BENDIX DOUBLE ANCHOR PIN CAM BRAKE Operating and maintenance instructions

1
®
Bendix®Double Anchor Pin Cam Brake
SD-22-3260
FIGURE 1
GENERALDESCRIPTION
The Bendix 16-1/2” x 7” double anchor pin cam brake is
designed for use on heavy duty highway vehicles. It is a
mechanically actuated, leading /trailing shoe brake with a
fixed position cam and anchors.
Thebrakeconsistsoftwofabricatedsteelshoeassemblies
individually anchored to a cast iron torque spider and
actuatedbyasingleforgedcam shaft.Tworetainingsprings
securethe shoe assemblies to theirrespectiveanchorpins.
Thetwinwebsof each shoe assembly engages the anchor
pin on one end and the cam roller on the other. A single
shoe to shoe return spring is used to maintain constant
contact between the shoe, cam roller and cam.
OPERATION
The Bendix cam brake operates in the following manner
during a braking application. The force of the push rod of
the actuator is converted from a linear force to a rotary
torque. This is accomplished by use of the slack adjuster.
Thistorqueistransferredtothecamshaftofthefoundation
brakeduetothesplineofthe cam shaft being connected to
the gear of the slack adjuster. On the opposite end of the
cam shaft is the S-Cam which when rotated lifts the cam
rollers. This spreads the brake shoe ends apart and pivots
the shoes about the anchor pin so the brake lining comes
incontactwiththerotating brake drum. The friction created
bytheliningpressure againstthedrum generatesthetorque
necessary to provide a retarding force to slow down the
vehicle.Theenergy of the vehicle inmotion isconverted to
heat at the surface of the drum and lining. The heat raises
thetemperatureofthedrum.Theheat is stored in the drum
and finally dissipated to the air.

2
FIGURE2 - 16-1/2”DOUBLE ANCHOR PINS-CAM BRAKE
16
17
14
30
18
15
13
19
89
13
26 25
24
11 10
987
1
2
4
3
6
5
12
20
21
23
22
Key No. Description Qty.
1 Snap ring 1
2 Spacer washers #reqd.
3 Yoke pin 1
4 Slack adjuster 1
5 Yoke 1
6 Cotter pin 1
7 Washer 1
8 Grease seal 2
9 Bushing 2
10 Cap screw 4
11 Lock washer 4
12 Actuator bracket and cam tube 1
13 Brake shoe assembly 2
14 Cam roller 2
15 Cam roller bushing 2
Key No. Description Qty.
16 Anchor pin 2
17 Anchor pin bushing 2
18 S-Cam shaft 1
19 Cam head washer 1
20 Shoe return spring 1
21 Spring retainer pin 2
22 Anchor spring 2
23 Dust shield 2
24 Rubber inspection plug 2
25 Cap screw 6
26 Star washer 6
27 Actuator 1
28 Nut 2
29 Washer 2
30 Sealing Ring 1
2
28
29
27

3
PREVENTIVE MAINTENANCE
1. BRAKEADJUSTMENT
Weekly,orwheneverpushrodstrokeexceedsmaximum
distance listed on the following chart. For complete
adjustmentinformation, see Bendix Service DataSheet
SD-05-1.
Full Pressure
Ser- Service Max. Max.Stroke
vice Diaphragm Stroke at which
Act- Effective With Brakes
uator Area Outside Max. Brakes Should Be
Type (Sq. In.) Diameter Stroke Adjusted Readjusted
short as
possible
without
24 24 7-7/32 2-1/4 brakes 1-3/4
30 30 8-3/32 2-1/2 dragging 2
2. BRAKELUBRICATION
Grease camshaft bracket with vehicle manufacturer’s
recommendedchassislube.Lubeonceeverysixmonths
or at each chassis lubrication.
3. BRAKERELINE
Thelife of the brake liningisdependentonmany factors
such as the material of the lining, type of operation the
vehicleis usedfor,andthe driver ofthevehicle. If driving
conditionsrequirefrequent braking, lining replacement
willbe requiredmoreoften. Reline whenliningthickness
at center of shoe is 1/4”. Refer to section “Reline
Procedure”.
4. BRAKEOVERHAUL
As often as necessary to maintain adequate brake
performance.NOTE:When overhauling brake system,
provide equal service to all drive axle brakes on the
vehicle.
