Maintenance Manual 4B

Asbestos and Non-Asbestos FibersAsbestos and Non-Asbestos FibersASBESTOS FIBER WARNINGNON-ASBESTOS FIBERS WARNINGThe following procedures for servicing brakes are recommended to reduce exposure toasbestos fiber dust, a cancer and lung disease hazard. Material Safety Data Sheets areavailable from Meritor.The following procedures for servicing brakes are recommended to reduce exposure tonon-asbestos fiber dust, a cancer and lung disease hazard. Material Safety Data Sheets areavailable from Meritor.Hazard SummaryHazard SummaryBecause some brake linings contain asbestos, workers who service brakes must understandthe potential hazards of asbestos and precautions for reducing risks. Exposure to airborneasbestos dust can cause serious and possibly fatal diseases, including asbestos (a chroniclung disease) and cancer, principally lung cancer and mesothelioma (a cancer of the lining ofthe chest or abdominal cavities). Some studies show that the risk of lung cancer amongpersons who smoke and who are exposed to asbestos is much greater than the risk fornon-smokers. Symptoms of these diseases may not become apparent for 15, 20 or moreyears after the first exposure to asbestos.Accordingly, workers must use caution to avoid creating and breathing dust when servicingbrakes. Specific recommended work practices for reducing exposure to asbestos dustfollow. Consult your employer for more details.Most recently manufactured brake linings do not contain asbestos fibers. These brakelinings may contain one or more of a variety of ingredients, including glass fibers, mineralwool, aramid fibers, ceramic fibers and silica that can present health risks if inhaled.Scientists disagree on the extent of the risks from exposure to these substances.Nonetheless, exposure to silica dust can cause silicosis, a non-cancerous lung disease.Silicosis gradually reduces lung capacity and efficiency and can result in serious breathingdifficulty. Some scientists believe other types of non-asbestos fibers, when inhaled, cancause similar diseases of the lung. In addition, silica dust and ceramic fiber dust are knownto the State of California to cause lung cancer. U.S. and international agencies have alsodetermined that dust from mineral wool, ceramic fibers and silica are potential causes ofcancer.Accordingly, workers must use caution to avoid creating and breathing dust when servicingbrakes. Specific recommended work practices for reducing exposure to non-asbestos dustfollow. Consult your employer for more details.Recommended Work Practices1. Separate Work Areas. Whenever feasible, service brakes in a separate area away fromother operations to reduce risks to unprotected persons. OSHA has set a maximum allowablelevel of exposure for asbestos of 0.1 f/cc as an 8-hour time-weighted average and 1.0 f/ccaveraged over a 30-minute period. Scientists disagree, however, to what extent adherence tothe maximum allowable exposure levels will eliminate the risk of disease that can result frominhaling asbestos dust. OSHA requires that the following sign be posted at the entrance toareas where exposures exceed either of the maximum allowable levels:DANGER: ASBESTOSCANCER AND LUNG DISEASE HAZARDAUTHORIZED PERSONNEL ONLYRESPIRATORS AND PROTECTIVE CLOTHINGARE REQUIRED IN THIS AREA.2. Respiratory Protection. Wear a respirator equipped with a high-efficiency (HEPA) filterapproved by NIOSH or MSHA for use with asbestos at all times when servicing brakes,beginning with the removal of the wheels.3.Procedures for Servicing Brakes.a) Enclose the brake assembly within a negative pressure enclosure. The enclosureshould be equipped with a HEPA vacuum and worker arm sleeves. With theenclosure in place, use the HEPA vacuum to loosen and vacuum residue from thebrake parts.b) As an alternative procedure, use a catch basin with water and a biodegradable,non-phosphate, water-based detergent to wash the brake drum or rotor and otherbrake parts. The solution should be applied with low pressure to prevent dust frombecoming airborne. Allow the solution to flow between the brake drum and thebrake support or the brake rotor and caliper. The wheel hub and brake assemblycomponents should be thoroughly wetted to suppress dust before the brake shoesor brake pads are removed. Wipe the brake parts clean with a cloth.c) If an enclosed vacuum system or brake washing equipment is not available,employers may adopt their own written procedures for servicing brakes, providedthat the exposure levels associated with the employer’s procedures do not exceedthe levels associated with the enclosed vacuum system or brake washingequipment. Consult OSHA regulations for more details.d) Wear a respirator equipped with a HEPA filter approved by NIOSH or MSHA for usewith asbestos when grinding or machining brake linings. In addition, do such work inan area with a local exhaust ventilation system equipped with a HEPA filter.e) NEVER use compressed air by itself, dry brushing, or a vacuum not equipped with aHEPA filter when cleaning brake parts or assemblies. NEVER use carcinogenicsolvents, flammable solvents, or solvents that can damage brake components aswetting agents.4. Cleaning Work Areas. Clean work areas with a vacuum equipped with a HEPA filter or bywet wiping. NEVER use compressed air or dry