Bendix Commercial Vehicle Systems ADB22X-V Air Disc Brakes User Manual

Bendix® ADB22X™, ADB22X-V™ Air Disc Brakes

SD-23-7541

SECTION ONE: AIR DISC BRAKE OVERVIEW

1.1 DESCRIPTION

Bendix® ADB22X™ and ADB22X-V™ Air Disc Brakes (ADB) use a ﬂ oating caliper design to provide foundation braking on all axles of heavy commercial vehicles, buses and trailers. Bendix Air Disc Brakes provide safety and performance as well as ease of service.

The ADB22X disc brakes mount to the axle's anchor plate (torque plate) using fasteners that are installed parallel to the axle, while the anchor-plate fasteners used for the Bendix to the axle.

Available with or without a combination spring brake unit, these brakes may also include optional wear sensors and wear diagnostic equipment.

ADB22X-V™ air disc brakes install at right angles

Sections in this Document

Section Page

1 Overview . . . . . . . . . . 1-5

2 Preventive Maintenance and

Wheel-on Inspections . . . . . . 6-8

3 Troubleshooting Flowchart . . . . . 9

4 Wheel-off Maintenance Inspections . 10-15 5 Maintenance Kits and Procedures. . 16-37

Full Index - see Page 38

1.2 Air Disc Brake Identiﬁ cation

Locate the identiﬁ cation label near the guide pin housing. See below for information about the label ﬁ elds used.

FIGURE 1 - BENDIX® ADB22X™ AIR DISC BRAKES

FIGURE 2 - TYPICAL PART NUMBER LABEL LOCATION

Bendix Part Number

Serial No.

Customer Part Number

FIGURE 3 - PART NUMBER LABEL INFORMATION

Section One

Section Page

1.1 Description . . . . . . . . . . 1

1.2 Air Disc Brake Identiﬁ cation. . . . . 1

1.3 Rotor Identiﬁ cation . . . . . . . 3

1.4 Wear Sensor Identiﬁ cation . . . . . 3

1.5 Operation . . . . . . . . . . 3

1.5.1 Brake Release and Adjustment . . . 3

GENERAL SAFETY GUIDELINES

WARNING! PLEASE READ AND

FOLLOW THESE INSTRUCTIONS

TO AVOID PERSONAL INJURY OR DEATH:

When working on or around a vehicle, the following guidelines should be observed AT ALL TIMES:

▲ Park the vehicle on a level surface, apply the parking

brakes and always block the wheels. Always wear personal protection equipment.

▲ Stop the engine and remove the 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.

▲ Do not attempt to install, remove, disassemble or

assemble a component until you have read, and thoroughly understand, the recommended procedures. Use only the proper tools and observe all precautions pertaining to use of those tools.

▲ 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 AN Y wo rk on the vehicle. If the vehicle is equipped with a Bendix Bendix AD-9si™ air dryer, be sure to drain the purge reser voir.

▲

Following the vehicle manufacturer’s recommended procedures, deactivate the electrical system in a manner

that safely removes all electrical power from the vehicle ▲ Never exceed manufacturer’s recommended pressures. ▲ 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. ▲ Use only genuine Bendix

components and kits. Replacement hardware, tubing,

hose, ﬁ ttings, etc. must be of equivalent size, type

and strength as original equipment and be designed

speciﬁ cally for such applications and systems. ▲ Components with stripped threads or damaged parts

should be replaced rather than repaired. Do not

attempt repairs requiring machining or welding unless

speciﬁ cally stated and approved by the vehicle and

component manufacturer. ▲ Prior to returning the vehicle to ser vice, make certain all

components and systems are restored to their proper

operating condition. ▲ For vehicles with Automatic Traction Control (ATC),

the ATC function must be disabled (ATC indicator

lamp should be ON) prior to performing any vehicle

maintenance where one or more wheels on a drive axle

are lifted off the ground and moving. ▲ The power MUST be temporarily disconnected

from the radar sensor whenever any tests USING A

DYNAMOMETER are conducted on a Bendix

Advanced ▲ You should consult the vehicle manufacturer's

operating and service manuals, and any related

literature, in conjunction with the Guidelines above.

