MAXX22T Air Disc Brake Maintenance
LIT NO: P76033
DATE: October 2018
Hendrickson Trailer Commercial Vehicle Systems was recently made aware of a bulletin* published by WABCO
regarding inspection procedures for PAN and MAXX series air disc brake systems.
Hendrickson has always maintained that thorough, proper and routine maintenance inspections of key
MAXX22T™ components should take place within our recommended inspection frequencies. While the
perception may be that air disc brakes are maintenance-free, the reality is that, like any other braking system, a
regularly planned maintenance schedule is integral to maximizing performance, enhancing safety and achieving
optimal life.
Performing regular inspections for integral air disc brake components like brake pads, retaining hardware and
calipers can significantly impact system life and performance. Brake life varies depending on the vehicle’s duty
cycle and operating conditions. Adjusting inspection intervals to account for these differences and ensuring the
brakes are serviced before exceeding their wear limits will help maximize system life and performance.
As a reminder, Hendrickson has several resources available to assist with determining maintenance intervals
and proper maintenance procedures for MAXX22T trailer air disc brake systems. These resources include
T72009 MAXX22T Maintenance Procedures and L578 Preventative Maintenance Manual, which are available
on Hendrickson’s website at www.hendrickson-intl.com.

Additionally, Hendrickson’s online training portal provides step-by-step guidance in the form of videos and
training courses. Technicians can log on to www.hendrickson-academy.com to learn about Hendrickson’s
recommended practices for MAXX22T™ trailer air disc brake systems.
As always, if you have any questions regarding warranty, maintenance or service of MAXX22T air disc brakes,
please contact Hendrickson for further details. If you have air disc brakes systems other than MAXX22T,
please refer to the specific manufacturer for maintenance recommendations.
*For your reference, WABCO’s technical bulletin is included in this announcement.

WABCO PAN19-1, PAN22-1
AND MAXX22T TRAILER
AIR DISC BRAKE INSPECTION
TECHNICAL BULLETIN

Table of contents

Table of contents

EN

1

General Information ......................................................................................................................................... 4

2

Safety Information............................................................................................................................................ 6

3

Mandatory Air Disc Brake Component Inspection........................................................................................ 7
3.1
Inspection Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

4

Inspection Procedures .................................................................................................................................... 8
4.1
Pad Spring Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.2
Pad Retainer Bar Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.3
Pad-to-Caliper Abutment Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.4
Caliper Guiding Pin Bearing Play Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

5

Revised Inspection Schedule for WABCO Air Disc Brakes ....................................................................... 13

6

Warranty Information ..................................................................................................................................... 14

Edition 1 (10/2018)
Document no.: TP18042

This publication is not subject to an updating service.

3

General Information

EN

1

General Information

Symbols used in this document

DANGER
Description of an immediate situation which will result in irreversible injury or death if the warning is
ignored.

WARNING
Description of a possible situation which may result in irreversible injury or death if the warning is
ignored.

CAUTION
Description of a possible situation which may result in irreversible injury if the warning is ignored.

NOTICE
Description of a possible situation which may result in material damage if the warning is ignored.
Important information, notes and/or tips

Reference to information on the internet

– Action step
-

Action step

 Consequence of an action
 List
•

List
Note on the use of a tool/WABCO tool

How to Obtain Additional Maintenance, Service and Product Information
If you have any questions about the material covered in this publication, or for more information about
the WABCO product line, please contact WABCO Customer Care Center at 855-228-3203, by email at
[email protected], or visit our website, www.wabco-auto.com.

4

General Information

WABCO Academy

EN

https://www.wabco-academy.com/home/

WABCO Online product catalogue
http://inform.wabco-auto.com/

Your direct contact to WABCO

WABCO North America LLC
WABCO USA LLC
1220 Pacific Drive
Auburn Hills, MI 48326
Customer Care Center: (855) 228-3203
www.wabco-auto.com

5

Safety Information

EN

2

Safety Information

Provisions for a safe work environment
Read and observe all Danger, Warning and Caution hazard alert messages in this publication. They provide
information that can help prevent serious personal injury, damage to components, or both.
 Read this publication carefully.
 Follow all warnings, notices and instructions to avoid personal injury and property damage.
 Only trained and qualified technicians may carry out work on the vehicle.
 Always abide by the vehicle manufacturer's specifications and instructions.
 The workplace should be dry, sufficiently lit and ventilated.
 Use personal protective equipment if required (safety shoes, protective goggles, respiratory protection
and ear protectors).

