DURAFLO 596 COMPRESSOR 10/04
®
Bendix® DuraFlo™ 596 Air Compressor
SD-01-670
DISCHARGE
VALVE
VALVE BODY
ASSY.
PISTON
PISTON RINGS
CRANKSHAFT
DISCHARGE
VALVE
HOLDER
CONNECTING
ROD
CYLINDER
HEAD
CRANKCASE
CYLINDER
HEAD
VALVE BODY
ASSEMBLY
UNLOADER
PORT
CRANKCASE
WATER
INLET
PORT (2)
DISCHARGE
SAFETY VALVE
WATER
OUTLET
PORT (1)
REAR END
COVER OIL
PORT
CRANKCASE
BOTTOM
COVER (2)
DESCRIPTION
The function of the air compressor is to provide and maintain air under pressure to operate devices in the air brake
and/or auxiliary air systems. The DuraFlo™ 596 compressor
is a two cylinder reciprocating compressor with a rated displacement of 27 cubic feet per minute at 1250 RPM.
The compressor consists of a water cooled cylinder head
and valve body assembly and an air cooled integral
crankcase and cylinder block. The cylinder head is an
aluminum casting which contains the required air and water
ports as well as inlet check valves for each cylinder. The
valve body assembly consists of steel upper and lower
halves, each of which incorporate various valve openings
and channels for conducting air and engine coolant into
and out of the cylinder head. The discharge valves for
each cylinder are part of the valve body assembly. The
valve body assembly is secured to the cylinder head
DISCHARGE
VALVE HOLDER
DISCHARGE
VALVE
DISCHARGE
PORTS (2)
CYLINDER
BORE
PISTON
DISCHARGE
CAVITY
VIEW OF CYINDER HEAD AND ONE CYLINDER BORE
FIGURE 1 - DURAFLO™ 596 AIR COMPRESSOR
1
DETROIT DIESEL CATERPILLAR
FIGURE 2 - TYPICAL COMPRESSOR DRIVE FLANGES
assembly using two cap screws and the cylinder head is
secured to the cylinder block with six cap screws. The
cylinder head, with the valve body halves comprise a
complete cylinder head assembly.
The cast iron crankcase and cylinder block assembly, houses
the pistons, connecting rods, crankshaft and related
bearings. Unloader plungers and related seals and springs
are contained in bores in the cylinder block. Sliding inlet
valves and their pivot arms are sandwiched between the
cylinder block and valve body assembly.
The DuraFlo™ 596 compressor incorporates an unloader
system that features an energy saving system or ESS which
reduces compressor power consumption by approximately
80% in the unloaded mode. The ESS also reduces
compressor oil consumption (oil passing) when the
compressor is in the unloaded mode.
A nameplate identifying the compressor piece number and
serial number is attached to the end of the cylinder block
opposite the drive end.
OPERATION
The compressor is driven by the vehicle engine and functions continuously while the engine is in operation. Actual
compression of air is controlled by the compressor unloading mechanism operating in conjunction with a remote
mounted governor and synchro valve. Unlike the Tu-Flo
compressor series, the DuraFlo™ compressor requires the
addition of a synchro valve to assure proper operation and
service life. The governor and synchro valve combination
maintains brake system air pressure between a preset maximum and minimum pressure level. Refer to Figure 3.
The compressor has a built in unloading and ESS or
Energy Saving System.
®
AIR
DRYER
DURAFLO
COMPRESSOR
FIGURE 3 - DURAFLO™ 596 AIR COMPRESSOR UNLOADER SYSTEM
2
SYNCHRO VALVE
GOVERNOR
™
596
DELIVERY
TO
COMPRESSOR
UNLOADERS
TO AIR
DRYER
SUPPLY
RESERVOIR
SUPPLY
SYNCHRO
VALVE
CONTROL
FROM
SUPPLY
RESERVOIR
GOVERNOR
(110 CUTIN 130
CUTOUT)
FROM
SUPPLY
RESERVOIR
AIR
INLET
PORT
ESS
CHAMBER
INLET
VALV E
OPEN
INLET CHECK
VALVE OPEN
PISTON
MOVING
DOWN
AIR
DISCHARGE
PORT
DISCHARGE
VALV E
CLOSED
UNLOADER
PISTON
FIGURE 4 - OPERATIONAL-LOADED (INTAKE)
AIR INTAKE (LOADED)
The piston strokes are 180 degrees opposed. As one piston
is on an up stroke the opposing piston is on a down stroke.