WARNING! PLEASE READ AND FOLLOW
THESE INSTRUCTIONS TO AVOID PERSONAL
INJURY OR DEATH:
When working on or around brake systems and
components, the following precautions should be
observed at all times:
1. Park the vehicle on a level surface, apply the
parking brakes, and always block the wheels.
When working around or under the vehicle, stop
the engine and remove the key from the ignition.
Always keep hands away from chambers as they
mayapply as system pressure drops. Always wear
safetyglasses.
2. When working in the engine compartment, the
engine should be shut off and the ignition key
should be removed. Where circumstances require
thatthe enginebe inoperation, EXTREMECAUTION
shouldbe used to prevent personal injury resulting
from contact with moving, rotating, leaking, heated
or electrically charged components.
3. Do not attempt to install, remove, disassemble or
assemble a component until you have read and
thoroughly understand the recommended
procedures. Use only the proper tools and observe
all precautions pertaining to the use of those tools.
4. Following the vehicle manufacturer’s
recommendedprocedures, deactivate the electrical
system in a manner that safely removes all
electrical power from the vehicle.
5. If the vehicle is equipped with an air over hydraulic
brake system or any auxiliary pressurized air
system, 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.
6. Never connect or disconnect a hose or line
containing pressure; it may whip. Never remove a
component or pipe plug unless you are certain all
system pressure has been depleted.
7. Never exceed manufacturer’s recommended
pressure.
8. Never attempt to disassemble a component until
you have read and understand all recommended
procedures. Some components contain powerful
springs and injury can result if not properly
disassembled. Use only proper tools and observe
all precautions pertaining to use of those tools.
9. Use only genuine Bendix®replacement parts,
components and kits.
A. Use only components, devices and mounting
and attaching hardware specifically designed
for use in hydraulic brake systems.
B. All replacement hardware, tubing, hose,
fittings, etc. must be of equivalent size, type
and strength as the original equipment.
10. 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.
11. Prior to returning the vehicle to service, make
certain all components and systems are restored
to their proper operating condition.

4
FIGURE5-REMOVINGSHOES
FIGURE4-REMOVING SHOE RETURN SPRING
FIGURE7 - REMOVINGACTUATORBRACKET
FIGURE6-REMOVING SLACK ADJUSTER
PREPARATION
1. Park vehicle on a level surface and prevent movement
by means other than the brakes.
2. If equipped with spring brakes, cage the spring on all
axles to be worked on.
3. Drainair from all reservoirs.
4. Raise the axle, to be worked on until the tires clear the
ground.
5. Turn the slack adjuster adjusting screw in the opposite
direction used to adjust the brakes until the cam rollers
return to the start position on the S-cam.
6. Removewheelsanddrumsusingtheproceduresspecified
inthevehiclemaintenancemanual.
FIGURE 3 - REMOVING CAM ROLLERS

5
DISASSEMBLY (See Figure 2)
1. Insert a sturdy lever between one of the shoes and the
camshaft housing. Pry shoe awayfrom camroller until
pin and roller assembly can be removed. Repeat on
oppositeshoe(See Figure3). (Ifcam rollersor pinsshow
signs of wear, galling, pitting or cracks, discard and
replacewith new.)
2. Remove shoe return spring and discard. Force shoes
towardstheS-cam to relieve spring tension(Figure 4).
3. Remove shoes. Lift one of the shoesoff anchor pin and
lower both shoes to the floor (see Figure 5).
4. Removethetwoshoeretainerspringsanddiscard.NOTE:
Ifonlyreplacingthe brakeshoes,no furtherdisassembly
isrequired.ReverseSteps1thru4. NOTE:Alwaysinstall
newsprings.
5. Remove the two anchor pins by sliding them out of the
bushings. If bushings are to be replaced, drive them
out of the spider using a tool of the proper diameter (a
15/16" socket will work as a driver).
6. Remove the cotter pin from the yoke of the actuator.
Remove yoke pin so the slack arm is free of the yoke.
Remove the two nuts and washers that secure the
actuator to the bracket and remove the actuator.