sweeping to clean work areas. When youempty vacuum cleaners and handle used rags, wear a respirator equipped with a HEPA filterapproved by NIOSH or MSHA for use with asbestos. When you replace a HEPA filter, wet thefilter with a fine mist of water and dispose of the used filter with care.5. Worker Clean-Up. After servicing brakes, wash your hands before you eat, drink orsmoke. Shower after work. Do not wear work clothes home. Use a vacuum equipped with aHEPA filter to vacuum work clothes after they are worn. Launder them separately. Do notshake or use compressed air to remove dust from work clothes.6. Waste Disposal. Dispose of discarded linings, used rags, cloths and HEPA filters withcare, such as in sealed plastic bags. Consult applicable EPA, state and local regulations onwaste disposal.Regulatory GuidanceReferences to OSHA, NIOSH, MSHA, and EPA, which are regulatory agencies in the UnitedStates, are made to provide further guidance to employers and workers employed within theUnited States. Employers and workers employed outside of the United States should consultthe regulations that apply to them for further guidance.Recommended Work Practices1. Separate Work Areas. Whenever feasible, service brakes in a separate area away fromother operations to reduce risks to unprotected persons.2. Respiratory Protection. OSHA has set a maximum allowable level of exposure for silicaof 0.1 mg/m3 as an 8-hour time-weighted average. Some manufacturers of non-asbestosbrake linings recommend that exposures to other ingredients found in non-asbestosbrake linings be kept below 1.0 f/cc as an 8-hour time-weighted average. Scientistsdisagree, however, to what extent adherence to these maximum allowable exposure levelswill eliminate the risk of disease that can result from inhaling non-asbestos dust.Therefore, wear respiratory protection at all times during brake servicing, beginning withthe removal of the wheels. Wear a respirator equipped with a high-efficiency (HEPA)filter approved by NIOSH or MSHA, if the exposure levels may exceed OSHA ormanufacturers’ recommended maximum levels. Even when exposures are expected to bewithin the maximum allowable levels, wearing such a respirator at all times during brakeservicing will help minimize exposure.3. Procedures for Servicing Brakes.a) Enclose the brake assembly within a negative pressure enclosure. The enclosureshould be equipped with a HEPA vacuum and worker arm sleeves. With theenclosure in place, use the HEPA vacuum to loosen and vacuum residue from thebrake parts.b) As an alternative procedure, use a catch basin with water and a biodegradable,non-phosphate, water-based detergent to wash the brake drum or rotor and otherbrake parts. The solution should be applied with low pressure to prevent dust frombecoming airborne. Allow the solution to flow between the brake drum and thebrake support or the brake rotor and caliper. The wheel hub and brake assemblycomponents should be thoroughly wetted to suppress dust before the brake shoesor brake pads are removed. Wipe the brake parts clean with a cloth.c) If an enclosed vacuum system or brake washing equipment is not available,carefully clean the brake parts in the open air. Wet the parts with a solution appliedwith a pump-spray bottle that creates a fine mist. Use a solution containing water,and, if available, a biodegradable, non-phosphate, water-based detergent. Thewheel hub and brake assembly components should be thoroughly wetted tosuppress dust before the brake shoes or brake pads are removed. Wipe the brakeparts clean with a cloth.d) Wear a respirator equipped with a HEPA filter approved by NIOSH or MSHA whengrinding or machining brake linings. In addition, do such work in an area with a localexhaust ventilation system equipped with a HEPA filter.e) NEVER use compressed air by itself, dry brushing, or a vacuum not equipped with aHEPA filter when cleaning brake parts or assemblies. NEVER use carcinogenicsolvents, flammable solvents, or solvents that can damage brake components aswetting agents.4. Cleaning Work Areas. Clean work areas with a vacuum equipped with a HEPA filter or bywet wiping. NEVER use compressed air or dry sweeping to clean work areas. When youempty vacuum cleaners and handle used rags, wear a respirator equipped with a HEPA filterapproved by NIOSH or MSHA, to minimize exposure. When you replace a HEPA filter, wet thefilter with a fine mist of water and dispose of the used filter with care.5. Worker Clean-Up. After servicing brakes, wash your hands before you eat, drink orsmoke. Shower after work. Do not wear work clothes home. Use a vacuum equipped with aHEPA filter to vacuum work clothes after they are worn. Launder them separately. Do notshake or use compressed air to remove dust from work clothes.6. Waste Disposal. Dispose of discarded linings, used rags, cloths and HEPA filters withcare, such as in sealed plastic bags. Consult applicable EPA, state and local regulations onwaste disposal.Regulatory GuidanceReferences to OSHA, NIOSH, MSHA, and EPA, which are regulatory agencies in the UnitedStates, are made to provide further guidance to employers and workers employed within theUnited States. Employers and workers employed outside of the United States should consultthe regulations that apply to them for further guidance.1

