Truck & Off-Highway Engineering - October 2024 - 23

PROPULSION FEATURE
is fundamentally different than it was 15
years ago, " said Eaton's Dorobantu.
Carbon emissions reduction and performance
that exceeds what's possible
with conventional powertrains highlight a
new technology Eaton developed in partnership
with the U.S. Army. The hybrid
transmission - an electrically powershifting
automated manual transmission
(AMT) - is undergoing various field tests.
" This is a novel architecture, "
Dorobantu said. " The transmission has
the ability to switch between two standard
hybrid modes. Electric power is being
introduced ahead of the transmission
in some modes of operation. And in other
modes of operation, the electric power
goes directly into the prop-shaft. "
Potential applications for the hybrid
" There is a future where
20-30% of heavy-duty
vehicles might be all-electric
or hydrogen fueled. But
there's also a future with a
broader penetration of lower
emission trucks using hybrid
technology, " said Eaton's
Mihai Dorobantu.
transmission include military and vocational vehicles. " For instance, with
a traditional transmission that's being used in difficult launches such as
mud or on high grades, if you need to interrupt the torque while shifting,
the vehicle will stop or it will start rolling backward, " Dorobantu said.
Initial test results with the electrically power-shifting AMT have
demonstrated an ability to launch a 36-metric-ton vehicle
on a 60% grade in third gear EV-only mode in
both forward and rearward directions. The hybrid
transmission also has shown low-speed maneuverability
at speeds less than 2 mph (3.2 km/h), and it is 1.25
times better at reaching 55 mph (89 km/h) compared
to a conventional transmission.
" Electrically generated torque helps with acceleration, "
Dorobantu said. " For example, the wide-open
throttle time from zero to 55 mph is 60-plus seconds
with a torque converter automatic transmission compared
to 50 seconds with this technology. "
Testing also reveals that the hybrid transmission can
cut carbon emissions by 20% to 30%. No production
plans have been announced yet for this electrically
power-shifting AMT.
Government regulations for truck fleets tag a 40%
reduction in carbon emissions by 2030. " The choice is
open as to how to achieve the target, " Dorobantu said,
noting that one battery-electric vehicle provides the
same emissions reduction as three hybrid vehicles.
" We can deploy a large fleet of hybrid vehicles as an
industry much faster than we can save on carbon
emissions with battery-electric vehicles, " he said.
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TRUCK & OFF-HIGHWAY ENGINEERING
October 2024 23
EATON
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Truck & Off-Highway Engineering - October 2024

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