7. Removesnapringandwasherfromsplinedend of cam
shaft. Remove slack adjuster from cam shaft. (A puller
mayberequired.)Removespacersand thethickwasher
from cam shaft (See Figure 6).
8. Removecam shaft from actuatorbracketandcamtube.
Removelarge flatcamheadwasher from thecamshaft.
9. Mark and remove the dust shields from the spider by
removing the six cap screws using a 3/8" socket. Do
notremoveunlessthereisapparentdamage.
10. Remove the actuator bracket and cam tube from the
spiderbyremovingthefourcapscrewsandlockwashers
using a 3/4“ socket. Remove and discard the sealing
gasketfromtheend oftheactuator bracket(SeeFigures
2 and 7).
11. Remove and discard the two cam shaft grease seals.
One at the end of the actuator bracket and one at the
cam entrance in the spider. Pry out with a large
screwdriver.
12.Remove the spider from the axle flange by removing
the twelve bolts, nuts, and lockwashers that secure it.
To facilitate assembly, note or mark the relationship of
the spider to the axle (driver or curb side) and the
orientationonthe axle flange.
13. Removeanddiscardthetwocamshaftbushings located
in the same area as the seals in Step 11. Use a drift of
adequatelengthtodrive the bushings out. NOTE: Prior
toremoval,see the “Inspection of Parts”section, Steps
1B and 3B.
CLEANINGOF PARTS
Afterdisassemblingthe foundationbrake,Washthemetallic
components in mineral spirits and wipe dry. Be careful not
to get any foreign material, especially grease on the brake
shoes or interior of the brake drum. Use a wire brush to
remove heavy contamination from the spider and outside
of the brake drum.
INSPECTION OF PARTS
1. ACTUATORBRACKETANDCAMTUBE
A. Checkassemblyforbentactuatorbracketandbroken
or cracked cam tube welds.
B. Inspectcam shaftbushing forsignsofwear.Bearing
surfacesshould be smooth and free of any pitting or
fractures.Insert cam shaft andmeasure looseness
atboth ends withadial indicator. Ifmore than .020"
movement is noted, replace bushings and/or cam
shaft. NOTE: If it is determined that a bushing
requires replacement, both cam shaft bushings
shouldbereplaced.
2. CAMSHAFT
A. Inspect cam shaft spline for cracks and excessive
deformation.Replaceasnecessary.
B. Inspect the cam shaft bearing journals for wear or
corrosion.If the shaft shows wear or roughness that
isvisibleor roughness that can bedetected byfeel,
it must be replaced.
C. Inspectcam head for cracks,and its roller surfaces
forflatspots,brinneling,orridges.Noteunusualwear
patterns which may indicate an out-of-square
condition. Replace if any of these conditions exist.
3. SPIDER
A. Inspectfor crackedorbrokensurfacesanthe spider
at the cam, anchor pins, and mounting bolt holes.
Replace any spiders with visible damage. Do not
attemptto weld or repair. Check fitof anchorpins in
torque spider. Radial clearance in excess of .010"
indicates excessive wear. Replace anchor pin
bushingsand/oranchorpins.
B. Check cam shaft bushing for signs of wear. (See 1
B) Bearing surface should be smooth and free of
any pitting or fractures. NOTE: If it is determined
thatthe bushing requires replacement, change both
cam shaft bushings.
4. ROLLERSAND PINS
A. Inspectrollers and pinsforflatspots,galling,broken
or cracked surfaces. Replace as necessary.
5. ANCHORPIN
A. Inspect anchor pin for worn, broken or cracked
surfaces.Replace as necessary.

6
FIGURE9- SEALINSTALLATION
SLACKADJUSTEREND
.094”
NOTE: BOTH LIP SEALS POINT THE SAME DIRECTION LIP
TOWARDSLACKADJUSTER
LIPSEAL
FIGURE8 - CHECKING SLACKADJUSTERBACKLASH
6”
ACTUATOR BRACKET
ANDCAMTUBE
CAMEND
LIPSEAL
6. SHOESANDLINING
A. Check shoes for bent shoe webs, cracks in shoe
table welds or webs, and elongated rivet holes.
Replace shoes if any of these conditions exist.
B. Measure the shoe span by loosely installing the
anchorpinandcamrollerinthe appropriate ends of
the shoe web. If the distance from center of anchor
pin to center of cam roller exceeds 11.72" replace
shoe.
