BENDIX ASA-5 AUTOMATIC SLACK ADJUSTER User manual

1
®
SD-05-1269
Bendix®ASA-5™Automatic Slack Adjuster
DESCRIPTION
The Bendix®ASA-5™automatic slack adjuster is designed
for use on cam actuated drum brakes of the type in use on
most highway vehicles. Like a manual slack adjuster, the
ASA-5™slack adjuster multiplies and transforms the linear
forceoftheairactuatorintoarotationalforceortorquewhich
is used to apply the foundation brake. Additionally, the
ASA-5™slack adjuster automatically adjusts the clearance
betweenthebrake lining anddrumto compensate forwear.
AvarietyofASA-5™slackadjusterconfigurationsareoffered
including both straight arm and 5/8" yoke offset models.
The ASA-5™slack adjuster is offered in arm lengths of 5,
5-1/2and6 inchesandworm gear splinestoaccommodate
the standard 1-1/4" and 1-1/2" SAE 10C, 24, 28 and 37
tooth splines.
Either of two yoke designs (easy-on and quick connect) in
combinationwith an externalmanual adjuster hexprovides
forconvenient installationand maintenance of theASA-5™
slack adjuster. Note: The manual adjuster hex is
intended for use during installation. CAUTION:
Automatic slack adjusters should not be adjusted
manually to correct excessive pushrod stroke.
OPERATION
GENERAL
Theautomaticadjustment providedbythe Bendix®ASA-5™
slack adjuster results in consistent brake lining to drum
clearanceandbrakeactuatorstroke.Thekeytoitsoperation
is the ability to complete the brake adjustment during the
earlypart ofeach brakeapplication andto ceaseadjusting
as resistance to brake cam rotation begins to build. This
aspectoftheadjustermechanism’soperationpreventsover-
adjustmentcaused by liningcompression,actuator bracket
deflection, drum and foundation brake component distor-
tion, or brake component wear.
The ASA-5™slack adjuster incorporates a clutch-type
adjustermechanism that continuouslyadjusts in verysmall
incrementsaslininganddrumwearoccurs.Theadjustments
made by the ASA-5™slack adjuster are, therefore, not in
specific increments relative to actuator stroke.
BOOT
LINK
LINK PIN
YOKE PIN
YOKE
WORM
GEAR
LUBE
FITTING
FIGURE 1 - ASA-5™AUTOMATIC SLACK ADJUSTER
BRAKE APPLICATION
When the brakes are applied, the linear travel of the brake
actuator’s push rod causes the ASA-5™slack adjuster to
rotate the foundation brake camshaft which in turn begins
to force the brake shoes into contact with the drum. When
theASA-5™slackadjusterrotates, the yoke assemblypivots
on the yoke pin causing the link to be pulled upward.
The “teeth” on the link mesh with the adjuster mechanism
pinion. As the link is pulled it travels first through its free
play and then causes the pinion to rotate. Rotation of the
pinion is transmitted through the clutch spring to the worm
and shaft. Worm and shaft rotation results in worm gear
rotation which in turn adjusts (or repositions) the brake
camshaft.
When the foundation brake shoes contact the drum, the
camshaft begins to resist rotation and friction between the
worm gear and worm builds, preventing further rotation of

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ADAPTER
BUSHING
YOKE YOKE PIN
LINK PIN
BOOT
LUBE
RELIEF
OPENING
CLUTCH
SPRING
WORM
ANTI-
REVERSE
SPRING
SPRING
RETAINER
WORM
GEAR
FIGURE 2 - SECTIONAL VIEW OF PROFILE AND END
MANUAL
ADJUSTER
HEX
FREE
PLAY
and slippage of the clutch spring during release is due to
the direction of the coil windings of each.
YOKE DESIGNS
ASA-5™slack adjustersmay be equippedwith eitheroftwo
yoke designs. Both are designed to permit installation or
removal of the slack adjuster along with its yoke body and
its attached adjusting linkage.
