*37 Adjuster
Caps (2 styles
supplied in kits)

Carrier
Mounting
Hardware

1
Caliper
(or Caliper Kit)
9
58 Inner Boot
Ring

Bendix® ADB22X®
Anchor Plate
2A
Bendix
ADB22X
Carrier

(Rotor Shield for Trailers)

U-shaped
Rotor
Fasteners

2B
Bendix®
ADB22X®-V
Carrier

SD-1

Drive Hub
SD-2

Splined Disc®
Rotor
Hardware
SD-3
SD-1, -2, -3

Steer Hub

Splined Disc Rotor
(SD)

Bendix
ADB22X-V
Anchor Plate

Carrier
Mounting
Hardware

See Section 5.2 for
exploded view of electronic
wear indicator.

Figure 8 – Exploded View - Bendix ® ADB22X®, ADB22X® -V, and ADB22X® -LT 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
Spring . . . . . . . . . . . . . . . 27
Spring Brake Actuator . . 18/1
Spring Brake Chamber (DoubleDiaphragm-Style) . . . . . . . 35

Spring Clip . . . . . . . . . . . . 26
Tappet and Boot
Assembly . . . . . . . . . . . 13
Tappet Bushing . . . . . . . 161
Threaded Tube . . . . . . . . 16
Turning Device . . . . . . . . 24
Washer . . . . . . . . . . . . . . 45
Wear Sensor . . . . . . . . . . 33

7

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.

Section Two
Section

2.0
2.1
2.2

Page

Preventive Maintenance . . . . . . 8
Brake Pad and Rotor Inspections . . 9-10
Running Clearance Quick Inspection . . 10

Table 1: Inspection Period
(4 to 5 times during the pad lifetime)

* For vehicles with
electronic wear
indicators, use the
dash indicator(s)
and/or the hand‑held
diagnostic tool to
regularly monitor the
pad wear.

When
you
check
the tire
pressure

About every four (4)
months for over-theroad applications:

About every three (3) months
for higher-duty applications:

e.g. line haul, RV,
open-highway
coaches, etc.

e.g. pick-up & delivery,
off-highway, construction,
logger, concrete mixer, dump
truck, city transit bus, refuse,
school buses, etc.

See Section 5.2.

Inspections with the wheel mounted (Sections 2.1 - 2.2)
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 2.1.3.

Inspections with wheel removed (Section 4)
Inspect the pads and entire rotor
surfaces for cracks, etc. (Bendix®
Splined Disc® rotors: Inspect
retaining hardware and check
torques) See Section 2.1.3 and 4.4.
Inspect the running clearances and
adjuster operation.
See Sections 2.2 and 4.2.
Inspect the caliper running
clearance. See Section 4.1.
Inspect the tappet and boot
assemblies. See Section 4.6.
Inspect all caps, hoses, and brake
exterior for damage etc.

Table 1 – Preventive Maintenance Schedule
8

At the
very
least,
every
four (4)
months

At least
once
every
year
(and at
every
pad
replacement)

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 have a shiny
appearance. Surface rust on these surfaces indicates a
malfunctioning brake that should be inspected immediately.

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

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.

Notch in
the carrier

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).
Quick Visual
Inspection of Pad
Thickness and
Rotor
Location of Wear
Indicator Notches
(Both sides of
brake)

When the notches
line up, it is time
to schedule an
inspection of the pads
and rotor
Figure 10 – Style A - Both Carrier and Caliper have a
Cast Notch

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.

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.

Notch in
the caliper

No notch
in the
carrier

When the torque
plate edge lines
up with the
notch, it is time
to schedule an
inspection of the
pads and rotor

Torque
plate

Figure 11 – Carrier Wear Indicator Notch and
Backing Plate Alignment
9

H

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

Rotor
Friction
Surface
Width “f”

Area
F

• 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 Area 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).

Area
H

f

Area G
G
Cracks reaching
either edge of the
rotor
are not
acceptable
for either
type of
rotor.

Area J

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

• 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 Area 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 find. See the criteria below for whether the
rotor needs to be replaced and/or scheduled for a full
inspection.

If the caliper movement or running clearance are unable
to be confirmed, complete a wheels-off inspection. (See
Section 4.1).

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, verify there is sufficient
running clearance between the pads. Using hand pressure
only (no tools) check for inboard/outboard movement
of the brake caliper. The small movement is less than
0.08“ (2 mm) – approximately the thickness of a nickel
– indicates that there is sufficient running clearance and
the caliper is sliding freely. For a more accurate reading, a
dial indicator may be used to measure running clearance.
Recommended running clearance range is 0.6 - 1.2 mm.
10

Push/Pull
By Hand to
Check the
Running
Clearance

Figure 13 – Caliper Running Clearance (Wheel Not
Shown)

SECTION THREE: TROUBLESHOOTING PROCEDURE FLOWCHART

Air Disc Brake Inspection

Follow safe maintenance practices;
chock wheels. Engage the spring
brakes and cage the spring.
Release the spring brakes and drain
the air from the system.

Raise the axle,
spin the wheel by
hand.

Does
the wheel
turn smoothly?
YES

NO
Is
the
spring brake
fully/partially
applied?

Check
running clearance
(4.1)
- OK?

NO

YES

YES

NO

YES
Check
running
clearance (4.1)
- OK?

YES

Check
adjuster (4.2)
- OK?
YES

NO

NO
Drain the air pressure from
the system. Restart test
after caging spring brakes.

Check
adjuster (4.2)
- OK?
Check
caliper guidance
(4.5)
- OK?

Replace caliper/
carrier assembly
(5.3).

Check
pad and rotor
wear (4.3-4.4)
- OK?
YES

YES

NO

NO

Replace caliper/
carrier assembly
(5.3).

NO

Tightness not due to
air disc brake. See
vehicle manual.

Replace components
as needed
with genuine
Bendix® parts.

Disc brake OK.

Replace the guide
pins (5.6) OR replace
caliper/carrier
assembly (5.3).

Figure 14 – Troubleshooting Bendix ® Air Disc Brakes
11

Component
(Item / Condition)

Investigation

Specs

See
Section(s)

BENDIX ® ADB22X ® TROUBLESHOOTING GUIDE
What To Replace

Consumable Items: These are considered to be normal wear items and should be repaired as part of regular preventive
maintenance.

Guide Pins

Boots & Seals

Disc Brake Pads

A

Worn

Measure the thickness of the
remaining friction material.

Pads must be replaced when they reach
0.080 in. (2 mm) of friction material.
- NA CVSA Out of Service limit = .0625 in. (1.6 mm)
- US DOT min. pad thickness = .125 in. (3.2 mm)
- CA CCMTA min. pad thickness = .080 in. (2 mm)

4.3

B

Measure the thickness of the
Uneven wear total pad in at least two (2)
on single
places at the top and two (2)
pad
places at the bottom, at least
1/2 in. from the edge.

The average difference of top vs. bottom or
left vs. right should be no greater than
0.080 in. (2 mm).

4.3.2

C

Measure the pad thickness as
Uneven wear
described for Item B above, but
on inboard
also check guide pin wear and
vs. outboard
slide-ability.