BOOTRETAININGCLAMPBOOTSMALLCLEVIS PINACTUATOR RODPISTON RETAININGRINGROLLER (PIN)LARGECLEVIS PINRETAINER CLIPMeritor AutomaticSlack AdjusterCurrent Models:January 1993 or LaterACTUATORASSEMBLYACTUATOR PISTONACTUATOR(ADJUSTING SLEEVE)LARGECLEVIS PINSTRAIGHTOR OFFSETCLEVISSMALLCLEVIS PINRETAINERCLIPHOUSINGWORM GEARBUSHINGMANUALADJUSTINGNUT (ENDOF WORM)GASKETPULL PAWL ASSEMBLY(Replaces all previous pawl assemblies.)WORMRETAININGRINGFACESEALNOTE: Parts shown in this box arenot serviceable or interchangeablewith parts from earlier LBOOTRETAININGCLAMPBOOTSMALLCLEVIS PINModels BeforeJanuary 1993ACTUATOR RODPISTON RETAININGRINGROLLER (PIN)COTTERPINACTUATORASSEMBLYACTUATOR PISTONACTUATOR(ADJUSTING SLEEVE)LARGECLEVIS PINGEARSEALCOTTERPINTHRUSTWASHERBUSHINGSTRAIGHT OROFFSET CLEVISGASKETPULL PAWL ASSEMBLY(Replaces all previous pawl assemblies.)HOUSINGWORM GEARTHRUST RMRETAININGRINGWORMGREASE SEALii2GEARRETAININGRINGMANUALADJUSTING NUT(END OF WORM)

PUSHRODLARGECLEVISPINCLEVISBRAKE AIRCHAMBERMeritor AutomaticSlack AdjusterLARGE CLEVIS PINRETAINER CLIPCutaway ViewSMALL CLEVIS PINRETAINER CLIPSMALL CLEVIS PINACTUATOR RODJAMNUTBOOTCOLLARBOOT RETAININGCLAMPHOUSINGPISTONRETAINING RINGROLLER (PIN)ACTUATOR PISTONACTUATOR(ADJUSTING SLEEVE)PULL PAWL ASSEMBLYCorrect position for “unhanded” design.Shown 90 out of position for handed design.GEARGASKETWORMWORM RETAININGRINGGREASE FITTINGGEAR RETAINER/SEALWORM GREASE SEALMANUAL ADJUSTINGNUT (END OF WORM)Offset Clevis forFront Axle Slack AdjusterCLEVISOFFSET CLEVISLARGECLEVIS PINCOTTERPINCOLLARSPRINGUse withtype 9 and 12air chambers.SPRINGACTUATOR RODSMALLCLEVIS PINLARGECLEVISPINSLACKADJUSTERARM3