DRM™ dryer reservoir module, or a Bendix

™

-equipped vehicle.

AD-IS® air dryer system, a

brand replacement parts,

Wingman®

WARNING: Not all wheels and valve stems

are compatible with Bendix Air Disc Brakes. Use only wheels and valve stems approved by the vehicle manufacturer to avoid the risk of valve stem shear and other compatibility issues.

WARNING: AVOID CREATING

DUST. POSSIBLE CANCER AND LUNG DISEASE HAZARD.

While Bendix Spicer Foundation Brake LLC does not offer asbestos brake linings, the long-term affects of some non-asbestos ﬁ bers have not been determined. Current OSHA Regulations cover exposure levels to some components of non-asbestos linings, but not all. The following precautions must be used when handling these materials.

• Avoid creating dust. Compressed air or dry

brushing must never be used for cleaning brake assemblies or the work area.

• Bendix recommends that workers doing brake

work must take steps to minimize exposure to airborne brake lining particles. Proper procedures to reduce exposure include working in a well-ventilated area, segregation of areas

where brake work is done, use of local ﬁ ltered ventilation systems or use of enclosed cells with ﬁ ltered vacuums. Respirators approved by the Mine Safety and Health Administration (MSHA) or National Institute for Occupational Safety and Health (NIOSH) should be worn at all times during brake servicing.

• Workers must wash before eating, drinking or

smoking; shower after working, and should not wear work clothes home. Work clothes should be vacuumed and laundered separately without shaking.

• OSHA Regulations regarding testing, disposal

of waste and methods of reducing exposure for asbestos are set forth in 29 Code of Federal Regulations §1910.001. These Regulations provide valuable information which can be utilized to reduce exposure to airborne particles.

• Material Safety Data Sheets on this product, as

required by OSHA, are available from Bendix. Call 1-800-247-2725 and speak to the Tech Team or e-mail techteam@bendix.com

1.3 Rotor Identiﬁ cation

See Figure 4 to help you identify which type of rotor is used on the axle being inspected. Note that the maintenance

inspection procedure will depend on the type of rotor installed.

Splined

Bendix

Disc® Rotor

Conventional

Rotor

1.5 Operation

Bendix air disc brakes convert air pressure into braking force. (See Figure 6.) When the vehicle brakes are applied, air enters the service brake chamber through the supply port, applying pressure within the diaphragm. The pressure expands the diaphragm — applying force to, and moving, the pressure plate and push rod forward. The push rod acts against a cup in the internal lever which pivots on an eccentric bearing moving the bridge. Moving against a return spring, the bridge transfers the motion to two threaded tubes and tappets, which move the inner brake pad. The inner brake pad (from its normal position of having a running clearance between it and the rotor) moves into contact with the brake rotor. Further movement of the bridge forces the caliper — sliding on two stationary guide pins — away from the rotor. That, in turn, pulls the outer brake pad into the rotor. The clamping action of the brake pads on the rotor applies braking force to the wheel.

FIGURE 4 - ROTOR IDENTIFICATION

CAUTION: Rotors may not be mixed on a single axle: axles are only permitted to have all conventional or all splined disc rotors.

1.4 Wear Sensor Identiﬁ cation

See Figure 5 for the electronic wear sensor that may be present.

104

Cable Protection

Plate

101

Sensor

103

Cable to Electrical

Supply

Sensor . . . . . . . . . . . . . . . . . . . . .101

Cable to Electrical Supply. . . . . . .103

Cable Protection Plate . . . . . . . . .104

Cable Guide (two designs). . . . . . 105

Consult the instruction sheet included with wear

indicator kits for installation information.

