on a daily basis, these valves MUST be routinely checked for proper operation.
Don’t overlook them until they fail and a road call is required.

A-21

Appendix E

Application Matrix for Bendix® 360cc Single Cylinder and 720cc Twin Cylinder
Compressors for International Maxxforce® Big Bore Engines
This useful Compressor Application Guide is a simple point system
using vehicle configuration and vocation options to help calculate the
Bendix® compressor right for your vehicle. Review items 1 – 13, fill in
the applicable points on each line, then refer to the application grid on the
next page for the Bendix compressor selections that can meet your vehicle’s
intended use. When completing the worksheet, if a particular entry is not
valid for your application, enter zero on that line. See the examples of how
to use this calculator at the end of the next page.

Vehicle Configuration

Points

1. Vehicle is equipped with bulk offloading or central tire inflation

(See Note 1)

2. For every axle (tractor & trailer – including lifts):

Add 1.0 point/axle 4

3. For each non-steerable lift axle (additional points):

Add 1.0 point/axle 4

4. For each steerable lift axle (additional points):
5. Tractor and/or trailer is equipped with air suspension

Add 0.5 points/axle 4
Add 0.5 points 4

Vocation Options (Select the description that best fits)
6. Vehicle is used as a city transit bus
7. Vehicle is used for pickup & delivery

(See Note 1)

a) Non-fuel hauler:
add 0.5 points 4
b) Fuel hauler:
add 1.0 point 4

8. Vehicle is used for residential refuse

9.

• Vehicle with a work brake

Add 4.5 points 4

• Vehicle without a work brake

Add 7.5 points 4

Vehicle is used for rural or commercial refuse

Add 3.5 points 4

10. Vehicle is used as a yard or terminal jockey

Add 7.5 points 4

11. Vehicle is a dump truck, a concrete mixer, or is used in
logging or construction

Add 2.0 points 4

12. Vehicle is a fire truck -- “Fast Fill” system (See Note 2)

Add 6.0 points 4

13. Vehicle is used for line haul

Add 0.0 points 4

0

Total Score

(Add lines 1 – 13 and use that sum on page two of this guide)

Note 1: Vehicles equipped with either bulk offloading, central tire inflation or used in City Transit bus applications are required to use a 720cc
compressor. No points need to be calculated. Refer to next page for proper compressor selection.
Note 2: It is recommended that a 720cc compressor be used on all Fire Truck and Aircraft Rescue applications to reduce the complexity of the “Fast
Fill” system.

36

Appendix E
Increasing Performance

Compressor Application

Point
Total

360cc Single

School Bus / RV / Air over Hydraulic

any

a

City Transit Bus / Highway Travel Coach / Express Route
Coach

any

School Bus Rural Route (No Auto Brake)

any

School Bus City Route (No Auto Brake)

any

a
a
a
a

2.5 - 9

Pick-up & Delivery

Furniture

a

9.5 -13

a
a

3-6
6.5 - 9

Line Haul

a

9.5 - 13

Dump

Rural or Commercial Refuse

6.5 - 9

Rural or Commercial Refuse / Yard or Terminal Jockey

9.5 - 13

Residential Refuse (with Work Brake)

6.5 - 9

Residential Refuse (without Work Brake)

9.5 - 13

a
a
a
a
a

4-9

Concrete Mixer / Dump Truck /
Off-Highway / Construction / Logger

a

9.5 - 13

a

6.5 - 9

Fire Trucks

a
a
a

9.5 - 13

Bulk Off-loader

any

Central Tire Inflation

any

720cc Dual

This compressor application matrix offers directional information when sizing a Bendix compressor for the applicable vehicle vocation.
Testing should still be performed on the specific application to verify that the compressor remains within the 25% maximum allowable
duty cycle. This application matrix assumes that all compressor installations use an air induction system that is naturally aspirated.
The “Compressor Installation & Application Review” form explains the methods used to measure the vehicle’s duty cycle.

