june2021 - 20

┬╗ For manual transmissions, clutch pedal feel
and visual inspection are the main diagnostic
methods. AMTs will typically offer alerts and
fault codes and can be more readily diagnosed
with a diagnostic scan tool and software.
Photo courtesy of Rihm Kenworth
He also noted that Volvo offers a remote
programming service which allows fleets to
change parameter settings on Volvo AMTs to
optimize the truck for a specific application.
" This makes sense if a fleet's assignments
vary in weight, topography, and other factors, "
Agebrand explained. " Each truck can be tailored
to deliver optimum fuel efficiency, productivity,
and drivability based on its assignment. "
In cases where a truck will maintain a set application
for the majority of its life, the fleet can
choose to spec the transmission for that specific
duty cycle.
" If your vehicle is being run OTR (over the road),
make sure your AMT is spec'd for the road speeds
it will encounter, " said Len Copeland, Detroit product
marketing manager. " Likewise, if you are a
heavy haul application, make sure the transmission
selected is designed to handle the weights and
operating conditions it will encounter. Selecting
the right AMT is important for fleet operations as
well as driver satisfaction. "
Some vocational AMTs, for example, offer
unique features specific to the vocational market
such as off-road mode and rock-free mode.
While the majority of new commercial vehicles
being delivered are spec'd with AMTs, there are
still many trucks with manual transmissions on
the road today. Plus, it is important to account for
older truck models still being operated by fleets.
That means fleet technicians need to be trained
on maintaining and servicing both AMTs and
manual transmissions for the foreseeable future.
While there are apparent differences between
the two, AMTs and manuals are more similar than
they may first appear. One of the most important
similarities that should be a key focus for fleet
maintenance departments is the clutch.
Clutch operation
For a driver operating a truck with a manual
transmission or an AMT, the difference
is obvious: one has a clutch
pedal and the other does not.
Similar to driving a truck with
a fully automatic transmission,
an AMT requires only
┬╗Clutch issues can be
avoided by implementing
proper preventive
maintenance practices. In
all cases, it is crucial to follow
manufacturer recommended
maintenance intervals.
Image courtesy of Eaton
the use of the accelerator and brake pedals. That
is where the similarity ends, however; AMTs are
more similar to a manual than an automatic transmission
in how they operate mechanically.
According to Allison Transmission, an automatic
transmission utilizes a hydraulic torque
converter to couple the engine to a planetary-geared
transmission. An AMT, on the other
hand, uses a standard manual gearbox with either
electrical or pneumatic clutch actuation.
In other words, an automatic transmission
in a truck, like an automatic transmission in a
passenger car, provides steady, near-constant
acceleration. An AMT, on the other hand, shifts
like a standard manual transmission truck where
acceleration pauses while it shifts.
" Mechanically, there is no difference [between
manuals and AMTs], " Volvo's Agebrand explained.
" However, in an AMT, the vehicle's computers
operate the clutch versus the human driver in a
manual. The algorithms in today's AMTs are so
good that when it comes to the actual shift and
impact on the clutch, the AMT will perform a more
technically perfect shift 100 percent of the time. "
AMTs utilize a control module along with a
mechanical or pneumatic switch to actuate the
clutch itself, Detroit's Copeland said. This allows
the transmission to shift gears as efficiently as
possible. Some AMTs, he added, offer multiple
driving modes to help the driver stay in control
of how the transmission shifts.
Shifting more efficiently to always be in the
correct gear as required means AMTs shift more
frequently. Manufacturers have taken this into
consideration by using different clutch materials
than what would traditionally be used for a manual
transmission clutch.
" Manual clutches are made of a semi-metallic
composition while AMTs use an organic fiber
material because they shift more frequently based
on the different shifting strategies, which require
20 Fleet Maintenance | June 2021


Table of Contents for the Digital Edition of june2021

Uptime: The path to predictive maintenance
Editor's Note: Using resources wisely
Equipment: Getting to the bottom of air brake system leaks
In the Bay: Commercial vehicle clutch care
Shop Operations: How digitizing driver communication can improve maintenance
Fluid & Filtration: Why fleets shouldn't skimp on oil filters
Technology Trends: Gaining an advantage
Management: KPI fundamentals
Economic Outlook: Economic recovery update
Fleet Parts & Components
Tools & Equipment
Guest editorial: Benefits of remote brake system monitoring
june2021 - 1
june2021 - 2
june2021 - 3
june2021 - 4
june2021 - 5
june2021 - 6
june2021 - 7
june2021 - Uptime: The path to predictive maintenance
june2021 - 9
june2021 - Editor's Note: Using resources wisely
june2021 - 11
june2021 - Equipment: Getting to the bottom of air brake system leaks
june2021 - 13
june2021 - 14
june2021 - 15
june2021 - 16
june2021 - 17
june2021 - In the Bay: Commercial vehicle clutch care
june2021 - 19
june2021 - 20
june2021 - 21
june2021 - 22
june2021 - 23
june2021 - Shop Operations: How digitizing driver communication can improve maintenance
june2021 - 25
june2021 - 26
june2021 - 27
june2021 - 28
june2021 - 29
june2021 - 30
june2021 - 31
june2021 - 32
june2021 - 33
june2021 - Fluid & Filtration: Why fleets shouldn't skimp on oil filters
june2021 - 35
june2021 - 36
june2021 - 37
june2021 - Technology Trends: Gaining an advantage
june2021 - 39
june2021 - Management: KPI fundamentals
june2021 - Economic Outlook: Economic recovery update
june2021 - Fleet Parts & Components
june2021 - 43
june2021 - Tools & Equipment
june2021 - 45
june2021 - 46
june2021 - 47
june2021 - 48
june2021 - Classifieds
june2021 - Guest editorial: Benefits of remote brake system monitoring
june2021 - 51
june2021 - 52