101

Sensor

105

Cable Guide

(2 alternate

designs used)

Pressure

Service Brake

Chamber

Inner Brake Pad

Outer Brake

Pad

Rotor

FIGURE 6 - CROSS-SECTION VIEW SHOWING BRAKE OPERATION

Lever

Return Spring

Plate

Push Rod

Bridge

Eccentric Bearing

Supply Port

Diaphragm

1.5.1 Brake Release and Adjustment

When the vehicle brakes are released, the air pressure in the service brake chamber is exhausted and the return springs in the chamber and the bridge return the air disc brake to a neutral, non-braked position. To maintain the running clearance gap between the rotor and the brake pads over time, the non-braked position is mechanically adjusted by a mechanism in the caliper. The adjustment mechanism operates automatically whenever the brakes are activated, to compensate for rotor and brake pad wear and to keep the running clearance constant. During pad or rotor maintenance, the technician manually sets the system’s initial non-braked position. The total running clearance (the sum of clearances on both sides of the rotor) should be between 0.024 to 0.043 in. (0.6 to 1.1 mm).

FIGURE 5 - ELECTRONIC WEAR INDICATOR COMPONENTS

161

Tappet Bushing

Caliper

Pad

Assembly

Ring

Inner Boot

Guide Pin

Inner Seal

Caliper Bolt

Brass Bushing

Top Sectional View

Cap

Adjuster Unit

Threaded Tube

Tappet and Boot

Assembly

45 Washer

Spring Clip

Pad Retainer Pin

Pad Retainer

Threaded Tube

161

Tappet

Bushing

Tappet and

Boot Assembly

Carrier

Inner

Seal

Turning

Device

Carrier

Chain Wheel

Adjuster Cap

Chain

Wear Sensor

Shear Adapter

27 Spring

Bridge

6 Guide Sleeve

Side Sectional View

Pad

Assembly

Rotor

FIGURE 7 - SECTIONAL VIEWS

Pad Assembly 12

Spring

Bridge

Lever

Eccentric

Bearing

Caliper Bolt

18/1 Spring Brake or

18/2

Brake Chamber

Bolt

Ring

9 Inner Boot

Guide Pin

Short Caliper Bolt Sectional View

Cap

Type A

(Fixed pin)

Wheel Rotation

(typically right hand)

Shield

Kit

(Drive or

Steer)

(Rotor Shield for Trailers)

U-shaped

Rotor

Fasteners

(Wheel turns toward

Type B

ﬁ xed pin side of

Wheel Rotation

(typically left hand)

161

Tappet Bushing

13 Tappet

and Boot

Assembly

U-shaped Rotor

ADB)

Pad Retainer Pin

Washer

Inner Seal

Ring

Actuator

Hardware

Inner Boot

11 Pad Retainer

26 Spring Clip

12/2 Pad Holder Spring

12/1 Pad

35 Double-Diaphragm Style

Spring Brake Chamber

(Pad Assembly

consists of

12/1 plus 12/2)

Brass

Guide

Caliper

Bolt

Bushing

37*

Shear

Adapter

Caliper

(or Caliper Kit)

Bendix

ADB22X

Carrier

Cap

4 Guide Pin

6 Guide Sleeve

Carrier Mounting Hardware

Bendix

Anchor Plate

™

18/1 Spring Brake

Actuator

Cap

39 Caliper Bolt

ADB22X™

18/2

Service

Actuator

*37 Adjuster

Caps (2 styles

supplied in kits)

Bendix

ADB22X-V

™

Carrier

Drive Hub

Splined Disc® Rotor

Hardware

SD-1, -2, -3

See Section 5.2 for

exploded view of electronic

Splined Disc

(SD)

