Bendix Tu Flo 400 500 1000 Air Compressor Manual de Usuario

®
SD-01-
Bendix® TU-FLO® 400, 500, 1000 Air Compressors
TU-FLO® 400 Air Compressor TU-FLO® 500 Air Compressor
TU-FLO® 1000 Air Compressor
1
DESCRIPTION AND OPERATION and they have no external moving parts. Both air and
water cooled type compressors are available. Various
GENERAL mounting and drive adaptations are used as required by
The function of the air compressor is to build up and different vehicle engine designs (Fig. 4).
maintain the air pressure required to operate air powered
devices in air brake or air auxiliary systems.
DESCRIPTION
Tu-Flo® Type 400, 500, and 1000 compressors are
single stage, reciprocating piston type compressors. Tu-
Flo® 400 (Fig. 1) and 500 (Fig. 2) compressors have two
cylinders while the Tu-Flo® 1000 compressor (Fig. 3) is a
V-type design having four cylinders. The rated capacity of
all Bendix compressors is their piston displacement in
cubic feet per minute when operating at 1,250 RPM. The
rated capacity of the Tu-Flo® 400 compressor is 7-1/4
cubic feet per minute. The Tu-Flo® 500 compressor is
rated at 12 cubic feet per minute and the Tu-Flo® 1000
compressor has a rating of 24 cubic feet per minute.
Tu-Flo® type compressors have automatic type inlet
valves. Their unloading mechanisms are located in the
cylinder block
FIGURE 1 - TU-FLO® 400 AIR COMPRESSOR FIGURE 3 - TU-FLO® 1000 AIR COMPRESSOR
FIGURE 2 - TU-FLO® 500 AIR COMPRESSOR
2
FIGURE 4 - VARIOUS COMPRESSOR
MOUNTINGS
Compressors are either engine or

self-lubricated. The majority used are
the engine lubricated types (Fig. 5)
which obtain the oil necessary to
lubricate their moving parts from the
engines on which they are mounted.
To meet the requirements of some
manufacturers and for field
installations, self-lubricated types (Fig.
6) are available. They are
compressors having a self-contained
oil supply and pumping system.
The method of lubricating the moving
parts of the compressor is the same in
either type. Oil is forced through the
oil passage in the crankshaft and out
around each connecting rod journal.
The turning motion of the crankshaft
throws the oil that is forced out at the
journals, against the cylinder bores
and crankcase walls, lubricating the
bores and crankshaft bearings.
The wrist pins and wrist pin bushings
are lubricated in two ways depending
upon the type connecting rods used.
Older design compressors had forged
steel rifle-drilled rods through which oil
was forced to the wrist pin bushings.
Later versions
3
OPERATION
GENERAL
All compressors run continuously while the engine is
running, but actual compression of air is controlled by a
governor, which stops or starts the compression of air by
FIGURE 5 FIGURE 6
loading or unloading the compressor in conjunction with
ENGINE LUBRICATED TYPE SELF-LUBRICATED its unloading mechanism. This is done when the air
TYPE pressure in the system reaches the desired maximum or
minimum pressures.
had either die cast aluminum, cast ductile iron, or forged
steel rods which were not rifle drilled but were drilled at
the top of the rod. The wrist pins and bushings are
lubricated by oil dripping from a drip-boss on the piston TO RESERVOIR INLETVALVE
into a “catch-funnel” at the top of the rod and through the UNLOADER PLUNGER
DISCHARGE VALVE
drilled passage to the bushings and pins. (SEE FIG. 7) PISTON
INTAKE STRAINER
TO GOVERNOR
PISTON WRIST PIN LOCK WIRE WRIST PIN BUSHING
CAST IRON PISTON

WRIST PIN STROKE
INTAKE
OIL PASSAGE
STEEL CONNECTING ROD FIGURE 9
OLD DESIGN
INTAKE AND COMPRESSION (Loaded)

“CATCH FUNNEL” During the down stroke of the piston, a slight vacuum
created above the piston causes the inlet valve to move
WRIST PIN BUSHING off its seat. Atmospheric air is drawn in through the
DIECAST PISTON compressor intake, by the open inlet valve, and on top of
the piston (Fig. 9). As the piston starts its upward stroke,
DIE CAST CONNECTING RODthe air that was drawn in on the down stroke is being
compressed. Now, air pressure on top of the inlet valve
NEWDESIGN
plus the force of its spring, returns the inlet valve to its
seat. The piston continues the upward stroke and
FIGURE 7- PISTONS & CONNECTING RODS compresses the air sufficiently to overcome the
discharge valve spring and unseat the discharge valve.
A nameplate is attached to the crankcase of all The compressed air then flows by the open discharge
compressors. It shows the piece number, type and serial valve, into the discharge line and on to the reservoirs
number (Fig. 8). A nameplate with a black background (Fig. 10).
denotes a new compressor, whereas a nameplate with a
red background designates that the compressor is a
factory reconditioned unit. All compressors are identified
by the piece number
TO RESERVOIR
which is the number to use when reference is made to a INLETVALVE
DISCHARGE
particular compressor. The type and serial number is VALVE UNLOADER
supplementary information. PLUNGER
PISTON
INTAKE
STRAINER
TO GOVERNOR
4
STROKE
COMPRESSION
FIGURE 8 - COMPRESSOR FIGURE 10
NAMEPLATE
5
As the piston reaches the top of its stroke and starts contaminants prior to
down, the discharge valve spring returns the discharge
valve to its seat. This prevents the compressed air in the
discharge line from returning to the cylinder bore as the
intake and compression cycle is repeated.
NON-COMPRESSION (Unloaded)
When the air pressure in the reservoir reaches the high
pressure setting of the governor, the governor opens,
allowing air to pass from the reservoir through the
governor and into the cavity beneath the unloader
pistons. This lifts the unloader pistons and plungers. The
plungers move up and hold the inlet valves off their seats
(Fig. 11).
TO RESERVOIR INLETVALVE
DISCHARGE VALVE UNLOADER PLUNGER
PISTON
INTAKE STRAINER
TO GOVERNOR
STROKE
UNLOADING
FIGURE 11
With the inlet valves held off their seats by the unloader
pistons and plungers, air is merely pumped back and
forth between the two cylinders. When air is used from
the reservoir and the pressure drops to the low pressure
setting of the governor, the governor closes, and in
doing so, exhausts the air from beneath the unloader
pistons. The unloader saddle spring forces the saddle,
pistons and plungers down and the inlet valves return to
their seats. Compression is then resumed.
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 air dryer is not used to remove these
6
entering the air system, the majority, but not all, will When the temperature of the compressed air that enters
condense in the reservoirs. The quantity of the air dryer is within the normal range, the air dryer can
contaminants that reach the air system depends remove most of the charging system oil. If the
on several factors including installation, temperature of the compressed air is above the normal
maintenance and contaminant handling devices in range, oil as oil- vapor is able to pass through the air
the system. These contaminants must either be dryer and into the air system. Larger diameter
eliminated prior to entering the air system or after discharge lines and/or longer
they enter. discharge line lengths can help reduce the temperature.
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.
DISCHARGE LINE TEMPERATURE
7
The Air Brake Charging System supplies the compressed
Optional Bendix® PuraGuard ® QC™

DischargeOptional “Ping” Tank Oil Coalescing Filter
LineAir Dryer
Compressor
Governor (Governor plus Synchro valve for the Bendix® DuraFlo™ 596
Compressor) Service Reservoir
(Supply Reservoir)
Reservoir Drain
FIGURE 12A - SYSTEM DRAWING
PREVENTIVE 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
HOLE
for a guide to various considerations that must be given to
the maintenance of the compressor and other related
charging system components.
If the compressor is a self-lubricated type, its oil level
should be checked daily. The oil level should be kept
between the bottom of the dipstick threads and the
THREAD bottom of the dipstick (Fig. 13). Every 8,000 miles or
300 operating hours, the oil should be drained and
FIGURE 12B - DISCHARGE LINE SAFETY VALVE refilled with SAE 10-20-30.
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 recommend installation of a Bendix ®
PuraGuard® QC™ oil coalescing filter, designed to
minimize the amount of oil present.
COOLING FIGURE 13 - OIL LEVEL - SELF-LUBRICATED
® COMPRESSOR
Tu-Flo 400, 500 or 1000 compressors may be air-cooled
or water- cooled and in some instances will have air-
POLYURETHANE SPONGE STRAINER (Fig. 14)
cooled blocks and water-cooled heads. The air-cooled
versions are easily recognized by the external fins. The Remove and wash all of the parts. The strainer element
water-cooled versions are cooled by vehicle coolant. should be cleaned or replaced. If the element is cleaned,
it should be washed in a commercial solvent or a
detergent and water solution. The element should be
saturated in clean engine oil, then squeezed dry before
replacing it in the strainer. Be sure to replace the air
8
strainer gasket if the entire air strainer is removed from
the compressor intake.
9
FIGURE 16 - COMPRESSOR INTAKE ADAPTER
FIGURE 14 - POLYURETHANE SPONGE STRAINER AIR LEAKAGE TESTS