Section 1IntroductionMeritor’s AutomaticSlack AdjusterSection 1IntroductionNOTE: As of January 1993 some parts of Meritor’sautomatic slack adjuster are no longer serviceableand are not interchangeable with parts from earliermodels. Refer to Exploded View, pages 2 and 3, formore information.How the Automatic SlackAdjuster WorksMeritor’s automatic slack adjuster automaticallyadjusts the clearance between the brake lining andthe brake drum (rotor). When linings wear, thisclearance increases and causes the chamber pushrod to move a greater distance to apply the brakes.When you install an automatic slack adjuster, youset the brake chamber stroke measurement, whichis the correct clearance between the linings anddrum (rotor). Figure 1.1.During operation, if the chamber stroke exceedsthe design limit, the automatic slack adjuster willautomatically adjust the push rod’s return stroke tocontrol clearance between the lining and drum(rotor) and reset the stroke to the correct length.Figure 1.1Pressed-In, Sealed Actuator Boot onMeritor Automatic Slack AdjustersManufactured from July 1998A pressed-in, sealed actuator boot is standardequipment on Meritor automatic slack adjustersmanufactured from July 1998.The boot features a metal retaining ring withadditional material that extends beyond the baseof the retainer and forms a seal once the boot ispressed into the slack adjuster body.r Meritor part numbers will not change.r All application information is printed on theslack adjuster’s identification tag.r A counterbore is machined into the slack bodyfor easier installation of the press-in boot.Factory-Installed Automatic SlackAdjusters on Q PlusTM LX500 andMX500 Cam Brake PackagesQ Plus LX500 and MX500 brake packagesinclude factory-installed automatic slack adjustersthat do not have grease fittings, and lubricationintervals differ from conventional slack adjusters.Refer to Maintenance Manual MM-96173,Q Plus LX500 and MX500 Cam Brakes, forcomplete information. Call Meritor’s CustomerService Center at 800-535-5560 to order thispublication.Handed and Unhanded Slack AdjustersThere are two automatic slack adjuster designs:HANDED and UNHANDED. For most applications,install a HANDED automatic slack adjuster so thatthe pawl faces INBOARD on the vehicle.The pawl can be on either side or on the front ofthe slack adjuster housing. Figure 1.2.Figure 1.2UNHANDEDHANDEDFigure 1.2AFigure 1.2BPAWLCONVENTIONALPAWL4PULL PAWLPRY UP

Section 1IntroductionPull PawlsOne-Piece Threaded ClevisPull pawls are spring loaded. Pry the pull pawl atleast 1/32-inch to disengage the teeth. Figure 1.2B.When you remove the pry bar, the pull pawl willre-engage automatically.Most of Meritor’s automatic slack adjusters,including the factory-installed slack adjusters onthe new Q Plus LX500 and MX500 cam brakes,have a one-piece threaded clevis.Replace Conventional Pawls withPull PawlsWhen you service an automatic slack adjuster,replace a conventional pawl with a pull pawl.Figure 1.2A and Figure 1.2B. Install the slackadjuster so that you can remove the conventionalpawl or disengage the pull pawl when you adjustthe brake.r The clevis has a threaded hole for the push rod.Figure 1.4.r The one-piece threaded clevis can be straightor offset.r All service replacement automatic slackadjusters have one-piece threaded clevises.Figure 1.4OFFSETCLEVISClevis Types and Thread SizesNOTE: Meritor’s automatic slack adjusters andclevises are designed to be used as a system.Always replace original components with genuineMeritor replacement parts. Although parts fromother manufacturers can look the same, significantdifferences can exist that can affect brake systemperformance.STRAIGHTCLEVIS“Quick Connect” ClevisTHREADSSome models of Meritor’s automatic slack adjusterhave a “Quick Connect” clevis. Figure 1.3.r A “Quick Connect” clevis is a three-pieceassembly that cannot be separated after itis assembled.r The collar has a threaded hole for the push rod.r A “Quick Connect” clevis can be straight oroffset. Use an offset clevis when more clearanceis necessary between the air chamber and thetire on the front axle.Figure 1.3Thread SizesStraight and offset clevises are available in twothread sizes (including metric threads) to matchpush rod threads.Table A: Thread SizesChambersThread Sizes9, 12, 161/2"-20 UNF20, 24, 30, 365/8"-18 UNFCLEVISRETAININGRING GROOVERETAINING RING“QUICK CONNECT”COLLARTHREADS5

