DRIVEN
When two component suppliers work closely
together, the outcome can be highly impressive –
Words by Dave Whyte and Chris Mullett
of AMTs in recent years while
Dave concentrated more on what
it meant for the driver. We hope you find the
outcome interesting.
two journalists
from the same publication
covering the same story can be a bit
like putting two sheepdogs in the same paddock.
One will sit back and watch, while the other runs in circles
making a lot of noise.
In the case of this evaluation of the latest Eaton
UltraShift PLUS, Dave and I both felt that two heads were
better than one. Rather than sitting back and letting Dave
do all the work, my view looked at the incredible advances
20 PowerTorque ISSUE 66
If you have negative views about the shift quality of
some of the early Automated Manual Transmissions
(AMTs), it’s time for a rethink. Admittedly, with some of
the first versions the engine rpm seemed to soar between
shifts or baulk at selection through the lower part of the
‘box, but with the latest systems so much has changed
that you really need a personal update.
THE ART OF INTEGRATION
The intervening years between the first AutoShifts and
the latest UltraShift PLUS have resulted in an amazing
transformation of performance, efficiency and drivability.
Gone is the occasional hesitancy between shifts, replaced
by smooth shift patterns and an almost uncanny ability
of the engine and transmission to predict and engage the
right ratio for any situation. And, as a by-product, there’s
every likelihood you’ll be extending your clutch life as well.
PowerTorque has always been a supporter of the AMT
principle, although admittedly we had our reservations
about the early versions, for the reasons already listed.
For a while it looked as though the Europeans such
as ZF with its AS-Tronic and Volvo with its I-Shift were
untouchable in terms of sophistication, even though their
North American counterpart, Eaton, had the reputation for
longevity and suitability for the Australian market.
As the leading truck manufacturers shift their emphasis
to vertical integration, we’ll see specific drivelines
becoming available only in particular brands. It may not suit
operators that preferred to mix and match their engines
and transmissions, but it’s of great appeal to the bean
counters that firmly believe a Daimler truck (Freightliner,
Western Star, Mercedes-Benz and Fuso), should have a
Daimler engine (Detroit 9, 11, 13, 15 and 16-litre), a Daimler
DT12 transmission (Detroit 12-speed), and run on Daimler
axles (again Detroit branded).
Navistar now openly embraces its relationship with
Cummins, and there’s every possibility the recently
released Cummins 12-litre will take a share of the US
market, in consort with the availability of the Navistar
MaxxForce 13.
PowerTorque ISSUE 66
21
DRIVEN
It’s a similar story with PACCAR brands Kenworth and
Peterbilt. Their future driveline options are becoming
focused on the PACCAR MX-13-litre, with the flexibility of
larger capacity engines being handled by Cummins. What
both PACCAR and Navistar have in common though, is
the centralised focus on Eaton as its major supplier for
transmissions, except where Allison automatics excel in
certain applications.
Because on-highway trucks in the North American and
Australian markets differ so greatly in terms of weights
carried, ambient temperatures and power requirements,
there’s a huge disparity when it comes to determining an
ideal powertrain solution that fits both markets. So much
so, in fact, that the US is now standardising on the sub
500 hp level matched to 10-speed transmissions to handle
gross weights of around the 40 tonnes mark.
Sam Abulughod is typical of the new breed of engineers
working in the Australian market. As a systems engineer
with Eaton Vehicle group, Sam’s background was based
in mechatronics, the implementation of robotics in
engineering applications. It’s a long way from being on the
spanners or twisting a few wires together.
Sam and his boss, Graeme Weston, have been
instrumental in developing the latest shift protocol for
the 18-speed Roadranger UltraShift PLUS transmissions
matched to the Kenworth T-Series.
A comprehensive test and development programme over
18 months has resulted in Eaton releasing a completely
new and more refined computerised shift programme
that can be uploaded into any existing UltraShift PLUS
transmission coupled to a PACCAR MX-13 engine.