During the piston down stroke, a vacuum is created in the
cylinder and ESS chamber within the cylinder head. The
vacuum causes the inlet check valve and sliding inlet valve
to flex open. Atmospheric air flows through the open inlet
check valve into and through the ESS chamber to the sliding inlet valve. Air flowing past the sliding inlet valve fills the
cylinder above the piston. See Figures 4 & 7.
AIR
INLET
PORT
ESS
CHAMBER
INLET
VALV E
CLOSED
INLET CHECK
VALVE CLOSED
AIR
DISCHARGE
PORT
DISCHARGE
VALV E
OPEN
pressure the discharge valves open and air flows into the
discharge line and air brake system.
NON-COMPRESSION OF AIR (UNLOADED)
When air pressure in the supply reservoir reaches the cutout setting of the governor, the governor delivers system
air to the control port of the synchro valve. The synchro
valve opens in response to control pressure from the governor and delivers system pressure to either of the two
compressor unloader ports. Air entering the unloader port
acts on one unloader plunger directly and is simultaneously
conducted through a passage in the valve body assembly
to the other unloader plunger.
The unloader plungers move horizontally in their bores in
response to control pressure from the governor and synchro valve. A guide pin in the unloader plunger rotates the
pivot arm which causes the inlet valve to slide. As the
inlet valve slides from the loaded to the unloaded position
it blocks the two discharge ports and opens the six inlet
ports connecting the cylinder bore to the ESS chamber.
When the piston travels upward, air in the cylinder is
trapped between the top of the piston and the closed inlet
check valve and is compressed. The intake check valves
prevent the intake air from escaping through the air intake
port when the compressor is in the unloaded ESS mode.
See Figures 5 & 7.
AIR
INLET
PORT
ESS
CHAMBER
INLET
VALV E
OPEN
INLET CHECK
VALVE CLOSED
AIR
DISCHARGE
PORT
DISCHARGE
VALV E
CLOSED
UNLOADER
PISTON
PISTON
MOVING
UP
FIGURE 5 - OPERATIONAL-LOADED (COMPRESSION)
AIR COMPRESSION (LOADED)
When the piston reaches approximately bottom dead center (BDC) the inlet check valve and sliding inlet valve close.
Air above the piston is trapped by the closed inlet valve
and is compressed as the piston begins to move toward
top dead center (TDC). When air in the cylinder bore
reaches a pressure greater than that of the system
UNLOADER
PISTON & PIVOT
PISTON MOVING
UP & DOWN
ARM SLIDES INLET
VALVE OVER
FIGURE 6 - OPERATIONAL-UNLOADED
The added volume of the ESS chamber lowers the amount
of compression. Air that is compressed during the upward
movement of the piston provides a driving force for the piston during its downward movement. As one piston is moving
downward the opposing piston is moving up. With the exception of losses in the form of heat, which is formed during
compression, the energy used to compress the air will be
reused as the driving force for the downward stroke of the
piston. This results in the compressor using very little power
in its unloading position. See Figures 6 & 7.
3
DISCHARGE
VALVE
INLET PORTS
air dryer is not used to remove these contaminants prior to
entering the air system, the majority, but not all, will condense in the reservoirs. The quantity of contaminants that
reach the air system depends on several factors including
installation, maintenance and contaminant handling devices
in the system. These contaminants must either be eliminated prior to entering the air system or after they enter.
DISCHARGE PORTS
CYLINDER HEAD SIDE OF VALVE BODY ASSY.
DISCHARGE
PORTS
COMPRESSOR LOADED COMPRESSOR UNLOADED
CYLINDER BLOCK SIDE OF VALVE BODY ASSY.
UNLOADER
PORT
UNLOADER AIR
PASSAGE
PIVOT
ARM
SLIDING
INLET VALVE
FIGURE 7 - UNLOADER MECHANISM
SLIDING INLET
VALVES
PIVOT
ARMS
UNLOADER
PLUNGER
GUIDE PIN
INLET
PORTS
COMPRESSOR & THE AIR BRAKE SYSTEM
GENERAL
The compressor is part of the total air brake system, more
specifically, the charging portion of the air brake system. As
a component in the overall system its condition, duty cycle,
proper installation and operation will directly affect other
components in the 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,
lubricated by the engine oil supply and has its inlet connected to the engine induction system.