Section 2Remove the Slack Adjuster from the CamshaftRemovalSection 2the Slack Adjuster from the CamshaftRemoveWARNINGTo prevent serious eye injury, always wear safeeye protection when you perform vehiclemaintenance or service.WARNINGWhen you work on a spring chamber, carefullyfollow the service instructions of the chambermanufacturer. Sudden release of a compressedspring can cause serious personal injury.WARNINGCAUTIONYou must disengage a pull pawl or remove aconventional pawl before rotating the manualadjusting nut, or you will damage the pawl teeth.A damaged pawl will not allow the slack adjusterto automatically adjust brake clearance. Replacedamaged pawls before putting the vehicle inservice.5. Use a wrench to turn the manual adjusting nutin the direction shown in Figure 2.1. Move theslack adjuster away from the clevis.Figure 2.1Block the wheels to prevent the vehicle frommoving. Support the vehicle with safety stands.Do not work under a vehicle supported only byjacks. Jacks can slip and fall over. Serious personalinjury can result.1. If the brake has a spring brake, compress andlock the spring, so that the brake is releasedcompletely. Check that no air pressure remainsin the service half of the air chamber.2. If it is necessary to raise the vehicle, use a jackand support the vehicle with safety stands.WARNINGWhen you remove a clevis pin that has a spring,hold the spring with pliers. The spring candisengage from the clevis with enough force tocause serious personal injury.3. Remove both clevis pins.4. Remove a conventional pawl or disengage apull pawl: Use a screwdriver or equivalent toolto lift the button of a pull pawl assembly atleast 1/32-inch from the actuator.66. Remove the snap ring and washers from thecamshaft. Remove the slack adjuster from thecamshaft.7. Remove the clevis from the push rod if the gapbetween the clevis and the collar of a “QuickConnect” clevis exceeds 0.060-inch (1.52 mm).You do not have to remove the clevis if it is ingood condition.

Section 3DisassemblyDisassembly8. Remove the pin from the rod and piston, ifnecessary. Figure 3.3.Section 3DisassemblyWARNINGTo prevent serious eye injury, always wear safeeye protection when you perform vehiclemaintenance or service.Figure 3.3PIN1. Cut the clamp and remove it from the boot.Use a new clamp and boot when you assemblethe slack adjuster.PISTON2. Remove the boot from the housing. Pull theactuator assembly from the housing.Figure 3.1.ACTUATOR RODFigure 3.1NOTE: You do not have to remove the slackadjuster arm bushing unless it is worn or“egg-shaped.”9. Inspect the condition and fit of the slackadjuster arm bushing.10. If necessary, install a new bushing onto theclevis pin. Use the clevis pin and mallet todrive out the old bushing while you drive in thenew bushing.3. Use a small screwdriver to push down on oneside of the piston retaining ring to force thering out of the groove. Figure 3.2.4. Extend the coils of the ring.5. Use pliers to unwind the ring and pull it out ofthe groove. Figure 3.2.Figure 3.2NOTE: Steps 11 through 21 apply only toautomatic slack adjusters manufactured BEFOREJanuary 1993. The gear set and seals are notserviceable on automatic slack adjustersmanufactured AFTER January 1993. Refer to theexploded views on pages 2 and 3 of this manualfor more information.11. Use a small screwdriver to remove the greaseseal from around the worm bore. Figure 3.4.Discard the seal. Use a new seal when youassemble the slack adjuster.Pull ring out.Push ring down.Figure 3.46. Use a new ring when you assemble the slackadjuster.7. Pull the actuator rod, piston and pin from theactuator.7