Rotor

SD-3

Steer Hub

FIGURE 8 - EXPLODED VIEW - BENDIX® ADB22X™ AND ADB22X-V™ AIR DISC BRAKES

INDEX TO FIGURES 7 & 8

Adjuster Caps. . . . . . . . . . 37

Adjuster Unit. . . . . . . . . . . 23

Bolt . . . . . . . . . . . . . . . . . . 43

Brass Bushing . . . . . . . . . .7

Bridge. . . . . . . . . . . . . . . . 17

Caliper . . . . . . . . . . . . . . . . 1

Caliper Bolt. . . . . . . . . 39, 40

Cap. . . . . . . . . . . . . . . . . . 68

Carrier. . . . . . . . . . 2 (A or B)

Chain . . . . . . . . . . . . . . . . 30

Chain Wheel. . . . . . . . . . . 32

Cap. . . . . . . . . . . . . . . . . . 10

Eccentric Bearing . . . . . . . 20

Guide Pins . . . . . . . . . . . 4, 5

Guide Sleeve . . . . . . . . . . . 6

Inner Boot. . . . . . . . . . . . . . 9

Inner Seal. . . . . . . . . . . . . 22

Lever. . . . . . . . . . . . . . . . . 19

Pad. . . . . . . . . . . . . . . . 12/1

Pad Holder Spring . . . . 12/2

Pad Assembly. . . . . . . . . . 12

Pad Retainer. . . . . . . . . . . 11

Pad Retainer Pin . . . . . . .44

Ring . . . . . . . . . . . . . . . . . 58

Service Actuator. . . . . . 18/2

Shear Adapter. . . . . . . . . .61

Splined Disc Hardware

. . . . . .SD-1, SD-2 and SD-3

Spring. . . . . . . . . . . . . . . . 27

Spring Brake Actuator. . 18/1

SD-1

SD-2

wear indicator.

Bendix

ADB22X-V™

Anchor Plate

Carrier Mounting Hardware

Spring Brake Actuator (Double-

Diaphragm style) . . . . . . .35

Spring Clip . . . . . . . . . . . . 26

Tappet and Boot

Assembly . . . . . . . . . . . 13

Tappet Bushing. . . . . . . . 161

Threaded Tube. . . . . . . . . 16

Turning Device . . . . . . . . . 24

Washer. . . . . . . . . . . . . . . 45

Wear Sensor. . . . . . . . . . . 33

SECTION TWO: PREVENTIVE MAINTENANCE SCHEDULE AND WHEEL-ON INSPECTIONS

2.0 PREVENTIVE MAINTENANCE

Regular inspection and maintenance of air disc brake components is an important part of vehicle maintenance.

The maintenance practices outlined here are recommended in addition to all standard industry practices (including daily pre-trip inspections.) Also, see the vehicle's manual for recommendations. Keep track of the results of your maintenance inspections to assist you in determining the ideal maintenance intervals for the vehicle.

Use the table below for a guide to maintenance interval

planning, however, depending on the particular vehicle's

use, more frequent checks of the components may be necessary.

(4 to 5 times during the pad lifetime)

About every four (4)

* For vehicles with electronic wear

months for over-the-

road applications:

indicators, use the dash indicator(s) and/or the hand-held diagnostic tool to regularly monitor the pad wear.

See Section 5.2.

When

you

check

the tire

pressures

e.g. line haul, RV,

open-highway

coaches, etc.

Section Page

2.0 Preventive Maintenance. . . . . . 6

2.1 Brake Pad and Rotor Inspections . . . 7-8

2.2 Running Clearance Quick Inspection. . 8

Table 1: Inspection Period

About every three (3) months

for higher-duty applications:

e.g. pick-up & delivery,

off-highway, construction,

logger, concrete mixer, dump

truck, city transit bus, refuse,

school buses, etc.

Section Two

At the

very least, every

four (4) months

At least

once

every

year

(and at

every

pad

replace-

ment)

Inspections with the wheel mounted (Sections 2.1 - 2.3)

Inspect the pad thickness by checking the mechanical wear indicators*. See Section 2.1.

Inspect the running clearances using the quick inspection technique. See Section 2.2.

Inspect the visible part of the rotors for cracks, etc. See Section 2.3.