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. If an
DUTY CYCLE
The duty cycle is the ratio of time the compressor spends
building air to the total engine running time. Air 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 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.
Refer to Table A in the Troubleshooting section for a guide to
various duty cycles and the consideration that must be given
to maintenance of other components.
COMPRESSOR INSTALLATION
While the original compressor installation is usually completed by the vehicle manufacturer, conditions of operation
and maintenance may require additional consideration. The
following presents base guidelines.
DISCHARGE LINE
The discharge line allows the air, water-vapor and oil-vapor
mixture to cool between the compressor and air dryer or
reservoir. The typical size of a vehicle's discharge line, (see
column 2 of Table A in the Troubleshooting section) 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.
The discharge line must maintain a constant slope down
from the compressor to the air dryer inlet fitting or reservoir
to avoid low points where ice may form and block the flow. If,
instead, ice blockages occur at the air dryer or reservoir
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. Shorter discharge line lengths or insulation may be required in cold climates.
While not all compressors and charging systems are
equipped with a discharge line safety valve this component
is recommended. The discharge line safety valve is installed
in the cylinder head or close to the compressor discharge
port and protects against over pressurizing the compressor
in the event of a discharge line freezeup.
4
Discharge
Line
Optional “Ping” Tank
Air Dryer
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.
Compressor
Governor
(Governor plus Synchro valve
for the Bendix
FIGURE 8A - SYSTEM DRAWING
THREAD
FIGURE 8B - DISCHARGE LINE SAFETY VALVE
®
DuraFlo™ 596
Compressor)
HOLE
DISCHARGE LINE TEMPERATURE
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 oilvapor 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 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.
Optional Bendix® PuraGuard® QC
™
Oil Coalescing Filter
Service Reservoir
(Supply Reservoir)
Reservoir Drain
For vehicles with accessories that are sensitive to small
amounts of oil, we recommend installation of a Bendix
PuraGuard® QC™ oil coalescing filter, designed to minimize
the amount of oil present.
LUBRICATION
The vehicle's engine provides a continuous supply of oil to
the compressor. Oil is routed from the engine to the compressor oil inlet. An oil passage in the crankshaft conducts
pressurized oil to precision sleeve main bearings and to the
connecting rod bearings. Spray lubrication of the cylinder
bores, connecting rod wrist pin bushings, and ball type main
bearings 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 drain holes in the compressor mounting
flange.
COOLING
Air flowing through the engine compartment from the action
of the engine fan and the movement of the vehicle assists in
cooling the compressor. Cooling fins are part of the crankcase/cylinder block casting. Coolant flowing from the engine
cooling system through connecting lines enters the head
and passes through internal passages in the cylinder head
and is returned to the engine. Proper cooling is important in
maintaining discharge air temperatures below the maximum
recommended 400 degrees Fahrenheit. Figure 9 illustrates
the various approved coolant flow connections. See the tabulated technical data in the back of this manual for specific
requirements.
®
5
AIR INDUCTION
The DuraFlo™ 596 compressor is approved for natural aspiration only. The compressor inlet is connected to the
vacuum side of the engine air induction system. See the
tabulated technical data in the back of this manual for specific requirements.
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. 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 it if necessary.
PREVENTATIVE MAINTENANCE
Regularly scheduled maintenance is the single most important factor in maintaining the air brake charging system.
Refer to Table A in the Troubleshooting section for a guide to
various considerations that must be given to the maintenance of the compressor and other related charging system
components.
Important Note: Review the warranty policy before performing any intrusive maintenance procedures. An extended
warranty may be voided if intrusive maintenance is performed
during this period.
AIR INDUCTION
One of the single most important aspects of compressor
preventive maintenance is the induction of clean air. Since
the DuraFlo™ 596 is connected to the engine air cleaner,
proper periodic maintenance of the engine air filter eliminates
the need for separate filter maintenance.
Inspect the compressor intake adapter, and the connecting
hoses each time engine air cleaner maintenance is
performed.
x
13
13 x 85mm
CYL. BOLT
(6)
60mm
CYL. BOLT (2)
LIFTING
LUG
DISCHARGE
PORT
EVERY 6 MONTHS, 1800 OPERATING HOURS
OR AFTER EACH 50,000 MILES WHICHEVER OCCURS FIRST PERFORM THE FOLLOWING
INSPECTIONS AND TESTS.