Section 3Disassembly12. Use snap ring pliers to remove the retainingring from the worm bore. Figure 3.5.Figure 3.517. Unwind the ring by hand and pull it out of thegroove. Figure 3.7.Figure 3.7NOTCH13. Use a wrench to turn the manual adjusting nutand wind the worm out of the bore. Figure 3.6.18. Remove the thrust washer.CAUTIONFigure 3.6Push one seal out of one side of the slack adjusterhousing and the other seal out of the other side ofthe housing to avoid damaging the seals.19. Push the gear out of the housing only farenough to enable you to remove one gear seal.20. Push the gear out of the opposite side of thehousing and remove the other seal.21. Inspect the seals. Discard damaged seals.14. Remove the retaining rings and thrust washersfrom both sides of the gear.15. Fit a small screwdriver into the notch at theend of the retaining ring.16. Remove the end of the retaining ring from thegroove.8

Section 4Prepare Parts for AssemblyPrepare Parts for AssemblySection 4Parts for AssemblyPrepareWARNINGTo prevent serious eye injury, always wear safeeye protection when you perform vehiclemaintenance or service.WARNINGSolvent cleaners can be flammable, poisonous andcause burns. Examples of solvent cleaners arecarbon tetrachloride, emulsion-type cleaners andpetroleum-based cleaners. To avoid seriouspersonal injury when you use solvent cleaners,you must carefully follow the manufacturer’sproduct instructions and these procedures:r Wear safe eye protection.r Wear clothing that protects your skin.r Work in a well-ventilated area.r Do not use gasoline, or solvents that containgasoline. Gasoline can explode.r You must use hot solution tanks or alkalinesolutions correctly. Follow the manufacturer’sinstructions carefully.CAUTIONDo not use hot solution tanks or water andalkaline solutions to clean ground or polishedparts. Damage to parts will result.CAUTIONOnly use solvent cleaners on metal parts. Damageto parts will result.Clean PartsInspect Parts1. You must carefully inspect all slack adjusterparts, including pawl teeth, for wear anddamage before you assemble the slackadjuster.2. Replace any part that is worn or damaged.Corrosion ProtectionNOTE: Parts must be clean and dry before youlubricate them.1. If you assemble parts immediately after youclean them: Lubricate parts with grease toprevent corrosion. Parts must be clean and drybefore you lubricate them.2. If you store parts after you clean them: Apply acorrosion-preventive material. Store parts in aspecial paper or other material that preventscorrosion.Automatic Slack AdjustersCAUTIONAlways replace used clevis pin retainer clips withnew ones when servicing the automatic slackadjuster or chamber. Do not reuse clevis pinretainer clips after removing them. Discard usedclips. When removed for maintenance or service,clevis pin retainer clips can be bent or “gappedapart” and can lose retention. Damage tocomponents can result.Check the clevis pins and the bushing in the arm ofthe slack adjuster. Replace the pins if they areworn. Replace the bushing if its diameter exceeds0.531-inch (13.5 mm).1. Use solvent cleaners to clean all automaticslack adjuster parts that have ground orpolished surfaces; for example, the gear, theworm and the inner bores of the housing.2. Use soap and water to clean non-metal parts.3. Use soft paper or cloth that is free from dirt, oilor abrasives to dry the parts completely.Dry Parts After CleaningDry the parts immediately after cleaning. Dry partswith clean paper or rags, or compressed air.9

Section 5AssemblyAssemblySection 5AssemblyWARNINGTo prevent serious eye injury, always wear safeeye protection when you perform vehiclemaintenance or service.NOTE: Steps 3 through 11 apply only to automaticslack adjusters manufactured BEFORE January1993. The gear set and seals are not serviceable onautomatic slack adjusters manufactured AFTERJanuary 1993. If you are working on a currentmodel, skip to Step 10.6. Push the gear o

brake parts. The solution should be applied with low pressure to prevent dust from becoming airborne. Allow the solution to flow between the brake drum and the brake support or the brake rotor and caliper. The wheel hub and brake assembly components should be thoroughly wetted to suppress dust before the brake