Leakage past the discharge valves can be detected by
removing the discharge line, applying shop air back
through the discharge port and listening for escaping air.
Also the discharge valves and the unloader pistons can
be checked for leakage by building up the air system
until the governor cuts out, then stopping the engine. With
the engine stopped, carefully listen for escaping air at the
intake. To pinpoint leakage if noted, squirt oil around the
unloader pistons. If there is no noticeable leakage at the
unloader pistons, the discharge valves may be leaking.
If the compressor does not function as described above,
or leakage is excessive, it is recommended that it be
returned to the nearest Bendix authorized distributor for
a factory rebuilt compressor under the repair exchange
FIGURE 15 - DRY ELEMENT- PLEATED PAPER AIR plan. If this is not possible, the compressor can be
STRAINER repaired with genuine Bendix parts, in which case the
DRY ELEMENT - PLEATED PAPER AIR following information should prove helpful.
STRAINER (FIG. 15) REMOVING AND INSTALLING
Remove the spring clips from either side of mounting
REMOVING
baffle and remove the cover. Replace the pleated paper
These instructions are general and in some cases additional
filter and remount the cleaned cover making sure the
precautions must be taken.
filter is in position. Be sure to replace the air strainer
Drain air brake system.
gasket if the entire air strainer is removed from the If water-cooled type compressor, drain engine cooling
compressor intake. (NOTE: Some compressors are fitted system, compressor cylinder head and block.
with compressor intake adapters (Fig. 16) which allow the Disconnect all air lines, water and oil lines to and from
compressor intake to be connected to the engine air compressor.
cleaner.) In this case, the compressor receives a supply Remove compressor mounting bolts and compressor from
of clean air from the engine air cleaner. When the engine engine.
air filter is changed, the compressor intake adapter Use a gear-puller to remove the gear or pulley from
should be checked. If it is loose, remove the intake compressor crankshaft.
adapter, clean the strainer plate, if applicable, and INSTALLATION
replace the intake adapter gasket, and reinstall the
adapter securely. Check line connections both at the ENGINE-LUBRICATED TYPES
compressor intake adapter and at the engine air cleaner. Clean oil supply line. Before connecting this line to the
Inspect the connecting line for ruptures and replace it if compressor, run the engine briefly to be sure oil is
necessary. flowing freely through the supply line.
Clean the oil return line or return passages through the
brackets; these passages must be unrestricted so oil can
return to the engine.
1
Prelubricate compressor cylinder walls and bearings with and drain the air pressure from all the reservoirs in the
clean engine oil before assembling compressor. system.
Always use a new mounting gasket and be sure oil hole
in gasket and compressor is properly aligned with oil
supply line.
SELF-LUBRICATED TYPES
Fill compressor crankcase with clean engine oil before
operating compressor. Refer to “Tabulated Data” section
for proper amount.
ALL TYPES
Inspect pulley or gear and associated parts for wear or
damage. They must be a neat fit on compressor
crankshaft. Replace pulley or gear if worn or damaged.
Install pulley or gear on compressor crankshaft making
sure it properly contacts the shaft and does not ride the
key. Tighten crankshaft nut to 65-70 ft. lbs. and install
cotter pin.
Be sure the air cleaner is clean and properly installed. If
the compressor intake is connected to either the engine
air cleaner or supercharger, these connections must be
tight with no leakage.
Clean or replace any damaged or dirty air or water lines
which may be corroded, before connecting them to the
compressor. Use a new discharge fitting gasket.
Align compressor drive and adjust proper belt
tension. Tighten mounting bolts securely and evenly.
After installation, run compressor and check for air, oil,
or water leaks at compressor connections. Also check
for noisy operation.
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
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.
REMOVING AND DISASSEMBLY
REMOVING
These instructions are general and are intended to be a
guide. In some cases additional preparations and
precautions are necessary. Chock the wheels of the
vehicle
11
Drain the engine cooling system and the cylinder head of (NOTE: Before removing the connecting rods, mark
the compressor. Disconnect all air, water and oil lines each connecting rod and its cap. Each
leading to and from the compressor. Remove the drive connecting rod is matched to its own cap for
gear(s) or pulley from the compressor crankshaft using a proper bearing fit, and these parts must not be
gear puller. Inspect the pulley or gear and associated interchanged.)
parts for visible wear or damage. Since these parts are
precision fitted, they must be replaced if they are worn or
damaged.
DISASSEMBLY
GENERAL
Remove 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 both the front and rear
end cover in relation to the crankcase. Mark the drive
end of the crankshaft in relation to the front end cover
and the crankcase. Mark the cylinder head in relation to
the block and block to crankcase. Mark the base plate or
base adapter in relation to the 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 a marking method that can be wiped
off or obliterated during rebuilding, such as chalk.
Remove all compressor attachments such as governors,
air strainers or inlet fittings, discharge fittings and pipe
plugs.
CYLINDER HEAD
Remove the cylinder head cap screws and tap the head
with a soft mallet to break the gasket seal. Remove the
inlet valve springs form the head and inlet valves from
their guides in the block. Remove inlet valve guides from
around the inlet valve seats on the block, taking care not
to damage seats. Scrape off any gasket material from the
cylinder head and block. Unscrew the discharge cap
nuts from the head and remove the discharge valves and
springs. Inspect the discharge valve seats for nicks,
cracks, and excessive wear and remove and replace if
necessary.
The discharge valve cap nuts should be inspected for
wear and replaced if excessive peening has occurred.
To determine if excessive peening has occurred,
measure the discharge valve travel. Discharge valve travel
must not exceed
.056 in. for the Tu-Flo® 400 compressor and .046 in. for
the Tu-Flo® 500 and 1000 compressors.
CRANKCASE BASE PLATE OR ADAPTER

Remove the cap screws securing the base plate or base
adapter. Tap with soft mallet to break the gasket seal.
Scrape off any gasket material from crankcase and plate
or adapter.
CONNECTING ROD ASSEMBLIES
1
FIGURE 17 - TU-FLO® 400 AIR COMPRESSOR VERTICAL MOUNT - ENGINE LUBRICATED
Straighten the prongs of the connecting rod bolt lock set screw, then bushing and shim.
strap and remove the bolts and bearing caps. Push the
piston with the connecting rods attached out the top of the
cylinders of the crankcase. Replace the bearing caps on
their respective connecting rods. Remove the piston
rings from the pistons. If the pistons are to be removed
from the connecting rods, remove the wrist pin lock wires
or teflon plugs and press the wrist pins from the
pistons and connecting rods.
If the pistons are removed from the rod, inspect the
bronze wrist pin bushing. Press out and replace the
bushing if it is excessively worn. (See Inspection of
Parts.) Discard the piston rings and the connecting rod
journal bearings. Discard the wrist pin bushings if they
were removed. New Tu-Flo® 400 compressors
manufactured after approximately September 1977
will have connecting rods without bearing inserts. Repair
size rods will have inserts.
REMOVING AND DISASSEMBLING BASE PLATE
SELF-LUBRICATED TYPE COMPRESSORS (Fig. 18)
Remove screws that hold base plate. Remove base
plate. Remove oil relief valve set screw, then oil relief
valve.
Remove oil strainer retaining ring and lift out oil strainer.
Unless it is necessary, the oil pump piston bushing
should not be removed. If necessary, remove the bushing
13
FIGURE 18 - BASE PLATE SELF-LUBRICATED
TYPE COMPRESSOR
Remove cotter pin from oil rod cap nuts, remove

nuts, oil pump piston rod and cap.
CRANKCASE (Fig. 19)
Remove end cover with oil seal, remove end cover
gasket. Replace oil seal after cleaning end cover.
Remove cap screws that hold opposite end cover
to crankcase; remove end cover and its gasket.
Some compressors have crankcases that have a
shoulder for positioning the crankshaft. In these
cases the crankshaft must be removed through one
particular end.
1
Press the crankshaft and ball bearings from the
crankcase, then press ball bearings from crankshaft.
Many compressors will have sleeve-type bearings in the
crankcase or in the end cover. If the clearance between
crankshaft journal and bearing exceeds .0065 in. the
sleeve bearing should be replaced with appropriate
undersize.
FIGURE 20 - CYLINDER BLOCK - EXPLODED VIEW
FIGURE 19 - CRANKCASE - TU-FLO® 400 & 500 AIR

COMPRESSORS
FIGURE 19A - CRANKCASE - TU-FLO® 1000 AIR

COMPRESSOR
BLOCK (Fig. 20)