COMPRESSOR COOLING
Inspect the compressor discharge port, inlet cavity and
discharge line for evidence of restrictions and carboning.
If excessive buildup is noted, thoroughly clean or replace
the affected parts. Since carbon buildup generally 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" 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. Carefully inspect the
air induction system for restrictions.
LUBRICATION
Check the external oil supply line for kinks, bends, or restrictions to flow.
I.D.
Refer to the tabulated technical data in the back of this
manual for oil pressure minimum values.
Check the exterior of the compressor for the presence of oil
seepage and refer to the TROUBLESHOOTING section for
appropriate tests and corrective action.
OIL PASSING
Supply lines must be a minimum of 3/16"
COOLANT
IN OR OUT
(ONE OR THE
OTHER
)
PLUGGED
CYLINDER HEAD PORT IDENTIFICATION
The cylinder head connection ports are identified with cast
in numerals as follows:
FIGURE 9 - TYPICAL DURAFLO™ 596 AIR COMPRESSOR
CYLINDER HEAD
6
DISCHARGE
SAFETY VALVE
Atmospheric AIR IN 0
Compressed AIR OUT 2
Coolant IN 91
Coolant Out 92
INLET
PORT
COOLANT
IN
OR
OUT
All reciprocating compressors currently manufactured will
pass a minimal amount of oil. Air dryers will remove the
majority of oil prior to entrance into the air brake system.
For particularly oil sensitive systems the Bendix® PuraGuard
QC™ oil coalescing filter can be used in conjunction with a
Bendix air dryer.
If compressor oil passing is suspected, refer to the
TROUBLESHOOTING section and TABLE A for the symptoms and corrective action to be taken. In addition, Bendix
has developed the "Bendix Air System Inspection Cup" or
BASIC test to help substantiate suspected excessive oil
passing. The steps to be followed when using the BASIC
test are presented in APPENDIX A at the end of the
TROUBLESHOOTING section.
COMPRESSOR DRIVE
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 and proper
unloader mechanism operation. Repair or replace parts as
necessary.
COMPRESSOR & GOVERNOR UNLOADER
SYSTEM
Test and inspect the compressor and governor unloader
system for proper operation and pressure setting.
1. Make certain the unloader system contains both the
governor and synchro valve as illustrated in figure 3.
2. Cycle the compressor through the loaded and unloaded
cycle several times. Make certain that the governor
cuts out at 130 psi (cut in should be approximately 110
psi). Adjust or replace the governor as required.
3. Note that the DuraFlo™ compressor cycles to the loaded
and unloaded conditions promptly. This can be definitely
confirmed by installing a test gauge in the unused
unloader port on the compressor and observing the reaction during transition from the loaded and unloaded
condition. Air pressure should be applied and exhausted
with a distinct “snap action” with no appreciable lag for
buildup or release of pressure. If prompt action is not
noted, repair or replace the synchro valve.
SERVICE TESTS
GENERAL
The following compressor operating and leakage tests need
not be performed on a regular basis. These tests should
be performed when; it is suspected that leakage is substantially affecting compressor buildup performance, or
when it is suspected that the compressor is “cycling”
between the load and unloaded modes due to unloader
plunger leakage.
OPERATING TESTS
Compressor Performance
Vehicles manufactured after the effective date of FMVSS
121 must have a compressor capable of raising air system pressure from 85-100 psi in 25 seconds or less, with
the minimum required reservoir volume for the vehicle.
This test is performed with the engine operating at maximum recommended governed speed. The vehicle
manufacturer must certify this performance on new vehicles
with appropriate allowances for air systems with greater than
the minimum required reservoir volume. As a less severe
alternative to running a high RPM test, a new compressor's
buildup time can be measured and recorded at high idle.
Subsequent testing throughout the compressor’s service life
can be compared to the base line new compressor performance. Compressor buildup times should be recorded and
kept with the vehicle maintenance files for reference. When
testing compressor buildup times it is essential that air system leakage be kept below the allowed maximum for the
vehicle type being tested. Before running buildup tests check
the service and supply systems for excessive leakage and
repair as necessary.
Note: Supply system leakage is
on the vehicle dash gauges and must be tested
separately. Supply system components such
as the governor, synchro valve, air dyer, reservoir drain cocks, safety valve and check valves
can leak without indication on the dash gauges.