WARNING
To prevent serious eye injury, always wear safe eye protection when you perform vehicle
maintenance or service.

WARNING
Park the vehicle on a level surface. Block the wheels to prevent the vehicle from moving. Support the
vehicle with safety stands. Do not work under a vehicle supported only by jacks. Jacks can slip or fall
over. Serious personal injury and damage to components can result.

WARNING
WABCO air disc brake linings do NOT contain asbestos. However, some manufacturers' brake
linings do contain asbestos fibers, a cancer and lung disease hazard. Some brake linings contain
non-asbestos fibers, whose long-term effects to health are unknown. You must use caution when you
handle both asbestos and non-asbestos materials.

6

Mandatory Air Disc Brake Component Inspection

3

Mandatory Air Disc Brake Component Inspection

EN

The following braking system components should be inspected immediately:
 Pad springs
 Pad retainer bar (if applicable)
 Pad-to-caliper abutment (if applicable)
 Caliper guiding pin bearing play (if applicable)

An updated preventive maintenance schedule (included herein) should be followed.

3.1

Inspection Guidelines
NOTICE
This service bulletin does not provide complete service information for individual products referenced
within. For appropriate service instructions related to your product visit our website,
http://inform.wabco-auto.com.

Refer to WABCO Document No. 815 010 109 3, “General Repair and Test Hints”, for additional information
During inspection, observe the following guidelines detailed in this reference document.
 Replace damaged equipment components.
 Always use all parts of the repair kit for the equipment.

7

Inspection Procedures

EN

4

Inspection Procedures

4.1

Pad Spring Inspection
Inspect all wheel end pad retaining springs. Verify the springs are not broken or cracked. Ensure all wheel
ends have three complete retaining springs in place. IF all springs are intact, no further action is needed.
If one or more retaining springs is cracked, broken or missing, install all components of a pad service
kit; including pads, springs, retainer bar, and all other supplied hardware. Before replacing the pads, an
additional inspection of the pad retainer bar and pad-to-caliper abutments, as detailed in this publication,
should also be performed. Figure 1 and Figure 2.
Fig. 1

1. SPREADER
PLATE SPRING
2. INBOARD
PAD SPRING
3. OUTBOARD
PAD SPRING

4014751a
Fig. 2

MISSING
PAD SPRING

4014790a

8

Inspection Procedures

4.2

Pad Retainer Bar Inspection

EN

Inspect the pad retainer bar mounting holes for excessive wear. If holes appear oblong, measure the holes
as shown in Figure 3. If they measure 12 mm (0.472 inches) or more at their widest point, replace the
caliper and carrier assembly.
Fig. 3

EXAMPLE - RETAINER BAR HOLES

12 MM

12 MM

4014752a

4.3

Pad-to-Caliper Abutment Inspection
Check depressions on carrier surfaces by running your fingernail over the surfaces (fingernail test). If you
notice grooving of pad abutment areas indicated below, replace the caliper and carrier assembly. Figure 4,
Figure 5 and Figure 6.
Fig. 4

PAD-TO-CALIPER

4014753a

9

Inspection Procedures

Fig. 5

EN

EXAMPLE REQUIRING REPLACEMENT

4014754a

Fig. 6

EXAMPLE REQUIRING REPLACEMENT

4014755a

10

Inspection Procedures

4.4

Caliper Guiding Pin Bearing Play Inspection

EN

Inspect the guide bushings for excessive play.
1. Press the dial indicator against the measuring point (arrow) on the brake caliper. Figure 7 and Figure 8.
Fig. 7

MAXX22T MODEL

4014756a

Fig. 8

PAN19-1 AND PAN22-1 MODELS

4014757a

11

Inspection Procedures

2. Applying little force, tilt the caliper as far as possible (direction as illustrated in Figure 9) and set the dial
indicator to the value zero.