If compressor is fitted with an air strainer, inlet elbow or
governor, remove same.
Remove cap screws securing cylinder block to
crankcase; separate crankcase and cylinder block and
scrape off gasket.
Remove unloader spring, spring saddle and spring seat
from cylinder block.
Remove unloader guides and plungers and, with the use
of shop air, blow unloader pistons out of cylinder block
unloader piston bores.
Remove inlet valve guides; inlet valve seats can be
removed but only if they are worn or damaged and are
being replaced. Unloader bore bushings should be
inspected but not removed unless they are damaged.
15
CLEANING AND INSPECTION OF PARTS
CLEANING
All parts should be cleaned thoroughly in a good
cleaning solvent before inspection.
CYLINDER HEAD ASSEMBLY
Remove all carbon deposits from discharge cavities and
all rust and scale from cooling cavities of cylinder head
body. Scrape all foreign matter from body surfaces and
use air pressure to blow dirt particles from all cavities.
Discharge valves can be dressed by lapping them on a
piece of fine crocus cloth on a flat surface, provided they
are not excessively worn.
CYLINDER BLOCK
Clean carbon and dirt from inlet and unloader passages.
Use air pressure to blow carbon and dirt deposits from
unloader passages.
Inlet valves, as in the case of discharge valves, not worn
excessively, can be cleaned by lapping them on a piece
of fine crocus cloth on a flat surface.
OIL PASSAGE
Clean thoroughly all oil passages through crankshaft,
connecting rods, crankcase, end covers and base plate.
If necessary, inspect passages with a wire and blow
foreign matter out with air pressure.
CRANKCASE - SELF-LUBRICATED TYPE
The breather should be thoroughly washed and cleaned.
The oil pump check valve in the base should be
removed and replaced. It is important when the oil pump
check valve is replaced that it be installed correctly with
the ball stop pin end pressed in first. When installed, the
ball and its seat should be visible from the crankcase
base.
INSPECTION OF PARTS
CYLINDER HEAD BODY
Inspect cylinder head body for cracks or damage.
WATER-COO LED TYPE
Use air pressure to test water jackets of cylinder head
and block for leakage. Replace unit if leakage is found.
DISCHARGE VALVES AND SEATS
If discharge valves are worn and grooved where they
contact the seats, they should be replaced. If the
discharge valve seats are worn excessively so that there
is no longer enough metal left to reclaim them by lapping,
the seats should be replaced.
DISCHARGE VALVE SPRING AND CAP NUTS
Replace all used discharge valve springs and cap nuts.
1
CRANKCASE AND END COVERS Clearance between cast iron pistons and cylinder bores
Check for cracks or broken lugs in crankcase and end should be between 0.002 in. minimum and 0.004 in.
covers. Also check their oil passages to make sure they maximum (Fig. 21).
are open and clean. PISTONS
If an oil seal ring is used in the end cover, check fit of Check pistons for scores, cracks or enlarged ring
ring in ring groove. There should be 0.008 in. to 0.015 in. grooves; replace pistons if any of these conditions are
clearance at the gap when placed in the end bore of the found. Measure each piston with a micrometer in relation
crankshaft. If the oil ring is worn thin or is damaged, it to the cylinder bore diameter to be sure the clearance is
should be replaced. Inspect oil ring groove in end cover; between 0.002 in. minimum and 0.004 in. maximum.
if groove is worn excessively replace end cover or Check fit of wrist pins on pistons and connecting rod
machine groove for next oversize oil seal ring. bushings. Wrist pin should be a light press fit in pistons.
If the crankshaft main bearings are installed in the end If wrist pin is loose fit, the pin, piston, or both should be
cover, check for excessive wear and flat spots and replaced. Check fit of wrist pin in connecting rod bushing
replace if necessary. by rocking the piston. This clearance should not exceed
0.0015 in. Replace wrist pin bushings if excessive
CYLINDER BLOCK clearance is found. Wrist pin bushings should be
Check for cracks or broken lugs on cylinder block. Also reamed after being pressed into connecting rods.
check unloader bore bushings to be sure they are not Replace used wrist pin lock wires. Tu-Flo® 400
worn, rusted or damaged. If these bushings are to be compressors manufactured after September 1977 will
replaced they can be removed by running a 1/8 in. pipe have Teflon plugs in each end of the wrist pins instead of
thread tap inside the bushing, then inserting a 1/8 in. pipe the lock wire. The Teflon plugs (pc. no. 292392) may be
threaded rod and pulling the bushing straight up and out. used instead of the lock wires on all compressors. See
Do not use an easy-out for removing these bushings. Fig. 22.
INLET VALVES AND SEATS PISTON RINGS
If inlet valves are grooved or worn where they contact Check fit of piston rings in piston ring grooves. Check
the seat, they should be replaced. If the inlet valve seats ring gap with rings installed in cylinder bores. Refer to
are worn or damaged so they cannot be reclaimed by Fig. 24 for correct gap and groove clearance.
facing, they should be replaced.
All rings must be located in their proper ring grooves as
CYLINDER BORES shown. The rings can be identified by the width and
Cylinder bores which are scored or out of round by more should be installed with the bevel or the pipmark (if any)
than 0.002 in. or tapered more than 0.003 in. should be toward the top of the piston. This applies to cast iron
rebored or honed oversize. Oversize pistons are available pistons (only as shown above).
in 0.010, 0.020, and 0.030 oversizes. Die cast pistons use five (5) narrow rings.
Cylinder bores must be smooth, straight and round. COMPRESSION RINGS (2)
COMPRESSION RINGS (2)
FIGURE 22 - TU-FLO® 400 AIR COMPRESSOR NEW STYLE
FIGURE 21 - MEASURING CYLINDER BORES
17
TU-FLO® 400 AIR COMPRESSOR be checked for scores and wear and replaced if
CORRECT GROOVE CLEARANCE necessary.
.0015”
.0030”
CORRECT GAP CLEARANCE WITH RING IN CYLINDER
.0035”
.014”
FIGURE 23 - TU-FLO® 400 AIR COMPRESSOR OLD STYLE
TU-FLO® 500 & 1000 AIR COMPRESSOR

CORRECT GROOVE
CLEARANCE
NARROW
WIDE
.0035” .002”
.0035” .004”
CORRECT GAP CLEARANCE WITH RING IN CYLINDER
.0035” NARROW WIDE

.014”
FIGURE 24 - PISTON RING POSITIONS - GAPS AND

GROOVE CLEARANCE
CRANKSHAFT
Check crankshaft screw threads, keyways, tapered ends
and all machined and ground surfaces for wear, scores,
or damage. Crankshaft journals which are out of round
more than 0.001 in. must be reground. Bearing inserts are
available in 0.010 in., 0.020 in., and 0.030 in. undersizes
for reground crankshafts. Main bearing journals must be
maintained so bearings are snug fit. The oil seal ring
groove or grooves in crankshafts fitted with oil seal rings
must not be worn. The ring groove walls must have a
good finish and they must be square. Check to be sure
the oil passages are open and clean through the
crankshaft.
CONNECTING ROD BEARINGS
Check connecting rod bearings on crankshaft journals
for proper fit. Used bearing inserts should be replaced.
Connecting rod caps are not interchangeable. The
locking slots of the connecting rod and cap should be
positioned adjacent to each other.
Clearance between the connecting rod journal and the
connecting rod bearing must not be less than 0.0003 in.
or more than 0.0021 in. after rebuilding.
MAIN BEARINGS
Check for wear or flat spots; if found, bearings should be
replaced. If type with sleeve bearing, this bearing should
1
UNLOADER MECHANISM block to the inlet valve seat should not exceed 0.118 in.
Used unloader mechanism should be replaced by nor be less than
unloader kits 265014 for Type Tu-Flo® 400 compressors 0.101 in.
and 265015 for Types Tu-Flo® 500 and 1000
compressors. The Tu-Flo® 1000 compressor requires two
kits per compressor.
The new unloader pistons should be a loose sliding fit in
the unloader piston bores of the cylinder block.
PARTS SPECIAL TO SELF-LUBRICATED

TYPE COMPRESSORS
OIL PUMP SCREEN
Check oil pump screen to be sure it is clean and not
damaged; replace if damaged.
OIL PUMP PISTON AND BUSHING
Check fit of oil pump piston in base plate pump bushing.
It must be a medium sliding fit. If excessive clearance is
found, the oil rod and/or bushing must be replaced.
OIL PUMP RELIEF VALVE
If the oil pump relief valve is defective, it should be
replaced.
OIL PUMP CHECK VALVE
The check valve should be replaced. It can be checked
by applying air pressure back through the pin stop end
and noting that the ball check seals on its seat.
REPAIRS
DISCHARGE VALVES AND SEATS
If discharge valve seats merely show signs of slight
wear, they can be dressed by using a lapping stone,
grinding compound and grinding tool. Install new
discharge valves and valve springs.
To test for leakage by the discharge valves, apply about
100 pounds of air pressure through the cylinder head
discharge port and apply soap suds at the discharge
valves and seats. Leakage which will permit the
formation of bubbles is permissible.
If excessive leakage is found, leave the air pressure
applied, and with the use of a fibre or hardwood dowel
and hammer, tap the discharge valves off their seats
several times. This will help the valves to seat and
should reduce any leakage.
With the air pressure still applied at the discharge port of
the cylinder head, check for leakage at the discharge
valve cap nuts. No leakage is permissible.
INLET VALVES AND SEATS
If inlet valve seats show sign of slight nicks or scratches,
they can be redressed with a fine piece of emery cloth or
by lapping with a lapping stone, grinding compound and
grinding tool. If the seats are excessively damaged to the
extent that they cannot be reclaimed, they should be
replaced. The dimension from the top of the cylinder
19
Slightly worn or scratched inlet valves can be reclaimed Remove connecting bolts and bearing cap from one
by lapping them on a piece of fine crocus cloth on a flat connecting rod. Turn crankshaft so one of its connecting
surface, but it is suggested that new inlet valves be rod journals is in the downward, center position.
installed. Compress the rings with a ring compression tool and
insert the connecting rod with piston through the top of
ASSEMBLY the cylinder whose journal is down. Position and attach
INSTALLING CYLINDER BLOCK the bearing cap to the connecting rod, making sure the
Position cylinder block gasket and block on crankcase bolt lock washers are properly positioned on the cap.
Tighten connecting rod bolts evenly and bend the two
according to markings made prior to disassembly. Using
new lock washer prongs up against the hex head of the
cap screws with lock washers, secure cylinder block to
bolt. Install the other connecting rod and piston in the
crankcase.
same manner.
INSTALLING CRANKSHAFT
If the crankshaft is fitted with oil seal rings, install rings.
Position ball bearings and crankshaft in crankcase,
making sure the drive end of the crankshaft is positioned
as marked before disassembly.
If one end of the crankcase is counterbored for holding a
bearing, be sure the crankshaft is installed through the
correct end of the crankcase.
Carefully press crankshaft and bearings into crankcase
using arbor press.
Position a new rear end cover gasket, when used, over
the rear end of the crankcase, making sure the oil hole in FIGURE 25 - UNLOADER MECHANISM
the gasket lines up with the oil hole in the crankcase.
Position end cover with oil seal ring, if used, installed over UNLOADER MECHANISM (Fig. 25)
crankcase and end cover gasket. The end cover should The unloader pistons and their bores must be lubricated
be positioned correctly in relation to the oil holes in the with special lubricant piece number 239379 (dimethyl
gasket and crankcase. Secure end cover to crankcase polysiloxane) prior to installation. If new unloader kits are
with cap screws and lock washers. being installed, the pistons in the kit are already
lubricated.
If the opposite end cover requires an oil seal which was
removed on disassembly, a new seal should be pressed Install the unloader pistons in their bores with caution
into end cover. Position new end cover gasket and against cutting the grommets or distorting the back-up
carefully install end cover over crankshaft and to rings. Position unloader plungers in their guides and slip
crankcase, avoiding damage to the seal. Secure end them in and over the tops of the pistons.
cover with cap screw and lock washers. Install the unloader spring seat in the cylinder block; a
small hole is drilled in the block for this purpose. Position
PISTONS AND CONNECTING RODS
the saddle between unloader piston guides so its forks
If new wrist pin bushings are to be used, they should be are centered on the guides. Install the unloader spring,
pressed into the connecting rods so that the oil hole in making sure it seats over the spring seats both in the
the bushing lines up with the one in the rod. The new block and on the saddle.
bushings should then be reamed or honed to provide Install inlet valve seats if they have been previously
between 0.0002 in and 0.0007 in. clearance on the wrist removed. Position and install inlet valve guides, then
pin. Position connecting rod in piston and press in wrist drop inlet valves in their guides. There should be a loose
pin so that lockwire hole in the pin aligns with that of the sliding fit between guides and valves.
piston. Install new lockwire through piston and wrist pin
and lock same by snapping short end into lockwire hole CYLINDER HEAD ASSEMBLY
at the bottom of the piston (Fig. 7). Teflon plugs in wrist If previously removed, the discharge valve seats should
pin ends may be used instead of the lockwires (Fig. 22). be installed. Drop discharge valves into their seats.
Install discharge valve springs and cap nuts.
Install piston rings in correct location with ring pipmarks
up (Fig. 24). Stagger the position of the ring gaps. Place the inlet valve springs in the cylinder head. Use a
small quantity of grease to hold them in place, just
Prelubricate piston, piston rings, wrist pin and enough grease to keep the springs from falling out.
connecting rod bearings with clean engine oil before Place cylinder head gasket on cylinder block. Carefully
installing them in the compressor. align cylinder head assembly on block and install cap
12 screws with lock washers. Tighten securely and evenly
cap screws that hold cylinder head to block.
21
BASEPLATE TESTING REBUILT COMPRESSOR
SELF-LUBRICATED TYPE COMPRESSORS In order to properly test a compressor under operating
Install oil pump piston and rod on crankshaft. conditions, a test rack for correct mounting, cooling,
Oil rod bearing fit must be the same as specified for lubricating and driving the compressor is necessary.
connecting rod bearings. Install oil rod cap nuts and Such tests are not compulsory if the unit has been
cotter pins to lock oil rod nuts. carefully rebuilt by an experienced person.
Install oil pump relief valve in base plate. The relief valve A compressor efficiency or build-up test can be run
can be tested at this stage by applying air pressure to which is not too difficult. Before the test, the crankcase of
the relief valve. The valve should open when the pressure a self- lubricated type compressor should be properly
is between 14 psi minimum and 24 psi maximum. When filled with lubricating oil. An engine lubricated
the relief valve is properly installed in the base plate, compressor must be connected to an oil supply line of at
install set screw that locks it in place. least 15 pounds pressure during the test and an oil return
line must be installed to keep the crankcase drained. The
Place oil pump screen in base and install retaining ring,
compressor (when tested) should be tested without a
making sure it snaps in place and secures the screw.
strainer.
Install oil filter fitting on base plate in its proper place.
To the discharge port of the compressor, connect a
Install blanking cover on opposite oil filter fitting hole in
reservoir or reservoirs whose volume plus the volume of
plate.
the connecting line equals 1,300 cubic inches. Run the
Install a new oil seal gasket around oil pump - check compressor between 1,700 and 1,750 RPM. Elapsed time
valve and position a new base plate gasket on the that the compressor takes to build up from 0 to 100 psi
crankcase. Position base plate assembly on crankcase, depends on the type compressor as follows:
making sure oil pump piston engages the oil pump
BUILD-UP TIME
bushing in the base plate. Install and tighten base plate
TYPE COMPRESSOR 0 TO 100 PSI
screws.
TU-FLO® 400 47 SECONDS MAXIMUM
During the above test the compressor should be
checked for oil leakage and noisy operation.
FIGURE 26 - AIR STRAINER - EXPLODED VIEW
AIR STRAINER COMPRESSOR TROUBLESHOOTING