The brake actuator push rod mustthread into the adapter a
minimum of 1/2 inch and must not extend more than 7/64
inch beyond the other end of the adapter. The yoke adapters
(quickconnect&easy-on)haveeithera 1or1-1/4inchhexto
allow tightening of the brake actuator push rod jam nut.
EASY-ON YOKE (REFER TO FIGURE 3)
The easy-on yoke assembly consists of an adapter which
is threaded internally to match the push rod threads and
externally to match female threads in the yoke. A special
extendedyokeadapterisalsoavailableasaseparateservice
item. The extended adapter is 1/2 inch longer than the
standardandis primarily intendedforuse when theexisting
brake actuator push rod is too short.
theworm.Brakeadjustment ceasesatthispointand further
rotation of theASA-5™slack adjuster will cause the pinion
and clutch spring to slip. The “free play” between the link
teeth and pinion results in a predetermined lining to drum
clearance.
BRAKE RELEASE
Whenthe brakeapplication isreleased, thebrake actuator
pushrod returnstheASA-5™slackadjusterto thereleased
position.During release,theASA-5™slackadjusterrotates
back toward the actuator causing the brake camshaft to
again rotate, but in the opposite direction, and the brake
shoes begin to move away from the drum. As the ASA-5™
slackadjuster rotatesback to the release positionthe yoke
again pivots causing the link to be pushed downward into
the slack adjuster body. The “free play” between the link
teeth and pinion is taken up during the initial part of the
release.Continuedmovement of theASA-5™slackadjuster
toward the released position causes the link to rotate the
pinion. The anti-reverse spring prevents counterclockwise
rotationofthe shaft andwormcausing the pinionandclutch
springto slip.The gripping actionof theanti-reverse spring
PINION
LUBE
FITTING

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2. Stop the engine and remove ignition key when
working under or around the vehicle. When
working in the engine compartment, the engine
should be shut off and the ignition key should
be removed. Where circumstances require that
the engine be in operation, 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 assemble a component until you have read
and thoroughly understand the recommended
procedures. Use only the proper tools and
observeallprecautions pertaining to use of those
tools.
4. If the work is being performed on the vehicle’s
air brake system, or any auxiliary pressurized
air systems, make certain to drain the air
pressure from all reservoirs before beginning
ANY work on the vehicle. If the vehicle is
equipped with an AD-IS®air dryer system or a
dryer reservoir module, be sure to drain the
purge reservoir.
5. Following the vehicle manufacturer’s
recommended procedures, deactivate the
electrical system in a manner that safely
removes all electrical power from the vehicle.
6. Never exceed manufacturer’s recommended
pressures.
7. Never connect or disconnect a hose or line
containing pressure; it may whip. Never remove
a component or plug unless you are certain all
system pressure has been depleted.
8. Use only genuine Bendix®replacement parts,
components and kits. Replacement hardware,
tubing, hose, fittings, etc. must be of equivalent
size, type and strength as original equipment
and be designed specifically for such
applications and systems.
9. Components with stripped threads or damaged
parts should be replaced rather than repaired.
Do not attempt repairs requiring machining or
welding unless specifically stated and approved
by the vehicle and component manufacturer.
10. Prior to returning the vehicle to service, make
certain all components and systems are restored
to their proper operating condition.
11. ForvehicleswithAntilock TractionControl (ATC),
theATC function must be disabled (ATC indicator
lamp should be ON) prior to performing any
vehicle maintenance where one or more wheels
on a drive axle are lifted off the ground and
moving.
YOKE
3/8" OUT
JAM NUT
MOUNTING
STUD ADAPTER
1-5/16"
PUSH ROD
FIGURE 3 - EASY-ON YOKE ASSEMBLY
QUICK-CONNECT YOKE
The adapter bushing in this case is threaded internally to
match the push rod, but is designed to slide into the yoke.