Inspect the pads and entire rotor surfaces for cracks, etc. (Bendix splined disc® rotors: Inspect retaining hardware and check torques) See Section 2.3.

Inspect the running clearances and adjuster operation.

See Sections 2.2 and 4.2.

Inspect the caliper travel.

See Section 4.1.

Inspect the tappet and boot assemblies. See Section 4.6.

Inspect all caps, hoses, and brake exterior for damage etc.

Inspections with wheel removed (Section 4)

TABLE 1 - PREVENTIVE MAINTENANCE SCHEDULE

2.1 BRAKE PAD AND ROTOR INSPECTIONS

Visual checks of the condition of the brake pad/rotor wear can be made without removing the wheels. Where dust guards are not used, the top of the pads and part of the rotor are visible through the opening at the top of the brake. Other visible portions of the rotor can be inspected at the same time.

Unless a vehicle has been stored for some time, the main rotor surfaces that contact the pads will always appear to be shiny . Surface rust on these surfaces would indicate a malfunctioning brake that should be inspected immediately .

Pads are 1.181 in. (30 mm.) thick when new and must be replaced when they reach 0.433 in. (11 mm.). Rotors are

1.77 in. (45 mm.) thick when new and must be replaced when they reach 1.46 in. (37 mm.). See Section 4.3 for

further inspection criteria.

2.1.1 Electronic Wear Indicators

Use the dash indicator(s) and/or a hand-held diagnostic tool to regularly monitor the pad wear. (See Section 5.2.)

2.1.2 Mechanical Wear Indicators

See Figure 9 for the location of the mechanical wear indicators. There are two types (See Figure 10 for Style A and Figure 11 for Style B).

Wear Indicator Style A: Where both the carrier and caliper have an

indicator notch.

Compare the relative position of two notches cast into the carrier and caliper. When the two notches align, it is time to schedule a full wheel-removed inspection of the pads and rotor.

Notch in the

caliper

Notch in the

carrier

When the notches

line up, it is time

to schedule an

inspection of the

pads and rotor

FIGURE 10 - STYLE A - WHEN BOTH CARRIER AND CALIPER HAVE A CAST NOTCH

Quick Visual

Inspection of Pad

Thickness and Rotor

Location of Wear

Indicator Notches

(Both sides of brake)

FIGURE 9 - LOCATION OF WEAR INDICATORS

Note: These mechanical wear indicators do

not constitute “out-of-service” criteria. These

inspections only show when to schedule a full wheelremoved inspection of the brake pads and rotor. The thicknesses of the pad and rotor will both affect the wear indicator position at which maintenance is actually needed.

Wear Indicator Style B: Where only the caliper has an indicator

notch.

When the notch in the caliper aligns with the front edge of the torque plate, it is time to schedule a full wheel-removed inspection of the pads and rotor.

Notch in

the caliper

No notch

in the

When the

torque plate

edge lines up

with the notch,

it is time to

schedule an

inspection of

the pads and

rotor

Torque

carrier

plate

FIGURE 11 - CARRIER WEAR INDICATOR NOTCH AND BACKING PLATE ALIGNMENT

No action is needed for small cracks spread over the surface (e.g. Area F)

Rotor Friction Surface

Width “f”

Cracks reaching either edge of the

rotor are not acceptable for either type of rotor

Area G

Area

Circumferential grooves, as in Area J, are acceptable if less than 0.06 in. (1.5 mm) deep.

Area J

• For standard Bendix rotors, cracks running in a radial direction — like spokes of a wheel (see Area H) — less than 0.06 in. (1.5 mm) deep or wide are acceptable if they do not reach either edge (see G). Cracks are only acceptable if the length of the crack is less than 75% of dimension “f” (the width of the rotor contact area).

• For Bendix Splined Disc rotors, radial cracks are only acceptable if they are less than 0.04 in. (1.0 mm) deep or wide and if they do not reach either edge (see G). Crack lengths must be less than 75% of dimension “f” (the width of the rotor contact area).