If the compressor is type with air strainer, assemble IMPORTANT: The troubleshooting contained in this
strainer (Fig. 26). Using a new strainer gasket, install section considers the compressor as an integrated
strainer on cylinder block. component of the overall air brake charging system and
assumes that an air dryer is in use. The troubleshooting
GOVERNOR
presented will cover not only the compressor itself, but
If compressor is type with pad mounted governor, install also other charging system devices as they relate to the
a new or factory rebuilt governor using a new governor
compressor.
gasket.
INSPECTION OF REBUILT UNIT
Check to be sure that covers, plugs or masking tape are
WARNING! PLEASE READ AND FOLLOW
used to protect all ports if compressor is not to be THESE INSTRUCTIONS TO AVOID
installed immediately. PERSONAL INJURY OR DEATH:
Fit the end of all crankshafts with keys, nuts and cotter When working on or around a vehicle, the following
pins as required and then protect the ends against general precautions should be observed at all times.
damage by wrapping with masking or friction tape. 1. Park the vehicle on a level surface, apply the
The open bottom of engine lubricated compressors parking brakes, and always block the wheels.
should be protected against the entrance of dirt during Always wear safety glasses.
handling or storage, by installing a temporary cover over 2. Stop the engine and remove ignition key when
base. working under or around the vehicle. When
working in the engine compartment, the engine
1
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.
3. Do not attempt to install, remove, disassemble or 8. Use only genuine Bendix® replacement parts,
assemble a component until you have read and components and kits. Replacement hardware,
thoroughly understand the recommended tubing, hose, fittings, etc. must be of equivalent
procedures. Use only the proper tools and size, type and strength as original equipment
observe all precautions pertaining to use of and be designed specifically for such
those tools. applications and systems.
4. If the work is being performed on the vehicle’s 9. Components with stripped threads or damaged
air brake system, or any auxiliary pressurized air parts should be replaced rather than repaired. Do
systems, make certain to drain the air pressure not attempt repairs requiring machining or
from all reservoirs before beginning ANY work welding unless specifically stated and approved
on the vehicle. If the vehicle is equipped with an by the vehicle and component manufacturer.
AD- IS™ air dryer system or a dryer reservoir 10. Prior to returning the vehicle to service, make
module, be sure to drain the purge reservoir. certain all components and systems are restored
5. Following the vehicle manufacturer’s to their proper operating condition.
recommended procedures, deactivate the 11. For vehicles with Antilock Traction Control
electrical system in a manner that safely (ATC), the ATC function must be disabled (ATC
removes all electrical power from the vehicle. indicator lamp should be ON) prior to performing
6. Never exceed manufacturer’s recommended any vehicle maintenance where one or more
pressures. wheels on a drive axle are lifted off the ground
7. Never connect or disconnect a hose or line and moving.
containing pressure; it may whip. Never remove
a component or plug unless you are certain all
system pressure has been depleted.
14 1
MAINTENANCE INSTRUCTIONS FOR SCHEDULED MAINTENANCE
LARGE SUMP TU-FLO® 1000 AIR NOTE: When checking or adding oil or servicing the
COMPRESSOR 288578 (SPECIAL crankcase breather, care should be taken to
APPLICATION) prevent dirt or foreign material from entering the
breather or oil sump.
This compressor is an air-cooled, belt driven, self
lubricated, V-four cylinder compressor. It is driven by an Every 7,500 miles or seven weeks, whichever occurs
electric motor and cooling air is supplied by a fan on the first: Check oil level - replenish to top of filler plug
driven pulley. The system air pressure is controlled opening. Replace both air cleaner filter elements and
between 135 psi and 150 psi by a pressure switch clean covers. Check belts and replace if broken,
starting and stopping the electric motor. damaged or missing.
Every 15,000 miles or 14 weeks, whichever occurs first:
INSTALLATION Remove crankcase ventilator, clean ports and replace
The base mounted compressor should be securely with freshly oiled curled hair.
bolted down with 1/2" grade five or better cap screws
Every 22,500 miles or 21 weeks, whichever occurs first:
torqued to 70 ft. pounds, making sure that motor and
Drain oil and refill with fresh SAE 20 W engine oil.
compressor pulleys are aligned and belt tension is correct.
Inspect all bolts, fittings and plugs to ensure that all are
The crankcase should be filled with five quarts (4.7 liter)
tight.
of SAE 20 W engine oil. The compressor must always be
installed to rotate clockwise when viewed from the pulley
end. The oil pump will not function if rotation is not
correct.
TABULATED DATA
TU-FLO® 400 TU-FLO® 500 TU-FLO® 1000
Air Compressor Air Compressor Air Compressor
Number Cylinders 2 2 4
Bore Size 2.0625" 2.5" 2.5"
Stroke 1.5" 1.6875" 1.6875"
Displacement at 1,250 RPM 7.25 cu. ft./min. 12 cu. ft./min. 24 cu. ft./min.
Maximum recommended RPM 3,000 water cooled 3,000 water cooled 3,000 water cooled
2,400 air cooled 2,400 air cooled 2,400 air cooled
Minimum coolant flow at 2.5 gal./min. 2.5 gal./min. 2.5 gal./ min.
maximum RPM water cooled water cooled water cooled
250 CFM air flow 250 CFM air flow 250 CFM air flow
Approximate horsepower required
at 1,250 RPM 1.2 H.P. 2.3 H.P. 4.6 H.P.
Maximum inlet air temperature 250° F. 250° F. 250° F.
Maximum discharge air temperature 400° F. 400° F. 400° F.
Minimum pressure required
to unload 60 PSI 60 PSI 60
PSI Minimum oil pressure required at
engine idling speed 5 PSI 5 PSI 5
PSI Minimum oil pressure required at
maximum governed engine speed 15 PSI 15 PSI 15 PSI
Approximate average weight 34 lbs. 46 lbs. 75 lbs.
Oil capacity of self-lubricated model .53 qts. .53 qts. .95 qts. to 5 qts.*
Minimum discharge line size 1/2" O.D. tubing 5/8" O.D. tubing 5/8" O.D. tubing or equivalent
or equivalent or equivalent from each head to a common
manifold with 1" tubing from
manifold.
Minimum coolant line size 3/8" O.D. tubing 1/2" O.D. tubing 1/2" O.D. tubing
or equivalent or equivalent or equivalent
Minimum oil supply line size 1/4" O.D. tubing 1/4" O.D. tubing 1/4" O.D. tubing
Minimum oil return line size 1/2" O.D. tubing 5/8" O.D. tubing 5/8" O.D. tubing
**Minimum air inlet line size 5/8" I.D. 5/8" I.D. 1" I.D. if equipped with inlet
manifold; or, dual 5/8" I.D. lines
from engine to compressor inlets.
*Part Number dictates oil capacity
**Inlet line sizes specified for compressors with inlet connected to engine manifold.
1
This troubleshooting guide obsoletes and supersedes all previous published
troubleshooting information relative to Bendix air compressors.
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
Symptom Page Number
Air
Coolant
Air brake charging system:
Slow build (9.0).....................................24 - 25 Compressor leaks coolant (17.0)......................28
Doesn’t build air (10.0)................................26 Engine
Air dryer:
Doesn’t purge (14.0)....................................27 Oil consumption (6.0)........................................24
Safety valve releases air (12.0)...................27 Oil
Compressor:
Oil Test Card results (1.0)..................................19
Constantly cycles (15.0)..............................27
Oil is present:
Leaks air (16.0)............................................28
On the outside of the compressor (2.0).......20
Safety valve releases air (11.0)...................26
At the air dryer purge/exhaust
Noisy (18.0).................................................28 or surrounding area (3.0).........................20
Reservoir: In the supply reservoir (4.0)..................21 - 23
Safety valve releases air (13.0)...................27 At the valves (5.0)........................................23
At air dryer cartridge (7.0)............................24
In the ping tank or compressor
discharge aftercooler (8.0)......................24
Test Procedures Maintenance & Usage Guidelines