Aretainer ringis used to secure the adapter bushing in the
yoke. (Refer to Figure 4.)
YOKE
FLUSH
JAM NUT
MOUNTING
STUD ADAPTER
BUSHING
PUSH ROD
1"
FIGURE 4 - QUICK-CONNECT YOKE ASSEMBLY
GENERAL SAFETY GUIDELINES
WARNING! PLEASE READ AND FOLLOW
THESE INSTRUCTIONS TO AVOID
PERSONAL INJURYOR DEATH:
When working on or around a vehicle, the
following general precautions should be
observed at all times.
1. Park the vehicle on a level surface, apply the
parking brakes, and always block the wheels.
Always wear safety glasses.
RETAINING RING

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INITIAL INSTALLATION PREPARATION
1. If necessary, carefully remove the manual or automatic
slack adjuster currently installed, including the brake
chamber yoke assembly.
2. Before mounting the ASA-5™slack adjuster on the
camshaft, check the brake chamber push rod length to
determinewhethershorteningorreplacementisrequired.
To accomplish this:
A. With the brake chamber in the released position,
placeasquare(orequivalentobject)sothatoneedge
is parallel to the actuator push rod while the other
edge bisects the brake camshaft. Measure the
distance from the push rod end to the vertical edge
of the square and compare it to the values in Figure
5.
B. Ifthemeasurement is lessthantheminimum shown
in Figure 5, the brake actuator push rod must be
shortened. If the measurement is greater than the
maximum values, the brake actuator push rod may
requirereplacement.Theextendedadapter,available
as a separate service part (5/18"-18 pc. no. 297700
and 1/2"-20 pc. no. 297701) may avoid the need to
replace the brake actuator push rod. The extended
adapter is available for the easy-on yoke assembly
only. Note: Installing any other type of push rod
extender is not recommended, because these
devices may loosen over time and result in an
improperlyadjusted brake.
3. Inspectthefoundationbrake,brakechamberandrelated
components. Make certain the camshaft bushings and
seals are not excessively worn. Lubricate the camshaft
bushings. Check the brake chamber bracket for cracks
and excessive corrosion. The brake actuator push rod
shouldnotbe loose orbentand the returnspringshould
be firm. Replace parts that are suspect.
4. Wire brush the foundation brake camshaft to loosen
contamination and wipe clean. Depending on
environmental conditions, an application of anti-seize
compound to both the camshaft and worm gear spline
may facilitate later slack removal.
INSTALLATION
1. Select the proper ASA-5™slack adjuster.
2. Install theASA-5™slack adjuster on the brake camshaft.
3. If theASA-5™slack adjuster has the easy-on yoke (see
Figure 3), position the brake actuator push rod jam nut
approximately 1-5/16 inches from the end of the brake
actuatorpush rod. Threadthe easy-on yokeadapter on
the brake actuator push rod until it is approximately 3/8
inch from the end of the brake actuator push rod end.
TurntheASA-5™slack adjustermanual adjustment hex
clockwise until the adapter extends into the threaded
bore of the yoke approximately 1/8 inch. Thread the
adapter into the yoke and tighten to 10 foot pounds.
TheinstallationangleofaproperlyinstalledASA-5™slack
adjuster:
SLACK "A" STD. "A"
ADJUSTER QUICK CONNECT EXTENDED
ARM OR EASY-ON EASY-ON
LENGTH ADAPTER ADAPTER
5" 1-15/16" - 3-1/32" 2-7/16" - 3-17/32"
5-1/2" 1-15/16" - 3-3/16" 2-7/16" - 3 11/16"
6" 1-3/16" - 3-3/16" 1-11/16" - 3-11/16"
MOUNTING
STUD
SQUARE
DISTANCE
"A"
FIGURE 5 - MEASURING THE BRAKE ACTUATOR PUSH
ROD
BRAKE ACTUATOR
PUSH ROD
Slack Adjuster
Arm Length Angle
5" 99°-113°
5.5" 98°-111°
6" 90°-109°
4. IftheASA-5™slackadjusterhas the quickconnect yoke
(seeFigure4), positionthebrake actuator pushrod jam
nut approximately 1 inch from the end of the brake
actuator push rod. Thread the quick connect adapter
bushing on the brake actuator push rod until it is flush
with the end of the brake actuator push rod. Install the
retaining ring on the adapter bushing, making certain it
FIGURE 6 - INSTALLATION ANGLE

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isinthe adapter bushinggroove.Turn theASA-5™slack
adjuster manual adjustment hex clockwise until the
adapter bushing begins to enter the yoke. Fully
compress the retaining ring “legs” and continue turning
theASA-5™slack adjuster manual adjustment hex until
the adapter bushing is completely in the yoke.