The Australian requirement for higher weights, long
distances and high ambient temperatures, puts our market
mainly in the 500-600 hp segment, except where singletrailer applications are the norm.
PowerTorque was the first Australian trucking magazine
to be invited to evaluate the new programme, and we did
so in the company of Eaton’s Sam Abulughod and Jon
Penrose, PACCAR’s MX-13 technical specialist.
The introduction of the PACCAR MX-13-litre engine
in Kenworth T-Series products brings us back to the
original topic of how to get the best driveline matching
between engines and transmissions for the B-double,
on-highway segment.
Our test bed for the day was a Kenworth T409 6x4 prime
mover powered by a PACCAR MX-13-litre producing
510 hp and with 1850 lb-ft of torque. This was coupled to
a tri-axle curtainsider carrying concrete blocks as a test
weight to gross out at 40 tonnes.
As an example of how fast the powertrain development
has moved in terms of engineering, the development
team responsible for improving and perfecting the match
between engine and transmission has a much broader
background in experience than simply being able to
select a bunch of different sized cogs and package
them in a gearbox.
The PACCAR MX13 engine is returning excellent
feedback from operators for good fuel economy and a
high acceptance rate amongst drivers. The new shift
protocols for the UltraShift Plus transmission enable a
complete integration of the driveline.
22 PowerTorque ISSUE 66
DRIVEN
As a bit of background to the development of the
UltraShift PLUS, Eaton has taken the basic RTLO-18918A
18-speed transmission and added components such as
an Electrical Clutch Actuator (ECA), an XY Shifter for gear
selection and an Electronic Control Unit (ECU) that controls
all aspects of the transmission.
The ECU performs the calculation for the grade of the
road and the weight of the vehicle, and it was the further
refinement of the ECU protocols that developed new shift
points for the Australian market in the MX configuration.
The aim of the programme development is to improve
the ratio skip-shifting performance of the transmission,
and it does so based on its availability with the optional
RTLO-18918A version of the Roadranger, rather than the
18918B model.
“The ratio spread for the first two gears in the “A” box is
12.9 and 10.41, versus the “B” box of 14.1 and 12.29:1,”
said Sam. “That allows us to have a 2nd gear start with a
2nd-3rd gear step of 18 percent, after which it skip-shifts
better than in a B-ratio, which has a 2nd-3rd gear step of
44 percent,” added Sam.
“By starting in 2nd gear, and with skip-shifting,
we get a better launch performance off from rest and
better acceleration as it skip-shifts through the gearbox.
This choice also extends clutch life.
“The ECU is constantly assessing the grade and throttle
position to choose the best skip-shift options. It also
measures the turning offsets of the steering angle, and by
doing so it prevents a skip-shift occurring when negotiating
a corner. Holding a ratio during the turn then ensures the
best engine performance through the corner.
“We wanted to use a mix of performance and economy.
We can do that through having grade-based shift files. It’s
about understanding how the engine likes to spend time
between 1000 and 1400 rpm, and keeping the shift point in
the most fuel-efficient zone. The MX engine loves to spend
its time where the peak horsepower and peak torque
meet, right at 1400 rpm, and every downshift on a hill goes
through this zone.
“When the transmission is upshifting at full throttle in the
first few gears we rev from 1675-1800 rpm. If you are at
full throttle you want to keep going, so we skip-shift in the
lower part of the box to get it moving. Then we reduce the
skip-shifting as you get higher in the box.
“It’s all a question of making the engine performance
more flexible. If the engine is at 1400 rpm and skip-shifts,
you land at about 1100 rpm, and can still pull this weight
on level ground at light throttle. When launching downhill,
I’ve seen it skip-shift five ratios from 2nd to 7th just to get
the truck going. This would be followed by 12th – 14th –
16th, whereas on the flat it would go 14th – 15th – 16th
individually,” said Sam.
24 PowerTorque ISSUE 66
The best way to evaluate the new protocols is of course
behind the wheel, and both Dave Whyte and I spent the
day behind the wheel getting a taste of the new technology.