These components must be checked for leakage separately and individually. Refer to the
various maintenance manuals for individual
component leakage tests and the Bendix “Test
and Checklist” published in the Air Brake System Handbook (BW5057) for air system leakage
testing.
not displayed
LEAKAGE TESTS
Cylinder Head
Check for cylinder head gasket air leakage.
1. With the engine running, lower air system pressure to
60 psi and apply a soap solution around the cylinder
head. Check the gasket between the cylinder head and
valve body assembly and the gasket between the valve
body assembly and cylinder block for air leakage.
2. No leakage is permitted. If leakage is detected replace
the compressor or repair the cylinder head using a
genuine Bendix maintenance kit available from authorized Bendix parts outlets.
Inlet, Discharge & Unloader
While it is possible to test for inlet, discharge, and unloader
plunger leakage it requires disassembly of the cylinder head
to accomplish. For this reason it is not recommended.
Inlet and discharge valve leakage can generally be detected
by longer compressor buildup and recovery times. Compare
current compressor buildup times with the last several recorded times. Make certain to test for Air system leakage,
as described under Operating Tests, before making a determination that performance has been lost.
7
CYLINDER
HEAD
FLANGE
MOUNT
25
41
19
2
26
1
9
10
9
10
11
12
11
12
VALVE BODY
ASSY.
7
6
7
6
5
4
3
5
4
3
8
14
15
16
13
17
18
CRANKCASE
&
CYLINDER
BLOCK
21
23
24
22
20
31
27
END COVER
29
30
28
Item Qty. Description Item Qty. Description Item Qty Description
1 6 13mm x 85mm Bolt 12 2 Discharge Valve 23 2 Backup Ring
2 2 13mm x 60mm Bolt 13 2 Sliding Inlet Vlv 24 2 Spring
3 2 10mm x 25mm Bolt 14 2 Pivot Arm 25 6 13mm Washer
4 2 Spacer Sleeve 15 2 Stud 26 1 Discharge Safety Valve
5 2 Holder 16 2 Guide Pin 27 2 Base Plate Gskt.
6 2 Inlet Check Valve 17 2 Guide Pin 28 8 Base Plate Cap Screw
7 2 Seat 18 1 Vlv. Assy. to Block Gskt. 29 2 Base Plate
8 1 Head to Vlv. Assy. Gskt. 19 1 Plug 30 1 End Cover O-Ring
9 4 10mm x 25mm Bolt 20 1 Sealing Washer 31 4 13mm x 20mm Bolt
10 4 Spacer Sleeve 21 2 Unloader Plunger
11 2 Holder 22 2 O-Ring
™
FIGURE 10 - DURAFLO
596 AIR COMPRESSOR EXPLODED VIEW OF SERVICEABLE PARTS
8
1. With the engine running, lower air system pressure to
90 psi and raise engine RPM to 1800. Measure and
record the time required to raise system pressure from
100 psi to 130 psi. Run this test three times and use
the average time.
Note: This test should be run with the engine and
air system at normal operating temperature (i.e. not
cold).
2. Compare the average time recorded in step 2 with previously recorded build up times to evaluate compressor
performance.
Unloader leakage is exhibited by excessive compressor
cycling between the loaded and unloaded condition.
1. With service and supply system leakage below the
maximum allowable limits and the vehicle parked, bring
system pressure to governor cutout and allow the
engine to idle.
2. The compressor should remain unloaded for a minimum
of 5-10 minutes. If compressor cycling occurs more frequently and service and supply system leakage is within
tolerance replace the compressor or repair the compressor unloader system using a genuine Bendix
maintenance kit available from authorized
Bendix parts outlets.
COMPRESSOR REMOVAL & DISASSEMBLY
GENERAL
The following disassembly and assembly procedure is presented for reference purposes and presupposes 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
Cylinder Head Maintenance Kit.
Unloader Maintenance Kit.
All components shown in Figure 10 with a key number are
available in kits and/or as individual service parts.
COMPRESSOR TROUBLESHOOTING
IMPORTANT: The troubleshooting contained in this section
considers the compressor as an integrated component of
the overall air brake charging system and assumes that an
air dryer is in use. The troubleshooting presented will cover
not only the compressor itself, but also other charging
system devices as they relate to the compressor.