Allowtheretainingringtoexpandintothe corresponding
groove in the yoke. Make certain the retaining ring is
seatedinboth the yokeandtheadapter bushing groove
by manually pulling the ASA-5™slack adjuster arm,
attempting to separate the adapter bushing and yoke.
5. Run the brake actuator push rod jam nut down against
the adapter or adapter bushing. Hold the adapter or
adapter bushing hex with a wrench and tighten the jam
nut to 300-400 inch pounds for the 1/2"-20 thread and
400-600inch pounds forthe 5/8"-18thread.
6. Manually adjust the brakes.
Note: The vehicle brakes should be adjusted using the
vehicleorbrakemanufacturer’srecommendation.Ifthey
are not available, the following procedure can be used:
Rotate the manual adjustment hex clockwise until the
linings are snug against the drum. Turn the adjustment
hex counterclockwise 1/2 turn. Pull the actuator push
rod to confirm that approximately 1/2 inch of push rod
free stroke exists.Apply 85 psi and check that the push
rod stroke is below the readjustment limit. If the stroke
exceeds the readjustment limit, check the condition of
the foundation brake. Refer to Brake Maintenance
Inspection.
7. Manuallyuncagethe springbrakesbefore returning the
vehicletoservice.
8. With the ASA-5™slack adjuster installed, check to
ensureclearancerequirementswiththebrakefullyreleas-
edandat the actuator’smaximumstroke.Also consider
clearances with the vehicle suspension springs
depressedtothejouncebumpers,aswellasinrebound.
PREVENTIVE MAINTENANCE
Important:AlwaysreviewtheBendix WarrantyPolicybefore
performinganyintrusivemaintenanceprocedures.Awarranty
maybevoided ifintrusivemaintenance is performedduring
thewarranty period.
No two vehicles operate under identical conditions, as a
result, maintenance intervals may vary. Experience is a
valuableguideindetermining the bestmaintenanceinterval
forair brakesystem components.At a minimum, theASA-5™
slack adjuster should be inspected every 3 months or 500
operatinghours,whichevercomesfirst,forproperoperation.
Should the ASA-5™slack adjuster not meet the elements
of the operational tests noted in this document, further
investigation and service of the adjuster may be
required.
Visuallycheckfor physical damagesuchas broken airlines
and broken or missing parts.
Every25,000 miles,or3 months,or 500 operatinghours or
atthe time ofroutine vehiclechassis lubrication, whichever
occurs first, the following steps should be followed (Also
observe any shorter brake adjustment inspections or
maintenanceintervalsspecifiedbythevehiclemanufacturer):
1. Lubricate the automatic slack adjuster through the lube
fitting with a quality multipurpose chassis lubricant
(N.L.G.I. Grade 2).
Lubricate the slack adjuster until clean lubricant flows
from the grease relief opening in the boot.
2. Perform the In Service Inspection described in this
manual.
IN SERVICE INSPECTION
1. Applyandreleasethevehiclebrakesseveraltimeswhile
observingtheASA-5™slackadjuster.TheASA-5™slack
adjuster and brake actuator should move freely without
binding or interference and should return to the full
released position. Observe the looseness that exists
between the yoke and adapter bushing and the yoke
and link pins and their mating parts (yoke, body, link).