C. Check linings. Replace when any of the following
conditions exist:
1. Lining thickness at thinnest point is 1/4” or less.
2. Liningsarecracked orworninan unusual orodd
pattern,i.e., liningweartaperedfrom side toside
across shoe table. Unusual wear patterns can
indicatedamagetofoundationbrake parts.
3. Rivet holes are elongated in lining or shoes.
4. Lining is oil soaked.
5. Liningscan be moved byhand, i.e.;loose rivets.
7. BRAKEDRUMS
A. Inspect drums for cracks, heat checking, glazing,
grooving, severe out-of-round condition or bell
mouthing(mustnotexceed .025T.I.R.).Replaceany
cracked drums. It is recommended that drums be
turned at reline to prevent hot spotting and achieve
quicker,morecompleteburnishingof the new lining.
B. Measurethe drum I.D. to be sure the maximumlimit
allowed(stamped ondrum)hasnot been exceeded,
duetowear or machining.
8. MANUALSLACKADJUSTER
A. Check for cracks in the body and arm of the slack
adjuster.
B. Check for spline wear. The amount of backlash in
the slack adjuster to camshaft should be no more
than .094" measured 6" from centerline of the cam
shaft(SeeFigure8).
C. Checkability to rotate theadjusting nutat leastone
completerevolutionineach direction.Forcerequired
to rotate the adjusting nut should not exceed 15 ft.
lbs.NOTE:Ifanyoftheaboveconditionsarefound,
replacethe slack adjuster. Do not attemptto repair.
9. AUTOMATICSLACKADJUSTERS
A. Consult manufacturer’s service information. (For
information on Bendix Automatic Slack Adjusters,
see Service Data Sheet SD-05-1200, formerly
SD-05-2).
10. ACTUATORS
A. Check for cracked housing, loose mounting studs.
B. Check for damage to the push rod, and push rod
boot(ifsoequipped).
C. Checkforbrokenpush rod return spring.
D. Check for excessive wear on yoke, yoke pin, and
slackadjusteryokepinholeorbushing.Thereshould
be no more than .031 combined free play in these
components.
CAUTION:If the vehicle isequippedwithspringbrakes,
refertomanufacturer’s instructions. High spring load, if
nothandledproperly,mayresultinseriousinjuryordeath
may result.
ASSEMBLY (SEE FIGURE 2)
1. Install the spider onto the axle flange using the twelve
bolts,lockwashers and nuts. Besure spideris properly
oriented,asnotedduringdisassembly.Tightenmounting
boltstovehiclemanufacturer’s specifications.
2. If anchor pin bushings or cam shaft bushings were
removed, replace with new bushings before installing
torque spider on axle. Drive into place using an
Owatonna630-7 piloted driverorsimilartool taking care
notto damage or distort the I.D. of the bushings. NOTE:
Oneofthecamshaft bushingsisinstalled intheactuator
bracket and cam tube.
3. Installnew cam shaft grease sealsintheendofthe cam
tubeandactuatorbracketand the cam shaft opening in
thespider.UseanOwatonna630-7piloteddriverorsimilar
tool to install grease seals.
SPIDER

7
FIGURE 10
USE RIVETS OF CORRECT LENGTH AS SHOWN
CORRECT TOO LONG
TOO SHORT
CAUTION:Thelipofthegreasesealsmustbeinstalled
correctly to prevent possible damage. The lip of the
sealthat is installedinthespider must entertheopening
first. The lip of the seal that is installed in the opposite
end of the cam tube must enter last. (See Figure 9).
4. Install a new actuator bracket seal ring between the
spider and cam tube of the bracket. Install the actuator
bracket and cam tube onto the spider using four cap
screwsand lockwashers.Torqueto 70-80ft.lbs.Secure
the actuator to the bracket using the two nuts and
washers.Torquetovehiclemanufacturer’sspecification.
5. If removed, reinstall the dust shields. Tighten the six
cap screws and lockwashers to 90-110 in. lbs. torque.
6. Placethecam head flat washer overthesplined end of
the cam shaft and slide it to the opposite end, next to
the head of the cam. Install washer so that the bent
endsfaceawayfromthe head. Coat cam shaft journals
withlight film ofchassislube.Donot coat “S”-cam head.