WARNING! PLEASE READ AND FOLLOW
THESE INSTRUCTIONS TO AVOID
PERSONAL INJURY OR DEATH:
When working on or around a vehicle, the following
general precautions should be observed at all times.
1. Park the vehicle on a level surface, apply the
parking brakes, and always block the wheels.
Always wear safety glasses.
2. Stop the engine and remove ignition key when
working under or around the vehicle. When
working in the engine compartment, the engine
should be shut off and the ignition key should be
removed. Where circumstances require that the
engine be in operation,
be used to prevent personal injury resulting from
contact with moving, rotating, leaking, heated or
electrically charged components.
3. Do not attempt to install, remove, disassemble or
assemble a component until you have read and
thoroughly understand the recommended
procedures. Use only the proper tools and observe
all precautions pertaining to use of those tools.
4. If the work is being performed on the vehicle’s air
brake system, or any auxiliary pressurized air
systems, make certain to drain the air pressure
from all reservoirs before beginning ANY work on
the vehicle. If the vehicle is equipped with an
AD-IS™ air dryer system or a dryer reservoir module,
be sure to drain the purge reservoir.
5. Following the vehicle manufacturer’s
recommended procedures, deactivate the electrical
system in a manner that safely removes all electrical
power from the vehicle.
6. Never exceed manufacturer’s recommended
pressures.
7. Never connect or disconnect a hose or line
containing pressure; it may whip. Never remove a
component or plug unless you are certain all
system pressure has been depleted.
8. Use only genuine Bendix® replacement parts,
components and kits. Replacement hardware,
tubing, hose, fittings, etc. must be of equivalent
size, type and strength as original equipment and
be designed specifically for such applications and
systems.
9. Components with stripped threads or damaged
parts should be replaced rather than repaired. Do
not attempt repairs requiring machining or welding
unless specifically stated and approved by the
vehicle and component manufacturer.
10. Prior to returning the vehicle to service, make
certain all components and systems are restored to
their proper operating condition.
11. For vehicles with Antilock 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.
EXTREME CAUTION should
9
REMOVAL
These instructions are general and are intended to be a guide.
In some cases additional preparations and precautions are
necessary. In all cases follow 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 and inlet fittings, if applicable, and
note their position on the compressor to aid in reassembly.
Note: If a cylinder head or unloader maintenance kit
is being installed, stop here and proceed to PREPARATION FOR DISASSEMBLY. If replacing the
compressor continue.
5. Remove any supporting bracketing attached to the
compressor and note their positions on the
compressor to aid in reassembly.
6. Remove the flange mounting bolts and remove the
compressor from the vehicle.
7. Inspect gear and associated drive parts for visible wear
or damage. Since these parts are precision fitted,
they must be replaced if they are worn or damaged. If
replacing the compressor or replacing the drive gear,
remove the drive gear from the compressor crankshaft using a gear puller.
8. If the compressor is being replaced stop here and
proceed to "Installing The Compressor" at the end of
the assembly procedure.
PREPARATION FOR DISASSEMBLY
Remove the balance of road dirt and grease from the exterior of the compressor with a cleaning solvent. Before
the compressor is disassembled, the following items should
be marked to show their relationship when the compressor is assembled. Mark the rear end cover or end cover
adapter in relation to the crankcase. Mark the relationship
of the cylinder head to the valve body assembly and crankcase and cylinder block assembly.
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
and or replacement parts are available. Refer to Figure 10
during the entire disassembly and assembly procedure.
UNLOADER & INLET VALVE
1. Remove the discharge safety valve (26) from the cylinder head.
2. Remove the unloader port plug and sealing washer
(19 & 20).
3. Loosen but do not remove the two 13mm x 60mm bolts (2).
4. Remove the six 13mm x 85mm cylinder head bolts
and washers (1 & 25) and tap the head with a soft
mallet to break the gasket seal. Lift off the cylinder
head and valve body assembly off the cylinder block.
IMPORTANT NOTE: Do not attempt to separate the two
halves of the valve body assembly. Service replacements
and gaskets are not available.
5. Remove the metal gasket (18).
6. Remove both sliding inlet valves (13).
7. Remove both pivot arms (14) and pivot arm studs (15).
8. To remove spring tension from the unloader plunger guide
pin (16), insert a 1/4” brass dowel into one of the unloader plunger bore and depress the plunger (21) slightly.
While holding the plunger (21) depressed, remove the
plunger guide pin (16). Slowly extract the dowel rod from
the unloader bore until spring tension is relieved.