Maintenance Schedule and
Oil Leakage at Head Gasket . . . 29 Usage Guidelines (Table A) . . 18
System Leakage29
Compressor Discharge and
Air Dryer Inlet Temperature29
Governor Malfunction30
Governor Control Line30
Compressor Unloader30
BASIC Test Information32-34
*This guide is only for vehicles that use desiccant air dryers.
16
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 dryer. The typical size of a vehicle's discharge line,
air compressor is typically cooled by the engine (see column 2 of Table A on page 18) assumes a
coolant system and lubricated by the engine oil compressor with a normal (less than 25%) duty cycle,
supply. operating in a temperate climate. See Bendix and/or
other air dryer manufacturer guidelines as needed.
The compressor's unloader mechanism and
governor (along with a synchro valve for the Bendix® When the temperature of the compressed air that
DuraFlo™ 596 air compressor) control the brake enters the air dryer is within the normal range, the air
system air pressure between a preset maximum and dryer can remove most of the charging system oil.
minimum pressure level by monitoring the pressure If the temperature of the compressed air is above the
in the service (or “supply”) reservoir. When the air normal range, oil as oil-vapor is able to pass through
pressure becomes greater than that of the preset the air dryer and into the air system. Larger diameter
“cut-out”, the governor controls the unloader discharge lines and/or longer discharge line lengths
mechanism of the compressor to stop the can help reduce the temperature.
compressor from building air and also causes the air The discharge line must maintain a constant slope
dryer to purge. As the service reservoir air pressure down from the compressor to the air dryer inlet fitting
drops to the “cut-in” setting of the governor, the to avoid low points where ice may form and block the
governor returns the compressor back to building air flow. If, instead, ice blockages occur at the air dryer
and the air dryer to air drying mode. inlet, insulation may be added here, or if the inlet
As the atmospheric air is compressed, all the water fitting is a typical 90 degree fitting, it may be changed
vapor originally in the air is carried along into the air to a straight or 45 degree fitting. For more information
system, as well as a small amount of the lubricating on how to help prevent discharge line freeze-ups, see
oil as vapor. Bendix Bulletins TCH-08-21 and TCH-08-22 (see
pages 35-37). Shorter discharge line lengths or
The duty cycle is the ratio of time the compressor
insulation may be required in cold climates.
spends building air to the total engine running time.
Air compressors are designed to build air (run The air dryer contains a filter that collects oil
“loaded”) up to 25% of the time. Higher duty cycles droplets, and a desiccant bed that removes almost all
cause conditions that affect air brake charging of the remaining water vapor. The compressed air is
system performance which may require then passed to the air brake service (supply)
additional maintenance. Factors that add to the duty reservoir. The oil droplets and the water collected are
cycle are: air suspension, additional air accessories, automatically purged when the governor reaches its
use of an undersized compressor, frequent stops, “cut-out” setting.
excessive leakage from fittings, connections, lines, For vehicles with accessories that are sensitive to
chambers or valves, etc. small amounts of oil, we recommended installation
The discharge line allows the air, water-vapor and of a Bendix® PuraGuard® system filter, designed to
oil-vapor mixture to cool between the compressor minimize the amount of oil present.
and
1
The Air Brake Charging System supplies the compressed air for
Optional Bendix® PuraGuard® System Filter or PuraGuard® QC™ Oil Co
DischargeOptional “Ping” Tank

LineAir Dryer
Compressor
Governor (Governor plus Synchro valve for the Bendix® DuraFlo™ 596™
Compressor) Service Reservoir
(Supply Reservoir)
Reservoir Drain
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 Column 3 Column 4 Column 5
Recom- Recom- Acceptable
Typical Discharge mended mended Reservoir
Compressors Line Air Dryer Reservoir Oil Contents3
No. of Spec'd Cartridge Drain at Regular
Vehicle Used for: Axles I.D. Length Replacement1 Schedule2 Drain Interval
Low Air Use

Compressor with less than 15% 1/2 in. 6 ft.
duty cycle BASIC test
5 For oil carry-over acceptable
e.g. Line haul single trailer
w/o air suspension, air over or control4 suggested Recom- range:
hydraulic brakes. upgrades: 3 oil units
less mended
5/8 in. 9 ft. per month.
Every 3 Every
Month - See
Years
Bendix® Tu-Flo® 550 air

Compressor with up to 25% duty cycle appendix
1/2 in. 9 ft. Max of
e.g. Line haul single trailer 5 every 90 A.
with air suspension, For oil carry-over
or control4 suggested days
school bus. less upgrades:
5/8 in. 12 ft. For the
Bendix® BA-921™ air
BASIC
High Air Use Test Kit:
Order
Compressor with up to 25% duty Bendix
cycle P/N
5013711
Bendix® Tu-Flo® 750 air compressor
e.g. Double/triple trailer, open

highway coach/RV, (most) 1/2 in. 12 ft.
pick-up & delivery, yard or
terminal jockey, off-highway, Every 2
8 For oil carry-over
construction, loggers, concrete control4
Years
or
mixer, dump truck, fire truck. suggested
less upgrades:
5/8 in. 15 ft. BASIC test
acceptable
range:
Every 5 oil units
Bendix® BA-922™, or DuraFlo™ 596 air
Month per month.

Compressor with up to 25% duty cycle
See
e.g. City transit bus, refuse, appendix
bulk unloaders, low boys, 5/8 in. 12 ft. A.
urban region coach, central
tire inflation. 12 Every
For oil carry-over Year
or control4 suggested
less upgrades:
3/4 in. 15 ft.
Footnotes:
1 With increased air demand the air dryer cartridge needs to be replaced more often. Note: Compressor and/or air dryer
2 Use the drain valves to slowly drain all reservoirs to zero psi. upgrades are recommended in
3 Allow the oil/water mixture to fully settle before measuring oil quantity. cases where duty cycle is greater
4 To counter above normal temperatures at the air dryer inlet, (and resultant oil-vapor than the normal range (for the
passing upstream in the air system) replace the discharge line with one of a larger examples above).
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. For Bendix® Tu-Flo® 550 and 750
Discharge line upgrades are not covered under warranty. Note: To help prevent compressors, unloader service is
discharge line freeze-ups, shorter discharge line lengths or insulation may be required in recommended every 250,000 miles.
cold climates. (See Bendix Bulletins TCH-08-21 and TCH-08-22, included in Appendix
B, for more information.)
5 For certain vehicles/applications, where turbo-charged inlet air is used, a smaller size
compressor may be permissible.
1
18
Air Brake Charging System Troubleshooting
How to use this guide:
Find the symptom(s) that you see, then move to the right Look for:
to find the possible causes (“What it may indicate”) and
remedies (“What you should do”).
Review the warranty policy before performing any intrusive Normal - Charging system is working within
compressor maintenance. Unloader or cylinder head normal range.
gasket replacement and resealing of the bottom cover plate
are usually permitted under warranty. Follow all standard
safety procedures when performing any maintenance. Check - Charging system needs further
investigation.
WARNING! Please READ and follow these instructions 5. Following the vehicle manufacturer’s recommended
to avoid personal injury or death: procedures, deactivate the electrical system in a manner
When working on or around a vehicle, the following general that safely removes all electrical power from the vehicle.
precautions should be observed at all times. 6. Never exceed manufacturer’s recommended pressures.
1. Park the vehicle on a level surface, apply the parking 7. Never connect or disconnect a hose or line containing
brakes, and always block the wheels. Always wear pressure; it may whip. Never remove a component or
safety glasses. plug unless you are certain all system pressure has
2. Stop the engine and remove ignition key when working been depleted.
under or around the vehicle. When working in the engine 8. Use only genuine Bendix® replacement parts,
compartment, the engine should be shut off and the components and kits. Replacement hardware, tubing,
ignition key should be removed. Where circumstances hose, fittings, etc. must be of equivalent size, type and
require that the engine be in operation, EXTREME strength as original equipment and be designed
CAUTION should be used to prevent personal injury specifically for such applications and systems.
resulting from contact with moving, rotating, leaking, 9. Components with stripped threads or damaged parts
heated or electrically charged components. should be replaced rather than repaired. Do not attempt
3. Do not attempt to install, remove, disassemble or repairs requiring machining or welding unless
assemble a component until you have read and specifically stated and approved by the vehicle and
thoroughly understand the recommended procedures. component manufacturer.
Use only the proper tools and observe all precautions 10. Prior to returning the vehicle to service, make certain all
pertaining to use of those tools. components and systems are restored to their proper
4. If the work is being performed on the vehicle’s air brake operating condition.
system, or any auxiliary pressurized air systems, make 11. For vehicles with Antilock Traction Control (ATC), the
certain to drain the air pressure from all reservoirs before ATC function must be disabled (ATC indicator lamp
beginning ANY work on the vehicle. If the vehicle is should be ON) prior to performing any vehicle
equipped with an AD-IS™ air dryer system or a dryer maintenance where one or more wheels on a drive axle
reservoir module, be sure to drain the purge reservoir. are lifted off the ground and moving.
Symptom:What it may indicate:What you should do:
1.0 Oil Test Card Not a valid test. Discontinue using this test.
Results Do not use this card test to diagnose
³
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 should be the
definitive method for judging excessive
oil fouling/oil passing. (See Appendix A, on
Bendix® page 32 for a flowchart and expanded
✓
BASIC explanation of the checklist used when
conducting the BASIC test.)
Test
1
2.0 Oil on the Engine and/or other accessories Find the source and repair. Return the vehicle
Outside of the leaking onto compressor. to service.
Compressor
2.1 Oil leaking at (a) Leak at the front or rear (fuel Ð Repair or replace as necessary. If the
compressor / engine pump, etc.) mounting flange. mounting bolt torques are low, replace the
connections: gasket.
(b) Leak at air inlet fitting. Ð Replace the fitting gasket. Inspect inlet
hose and replace as necessary.
(c) Leak at air discharge fitting. Ð Replace gasket or fitting as necessary to

ensure good seal.
(d) Loose/broken oil line fittings. Ð Inspect and repair as necessary.
2.2 Oil leaking

