Washer

l R ot ati o

n

Wh

Wh

ee

12/1 Pad

On most vehicles, Type B calipers
are used on the driver’s side of
the vehicle. (There are some rare
passenger’s side applications.)

7
Brass
Bushing

22
Inner Seal

Shield
Kit
(Drive or
Steer)

161
Tappet Bushing
13 Tappet
and Boot
Assembly

U-shaped Rotor

Actuator
Hardware

10
40 Cap
5 Caliper
Guide Bolt
Pin

61 37*
Shear
Adapter

68
Cap
39 Caliper Bolt

4 Guide Pin
6 Guide Sleeve

*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

SD-3

Steer Hub

Splined Disc Rotor
(SD)

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

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

6

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

Spring Brake Actuator (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

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.

Section Two
Section

2.0
2.1
2.2

Page

Preventive Maintenance . . . . . . 7
Brake Pad and Rotor Inspections . .
8–9
Running Clearance Quick Inspection . . 9

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.

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
pressures

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.

At the
very
least,
every
four (4)
months

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

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.

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 2.3.
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.

Table 1 – Preventive Maintenance Schedule

7

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.

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
Notch in
the caliper

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.

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
8

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 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).

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.

Push/Pull
By Hand
to Check
the Caliper
Movement

Figure 13 – Caliper Running Clearance (Wheel Not
Shown)
9

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

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 air pressure from
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