In addition, follow the recommendations of the vehicle manufacturer.

Note: Axles should have either all Bendix Splined Disc (or all conventional) rotors.

FIGURE 12 - EXAMPLES OF ACCEPTABLE AND NON-ACCEPTABLE ROTOR CRACKS AND GROOVES

2.1.3 Rotor Quick Inspection

See Figure 12. See the various potential rotor conditions that you may ﬁ nd. See the criteria below for whether the rotor needs to be replaced and/or scheduled for a full inspection.

2.2 RUNNING CLEARANCE QUICK INSPECTION

CAUTION: Follow all safe maintenance practices.

On level ground, with the wheels chocked and the parking brake temporarily released, check for movement of the brake caliper. This small movement, less than 0.08" (2 mm)

- approximately the thickness of a nickel - in the inboard/ outboard direction indicates that the brake is moving properly on its guide pins.

If the caliper has no movement or appears to move greater than the distances noted above, a full wheel-removed inspection will be necessary (See Section 4.1).

FIGURE 13 - CALIPER RUNNING CLEARANCE (FIGURE DOES NOT SHOW WHEEL)

Push/Pull

By Hand

to Check the Caliper Movement

SECTION THREE: TROUBLESHOOTING PROCEDURE FLOWCHART

Air Disc Brake Inspection

Follow safe maintenance practices,

chock wheels. Engage spring brakes

and cage spring. Release spring

brakes and drain air from system.

Raise axle, spin

the wheel by

hand.

Does

the wheel

turn smoothly?

YES

Check

running

clearance (4.1)

- OK?

Check

Adjuster (4.2)

- OK?

the

spring brake fully/

partially applied?

YES

Check

caliper

guidance (4.5)

- OK?

YES

Drain air pressure from

system. Re-start test after

caging spring brakes

YES

Check

running

clearance (4.1)

- OK?

Check

adjuster (4.2)

- OK?

Replace caliper/

carrier assembly

(5.3)

YES

Check

Pad and rotor

wear (4.3-4.4)

- OK?

YES

Replace caliper/

carrier assembly

(5.3)

FIGURE 14 - TROUBLESHOOTING BENDIX AIR DISC BRAKES

Replace guide pins

(5.6) OR replace

caliper/carrier

assembly (5.3)

Tightness not due to

air disc brake. See

vehicle manual.

Replace components

as needed with

genuine Bendix parts.

Disc brake OK

SECTION FOUR: WHEEL-OFF MAINTENANCE INSPECTIONS

Section Four

Section Page

4.0 Wheel-Off Inspections . . . . . . 10

4.1 Caliper Movement Test . . . . . . 10

4.2 Adjuster Mechanism Inspection . . . 11

4.3-4.4 Brake Pads and Rotors . . . . . 12-14

4.3 Inspect the Brake Pads . . . . . . 12

4.4 Inspect the Rotor . . . . . . . 13-14

4.4.3 Machining (Grinding or Turning) Rotors 14

4.5 Guide Pin Bearing Inspection . . . 14-15

4.6 Tappet & Boot Assembly Inspection . . 15

4.0 WHEEL-OFF INSPECTIONS

CAUTION: During these inspections, follow all safe maintenance practices, including those on page two of this service manual. Also, follow the vehicle manufacturer’s recommendations. When working on foundation brakes, be sure that the vehicle is on level ground, that the vehicle is parked by other means than the foundation brakes, and that the wheels are chocked.

4.1 CALIPER MOVEMENT TEST

CAUTION: Follow all safe maintenance practices.

Remove the wheel. With the spring brakes released or caged, push the caliper assembly inboard on its guide pins.