(a)Excessive leak at head gasket. Ð Go to Test 1 on page 29.
from compressor:
(b)Leak at bottom cover plate. Ð Reseal bottom cover plate using RTV
silicone sealant.
(c)Leak at internal rear flange Ð Replace compressor.
gasket. (d)Leak through crankcase. Ð Replace compressor.
(e)(If unable to tell source of leak.) Ð Clean compressor and check periodically.
(a)
Head gasket and rear flange gasket locations.
3.0 Oil at air dryer

Air brake charging system Ð Air dryers remove water and oil from the
purge/exhaust or
functioning normally. air brake charging system.
surrounding area
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.
2
4.0 Oil in Supply or Maintenance

Service Reservoir
(air dryer installed) (a) If air brake charging system Ð Drain all air tanks and check vehicle at
(If a maintained Bendix® maintenance has not been next service interval using the Bendix®
PuraGuard® system filter performed. BASIC test. See Table A on page 18,
or Bendix® PuraGuard® That is, reservoir(s) have not column 3 and 4, for recommended
QC™ oil coalescing filter been drained per the schedule in service schedule.
is installed, call Table A on page 18, Column 4
1-800-AIR-BRAKE and/or the air dryer
(1-800-247-2725) and
maintenance has not been
speak to a Tech Team
performed as in Column 3.
member.)
(b) If the vehicle maintenance has Ð 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 29),
stop inspection and check again at
See Table A, on page 18, been performed as recom- the next service interval. See the
for maintenance mended in Table A on page 18, BASIC test kit for full details. If less
schedule information. some oil in the reservoirs is than one "oil unit" of water (or water/
normal. cloudy emulsion mixture) is present, use
the BASIC cup chart on the label of the
(a) cup to determine if the amount of oil
found is within the acceptable level.
ÐIf 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.
Ð If outside the normal range go to
Symptom 4.0(c).
Also see the Table A on page 18, column
Drain all air tanks (reservoirs) 3 for recommended air dryer cartridge
into the Bendix® BASIC test replacement schedule.
cup. (Bendix kit P/N 5013711).
Duty cycle too high

(c) Air brake system leakage. The duty cycle is the ratio of time the compressor spend
(d) Compressor may be undersized

for the application.
2
Ð Go to Test 2 on page 29.
Ð See Table A, column 1, on page 18 for

recommended compressor sizes.
Ð 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.
Ð If the compressor is correct for the vehicle, go
to Symptom 4.0 (e).
2
4.0 Oil in Supply Temperature

or Service
Reservoir* Ð Check temperature as outlined in Test 3
(e) Air compressor discharge and/or on page 29. If temperatures are normal
(air dryer installed)
air dryer inlet temperature too go to 4.0(h).
(continued)
high.
Ð Inspect coolant line. Replace as
necessary (I.D. is 1/2").
(f) Insufficient coolant flow.
Ð Inspect the coolant lines for kinks and
restrictions and fittings for restrictions.
(f) Replace as necessary.
Ð Verify coolant lines go from engine block

to compressor and back to the water
pump. Repair as necessary.
Ð If discharge line is restricted or more than

Testing the temperature
at the discharge fitting.
1/16" carbon build up is found, replace
Inspecting the coolant hoses. the discharge line. See Table A, column
2, on page 18 for recommended size.
(g) Restricted discharge line. Replace as necessary.
Ð 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
Kinked discharge line shown. straight or 45 degree fitting. For more
information on how to help prevent
discharge line freeze-ups, see Bendix
Bulletins TCH-08-21 and TCH-08-22
(Appendix B). Shorter discharge line
lengths or insulation may be required in
cold climates.
Other
(h) Restricted air inlet (not enough air Ð Check compressor air inlet line for
to compressor). 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.
Ð Check the engine air filter and service if

Partly necessary (if possible, check the air filter
collapsed usage indicator).
inlet line
shown.
® ® ®
*If a maintained Bendix PuraGuard® system filter or Bendix PuraGuard QC™ oil coalescing
2
filter is installed, call 1-800-AIR-BRAKE (1-800-247-2725) and speak to a Tech Team
member.
2
4.0 Oil in Supply Other (cont.)

or Service
Reservoir* (i) Poorly filtered inlet air (poor air Ð Check for leaking, damaged or defective
(air dryer installed) quality to compressor). compressor air inlet components (e.g.
(continued) induction line, fittings, gaskets, filter
bodies, etc.). Repair inlet components as
needed. Note: Dirt ingestion will
damage compressor and is not
Inspect the covered under warranty.
engine air
cleaner.
(j) Governor malfunction or setting. Ð Go to Test 4 on page 30.
(k) Compressor malfunction. Ð 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)
Crankcase Flooding through 4.0 (j) above, the compressor
mayofbechronic
Consider installing a compressor bottom drain kit (where available) in cases passing oil.
oil passing where all other operating condition
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.
® ® ®
*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) and speak to a Tech Team
member.
5.0 Oil present at
Air brake system valves are required Ð A small amount of oil does not affect SAE
valves (e.g. at
to tolerate a light coating of oil. J2024** compliant valves.
exhaust, or seen
during servicing).
Ð 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 18). Return the vehicle
to service.
For oil-sensitive systems, see page 17.
** SAE J2024 outlines 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.
2
6.0 Excessive oil A problem with engine or other Ð See engine service manual.
consumption in engine accessory.
engine.
The engine
service
manual has
more
information.
7.0 Oil present at Air brake charging system is Ð Air dryers remove water and oil from the air
air dryer cartridge brake charging system. A small amount of
during functioning normally. oil is normal. Check that regular
maintenance. maintenance is being performed and that
the amount of oil in the air tanks
Oil shown (reservoirs) is within the acceptable range
leaking
from an air shown by the BASIC Test (see also
dryer column 5 of Table A on page 18). Replace
cartridge. the air dryer cartridge as needed and
return the vehicle to service.
8.0 Oil in ping tank Air brake charging system is Ð Follow vehicle O.E. maintenance
or compressor dis- functioning normally. recommendation for these components.
charge aftercooler.
9.0 Air brake (a) Air brake charging system Ð Using dash gauges, verify that the
charging system functioning normally. compressor builds air system pressure
seems slow to from 85-100 psi in 40 seconds or less
build pressure. with engine at full governed rpm. Return
the vehicle to service.
(b) Air brake system leakage. Ð Go to Test 2 on page 29.
(c) Compressor may be undersized Ð See Table A, column 1, on page 18 for

for the application. 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 Ð Go to Test 6 on page 30.

malfunction.
(e) Damaged compressor head Ð An air leak at the head gasket may
gasket. 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 re-use the safety
valve without testing. See Symptom
12.0(a).
2
9.0 Air brake

(f) Restricted discharge line. Ð If discharge line is restricted:
charging system
Ð By more than 1/16" carbon build up,
seems slow to
replace the discharge line (see Table A,
build pressure.
column 2, on page 18 for recommended
(continued)
size) and go to Test 3 on page 29.
Ð By other restrictions (e.g. kinks).
Replace the discharge line. See Table A,
(f)
size. Retest for air build. Return vehicle to
service or, if problem persists, go to
9.0(a).

compressor to the air dryer inlet fitting to
Dash gauges. avoid low points where ice may form and
Kinked discharge line shown. block the flow. If, instead, ice blockages
changed to a straight or 45 degree fitting.
For more information on how to help
prevent discharge line freeze-ups, see
Bendix Bulletins TCH-08-21 and
TCH-08-22 (Appendix B). Shorter
discharge line lengths or insulation may be
(g) Restricted air inlet (not enough air required in cold climates.
to compressor).
(g) Ð 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.
Ð Check the engine air filter and service if

necessary (if possible, check the air filter
Partly collapsed usage indicator).
inlet line shown. (h) Poorly filtered inlet air (poor air
quality to compressor).
Ð 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
(i) Compressor malfunction. warranty.
Ð Replace the compressor only after making

certain that none of the preceding
conditions, 9.0 (a) through 9.0 (h), exist.
2
10.0 Air charging (a) Governor malfunction*. Ð Go to Test 4 on page 30.

system doesn’t
build air. (b) Restricted discharge line. Ð See 9.0(f).
(c) Air dryer heater malfunction: Ð Replace air dryer heater.

exhaust port frozen open.
(d) Compressor malfunction. Ð Replace the compressor only after

making certain the preceding conditions
do but
* Note: For the Bendix® DuraFlo™ 596 air compressor, not only the governor, notalso
exist.
the SV-1™ synchro valve used would need to be tested. See
11.0 Compressor (a) Restricted discharge line. Ð If discharge line is restricted:

safety valve Ð By more than 1/16" carbon build up,
releases air replace the discharge line (see Table A,
(Compressor column 2, on page 18 for recommended
builds too much size) and go to Test 3 on page 29.
air). Ð By other restrictions (e.g. kinks).
Replace the discharge line. See Table A,
size.

Damaged compressor to the air dryer inlet fitting to
discharge avoid low points where ice may form and
line
shown. block the flow. If, instead, ice blockages
changed to a straight or 45 degree
fitting. For more information on how to
help prevent discharge line freeze-ups, see
Bendix Bulletins TCH- 08-21 and TCH-
08-22 (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 Ð Inspect air lines and verify check valves
blocked or damaged. are operating properly.
(c) Air dryer lines incorrectly installed.

Ð 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. Ð Verify relief pressure is 250 psi. Replace
if defective.
(e) Compressor unloader mechanism
malfunction. Ð Go to Test 6 on page 30.
(f) Governor malfunction.

2
12.0 Air dryer (a) Restriction between air dryer and Ð Inspect delivery lines to reservoir for
safety valve reservoir. restrictions and repair as needed.
releases air.
(b) Air dryer safety valve malfunction. Ð Verify relief pressure is at vehicle or
Air dryer safety valve component manufacturer specifications.
Replace if defective.
(c) Air dryer maintenance not Ð See Maintenance Schedule and Usage
performed. Guidelines (Table A, column 3, on page
18).
(d) Air dryer malfunction. Ð Verify operation of air dryer. Follow vehicle
O.E. maintenance recommendations and
component Service Data information.
(e) Improper governor control line Ð Go to Test 5 on page 30.

installation to the reservoir.
Technician removes
governor. (f) Governor malfunction. Ð Go to Test 4 on page 30.
13.0 Reservoir (a) Reservoir safety valve Ð Verify relief pressure is at vehicle or
safety valve malfunction. component manufacturer's specifications
releases air
(typically 150 psi). Replace if defective.