Note: As an alternative, to this procedure an appropriately sized nut or dowel rod can be placed in the unloader
bore and the plug (19) installed then removed after the
guide pin is removed.
9. Remove the unloader plunger (21), with its o-ring (22)
and backup ring (23) from the bore. Remove the unloader
spring (24).
10. Repeat steps 7 and 8 for the other unloader plunger.
11. Remove both pivot arm guide pins (17) from the
cylinder block.
DISCHARGE & INLET CHECK VALVES
1. Remove the two 13mm x 60mm cylinder head bolts
(2) and gently tap the head and valve body assembly
with a soft mallet to break the gasket seal. Separate
the cylinder head and valve body assembly.
IMPORTANT NOTE: Do not attempt to separate the two
halves of the valve body assembly. Service replacements
and gaskets are not available
2. Remove the gasket (8).
3. Turn the cylinder head over to expose the inlet check
valves and remove the 10mm x 25mm inlet check
valve bolt (3) that secures the inlet check valve components. Remove the spacer sleeve (4), holder (5),
check valve (6) and check valve seat (7).
4. Repeat step 3 for the second inlet check valve
assembly.
10
5. Remove the two 10mm x 25mm discharge valve bolts
(9) that secure the discharge check valve components.
Remove the spacer sleeve (10), holder (11) and discharge valve (12).
6. Repeat step 5 for the second discharge valve assembly.
OIL PASSAGES
Thoroughly clean all oil passages through the end cover or
end cover adapter. Inspect the passages with a wire to be
sure. Blow the loosened foreign matter out with air
pressure.
CRANKCASE COVER
1. Remove the four cap screws (28) securing the crankcase cover (29). Using a soft mallet, gently tap the
crankcase cover (29) to break the gasket seal. Scrape
off any gasket material (27) from the crankcase and
bottom cover or adapter.
2. Repeat step 1 for the second crankcase cover.
END COVER OR END COVER ADAPTER
1. Remove the cap screws (31) that secure the rear end
cover or end cover adapter to the crankcase.
Note: Some compressor models use four cap
screws while others use a combination of cap
screws and studs.
2. Remove the rear end cover or end cover adapter from the
crankcase. Remove the o-ring seal (30) from the end
cover if so equipped.
CLEANING OF PARTS
GENERAL
All parts should be cleaned in a good commercial grade of
solvent and dried prior to inspection.
CYLINDER HEAD
1. Carefully remove all gasket material adhering to the
cylinder head, valve body assembly and cylinder block.
Make certain not to deeply scratch or mar the gasket
surfaces. Pay particular attention to the gasket surfaces of the aluminum head.
2. Remove carbon deposits from the discharge and inlet
cavities of the cylinder head and valve body assembly. Make certain the inlet and discharge ports of the
valve body assembly are open and clear.
3. Remove rust and scale from the cooling cavities and
passages in the head and valve body assembly and
use shop air to clear debris from the passages.
4. Make certain the unloader air passages and coolant passages through the valve body are open and clear of
contamination.
5. Check the threads in all cylinder head ports for galling.
Minor chasing is permitted.
CYLINDER BLOCK UNLOADER BORES
Thoroughly clean the unloader bore on both sides of the
compressor cylinder block. Make certain not to scratch or
gouge the air pressure sealing surfaces of the bores
during the cleaning process.
INSPECTION OF PARTS
CYLINDER HEAD & VALVE BODY
1. Carefully inspect the cylinder head gasket surfaces for
deep gouges and nicks. If detected, the compressor
must be replaced.
2. Carefully inspect the valve body gasket surfaces for deep
gouges and nicks. Pay particular attention to the metal
gasket surface. A metal gasket (18) is used between
the valve body assembly and cylinder block. 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.
3. Inspect the cylinder head for cracks or damage. With
the cylinder head and head gasket secured to the valve
body, apply shop air pressure to one of the coolant ports
with all others plugged, and check for leakage by applying a soap solution to the exterior of the head. If leakage
is detected in the cylinder head casting, replace the
compressor.
END COVER OR END COVER ADAPTER
Check for cracks and external damage. Check the crankshaft
main bearing surface in the end cover or end cover adapter,
check for excessive wear and flat spots and replace the end
cover if necessary. Check for galling of the oil port threads
and replace the end cover or end cover adapter if necessary.