Note: To fully release the spring brakes, assure that the air system pressure is at least 90 PSI. Using a suitable

tool (for example a large ﬂ at-blade screwdriver), press the inboard pad (12) away from the tappets. Check that there is no dirt, etc. in the gap, and clean if necessary . Then use two long-blade feeler gauges to measure over the whole tappet surface the gap between them and the inboard pad backplate. (See Figure 16.) The gap should be between

0.024 in. (0.6 mm) and 0.043 in. (1.1 mm). If the gap is

within the range given, the test is complete.

4.0.1 Wheel Removal and Re-Installation

Refer to the vehicle manufacturer’s recommendations for removing the wheel.

Note: When removing the wheel, inspect ﬁ rst to see that there is no contact between the caliper and axle, vehicle, chassis sections or carrier, etc. that may be impeding the free movement of the caliper.

WARNING: Not all wheels and valve stems are compatible with Bendix Air Disc Brakes. Use only wheels and valve stems approved by the vehicle manufacturer to avoid risk of valve stem shear and

other compatibility issues. After re-installing a wheel

according to the vehicle manufacturer’s recommendations, please ensure that there is sufﬁ cient clearance between the tire inﬂ ation valve stem, the caliper and the wheel rim, to avoid damage.

Pull

Caliper

Inboard

FIGURE 15 - PULL CALIPER INBOARD

Check the clearance at

both tappets simultaneously:

0.024 in. to 0.043 in.

(0.6 mm. to 1.1 mm.)

FIGURE 16 - RUNNING CLEARANCE CHECK

CAUTION: If the clearance is too wide, there is a danger of brake failure. If the clearance is too small, or if there is no gap at all, there is a danger of the brake overheating. These conditions must be corrected before returning the vehicle to service.

For further investigation, where there is some gap, go to Section 4.2 and check the adjuster mechanism. Where there is no movement at all (and so no gap to measure), go to Section 4.5 “Guide Pin Inspection.”

4.2 ADJUSTER MECHANISM INSPECTION

CAUTION: Follow all safe maintenance practices.

Aside from the normal maintenance schedule, the adjuster mechanism inspection that follows is also carried out when the Caliper Movement Test (4.1) ﬁ nds that the running clearance is too small or too large.

4.2.1 With the spring brake released (or caged), remove the adjuster cap (37) using the tab, taking care not to move the shear adapter (61). Note: One of two styles of adjuster cap (stamped metal or plastic adjuster cap) may be used.

Adjuster Cap

Location

FIGURE 20 - BACKING-OFF (INCREASING) THE RUNNING CLEARANCE

If the shear adapter fails, you may attempt a second time with a new (unused) shear adapter.

Note: Always double-check that the spring brake is released (where applicable) if a shear adapter fails; if this step was missed, the shear adapter will break off, and it may appear that the caliper is seized.

In cases where a second failure of the shear adapter conﬁ rms that the adjustment mechanism is seized, the caliper must be replaced.

FIGURE 17 - ADJUSTER CAP LOCATION

Cap

23 Adjuster

61 Adapter

Cap

Tab

FIGURE 18 - EXPLODED VIEW OF ADJUSTER AND ADAPTER

FIGURE 19 - CAP INSTALLED: TAB LOCATION

Tab

For illustration purposes, the exploded view (Figure 18) shows the adjuster (23) and shear adapter (61) separated. When using the adjuster mechanism, always have the shear adapter installed on the adjuster.

4.2.2 Using a 10 mm. six-point box wrench, turn the Shear Adapter (61) counter-clockwise and listen for the sound of 3 clicks as the mechanism backs-off (increases) the running clearance. Note: Do not use an open-ended wrench as this may damage the adapter. See Figure 20.

CAUTION: Never turn the adjuster (23) without the shear adapter (61) installed. The shear adapter is a safety feature and is designed to prevent excessive torque from being applied to the adjuster. The shear adapter will fail (by breaking) if too much torque is applied.