Replace these parts if looseness appears excessive.
Make certain the brake actuator push rod jam nut is
tight against the yoke adapter.
2. Inspect theASA-5™slack adjuster for physical damage
paying particular attention to the link, boot and yoke.
Inspect for bent, broken, loose or misaligned brake
actuator push rods and cracked or damaged brake
actuator brackets. Repair or replace any components
foundtobe damaged.
ACTUATOR STROKE TABLE
STANDARD STROKE
Brake Recommended Maximum
Actuator Size Operating Stroke
30 2"
24 1-3/4"
20 1-3/4"
16 1-3/4"
12 1-3/8"
LONG STROKE
Brake Recommended Maximum
Actuator Size Operating Stroke
30LS 2-1/2"
24L 2"
24LS 2-1/2"
20L 2"
16L 2"
3. Measurethebrakeactuatorpushrodstrokewhilemaking
an 80-90 psi service brake application. Actuator push
rod strokes should not exceed the values shown in the
following actuator stroke tables. The correct pressure
forthistestcanbe achieved asfollows:Buildthesystem
pressure up to 100 psi reading on the vehicle gauge.

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brake components, which manual adjustment will not fix.
Replacement of the automatic slack adjuster or other
foundationbrake componentsmay be necessary. Consult
with the manufacturer's troubleshooting guidelines to find
and fix the problem.
WARNING: Manual adjustment of automatic slack
adjusters is a dangerous practice that could have
serious consequences, because it can give the
operator a false sense of security about the
effectiveness of the brakes, which are likely to go out
of adjustment again soon. Do not make manual
adjustments of an automatic slack adjuster once it can
no longer automatically adjust the brakes. Manual
adjustment DOES NOT fix the underlying wheel end
adjustment again. As soon as possible, have the
vehicle inspected by a qualified technician or consult
the manufacturer's troubleshooting guidelines to find
and fix the problem.
TESTING THE ASA-5™ADJUSTER MECHANISM
The following test can be made to determine if theASA-5™
adjuster mechanism is functioning properly.
1. Withthebrakesreleasedandthevehiclewheelsblocked,
de-adjustthe brakes byrotating the manualadjustment
hexcounterclockwiseapproximately 1/2 to1revolution.
Note: Considerable torque is required to rotate the
manual adjustment hex counterclockwise and should
be considered normal. The required torque may be as
high as 70 foot pounds.
2. Using a straight edge, scribe a line across the manual
adjustmenthex head andslack adjuster body. (Referto
Figure7).
3. ApplyandCOMPLETELYRELEASEtheservicebrakes
several times while observing the manual adjustment
hex and the scribed line. The ASA-5™slack adjuster
manual adjustment hex should rotate clockwise during
theapplicationandremainstationary during release. No
counterclockwiserotationofthehexshouldbeobserved.
The amount of clockwise rotation (adjustment) will
decrease progressively as the brake nears proper
adjustment. If the ASA-5™slack adjuster fails to
perform as described, it will be necessary to repair or
replace it.
4. ManuallyreadjusttheASA-5™slackadjusterbeingtested
before returning the vehicle to service. (See section
Installation, Step 6)
Note: While it is possible to use the automatic adjustment
featureoftheASA-5™slackadjustertobring the brakeback
into adjustment, it will require numerous applications and
COMPLETE RELEASES (the number of applications
depends on how much the slack was de-adjusted).
FIGURE 7 - TESTING ADJUSTER MECHANISM
ADJUSTER HEX
ROTATES
CLOCKWISE
DURING
ADJUSTMENT
STRAIGHT
LINE SCRIBED
ACROSS HEX
AND BODY
Shutthe engine off.Fan the brakesto attain a90-95 psi
reading.Makeandholda full brakeapplicationwhilethe
strokes are checked.