Minor thread chasing is permitted but do not “recut” the
threads if they are badly damaged.
CYLINDER BLOCK
1. Check the cylinder head gasket surface on the cylinder
block for nicks, gouges, and marring. A metal gasket is
used to seal the cylinder head to the cylinder block.
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.
11
ASSEMBLY
General Note: All torques specified in this manual are as-
sembly torques and typically can be expected to fall off
after assembly is accomplished.
initial assembly torques fall unless instructed otherwise. A
compiled listing of torque specifications is presented at
the end of this manual.
INCH POUNDS TO FOOT POUNDS
To convert inch pounds to foot pounds of torque, divide
inch pounds by 12.
Example:
FOOT POUNDS TO INCH POUNDS
To convert foot pounds to inch pounds of torque, multiply
foot pounds by 12.
Example: 1 Foot Pound
12 Inch Pounds
12
CRANKCASE COVER
1. Position one of the two crankcase cover gaskets (27) on
either the crankcase or crankcase cover and install the
crankcase cover (29) using the position marks made
prior to disassembly. Tighten the four cap screws (28),
securing the crankcase cover to a torque of 101-111
inch pounds for crankcase cover or cover in a crossing
pattern after first snugging all 4 screws.
2. Repeat this assembly for the second crankcase cover
(29).
CRANKCASE END COVER OR END COVER
ADAPTER
1. Install the end cover o-ring (30) on the crankcase end
cover.
2. Orient the crankcase end cover or end cover adapter
to the crankcase using the reference marks made during disassembly. Carefully install the end cover or end
cover adapter in the crankcase making certain not to
damage the crankshaft bearing surface in it.
3. Install the four 13mm x 20mm end cover or end cover
adapter bolts or studs (31) and tighten to 195 to 212
inch pounds.
CYLINDER HEAD INLET CHECK VALVES
1. Locate one of the two inlet check valve seats (7) and
note that one side is flat while the other has three protruding tabs around the bolt hole. Position one of the
two the inlet check valves (6) on the inlet check valve
seat (7) so that the three positioning and locating tabs
interlock with the corresponding tabs on the seat. When
properly fitted together, the valve (6) should lay flat against
the seat (7) and cover the slotted opening of the seat.
12
Do not re-torque after
= 1 Foot Pound
x 12 = 12 Inch Pounds
2. Locate one of the two inlet check valve holders (5). Place
the holder (5) on the inlet check valve (6) making certain that the three indentations around the bolt hole, on
the holder, interlock with the tabs on the inlet check
valve (5). When properly assembled the seat (7), valve
(6) and holder (5) should be parallel and interlocked.
3. Place the three components over one of the two slotted inlet openings in the cylinder head making certain
that the bolt holes in the components and head correspond.
4. Insert one of the two 10mm x 25mm bolts (3) through
a spacer sleeve (4). Using the bolt and sleeve, secure
the assembled seat (7), valve (6) and holder (5) in the
cylinder head. Tighten the bolt finger tight and check
that the seat (7), valve (6) and holder (5) are still interlocked. This can be done by attempting to rotate the
holder (5) and noting that the valve and seat follow
and are locked together.
5. Torque the 10mm bolt to 101 to 111 inch pounds.
6. Repeat steps one through five for the other inlet check
valve assembly.
DISCHARGE VALVES
1. Locate and place one of the two discharge valves (12)
on the valve body assembly with its bolt hole corresponding with the threaded hole on the outside edge
of the valve body assembly. When correctly placed,
the discharge valve (12) will cover the two discharge
holes in the valve body assembly. Refer to Figure 11.
Discharge Valve
Guide Lug
Discharge
Valve
FIGURE 11 - DISCHARGE VALVE INSTALLATION
2. Locate one of the two discharge valve holders (11) and
install it over the discharge valve (12) so that the free
end of the discharge valve (12) is contained between
the two guide lugs on the sides of the holder. Refer to
Figure 11.
3. Insert one of the four 10mm x 25mm bolts (9) through a
spacer sleeve (10). Using the bolt and sleeve, loosely
secure one end of the discharge valve (12) and holder
(11) to the valve body assembly. Insert a second 10mm
x 25mm bolts (9) through a spacer sleeve (10) and
loosely secure the other end of the discharge valve (12)
and holder (11) to the valve body assembly.
Before attempting to tighten the two 10mm bolts make
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