My immediate impression was that at last the driver
interested in making a difference can use the technology
by varying throttle pedal pressure to promote gear
shifts, both up and down through the box. It’s no longer
necessary to play with the manual over-ride controls,
as the system is so intuitive.
The steering-wheel controls for the exhaust brake
enable the driver to change the downshift rpm sets and
to maximise the additional retardation available. Similarly,
upshifting from a launch in 2nd gear depends on throttle
pedal pressure, as it selects whether to skip-shift or take
ratios on a one-by-one basis.
All my driving was completed around the road network
to the northeast of Melbourne, and on a light downhill
grade it’s not uncommon to see a skip-shift of up to five
ratios completed in a split second. In normal driving the
combination seems happiest with skip-shifting two ratios
at a time, but the outcome is sure to be noticeable in three
ways – first, by the reduction in driver fatigue; secondly,
by the reduction in driveline stress; and, thirdly, by an
improvement in fuel economy.
Sam from Eaton used the expression that the new shift
programme would “change your mind about changing
gears”. Eaton has a lot to show for all the hard work, and,
as the company upgrades existing transmissions already
in service, it’s not going to be a well-kept secret for much
longer. In simple terms, it’s very impressive.
Sam Abulughod Systems Engineer
with Eaton
Vehicle Group.
THE ART OF INTEGRATION
We’re a clever bunch here in Australia having made
an art out of beating other countries at their own game.
Cricket, tennis, golf, surfing and a whole swag of other
sports make up a list where we have learned from and then
beaten other nations at their own game. This is no different
in engineering, though it is often overlooked. The latest
conquest comes from two very well-known names in the
Australian transport industry working together to take on
the world with exceptional results.
It’s fair to say that the first generation Eaton AMT
transmissions were not very well received in this country.
There were numerous issues faced by operators at the
time, including the dreaded neutralisation and indecisive
gearshifts that left many drivers sitting still halfway through
a steep climb.
These issues can probably be put down to two factors:
the installation of American shift programmes, and the
higher weights we run here.
That in itself is no mean feat, given the number of
systems and sensors on a modern truck, and the engineers
at Bayswater knew they had to get it right or risk the same
result as Eaton had with their early AMTs. Having sorted
the engine fitment, and gained some very favourable
customer feedback, it was time for the next challenge. This
is where the Eaton UltraShift PLUS comes into the picture.
The driveline combination of the PACCAR MX-13
and Eaton UltraShift PLUS has been on sale to American
buyers in both Kenworth and Peterbilt products for a
little over four years now, so one might think it would
be a simple process to fit the same components to an
Aussie Kenworth.
It turns out the American MX-13 is actually a little
different to that on offer here, the most notable difference
being that it continues the American tradition of running
on a 12-volt system. Another big factor is that more and
more American prime movers are running 10-speed
transmissions and diff ratios as low as 2.9:1, which would
require a very different shift pattern from our standard
18-speed and 3.9:1 or 4.11:1 final drive ratios.
The combination of these two factors, along with little
or no operator training on how to get the best results from
an AMT, meant the uptake of Eaton’s first-generation AMT
was very short lived. It also left a bad taste in the mouths
of some operators, who are still hesitant about buying an
American AMT. Times have changed though, and so has
the Eaton AMT.
There is another part to this story, which also involves
some Australian engineering that leads the way.
The recent introduction of the PACCAR MX-13 engine
under the bonnets of Kenworth trucks was not as simple
as it may seem. Alongside all the engineering required to fit
the engine into the chassis rails of
a Kenworth T409, there was also
a lot of electrical engineering
needed to make it run.
Jon Penrose,
PACCAR’s resident
MX 13 engine
technical specialist.
For a long time now, Kenworth, like most Americanbased models, have run on a 12-volt electrical system.
The PACCAR MX engine fitted to Australian Kenworths
runs on a 24-volt system, so a lot of work went on in the
background to ensure that all of the systems on a truck
would work together seamlessly.
