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Worldwide Conditions and
New Transmission Technology
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With the technological advances of the past
100 years the world has become smaller. Fax machines, the
Internet, cell phones and the globalization of industry have
created a business climate that is evolving at an incredibly
rapid pace.
We have seen many changes in the automobile
and the components we work on, and the rate of change is only
going to increase rather than slow down. There are many factors
that are driving this endless development of new designs and
technology. It is important that we understand the forces that
are driving the new engineering and to be prepared for the new
types of transmissions we are about to see in the market.
The main issues that control the creation
of more-advanced technology are legislation, environmental
concerns, safety, increasing cost of fuel, advanced electronic
engineering and advances in engine design efficiency.
Governments create legislation in an effort to change for the
better; fuel economy, emissions and safety of vehicle
occupants, for example. This puts an added burden on
manufacturers to meet these new standards or withdraw from
certain markets.
At present there is a big push to limit
emissions of carbon dioxide (CO2) that are being blamed for
“global warming.” The ACEA, which is the European
vehicle manufacturers’ association, has put a target
limit of 140 grams per kilometer for automotive CO2 emissions
for 2008. Forget that “global warming” is a theory
and not based on scientific facts; it is influencing and
forming legislative and public opinion and causing a glut of
new regulations.
I am not a scientist, but I have common
sense, and all this theory flies in the face of established
science. For instance, geologists and paleontologists can show
that throughout the billions of years the earth has been in
existence the climate has warmed and cooled many times before
there was any industrial input by man. Another commonly ignored
fact is that plants take in CO2 and sunlight and through
photosynthesis produce oxygen and plant growth that feeds and
houses the world population.
During the dinosaur ages, the earth’s
atmosphere was richer in CO2 because of the large amount of
volcanic activity. This produced millions of years of the
largest animals that ever walked the earth, the largest plants
that ever grew, insects of immense size etc. If you increased
the CO2 levels in the atmosphere by 2%, established science
says that you would double your crop yields and end hunger
worldwide.
All this global-warming theory is based on
computer models that may not be correct. So pardon me if I have
a jaundiced view of the current wave of pseudo-science sweeping
over the globe. I remember that these are the same geniuses who
said the world would end in 2000 with Y2K – which turned
out to be the greatest computer-equipment marketing scam in
history – and told us 40 years ago that margarine would
make us live forever and that fresh milk, butter and eggs were
bad for your health.
Sorry for the side trip, but the
frustration of listening to so many “talking heads”
and politicians who couldn’t find their butt with both
hands makes me mean and ornery. Regardless of whether the
science is sound, the governments are going to do it, so you
must have new technology to meet the new standards.
Automotive-engine technology in both gas
and diesel has advanced tremendously. In the 24 Hours of LeMans
race this year, a diesel-powered Audi prototype race car won
going away. Beyond that, the engine was the quietest of
anything in the field, produced the most horsepower and torque,
and was the most fuel-efficient and, obviously, the most
durable. The efficiency levels of the new power plants will
increase by small increments; the greatest gains will be made
with advanced transmission technology.
As safety standards are increased and
electronic systems such as traction and stability control
become common on lower-priced models, the design of the
component package of the vehicle becomes tighter and tighter.
This is driving the transmission designers to smaller,
more-efficient and stronger transmissions using highly advanced
technology. The increase in horsepower now available from every
manufacturer with smaller-displacement engines has created the
need for more-durable and efficient gearboxes.
I have seen a GM four-cylinder Ecotech
engine that is producing more than 1,000 horsepower on
gasoline. Since 1990 you have seen continual changes in
transmission design, in which manual transmissions went from
four-speeds to six-speeds and automatics went from three- and
four-speeds to five- and six-speeds, with a couple of
seven-speed units making appearances.
If you think this was a lot of change, be
prepared for a whole new world. The manual transmission as we
know it is the most-efficient design, with relatively light
weight, cheap production costs, highest fuel efficiency and
high torque ratings. The drawbacks have been poor emission
control because of variations in driver control, skill levels
and comfort. Since stick transmissions shift at closed throttle
and the driver has ultimate control of throttle opening and
gear selection, emissions control is very difficult.
Now, let’s look at the other designs
that we will see more of shortly.
Continuously variable transmissions (CVTs)
are evolving into more-efficient designs. These units always
had a design drawback because of low torque capacity. New
engineering has started to overcome these limitations. The ZF
VT1F CVT in the Mini Cooper gets better fuel economy and is
better off the line than current automatic units, in a very
small package.