7. Installthe cam shaft withcam head flat washerinto the
cam tube. Be careful not to damage the grease seals.
8. Installthethickcamshaftflatwasher,theslackadjuster,
spacers,washer,and anew snap ringin that sequence
ontothe splined end of the cam shaft.Adjustendplayof
the cam shaft to between .005" and .045" by using the
appropriate number of spacer washers. Make sure the
snap ring is seated into the groove at the end of the
splinedcamshaft.
9. Installthe two anchor pins into the anchor pin bushings.
Centerthe anchor pins in the bushings so they protrude
equallyfrom each end of thebushings.
10. Install new brake shoe retaining springs. Engage hook
endsofthetwosprings into each of the holes of thetwo
brakeshoes.
11. Placethe topshoeonto thespiderby engagingtheopen
slotsontheendwiththeretainingspringsontotheanchor
pin.Place opposite end oftheshoe against the S-cam.
Swing the opposite shoe with springs attached back
untilslotsintheshoeengagetheotheranchorpin,then
swingshoetowardsthe S-cam. Spring tension willhold
theshoesin this position. NOTE: Whenplacing slotsof
the shoes onto the anchor pins, be sure to match the
flat surfaces of the mating parts.
12. Place the short hook of the brake shoe return spring
ontothe top return spring pin. Be sure spring is installed
so that the long hook on the other end of the spring is
facing the web of the brake shoe. Hold shoes against
the S-cam and push the long hook of the brake shoe
return spring over the opposite return spring pin until it
snaps in place.
13. Insert a sturdybar between theend of oneof the brake
shoes and the spider housing at the S-cam end of the
shoe. Pry down until the brake shoe roller and pin can
beinstalledbetweentheS-camandthe slots in the end
of the brake shoe. Repeat the same procedure on the
othershoe.
14. Adjust the slack adjuster until the yoke pin can be
installed through the proper hole in the arm. Install a
new cotter pin to retain. Make sure the cam rollers are
in the lowest position on the cam.
15. Lubricatethe camshaftbushings byfillingthecam shaft
tubewithchassislube through the zerk fitting provided.
Fill until grease is forced out in the area of the slack
adjuster. Grease should not appear at the cam head
end. If it does, the seal has not been properly installed,
or the old seals should be replaced.
16. Reinstallbrake drumsand wheels.Torqueandadjustto
manufacturer’sspecifications.
17. Spin thewheelslowlyandadjusttheslackadjusteruntil
wheel will no longer turn. Back off slack adjuster just
enoughfor wheel tospinfreely.Besuretoadjust brakes
equally on each axle.
18. Apply andrelease brakesand observeslack adjusters.
Bothslacksoneach axle should respond rapidly andin
unisonduringapplicationandrelease.
19. Drivevehicle atalow speedina safeareaand checkfor
brakeeffectivenessprior to putting back into service.
RELINEPROCEDURE
When removing rivets from the brake shoes, be careful to
avoid doing any damage to the holes in the shoe. Do not
usea chisel to shearthem off as theforce will elongate the
rivetholes. Neglecting any elongated holesmayresult in a
loose lining installation. If holes are burred, they should be
fileddown flush withthe shoetable.
Rustoften develops on the surfaceof theshoe tableunder
the brake lining or blocks. In addition, scale may form from
salt on the highways, or tar and oil may find their way into
the brake assembly. During every reline job, shoe tables
shouldbethoroughlycleaned.Thebestprocedureistosteam
clean the entire shoe or put it in a degreaser.
After cleaning the shoe, the shoe table should be scraped
clean of rust and scale. Any burrs or nicks should be filed
smooth. At the same time, the entire shoe should be
examined to see whether it is worn or bent.
The shoe should be either reconditioned or discarded. It is
also necessary to check for flat spots on the shoe that can
becaused by cleaning away the rust from the area that was
under the block previously. This can cause a mismatch of
shoeandliningarcs.Aftertheshoeiscleanedandinspected,
itshouldbegivenacoatingof rust preventative paint. Such
treatment of a new, unpainted shoe is also suggested to

8
preventtheinitialrustingproblem. Beforeriveting,clamp the
blocks tightly to the shoe, placing the clamps close to the
rivet holes. Be sure the holes in the blocks and the shoes
are exactly matched.