Compressor
Selections

Point Totals

Bendix® 360cc
compressor
Bendix® 720cc
compressor
Points 2.5

3

4

5

6

6.5

7

8

9

9.5

10

11

12

13

14

15

16 or above

Certification to all applicable vehicle regulations is the sole responsibility of the vehicle manufacturer.
The application chart is for reference only. If your truck/tractor does not fall into these guidelines, please contact the
Bendix Compressor Engineering or Technical Services team at 1-800-AIR-BRAKE (1-800-247-2725, option 2).

37

Appendix E
Example #1: Typical Line Haul Application
Vehicle Configuration
1. Not Applicable
2. Total number of all axles 	
3. Total number of non-steerable lift axles 	
4. Total number of steerable lift axles 	
5. Tractor is equipped with air suspension 	

=	 3	
=	 0	
=	 0	
=	 .5	

points
points
points
point

Vocation Options
6, 7, 8, 9, 10, 11, 12 (Not Applicable) 	

=	

0	 points

Total [ 3 + 0.5 = 3.5 points ]

A typical single axle, line haul vehicle:
• Air suspension
• Three (3) axles total

Selection: Bendix® 360cc Air Compressors
Example #2: Line Haul Pulling Single Axle Double
Vehicle Configuration
1. Not Applicable
2. Total number of all axles 	
3. Total number of non-steerable lift axles 	
4. Total number of steerable lift axles 	
5. Tractor is equipped with air suspension 	

=	 5	
=	 0	
=	 0	
=	 .5	

points
points
points
point

Vocation Options
6, 7, 8, 9, 10, 11, 12 (Not Applicable) 	

=	

0	 points

Total [ 5 + 0.5 = 5.5 points ]

A 4x2 line haul vehicle pulling:
• (2) single axle trailers
• (1) single axle dolly
• Tractor air suspension
• Five (5) axles total

Selection: Bendix 360cc Air Compressors
Example #3: Bulk Gravel Hauler
Vehicle Configuration
1. Not Applicable
2. Total number of all axles 	
3. Total number of non-steerable lift axles 	
4. Total number of steerable lift axles 	
5. Tractor is equipped with air suspension 	

=	 7	
=	 2	
=	 0	
=	 .5	

points
points
points
point

Vocation Options
6, 7, 8, 9, 10, 12, 13 (Not Applicable) 	
=	 0	 points
11 (Vehicle is used as a dump truck/construction) 	=	 2	 points
Total [ 7 + 2 + 0.5 + 2 = 11.5 points ]
Selection: Bendix® 720cc Air Compressors

A bulk gravel hauling vehicle:
• Two (2) non-steerable lift axles
• Truck equipped with air suspension
• Seven (7) axles total

Example #4: Fuel Hauler (Not Equipped with Bulk Offloading)
Vehicle Configuration
1. Not Applicable
2. Total number of all axles 	
3. Total number of non-steerable lift axles 	
4. Total number of steerable lift axles 	
5. Tractor is equipped with air suspension 	

=	
=	
=	
=	

7	
1	
0	
.5	

points
point
points
points

Vocation Options
6 (Vehicle is used as a fuel hauler)	
=	 1	 point
7, 8, 9, 10, 11, 12, 13 (Not Applicable) 	
=	 0	 points
Total [ 7 + 1 + 0.5 + 1 = 9.5 points ]
Selection choices include: Bendix® BA-922® Air Compressor

38

A fuel delivery vehicle:
• Air suspension
• One (1) non-steerable lift axle
• Seven (7) axles total

39

Log-on and Learn from the Best

On-line training that's available when you are
Visit www.brake-school.com.

24/7/365.

BW2830 © 2014 Bendix Commercial Vehicle Systems LLC, a member of Knorr-Bremse Group • 9/2014 • All rights reserved.

40

Printed on recycled paper



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