4. The Bendix®SureStroke™indicator is also available as
a visual stroke indicator. The SureStroke™indicator is
a metal bracketing system that bolts onto the brake
chamber and allows drivers to check the indicator for
operatingstroke.
IF THE SLACK ADJUSTER DOES NOT
AUTOMATICALLY ADJUST THE BRAKES
If the actuator stroke exceeds those shown in the stroke
table, inspection of the foundation brake and/or the
automatic slack should be performed. Maintenance of the
foundation brake may be a factor in the excessive stroke
conditions. Inspecting the foundation brake per the Brake
Maintenance Inspection presented in this manual should
determinehow muchof the longstroke conditionis caused
bythe conditionof the foundationbrake.TheASA-5™slack
adjuster can be tested using the instructions presented in
this manual under Testing the ASA-5™Adjuster
Mechanism. The automatic slack adjuster is not designed
tofunctionasamanualadjusteronceitisunableto maintain
adjustment automatically. Manual adjustment should only
be done as a temporary measure to correct brake
adjustmentin an emergencysituation. The routinemanual
adjustmentof anautomatic slackadjuster thatis stillwithin
adjustment limits may shorten its service life. Automatic
slackadjustersshould notbemanually adjusted inan effort
tocorrectexcessive pushrod stroke,becausethis condition
indicatesthat aproblem existswith theautomatic adjuster,
withtheinstallationoftheadjuster,orwithrelatedfoundation

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BRAKE MAINTENANCE INSPECTION
Note:Makecertainthevehiclehasbeenpreparedaccording
to the instructions under the heading GENERAL SAFETY
GUIDELINES.
The following test can be used to inspect the maintenance
conditionofthefoundationbrakeandtodeterminehowmuch
of the chamber stroke is caused by the condition of the
foundationbrake.
1. Always chock wheels to keep vehicle from moving.
2. Raise axle so wheel can be rotated.
3. Adjust slack adjuster to produce light brake drag with
wheelrotation.
4. Applybrake to 80-90psi and measurestroke (SeeItem
3 of In Service Inspection for pressure tips).
5. If stroke significantly exceeds the values shown in the
chart, the brake may be out of the norm and brake
maintenancemay be required.
AL Factor 15"x4" 16.5"x7" 16.5"x7"
Front Tractor, Truck Trailer
Brake or Bus Brake Brake
12 X 5.0" 1/2" N/A N/A
12 X 5.5" 1/2" N/A N/A
16 X 5.0" 5/8" 1/2" N/A
16 X 5.5" 3/4" 1/2" N/A
16 X 6.0" 7/8" 5/8" N/A
20 X 5.0" 5/8" 1/2" 3/8"
20 X 5.5" 3/4" 5/8" 1/2"
20 X 6.0" 7/8" 3/4" 5/8"
24 X 5.0" N/A 5/8" 1/2"
24 X 5.5" N/A 5/8" 5/8"
24 X 6.0" N/A 3/4" 5/8"
30 X 5.0" N/A 3/4" 5/8"
30 X 5.5" N/A 7/8" 3/4"
30 X 6.0" N/A 1" 7/8"
ASA-5™SLACK ADJUSTER REMOVAL
Note:Makecertainthevehiclehasbeenpreparedaccording
to the instructions under the heading GENERAL SAFETY
GUIDELINES.
1. IftheASA-5™slackadjusterisequippedwiththeeasy-on
yoke assembly illustrated in Figure 3:
A. Loosenthebrake actuator pushrod jam nutandrun
itbackonthebrakeactuatorpushrod approximately
5/8 inch.
B. Loosentheeasy-on yoke adapterandrun it backon
thebrakeactuatorpushroduntilitis free of theyoke.
C. Rotatethemanualadjustmenthexcounterclockwise
until theASA-5™slack adjuster is clear of the brake
actuator push rod.
Note: Considerably more torque is required to rotate the
manualadjustmenthexcounterclockwisethan is necessary
torotate itclockwise. Thetorque maybe as high as 70 foot
pounds.