Nevershimthebrakeliningsasthiswillonlycauseproblems.
Brakenoise may result because ofcrackedandlooselining
since a tight installation is not possible. The inside surface
of the lining is the correct arc to match the shoe table, and
therivetholesintheliningswillonlylineupwithholesinthe
shoes when they are in direct contact.
The sequence of riveting should be such that the center of
the block is attached first and then the ends.
Some brake failures result from the use of rivets which are
tooshort, too long, or thewrong diameter. Incorrectsetting
of the riveting machine may induce other types of failures.
Thecorrectlengthrivetmustbeselectedforeachapplication.
A variation in shoe table thickness may require a different
lengthrivet.
The solid portion of the rivet should end just at the inner
surface of the shoe. The hollow portion of the rivet should
protrudepast the inner surface ofthe shoe.
Theproper size rivetmustbeusedto completely filltherivet
hole.
Brass plated steel rivets are recommended but cartridge
brass rivets can be used if so desired.
USEONLY
#10-10RIVETS
FIGURE 11
ROLL SET EXPANDS RIVET INTO
HOLE BEFORE UPSETTING.
WHEN RIVETING BRAKE LINING
USE ROLL SET NOT STAR SET
START SET SPLITS TUBE AND
RIVET DOES NOT FILL HOLE
Theriveting machine must be adjustedsothattherollof the
rivetiscomplete,buttherivetshouldnotsplit.Alwaysusea
roll set, never a star set, when riveting brake linings.Astar
set does not compress the rivet and expand it to fill the
hole. Consequently, the lining may work loose in service.

9
FOUNDATIONBRAKE TROUBLESHOOTING CHART
SYMPTOM CAUSE REMEDY
1. Degradedbrake A. Too muchpushrodfreetravel. A. Adjust brakes.
performance. B. Severely glazed or worn out linings. B. Deglazelinings or replace.
C. Grease or oil on linings. C. Replacelinings.
D. Worn, heat checked, cracked drums. D. Replacepart.
E. Push rod length too long. E. Adjust device, shorten pushrod
length.
F. Airchamber in wrongpositionin F. Reposition.
G. Broken or bent parts. G. Replace part.
H. Camflipover, drum I.D. toolarge. H. Replacedrum.
I. Flat spots on cam or rollers. I. Replaceflat-spottedparts.
2. Slowbrake A. Camshaftbushingsbinding. A. Cleanand lubricate. Check for
application. sealleakage.
3. Slowbrakerelease. A. Bindingcam shaftand bushings. A. Cleanandlubricate.
B. Weakor broken shoereturn spring. B. Replacepart.
C. Flat spotted cam or rollers. C. Replaceflat-spottedparts.
4. Grabbingorpulling A. Grease, oil or dirt on lining. A. Replace lining.
B. Glazedlinings. B. Deglazeliningorreplace.
C. Brake linings not a balanced set, C. Replacelinings.
differentfrictioncodes,orlining brand.
D. Looseor broken linings. D. Replacelinings.
E. Brakedrumout-of-round. E. Turn,permanufacturer’s
specifications.
F. Defectivebrakedrum. F. Replacepart.
G. Clevis pin orcam shaft binding atone G. Cleanand lubricate.
ormorewheels.
H. Defectiveslackadjuster. H. Replacepart.
I. Unevenbrakeadjustment(sidetoside) I. Adjust brakes.
J. Broken or bent parts. J. Replace part.
K. Loosespideror drum mounting bolts. K. Retorque, permanufacturer’s
specifications.
L. Different airchamber sizeor slack L. Use same size and materials on
adjuster length (side to side). all brakes.

10
BRAKESHOE ANDLINING TROUBLESHOOTINGCHART
SYMPTOM CAUSE REMEDY
1. Poorlining to drum A. Bell-mouthdrum. A. Replacepart.
contact. B. Bent brakespider. B. Replacepart.
C. Bent or stretched brake shoe. C. Replacepart.
D. Undersizelinings. D. Replacelinings.
E. Loosewheelbearing. E. Correctas required.
F. Improperlininggrind. F. Regrindliningstodrumradius
minus .015".