There is also the communication between the engine
and transmission to take into account, and, as these two
components had never been paired up before, a good
translator would be required to enable this to happen.
Andrew Mills,
PACCAR marketing
brand specialist
for Kenworth.
This translation
needs to work between
three different control
modules, which, to
make matters difficult,
are shared between
PACCAR and Eaton.
Firstly, PACCAR’s
MX-13 Engine Control
Module (ECM) needs
to communicate with
Eaton’s Electronic
Control Unit (ECU).
PowerTorque ISSUE 66
25
DRIVEN
While the MX-13 passed Eaton’s
certification test (which tests to see
how an engine responds to requests
from the transmission) with flying colours,
there were some glitches to be sorted.
These were mostly related to gear
changes while the cruise control was
activated, and were resolved using a
separate MX integration control unit.
The result is clear communication
between the engine and gearbox control
modules, and perfect co-operation
between the two.
The integration goes well beyond
electronics, though. The gear ratios
have been optimised to suit the MX-13,
delivering improved launch characteristics
with the bonus of reduced clutch wear.
The use of slightly taller ratios in the
bottom end of the gearbox also allows
for better skip shifting while still keeping
engine rpm in the sweet spot for horsepower
and torque. This in turn contributes to good fuel economy,
something every operator is seeking, while still giving the
feeling that the engine is performing.
Gear shift points, and the actual gear chosen, are
determined by a combination of factors. These include
the grade on which the vehicle is operating, the weight of
the combination (as determined by the Eaton ECU) and,
most importantly, throttle position. The transmission is
programmed with grade-based shift files, and will make
more aggressive changes on steeper climbs while
skip-shifting on level ground.
This programme also has different parameters for
various stages of shifting, with the lower range gears
working higher in the rev range to maximise horsepower,
while the higher gears utilise the lower rpm torque band to
maintain momentum. The MX also benefits from a turning
offset programme, which restricts skip-shifting during
turning manoeuvres. This eliminates the chances of finding
the truck in the wrong gear half way around a corner –
another shortcoming of early model AMTs.
In order to find out if all of this technology works,
PowerTorque took the first T409 with the optimised shift
programme for a drive in the hilly country to the east
of Melbourne.
After only a short while, it was obvious that there had
been a lot of work put into this programme. The shift
quality was seriously smooth, with the Roadranger
skip-shifting flawlessly, and the MX-13 providing plenty
of power to get the single-trailer combination motivated.
From a standstill, the combination worked well on a
5% grade, providing fast, smooth and accurate gear
changes without over revving the engine. On the downhill
side, with only a light foot on the accelerator, at one stage
the transmission jumped four gears.
The shift from 4th to 8th seemed like a big one, but with
gravity doing its thing and plenty of torque on tap at low
revs there was no need for a gear in between.
26 PowerTorque ISSUE 66
Mr. Whyte at the wheel - never happier than when he’s driving someone
else’s new truck and using their fuel.
The market for 13-litre engines between 424 hp and
524 hp is a big one, considering it takes in single-trailer,
B-double, truck and dog combinations and vocational
units. It is also a market that sees 85 percent of new units
sold being fitted with AMT transmissions, which may
explain why Kenworth has invested so heavily in the
MX-13 and Eaton UltraShift PLUS combination.
What it means, though, is that Kenworth now has a
genuine contender for this segment, where it has fallen
short in previous years due to engine supply issues and
the stigma associated with Eaton AMTs.
But here’s the clincher – in typical Aussie style, they have
taken an idea from overseas and made it better.
Having driven the American version of this driveline,
I can honestly say that the Australian-engineered version
is better in terms of shift quality and timing. What’s more,
in a real stroke of genius, they have given the Europeans,
the leaders in AMT technology, something to worry about.
Without overstating it, this is the smoothest driveline
I’ve ever experienced in an American-style prime mover.
Not only have the engineers from Eaton and Kenworth
achieved what they set out to do, they have shown the rest
of the world how it’s done. Aussie Aussie Aussie, Oi Oi Oi!