FIGURE 21 - APPLYING MODERATE APPLICATIONS OF THE

BRAKES: THE WRENCH MOVES CLOCKWISE AS THE RUNNING CLEARANCE IS DIMINISHED

4.2.3 Where the adjuster mechanism is able to be backedoff normally , position a box-end wrench on the shear adapter so that it can turn clockwise freely without coming into contact with parts of the vehicle (See Figure 21). Make ﬁ ve to ten moderate applications of the brakes [at about 30 psi (2 Bar)], and observe that the box-end wrench or socket should turn clockwise in small increments.

NOTE: As the number of applications increases,

the turning movement will decrease (as the brake reaches its normal calibration point).

If the box-end wrench does not: (a) turn at all; (b) turns only with the ﬁ rst application; or (c) turns forward and backward with every application, the automatic adjuster has failed and the caliper/carrier assembly must be replaced.

After completing these wheel-off tests, Bendix recommends installing a new adjuster cap (lightly greased using white, lithium-based grease) when returning the brake to service. Ensure that the tab is in the position shown in Figure 19.

4.3- 4.4 BRAKE PADS AND ROTORS

CAUTION: Follow all safe maintenance practices.

If electronic wear sensors are present, see Section 5.2. If dust covers are present, see Section 5.1. See Figure 23. While pressing down against the pad

retaining bar (11), remove and retain the clip (26), washer (45) and pin (44). Remove the pad retainer bar (1 1). Bendix recommends that these items should be replaced with new (See available kits and parts, Section 5.0).

Follow the steps in Section 4.2 for backing-off the adjuster mechanism. Slide the caliper inboard then outboard to

permit easy removal of the brake pads.

Brake Rotor

Outboard

Brake Pad

Inboard

Brake Pad

A Thickness of a new pad (1.181 in.) (30 mm.). B Backing plate thickness (0.360 in.) (9 mm.) C Minimum thickness of friction material (0.080 in.)

(2 mm.)

D Minimum thickness of a worn pad (0.433 in.)

(11 mm.); replace pads.

E Thickness of a new rotor (1.77 in.) (45 mm.).

Minimum rotor thickness (1.46 in.) (37 mm.)

FIGURE 22 - PAD AND ROTOR DIMENSIONS

See Figure 22 for initial brake pad and rotor dimensions, as well as minimum acceptable dimensions.

4.3 INSPECT THE BRAKE PADS

Regular inspection of the brake pads (even for vehicles that use an electronic wear indicator) is an important part of vehicle maintenance.

4.3.1 See Figure 22. If the thickness of the friction material — dimension “C” — is less than 0.080 in. (2 mm.), the pads must be replaced.

Bendix (9 mm.) backing plates, so dimension “D” (the combined pad and backing plate thickness) must be a minimum of

0.43 in. (11 mm.).

4.3.2 Check for uneven end-to-end pad wear. If the

4.3.3 Compare the thickness of the inboard and outboard

If the results of the pad inspections are within the acceptable range, inspect the pad surface. (See Figure 24).

FIGURE 24 - BRAKE PAD SURFACE INSPECTION

Minor damage at the edges is permitted, but replace the pads if major damage on the surface of the pad is found.

ADB22X™, ADB22X-V™ air disc brakes use 0.35 in.

difference in wear is greater than 0.080 in. (2 mm.), replace the brake pads and also inspect the guide pins (See Section 4.5).

pads of each set. If the difference between the inboard and outboard pad thickness is greater than

0.138 in. (3.5 mm.), replace the brake pads and inspect the guide pins (See Section 4.5).

small amount

Minor Damage -

Is Acceptable

chipped from

Major Damage -

Is Not Acceptable

Section

damaged or

missing

Where a

of brake material

the edge

26 Spring Clip

FIGURE 23 - RETAINER BAR REMOVAL

When replacing brake pads, Bendix strongly recommends that all the brake pads on an axle be replaced at one time. See Section 5.1 for the pad replacement procedure. Also see the vehicle manufacturer’s recommendations found in the operator’s manual.

11 Pad Retainer Bar

45 Washer

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