POWERTRAIN
In the trucking industry today, noise, vibration
and harshness (NVH) levels are at the forefront
of vehicle design strategy for many reasons.
Driver comfort is extremely important, and
drivers have come to expect heavy duty line
haul trucks to operate similar to a passenger
car. Unexpected vibrations can lead to driver
fatigue and dissatisfaction, as well as expensive
downtime in diagnostic and repair eff orts.
In the midst of this quest for a smoother,
quieter ride, other trucking industry trends
such as engine downspeeding have had an
eff ect on vehicle dynamics and harmonics,
oft en contributing to NVH issues. Component
manufacturers and OEMs have adapted truck
designs accordingly.
A collaborative solution
Th is multifaceted industry concern requires a
highly-engineered, collaborative solution. Th e
44 Fleet Maintenance | November/December 2017
Technology & Maintenance Council (TMC) of
the American Trucking Associations has
made the investigation of ride complaints and
NVH issues a top priority, led by Jim Holman,
engineering manager at Dana Incorporated.
Holman and a team of fellow industry
experts are in the process of updating TMC’s
Recommended Practice (RP) on troubleshooting
vehicle ride complaints – otherwise known
as RP 648.
While the driveshaft or tires are oft en
assumed to be the NVH culprit, the group
believes that the problem of vibration in the
powertrain should be handled with a systematic
approach.
NVH issues may be rooted in a variety of
vehicle confi gurations and can interact
with the natural frequency of many
parts of the vehicle such as the transmission,
axle, suspension, clutch, tires,
dashboard, door panels or other components.
A technician should investigate beyond
where the immediate symptom is being
experienced, and the updated RP 648 will
systematically lead the technician through
a step-by-step process.
TMC’s main purpose is to publish recommended
practices on a wide variety of trucking
industry topics. For more than 30 years,
their Recommended Practices Manual has been
recognized as one of the leading maintenance
guides for commercial vehicles, containing the
best equipment maintenance and maintenance
shop management information available.
RP 648 off ers comprehensive guidelines to
diagnosing ride complaints in heavy duty tractors
and trucks. In its current form, it exists as
a 58-page document that proves challenging for
the average technician to use as a diagnostic
tool. Th e update will make it more user-friendly,
written so that a qualifi ed truck technician
with limited prior ride and vibration diagnostic
experience will be able to follow a simple procedure
to identify the root cause component in
a timely manner. Th e group plans to take RP
648 and compartmentalize it into three easy
to follow sections including:
Troubleshooting to identify and document
the complaint
Diagnostic procedure in the form of a fl ow
chart to identify the root cause component
Reference/glossary to identify terms
Th is update is supported by leading OE
manufacturers and suppliers across the trucking
industry. Th e group plans to provide an
update at the next TMC Annual Meeting &
The importance of
diagnosing NVH issues
Addressing noise, vibration and harshness
levels in heavy duty vehicles can help maximize
performance and improve driver comfort.
By Tom Bosler
DIRECTOR OF GLOBAL DRIVESHAFT PRODUCT PLANNING
FOR THE COMMERCIAL-VEHICLE BUSINESS, DANA INCORPORATED
Based in Maumee, Ohio, Dana (www.dana.com/commercial-vehicle) is a world leader in highly engineered
solutions for improving the efficiency, performance and sustainability of powered vehicles and machinery.
Dana supports the passenger vehicle, commercial truck, and off-highway markets, as well as industrial and
stationary equipment applications. With a career at Dana spanning more than 30 years, Bosler is proficient in
Six Sigma operations management, as well as program and product development.
» Unexpected vibrations can lead to
driver fatigue and dissatisfaction.
Photo from iStock
» Designed with
fewer components to
reduce weight, the SPL 350 Lite
driveshaft also improves performance
and vehicle dynamics with reduced
noise, vibration, and harshness levels.
Photo courtesy of Dana Incorporated
/commercial-vehicle