(b) Governor malfunction.
(c) Compressor unloader mechanism
malfunction.
14.0 Air dryer Ð Verify operation of air dryer. Follow vehicle
doesn’t purge. (a) Air dryer malfunction. O.E. maintenance recommendations.
(Never hear
exhaust from air
dryer.) (b) Governor malfunction.
(c) Air brake system leakage.
(d) Improper governor control line
installation to the reservoir.
15.0 Compressor
Ð Available reservoir capacity may be
constantly cycles (a) Air brake charging system reduced by build up of water etc. Drain
(compressor maintenance not performed. and perform routine maintenance per
remains unloaded
Table A, columns 3 & 4, on page 18.
for a very short
time.)
(b) Compressor unloader mechanism
malfunction.
Ð Verify operation of air dryer. Follow vehicle
(c) Air dryer purge valve or delivery O.E. maintenance recommendations and
check valve malfunction. component Service Data information.

(d) Air brake system leakage.
2
16.0 Compressor (a) Compressor leaks air at Ð Check for leaking, damaged or defective
leaks air connections or ports. compressor fittings, gaskets, etc. Repair
or replace as necessary.
(b) Compressor unloader mechanism Ð Go to Test 6 on page 30.

malfunction.
(c) Damaged compressor head Ð An air leak at the head gasket may
gasket. indicate a downstream restriction such as
Head gasket a freeze- up or carbon blockage and/or
Testing for leaks could indicate a defective or missing
with soap solution. location
12.0(a).
17.0 Compressor
(a) Improperly installed plugs or Ð Inspect for loose or over-torqued fittings.
leaks coolant
coolant line fittings. Reseal and tighten loose fittings and
plugs as necessary. If overtorqued fittings
and plugs have cracked ports in the
head, replace the compressor.
(b) Damaged compressor head Ð An air leak at the head gasket may
gasket. indicate a downstream restriction such as
a freeze- up or carbon blockage and/or
could indicate a defective or missing
12.0(a).
(c) Porous compressor head casting.
Ð If casting porosity is detected, replace the
compressor.
18.0 Noisy (a) Damaged compressor. Ð Replace the compressor.

compressor
(Multi-cylinder
compressors only)
Other Miscellaneous Areas to Consider

This guide attempts to cover most
• Where a compressor does not have a
compressor system problems. Here are
safety valve installed, if a partial or
some rare sources of problems not
complete discharge line blockage has
covered in this guide:
occurred, damage can occur to the
• Turbocharger leakage. Lubricating oil
connecting rod bearings. Damage of this
from leaking turbocharger seals can
kind may not be detected and could lead
enter the air compressor intake and
to compressor problems at a later date.
give misleading symptoms.
2
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
Observe the amount of weepage from the head gasket. FOR
If the oil is only around the cylinder head area, it is acceptable (return the WEEPAGE
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 pedal in position.) Observe the dash gauges.
repair them promptly. If you see any noticeable decrease of the dash
air Park the vehicle on level ground and chock wheels. gauge readings (i.e. more than 4 psi, plus two psi
Build system pressure to governor cut-out and allow for each additional trailer) during either two minute
the pressure to stabilize for one minute. test, repair the leaks and repeat this test to
confirm Step 1: Observe the dash gauges for two additional that they have been repaired.
minutes without the service brakes applied. Air leaks can also be found in the charging system,
Step 2: Apply the service brakes and allow the parking brakes, and/or other components - inspect
pressure to stabilize. Continue holding for two and repair as necessary.
minutes (you may use a block of wood to hold the
Test 3: Air Compressor Discharge

Temperature and Air Dryer Inlet
(* Note that only vehicles that have passed Test 2
Temperature* would be candidates for this test.)
Caution: The temperatures used in this test
are not normal vehicle conditions. 4. Then, while maintaining max rpm and
Above normal temperatures can cause oil pressure range, measure and record the
(as vapor) to pass through the air dryer into surface temperature of the fittings:
the air brake system. Ð at the compressor discharge port. (T1).
This test is run with the engine at normal Ð at the air dryer inlet fitting. (T2).
operating temperature, with engine at max. rpm. Use a touch probe thermocouple for
If available, a dyno may be used. measuring the temperature.
1. Allow the compressor to build the air system 5. See table below.
pressure to governor cut-in. 6. Retest before returning the vehicle to service.
2. Pump the brakes to bring the dash gauge
pressure to 90 psi. T1 T2
3. Allow the compressor to build pressure from Compressor Air Dryer
95 to 105 psi gauge pressure and maintain
Discharge Inlet Action
Fitting Fitting
this pressure range by cycling the brakes
under under Temperatures are within
for five (5) minutes.
360°F 200°F normal range for this test, check
other symptoms. Go to 4.0 (h).
T1
under over This could indicate a discharge
360°F 200°F line problem (e.g. restriction).
Call 1-800-AIR-BRAKE
T2 (1-800-247-2725)
and speak with our Tech Team.
over Compressor is running hot.

360°F Check coolant 4(f) and/or
discharge line 4(g).
Discharge Line
2
Tests (continued)
Test 4: Governor Malfunction
reservoir, service reservoir, or reservoir port
1. Inspect control lines to and from the of the D-2™ governor, verify cut-in and cut-
governor for restrictions (e.g. collapsed or out pressures are within vehicle OEM
kinked). Repair as necessary. specification.
2. Using a calibrated external gauge in the 3. If the governor is malfunctioning, replace it.
supply
Test 5: Governor Control Line
1. Ensure that the governor control line from the 2. Perform proper reservoir drain intervals and
reservoir is located at or near the top of the air dryer cartridge maintenance per
reservoir. (This line, if located near the Maintenance Schedule and Usage
bottom of the reservoir, can become Guidelines (Table A on page 18).
blocked or restricted by the reservoir 3. Return the vehicle to service.
contents e.g. water or ice.)
Test 6: Compressor Unloader Leakage
Bendix ® Compressors: Park vehicle, chock off and charge the unloader port by allowing air
wheels, and follow all standard safety procedures. pressure to enter the hose and unload the
Remove the governor and install a fitting to the compressor. Shut off the air supply and observe
unloader port. Add a section of air hose (min 1ft the gauge. A steady reading indicates no
leakage long for a 1/2" diameter line) and a gauge to the at the unloader port, but a falling reading
shows fitting followed by a shut-off valve and an air that the unloader mechanism is leaking and
needs source (shop air or small air tank). Open the shut to be serviced.
3
NOTES
3
Appendix A: Information about the BASIC Test Kit (Bendix P/N 5013711)
Service writer records info - including
days the number of days since all air tanks

Bendix® Air System Inspection Cup
were drained - and fills out symptom
(BASIC) Test Information
START BASIC TEST
Park vehicle on LEVEL ground.

ChockDrain contents
wheels, drain air of ALL air
from
tanks into BASIC cup
Is there YES
less than one Vehicle OK.
END TEST
Return
unit of liquid? vehicle to
NO
Is
there more
than one unit of: YES Cloudy emulsion mixture
• water, or
• cloudy emulsion
mixture?
NO, only oil.
Is this a Is this vehicle

YES, this is a high NO, this is a low air
transit vehicle, bulk being re-tested (after
air use use vehicle. YES
unloader, or has more water, etc. was found NO
vehicle.
than 5 axles? last time?)
Find the point on the label

Find the point on the label
where the number of oil units
where the number of oil units
meets the number of days*
meets the number of days* Change air dryer
since the vehicle's air tanks Go to the
since the vehicle's air tanks cartridge**
were last drained. Advanced
were last drained.
Troubleshootin
g Guide to find
reason(s) for
Is the presence of
Is the
point above Test for air
the HIGH Air Use point above Use Test 2:
leakage
NO the LOW Air END TEST
line on the
Use line on the Air Leakage
cup?
cup?
NO Re-test with
YES
YES the BASIC
Test after
Test for air

leakage Use Test 2: END TEST
Air Leakage Vehicle OK.
END TEST
Return
vehicle to
Does YES
the vehicle have Repair leaks * If the number of days since the air tanks were drained is
END TEST
excessive air and return unknown - use the 30 day line.
leakage? vehicle to
** Note: Typical air dryer cartridge replacement schedule is
NO every 3 yrs/ 300K miles for low air use vehicles and every
NO (did not know year/100K miles for high air use vehicles.
Was when last
the number of drained) Re-test with
*** To get an accurate reading for the amount of oil collected
days since last
the BASIC END TEST during a 30 day period, ask the customer not to drain the air
draining
known? Test after tanks before returning. (Note that 30-90 days is the
YES, number of days recommended air tank drain schedule for vehicles equipped
was known (30 - 90 days) with a Bendix air dryer that are properly maintained.) If, in cold
Replace the Compressor. If under warranty, follow weather conditions, the 30 day air tank drain schedule is longer
standard procedures. than the customer's usual draining interval, the customer must
If, after a compressor was already replaced, the vehicle determine, based on its experience with the vehicle, whether to
Compressor
fails the BASIC test again, do not replace the participate now, or wait for warmer weather. See the cold
compressor**** - use the Advanced Troubleshooting Guide weather tips in Bulletins TCH-008-21 and TCH-008-22
to investigate the cause(s). (included on pages 35-37 of this document).
****Note: After replacing a compressor, residual oil may take a
END TEST considerable period of time to be flushed from the air brake
system.
3
Appendix A 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 Lo
Checklist for Technician