EN

Fig. 9

4014758a
3. Now, and again applying little force, tilt the brake caliper as far as possible in the opposite direction.
4. Read the dial indicator. The bearing play must not be greater than 2 mm.
5. If the bushings are worn beyond specification, replace them.

12

Revised Inspection Schedule for WABCO Air Disc Brakes

5

Revised Inspection Schedule for WABCO Air Disc
Brakes
Inspection Schedule*
Every 6 months
(4 months
severe duty**)

Every
12 months

Wheel ON

Every
Pad Change

Wheel OFF

Inspect the pad thickness by visual
inspection or measure caliper position
with a ruler.

X

X

Inspect the rotors for cracks through
to vent channels, etc. (see manual for
details).

X
(only visible parts)

X

X

X

X

X

X

Measure pad wear and inspect
all retaining hardware for damage
(pad retainer bar, pad springs and
mounting holes)

X

X

Check running clearances and
adjuster operation.

X

X

Check boots, seals and end caps for
rips, tears, damages, or cracks.
Inspect all retaining hardware for
damage (pad retainer bar, pad
springs).

X

Check caliper slide movement (should
move easily in and out by hand) and
check caliper guiding pin bearing play
(see manual).

X

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

X

Ensure brake pad retainer bar is
torqued to specification (see manual
for details).

X

* Visually inspect the brakes through the wheel during every tire pressure check.
WABCO Warranty Terms & Conditions Defines Standard & Severe Duty Application as follows:
Standard application: Line-Haul/On-highway operation is defined as 100% on-highway use.
**Severe Duty/Off-Highway: e.g. Severe Duty/Off-Highway operation includes, but is not limited to, garbage trucks, cement trucks,
logging trucks, oil/gas field trucks, utility trucks, or trucks with mixed on/off highway use.
Note: The table above is meant to provide a guide to maintenance interval planning. However, depending on the particular vehicle’s
application (e.g., corrosive environment, heavy usage on rough or gravel roads, etc.) more frequent inspections of the braking
system components may be necessary

13

EN

Warranty Information

EN

6

Warranty Information
The inspection procedure presented in this document is intended to reduce, not eliminate, the risk of
component failure.
Contact WABCO for warranty support:
[email protected]/

+1 (855) 228-3203

DISCLAIMER
This Technical Bulletin is provided as a service to our Customers. While every care has been taken to
ensure the accuracy of this Technical Bulletin as well as the reliability of the sources and information upon
which this publication is based, WABCO does not guarantee nor make any representation or warranty
as to the completeness or accuracy of the facts, assessments, opinions or any other information stated
herein and disclaims all liability therefore. WABCO makes no commitment to update or keep current the
information in this Technical Bulletin and reserves the right to make improvements to this publication and/
or to the products described herein, at any time without notice. The terms of this Technical Bulletin and the
information provided herein shall not benefit, nor create any right or cause of action in, or on behalf of, the
user of the publication. WABCO and any of its affiliated entities disclaim liability whatsoever for damages,
costs or expenses, howsoever arising, in connection with the Technical Bulletin. Any use of the Technical
Bulletin will be at the entire risk and peril, and under the sole responsibility of, the user.

14

EN

15

(NYSE: WBC) is a
leading global supplier of technologies and services that improve the
safety, efficiency and connectivity
of commercial vehicles. Originating
from the Westinghouse Air Brake
Company founded nearly 150
years ago, WABCO continues to
pioneer breakthrough innovations
to enable autonomous driving in
the commercial vehicle industry.
Today, leading truck, bus and trailer brands worldwide rely on WABCO’s differentiating technologies,
including advanced driver assis-

© 2018 WABCO North America – TP18042 / 10.2018

tance, braking, steering and stability control systems. Powered by its
vision for accident-free driving and
greener transportation solutions,
WABCO is also at the forefront of
advanced fleet management systems that contribute to commercial
fleet efficiency. In 2017, WABCO
reported sales of $3.3 billion and
has nearly 15,000 employees in 40
countries. For more information,
visit

www.wabco-auto.com