New designs using chains, such as the Audi
Multitronic, have overcome the problem of belt drives’
torque limitations. In 1998 Audi demonstrated that in
collaboration with LuK, it could develop a CVT that could live
behind a 2.8-liter engine with 206 lb.-ft. of torque. This
gearbox has ratios that start at 12.5-1 and end up with an
overdrive ratio. Through advanced electronic systems the engine
speed is closely controlled to make the transmission use all
the available torque with low slippage and high efficiency.
This unit weighs 20 pounds less than the ZF five-speed and gets
10% better fuel mileage than the five-speed automatic. Ongoing
development in design has a torque-limit goal of 368 lb.-ft.
The Japanese are not sitting idly by,
either, and have extensive CVT programs going between Bosch and
Aisin AW. You will see CVTs in Hondas, Mexican-built Nissan
Sentras and American-built Nissan Altimas and Maximas. The
Nissan Murano has a CVT, and one is supposed to be in the Dodge
Caliber for production in the 2007 model year.
Infinitely variable transmissions (IVTs)
often are confused with CVTs but are not of the same design.
Actually a toroidal or bevel-ring-drive transmission, this
design has the ability to handle very high torque loads, and
many companies are working on advancing this design. This
transmission has been used in motor scooters, motor cycles and
John Deere tractors. A British company, Torotrak, has
variations running in large U.S. 4x4s and 34,000-lb.-GVW trucks
and recently demonstrated the technology in a Ford Expedition
with a 5.4-liter engine. The company was able to show better
fuel mileage than with a conventional four-speed automatic in
that vehicle. This design ultimately will deliver a 10% fuel
savings over a six-speed automatic, with lighter weight and a
smaller package. Present drawbacks include low volumes of
production keeping costs high. You will see this design become
a presence in the next decade.
Antonov Automatic Driver (AAD) is a
transmission design that uses two simple planetaries but
eliminates the torque converter and the high-pressure hydraulic
system found in present automatics. A six-speed electronically
controlled design was introduced in 2002 and has been in
development since then. The design uses forces naturally
created within a helical-gear transmission, in that it combines
the axial thrust levels generated by the gear train with the
inertia generated by the moving assemblies. The advantages
claimed over a four-speed automatic are quicker acceleration,
greater top end, better throttle response and kick-down,
increased fuel savings by up to 20%, better wheel dynamics, no
interruption of power to the wheels during shifts, less
precision manufacturing than required for a CVT and low unit
costs. Honda is now in agreement to begin development of this
technology.
Automated manual transmissions (AMTs) are
already on the market and will continue to grow. These often
are called “clutchless” manual transmissions
because there is no clutch pedal. There is, however, a clutch
that is computer controlled with no driver input. The BMW SMG
(sequential manual gearbox) is used in the M3 and M5 models,
and the Selespeed is found in Ferrari models. These can be
driven in either an automatic-shift mode or manual control
using a shift lever or paddles mounted on the steering wheel to
permit the driver to upshift or downshift. The computer
controls will even blip the throttle during a downshift to
match the rpm level of racing “double-clutch”
shifting. The design permits absolute emission control by the
engine-management system for lower emissions levels; better
fuel economy, since the computer can control engine speed and
shifts better than the average driver; protection of the engine
from over-revving; and prevention of missed shifts. GM has a
version called Easytronic that has a self-adjusting clutch and
can be added to a five-speed gearbox without modification. The
inherent efficiency gained by losing the weight and slippage in
a torque converter and the easy adaptation of this package to
most existing designs will make this type of unit increase in
volume.
Dual-clutch technology (DCT) is a design
being developed by VW and BorgWarner. The transmission is known
as the DSG250 and is available in the VW Golf and Touran and
Audi TT with the 3.2-liter engine. It consists of two parallel
shafts with two clutches, one of which handles 1st, 3rd and 5th
and the other 2nd, 4th and 6th gears. To make a shift from 1st
to 2nd, the transmission selects 2nd gear when its shaft is
inactive. At that point the 1st-gear shaft is declutched and
the 2nd-gear clutch is engaged, providing a shift quite similar
to that of an automatic transmission with no clutch input by
the driver. This design shifts better than the present AMTs
because of less-abrupt torque transfer. Development of better
clutch applications and shift controls is ongoing. This design
is here to stay, since it is cheaper and more efficient than an
automatic and has more-comfortable shifts than an AMT.
The ongoing electronic-shift designs of
automatic transmissions will continue to improve, and new
designs of all these transmissions will become necessary as
more hybrid and alternative-fuel technology enters the market.
There will be more different designs to diagnose and repair,
and the changes are going to keep coming. If you thought that
you had seen it all, you are going to be amazed at what is
created by high fuel costs, emissions regulations and the need
for safer vehicles.
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©2006 Transmission Digest
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