2. If the ASA-5™slack adjuster is equipped with the
quick-connect yoke assembly illustrated in Figure 4:
A. Rotate the ASA-5™slack adjuster's manual
adjustment hex counterclockwise until the brake
actuator push rod just begins to move out of the
actuator.
B. Pinchthe legsof theretaining ringtogether and pull
the ASA-5™slack adjuster away from the brake
actuatorpushrod until theadapterbushing is freeof
theyoke.Removetheretainingringfromtheadapter
bushing.
C. Rotatethemanualadjustmenthexcounterclockwise
until theASA-5™slack adjuster is clear of the brake
actuator push rod.
3. Remove the ASA-5™slack adjuster from the camshaft
of the foundation brake by removing the retaining clip
and any spacers or washers that may be present.
DISASSEMBLY
GENERAL
Areasonablelevel of cleanlinessshouldbe observed when
working on the ASA-5™slack adjuster. Clean the exterior
beforedisassembly.
The following disassembly and assembly procedure is
presented for reference purposes and presupposes that a
rebuild or repair of the ASA-5™slack adjuster is being
undertaken. Several replacement parts and maintenance
kitsareavailable which donot require fulldisassembly.The
instructions provided with these parts and kits should be
followed in lieu of the instructions presented here.
1. Clamp theASA-5™slack adjusterARM in a bench vise.
Donotclampacrosstheportionofthebodythatcontains
theadjusterassemblyorwormgear.Usinga wire brush,
thoroughlycleantheexterioroftheslackadjusterpaying
particular attention to the area around the manual
adjustment hex and its retaining ring. Wipe all loose
contaminantsawaybefore proceeding.
2. Remove the cotter pins and washers from the yoke pin
and link pin.
3. Removetheyoke pin andlinkpinandseparate the yoke
from the ASA-5™slack adjuster.
4. If the ASA-5™slack adjuster has a yoke pin bushing,
press it out of the slack adjuster arm.
5. No further disassembly of theASA-5™slack adjuster is
permitted.

8
CLEANING AND INSPECTION
1. Inspect the worm gear camshaft splines for damage. If
damaged, replace theASA-5™slack adjuster.
2. Clean and inspect the yoke pin and link pin holes in the
yoke, adjuster link and slack adjuster body. The holes
should be visually round with no perceptible “egg
shaping.” A new yoke pin and link pin can be used to
make this inspection. If this condition is noted, the
affected part must be replaced.
3. Clean out the retaining ring grooves in the yoke.
REASSEMBLY
1. If the ASA-5™slack adjuster uses a yoke pin bushing,
press it into the slack adjuster arm.
2. Depending on environmental conditions an application
of anti-seize compound to both the yoke and link pins
may facilitate later removal. Install the yoke and secure
it to the ASA-5™slack adjuster body and link using the
yoke pin and link pin. Install washers and cotter pins in
the yoke pin and link pin, and secure each. Bend each
leg of the cotter pins to a minimum of 25 degrees,
creatinganincludedangleofatleast50degreesbetween
the legs.
3. Lubricate the automatic slack adjuster through the lube
fitting with a quality multipurpose chassis lubricant
(N.L.G.I.Grade2).Lubricatetheslackadjusteruntilclean
lubricantflowsfromthegreasereliefopeningintheboot.
RETROFITTING THE ASA-5™SLACK
ADJUSTER
PREPARATION
The Bendix®ASA-5™automatic slack adjuster can replace
a manual slack or competitive automatic slack adjuster
provided some considerations are kept in mind:
1. Excessive duty cycles, high application pressures and
brake force compounding can result in reduced slack
adjusterdurability.
2. DeterminethattheALfactorofthevehicletoberetrofitted
is 195 or less. To determine the AL factor multiply the
slack adjuster arm length (from the center of the cam
spline to the center of the yoke pin hole in use) times
the brake chamber size. Example: a type 30 brake
chamber connected to a 6 inch arm slack adjuster,A =
30 square inches, L = 6 inches; therefore, 30 x 6 = 180,
AL factor.