Customer’s Complaint Have you confirmed
complaint? (Please check all that apply)
“Relay valve ❑ leaks oil / ❑ malfunctions”.......❑ no ❑ yes* The Technician
“Dash valve❑ leaks oil / ❑ malfunctions”.........❑ no ❑ yes* checks boxes for
The Service ❑ “Air dryer leaks oil”.....................................❑ no ❑ yes*
Writer also any of the
❑ “Governor malfunction”................................❑ no ❑ yes* complaints that
checks off any ❑ “Oil in gladhands”.......................................❑ no ❑ yes*
complaints that the howmuch oil did you find? can be
customer makes ❑ “Oil on ground or vehicle exterior”................❑ no ❑ yes* confirmed.
to help the amount described:
Technician in ❑ “Short air dryer cartridge life”
investigating. replaces every: ❑ miles, ❑ kms, or ❑
months
❑ “Oil in air tanks” amount described: * Note: A confirmed com-
plaintabovedoesNOTmean
Wewill measure amount currently found when we get to step B of the that the compressor must
test. be replaced.
❑ “Excessive engine oil loss”amount described: The full BASICtest
Is the engine leaking oil?................................❑ no ❑ yes* belowwill investigate the
facts.
Is the compressor leaking oil?.........................❑ no ❑ yes*
❑ Other complaint:
❑ No customer complaint.
BASIC test starts here: The Technician selects the air use
category for the vehicle. This
STEP A - Select one:
decided which of the two accep-
❑ This is a low air use vehicle: Line haul (single trailer) with 5 or less tance lines on the cup will be
axles,or used for the test below.
❑ This is a high air use vehicle: Garbage truck, transit bus, bulk
unloader, or line haul with 6 or Then
more go
axles.
to Step B.
STEP B - Measure the Charging System Contents For an accurate test, the
1. Park and chock vehicle on level ground. Drain the air system contents of all the air tanks on
by pumping the service brakes.
2. Completely drain ALL the air tanks into a singleBASICcup. the vehicle should be used.
3. If there is less than one unit of contents total, end the test
now and return the vehicle to service. Vehicle passes. Notefor returningvehiclesthatarebeing retested after a water/c
4. If morethanoneoilunitofwater(oracloudyemulsionmixture)
is found:
(a) Change the vehicle’s air dryer cartridge
- see Footnote 1, Oil
Units
(b) Conduct the 4 minute leakage test (Step
D),
(c) STOPtheinspection,andchecktheve
hicle again after 30 days - see
Footnote 2. STOP
+ CK.
Otherwise, go to Step C.
3
Footnote 1:Note: Typical air dryer cartridge replacement schedule is every 3 yrs/ 300Kmiles for lowair 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 cowldeather tips in Bulletins TCH-008-21 and TCH-008-22 (included inAppendix B of the advanced troubleshooting
guide).
3
Appendix A 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.
STEP C - How to Use the BASIC Test 1. Record days since air tankswere
2. Record last
amount
drained.
of oil found:
3. Action to take
days units
TheTechnicianuses thechart (label) on
theBASIC test cup to help decide the action to
take, based on the amount of oil found. Use
the lower acceptance line for lowair use if oil level is at or below System OK.
If number ofdays STOP
vehicles, andupper line for high air use acceptance line for
is: 30-60 days number of days€ Return to
vehicles (from StepA). TEST
(high air use) or service.
if oil level is above
30-90 days (low air ) acceptance line for Go to Step D
use number
€ of days €
if oil level is at or System OK. STOP
Otherwise . . . below Return to
€ 30-day acceptance TEST
line€ service.
(if the number of days Stop inspection.
if oil level is above30- Test again STOP
Acceptance
BASIC Test Example Lines
Oil
Anoil level of 4units inasixty-dayperiod iswithin Level
the acceptance area (at or below the line) for
both low andhighairusevehicles.
Returnthevehicletoservice.
X
The Technician looks for the point where the
number of days since the air tanks were drained Sixty days since last Decision
meets the oil level. If it is at or below the (low or air tank draining point
high use) acceptance line, the vehicle has
passed the test. If
the point is above the line we go to the leakage test.
Air leakage is the number
cause of compressors
one
STEP D - Air Brake System Leakage Test having to pump excessive
amounts of air, in turn run
too hot and
Park the vehicle on level ground and chock wheels. Build system pressure to governor pass oil vapor along into the
cut-out system. Here the Technician
and allow the pressure tostabilize for oneminute. conducts a four-minute test
1: Observe the dash gauges for two additional minutes without the service brakes
to see if leakage is a
applied. 2: Apply service brakes for two minutes (allow pressure to stabilize) and
problem with the vehicle
observe the dash gauges.
If you see any noticeable decreaseof the dash air gauge readings repair being tested.
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.
Note: If the compressor is within

STEP E - If no air leakage was detected in Step D warranty period, please follow
standard warranty procedures. Attach
the completed checklist to warranty
Replace the compressor. claim.
3
The Technician only reaches Step E if the
amount of oil found, for 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).
3
Appendix B
Technical Bulletin
Bulletin No.: TCH-008-021 Effective Date: 11/1/92 Page: 1 of 2
Subject: 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 form 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. Fitting extensions must be
avoided. Recommended discharge line lengths and inside diameters are dependent on the vehicle
application and are as follows.
Typical P&D, School Bus and Line Haul
The maximum discharge line length is 16 feet.
Length I.D. Min. Other Requirements

6.0-9.5 ft. ½ in. None
9.5-12 ft. ½ in. Last 3 feet, including fitting at the end of the
discharge line, must be insulated with ½ inch thick closed
cell polyethylene pipe insulation.
12-16 ft. 5/8 in. Last 3 feet, including fitting at the end of the
discharge line, must be insulated with ½ inch thick
closed cell polyethylene pipe insulation.
If the discharge line length must be less than 6 feet or greater than 16 feet, contact your local
Bendix representative.
3
Appendix B: Continued
High Duty Cycle Vehicles (City Transit Coaches, Refuse Haulers, Etc.)
The maximum discharge line length is 16 feet.
Length I.D. min. Other Requirements
10-16 ft. ½ in. None
If the discharge line length must be less than 10 feet or greater than 16 feet, contact your local Bendix
representative.
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 more moisture into the brake system.
Reservoir Draining (System Without Air Dryer)
Routine reservoir draining is the most basic step (although not completely effective) 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. 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.
Alcohol Evaporator or Injector Systems
Check for proper operation of these systems by monitoring alcohol consumption for a few days
(Reference Service Data Sheet SD-08-2301 for the Bendix Alcohol Evaporator). Too little means
the system is not receiving adequate protection and too much simply wastes alcohol. As a general
guide, these systems should consume approximately 1 to 2 ounces of alcohol per hour of
compressor loaded time (compressing air). City pick-up and delivery vehicles will operate with the
compressors loaded (compressing air) more while compressors on highway vehicles will be loaded
less. These figures are approximate and assume that air system leakage is within the limits of the
Bendix “Dual System Air Brake Test and Check List” (BW1279). Last but not least, begin using
alcohol several weeks prior to freezing weather to ensure that the system is completely protected.
Use only methanol alcohol, such as Bendix “Air Guard”, in evaporators or injectors.
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.
AD-9™ Air Dryer Service Data Sheet SD-08-2412

AD-IP™ Air Dryer Service Data Sheet SD-08-2414
AD-SP™ Air Dryer Service Data Sheet SD-08-2415
Trailer System-Guard™ Air Dryer Service Data Sheet SD-08-2416
3
Appendix B: Continued
Technical Bulletin
Subject: Additional 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.
3
4
4
40 BW1420 © 2004 Bendix Commercial Vehicle Systems LLC All rights reserved. 10/2004 Printed in U.S.A.

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TU-FLO® 400 Air Compressor TU-FLO® 500 Air Compressor

TU-FLO® 1000 Air Compressor

FIGURE 2 - TU-FLO® 500 AIR COMPRESSOR

Compressors are either engine or

CAST IRON PISTON

INTAKE AND COMPRESSION (Loaded)

COMPRESSOR & THE AIR BRAKE SYSTEM

Optional Bendix® PuraGuard ® QC™

FIGURE 12A - SYSTEM DRAWING

FIGURE 14 - POLYURETHANE SPONGE STRAINER AIR LEAKAGE TESTS

CRANKCASE BASE PLATE OR ADAPTER

CONNECTING ROD ASSEMBLIES

Remove cotter pin from oil rod cap nuts, remove

FIGURE 20 - CYLINDER BLOCK - EXPLODED VIEW

FIGURE 19 - CRANKCASE - TU-FLO® 400 & 500 AIR

FIGURE 19A - CRANKCASE - TU-FLO® 1000 AIR

BLOCK (Fig. 20)

COMPRESSION RINGS (2)

FIGURE 22 - TU-FLO® 400 AIR COMPRESSOR NEW STYLE

FIGURE 21 - MEASURING CYLINDER BORES

FIGURE 23 - TU-FLO® 400 AIR COMPRESSOR OLD STYLE

TU-FLO® 500 & 1000 AIR COMPRESSOR

.0035” NARROW WIDE

FIGURE 24 - PISTON RING POSITIONS - GAPS AND

PARTS SPECIAL TO SELF-LUBRICATED

FIGURE 26 - AIR STRAINER - EXPLODED VIEW

AIR STRAINER COMPRESSOR TROUBLESHOOTING

Advanced Troubleshooting Guide

The guide consists of an introduction to air brake charging system

Test Procedures Maintenance & Usage Guidelines

DischargeOptional “Ping” Tank

Low Air Use

Bendix® Tu-Flo® 550 air

e.g. Double/triple trailer, open

Month per month.

Symptom:What it may indicate:What you should do:

(c) Leak at air discharge fitting. Ð Replace gasket or fitting as necessary to

(d) Loose/broken oil line fittings. Ð Inspect and repair as necessary.

2.2 Oil leaking

(c)Leak at internal rear flange Ð Replace compressor.

gasket. (d)Leak through crankcase. Ð Replace compressor.

Head gasket and rear flange gasket locations.

3.0 Oil at air dryer

4.0 Oil in Supply or Maintenance

Duty cycle too high

(d) Compressor may be undersized

Ð See Table A, column 1, on page 18 for

4.0 Oil in Supply Temperature

Ð Verify coolant lines go from engine block

Ð If discharge line is restricted or more than

Ð The discharge line must maintain a

Ð Check the engine air filter and service if

4.0 Oil in Supply Other (cont.)

(j) Governor malfunction or setting. Ð Go to Test 4 on page 30.

(k) Compressor malfunction. Ð If you found excessive oil present in the

For oil-sensitive systems, see page 17.

** SAE J2024 outlines tests all air brake system

(b) Air brake system leakage. Ð Go to Test 2 on page 29.