2. Liningstapered A. Bell-mouthdrum. A. Replaceparts.
across width. B. Bentbrake shoe. B. Replace parts.
C. Bentbrake spider. C. Replacepart.
D. Loosewheelbearings. D. Correctasrequired.
3. Unequal wearon A. Mismatched lining friction codes. A. Replacelinings.
in same brake. B. Stretched shoe. B. Replacepart.
C. Flat spots on cam or roller. C. Replaceflat-spottedparts.
D. Wornanchorpin. D. Replacepart.
E. Worn cam shaft or bushings. E. Replacepart.
4. Unequalwearside A. Mismatched lining friction codes. A. Replacelinings.
to side brakes, B. Seized or binding cam shaft. B. Cleanandlubricate.
same axle. C. Brakedrumsurfacein poor condition. C. Replaceor turn I.D.
D. Loosewheelbearing. D. Correctas required.
E. Draggingspring brake E. Correctasrequired
F. Reline F. Reline both drags together.
5. Wearonedgeof A. Wrong width lining. A. Replacelinings.
lining. B. Holesimproperly drilledin lining. B. Clean and lubricate.
C. Wrongdrum,orimproperly machined. C. ReplaceorturnI.D.
D. Loosebearingadjustment;bearing D. Correctasrequired.
spacer missing or too thin.
E. Improperwheel bearingorcone. E. Correctas required.
F. Bent brake shoe. F. Replacepart.
G. Bent brake spider. G. Replacepart.
H. Worn axle spindle. H. Correctasrequired.
6. Glazedlinings A. Overheating,duetounbalanced A. Correctasrequired.
(hardand shiny) braking system.
B. Wrongtype linings forserviceinvolved. B. Replacelinings.
C. Draggingspringbrakechamber. C. Correctasrequired.
7. Scoredor grooved A. Scoredorworn drum, not machined A. Replaceorremachine.
liningsanddrum. at reline.
B. Abrasivematerial between liningand B. Clean,remove dirt anddebris.
drum.
C. Brokensprings. C. Replacesprings.

11
8. Looselining. A. Impropersize rivets (toolong, too A. Re-rivet.
short,improper diameter).
B. Impropercrimpingofrivet. B. Re-rivet.
C. Enlargedrivetholesinshoe. C. Replacepart.
D. Incorrectlining hole size or counter D. Replacelinings.
boredepth.
E. Rust build up on shoe table. E. Clean,remove rustand paintshoe
9. Crackedliningat A. Overtighteningbolts. A. Correctas required.
rivetholes or
bolt holes. B. Wrong type rivets or bolts. B. Replacepart.
C. Rivetsnotproperlycrimped. C. Replacelining.
D. Dirt or rust on shoe table. D. Clean,removedirtanddebris.
E. Wrongsize lining counterbore. E. Replacelinings.
10.Elongated rivet A. Looserivets orbolts. A. Replaceshoe and lining.
holes.
BRAKEDRUMTROUBLESHOOTING CHART
SYMPTOM CAUSE REMEDY
1. Brakedrumheat A. Out of roundbrake drum. A. Turn,permanufacturer’s
checked. specifications.
B. Eccentricmounting of drum. B. Inspect wheel and drum and
replace defectivepart.
C. Loosewheelbearing. C. Correctas required.
D. Glazedlinings. D. Replacelinings.
E. Improperfriction materials for duty E. Consultvehiclemanufacturer.
cycleof vehicle.
F. Overworkedbrake. F. Check for proper brake balance.
(Ref;Bendixprocedure to check
out system.)
G. Driverabuse. G. Correctas required.
H. Wrong drum, too light. H. Replace part.
2. Excessivescoring A. Defectivebrake lining. A. Replacelinings.
ofdrum. B. Abrasivematerial between liningand B. Clean,remove dirt anddebris.
drum.
C. Softdrum. C. Checkhardness on flange. Should
be187Brinnel minimum.
D. Excessiveliningwear, rivets D. Replacelining.
contactingdrum.
E. Drum not turned at last reline. E. Turnper manufacturer’s
specifications.
F. Buildup of abrasives in rivetholes. F. Blow outdebris.

12 BW1459 © 2004 Bendix Commercial Vehicle Systems LLC All rights reserved. 5/2004 Printed in U.S.A.