3. Makesurethefoundationbrakecomponentsareingood
condition. Excessive drum out-of roundness will result
in excessive lining wear. See the In Service Inspection
section contained in this manual.
4. In order to select the proper slack adjuster, choose an
ASA-5™slackadjuster withthe same armlength, spline
size,pushrodthreadsizeandoffsetasthe slackadjuster
it is replacing.
5. When retrofitting the Bendix®ASA-5™slack adjuster,
make certain to read the instructions packaged with all
service replacementASA-5™slack adjusters.

9
A. Repositioncomponents andtorque to
specification.
B. Replacedamaged or wornparts.
ASA-5™SLACK ADJUSTER TROUBLESHOOTING CHART
SYMPTOMS
1. Brake Actuator stroke is
too long.
WARNING:Automatic
slack adjusters should
not be manually
adjusted in an effort to
correct excessive push
rod stroke, because
this condition indicates
that a problem exists
with the automatic
adjuster, with the
installation of the
adjuster, or with
related foundation
brake components,
which manual
adjustment will not fix.
A. Loose actuator push rod
jam nut.
B. Excessiveclearance
betweenadapter/adapter
bushing and yoke due to
wear.
C. Excessiveclearance
betweencomponents:
yoke pin—yoke
link pin—link
yoke pin—body.
D. Damaged(worn)
splines on slack or
camshaft.
E. Weak or broken brake
actuatorreturn springs.
Weak or broken brake
shoereturn spring.
F. Wornor broken
foundationbrake
components,including
camshaft bushings,
brake chamber bracket,
etc.
G. ASA-5™adjuster
mechanism not
functioning.
H. Brakedrum—worn,
excessivelymachined,
bell-mouthed,
excessivethermal
expansion.
I. DamagedASA-5™slack
adjuster.
J. ASA-5™slack adjuster
improperlyinstalled.
CAUSE REMEDY
C. Replacewornparts.
D. Replacedamagedparts.
E. Replace weak or broken springs.
F. Repair or replace as required per In Service
Inspection.
G. Lubricate, test adjuster mechanism, conduct in
service inspection, repair components as
necessary, replace.
H. Replaceor repairas required.
I. Replace component(s) or slack adjuster.
J. Correct installation position.

10
ASA-5™SLACK ADJUSTER TROUBLESHOOTING CHART (Continued)
SYMPTOMS
A. ASA-5™slack adjuster
improperlyinstalled.Too
close to actuator: brakes
can’t fully release.
B. Loose actuator push rod
jam nut.
C. Spring brakes not fully
retracting.
CAUSE REMEDY
2. Brakesdragging—
apparent
over-adjustmentof
brakes.
A. Correct the ASA-5™slack adjuster installation.
B. Repositioncomponents andtorque to
specification.
C. Check spring brake release air pressure and
repairor replace airvalving asnecessary.Repair
orreplace springbrake.
D. Repair or replace as required per In Service
Inspection.
E. Check other brakes to ensure they are working.
Check air pressure balance and threshold pres-
sure(refertoBendix publication BW-1555).Check
driver braking habits, e.g. use of trailer control
valve. Use same friction material on all axles.
F. Replaceor repairas required.
D. Brokenfoundationbrake
components,including
camshaft bushings.
E. Vehicle braketorque
imbalance.(More work
done by some brakes
than others, thermal
expansionof drums).
F. Brakedrumout-of-round,
excessivethermal
expansion.
G. Air system malfunction,
not exhausting
completely.
H. New lining swells during
break-in.
G. Inspect and correct.
H. Back-off adjustment until brakes are free.

11

12 BW1602 © 2006 Bendix Commercial Vehicle Systems LLC. All rights reserved. 5/2006 Printed in U.S.A.