Fleet Maintenance - 26

unit director of wheels and braking systems,
Hendrickson Trailer Commercial Vehicle Systems.
Hendrickson is a manufacturer and supplier of
medium and heavy duty mechanical, elastomeric,
and air suspensions, axle and brake systems, and
other components for the commercial transportation industry.
Another change to routine maintenance will be
the focus on new and different areas of inspection
on the vehicle. For example, technicians who have
spent a majority of their careers working on S-cam
drum and shoe systems will need to understand
the critical service and maintenance points on
an ADB system. There are fewer parts to inspect,
maintain, and stock with ADBs when compared to
drum brakes. This should translate to less necessary inventory and less downtime associated with
preventive maintenance (PM) schedules.
Establishing a regular PM schedule that incorporates ADB inspections will be crucial in the
fleet's ability to capitalize on the adoption of ADBs
and ensure that the braking system's operation is
optimized. Inspections on integral ADB components, such as brake pads and calipers, will impact
the system's service life and performance.
"One factor that can negatively impact maintenance cost and system performance is allowing
brake pads to wear past minimum thickness,"
Wittlinger says. "When this happens, the pad's
metal backing plate can wear against the rotor.
The disc brake mechanism will continue applying
force to the worn pad, which, in turn, continues
to grind against the rotor. If left unchecked, the
rotor will likely require premature replacement
and repair costs can skyrocket."
When it is time to change the ADB friction
materials, most suppliers recommend utilizing
OEM or like-for-like parts. These are components
that were designed to work together and meet
OE specifications when the vehicle was manu-

» The P89 Plus air disc brake system by SAF-Holland can be specified on tractor or
trailer axles. Pictured is an example of P89 Plus ADBs on rear trailer axles.
Photo courtesy of SAF-Holland

Of the differences
between drum brakes
and ADBs, the most
notable are those
related to maintenance
and servicing.
factured. McComsey says Bendix Spicer tested
a number of aftermarket friction materials, and
confirmed some severely reduced performance
and increased stopping distance.
For those fleets researching the use of aftermar-

» The SAF-Holland P89 Plus air disc brake
system features a heavy duty vented rotor
which more evenly dissipates heat to reduce
rotor distortion for a long service life.
Photo courtesy of SAF-Holland

ket friction materials, be sure to verify compatibility and work with a trusted supplier.
Stemco has developed a comprehensive parts
interchange that takes original pad equipment
numbers and translates them into Stemco numbers.
The system then uses the Friction Material
Standard Institute numbers to culminate
an interchange that determines what
types of vehicles a pad fits, pad to caliper compatibility, etc. The interchange is
available at stemco.com through the site's
parts search section.

Specifying ADBs

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replacement parts that help you operate at your best. We're proud to be your
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VehicleServicePros.com/10123924

26 Fleet Maintenance | August 2019

With such drastically different architecture, mechanical operation, functionality, parts, and size, aftermarket
specification to ADBs from drum brakes
is a major undertaking. Although not
unheard of, it is rare, as there is much
to take into consideration when making
the change from drum brakes. It is not
only more expensive to specify ADBs as
a retrofit option, but also requires significant downtime and labor. Most fleets
opt to specify ADBs on the vehicle at the
time of production.
Fleets can specify ADBs through the
OE on any and all axles of heavy duty
commercial vehicles.
"The more axles that have ADBs on
them, the more improved the performance is - the shorter the stopping
distance [and] the longer the brake fric-


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Fleet Maintenance

Table of Contents for the Digital Edition of Fleet Maintenance

Uptime: Is assessing cost-per-mile enough?
Do you know your TCO?
Vehicles: How to ensure optimum air system performance
In the Bay: The ABCs of ADBs
Shop Operations: The importance of managing fluid dispensing in the shop
Training: Invest in the future
Diagnostics: All scan tools are not created equal
Management: Are you good at PM?
Fleet Parts & Components
Tools & Equipment
Guest Editorial: Cold weather solutions for fleets
Fleet Maintenance - 1
Fleet Maintenance - 2
Fleet Maintenance - 3
Fleet Maintenance - 4
Fleet Maintenance - 5
Fleet Maintenance - 6
Fleet Maintenance - 7
Fleet Maintenance - Uptime: Is assessing cost-per-mile enough?
Fleet Maintenance - 9
Fleet Maintenance - Do you know your TCO?
Fleet Maintenance - 11
Fleet Maintenance - 12
Fleet Maintenance - 13
Fleet Maintenance - 14
Fleet Maintenance - 15
Fleet Maintenance - 16
Fleet Maintenance - 17
Fleet Maintenance - Vehicles: How to ensure optimum air system performance
Fleet Maintenance - 19
Fleet Maintenance - 20
Fleet Maintenance - 21
Fleet Maintenance - In the Bay: The ABCs of ADBs
Fleet Maintenance - 23
Fleet Maintenance - 24
Fleet Maintenance - 25
Fleet Maintenance - 26
Fleet Maintenance - 27
Fleet Maintenance - Shop Operations: The importance of managing fluid dispensing in the shop
Fleet Maintenance - 29
Fleet Maintenance - 30
Fleet Maintenance - 31
Fleet Maintenance - 32
Fleet Maintenance - 33
Fleet Maintenance - Training: Invest in the future
Fleet Maintenance - 35
Fleet Maintenance - Diagnostics: All scan tools are not created equal
Fleet Maintenance - 37
Fleet Maintenance - Management: Are you good at PM?
Fleet Maintenance - Fleet Parts & Components
Fleet Maintenance - 40
Fleet Maintenance - 41
Fleet Maintenance - Tools & Equipment
Fleet Maintenance - 43
Fleet Maintenance - 44
Fleet Maintenance - 45
Fleet Maintenance - 46
Fleet Maintenance - 47
Fleet Maintenance - 48
Fleet Maintenance - 49
Fleet Maintenance - Guest Editorial: Cold weather solutions for fleets
Fleet Maintenance - 51
Fleet Maintenance - 52
Fleet Maintenance - S1
Fleet Maintenance - S2
Fleet Maintenance - S3
Fleet Maintenance - S4
Fleet Maintenance - S5
Fleet Maintenance - S6
Fleet Maintenance - S7
Fleet Maintenance - S8
Fleet Maintenance - S9
Fleet Maintenance - S10
Fleet Maintenance - S11
Fleet Maintenance - S12
Fleet Maintenance - S13
Fleet Maintenance - S14
Fleet Maintenance - S15
Fleet Maintenance - S16
Fleet Maintenance - S17
Fleet Maintenance - S18
Fleet Maintenance - S19
Fleet Maintenance - S20
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