A comment was
made that this had a previous incarnation and that makes sense. It just never
got into the mainstream, possibly because the need was not compelling.
Whatever its
history, here it is and it nicely simplifies the drive train while eliminating
much of the weaknesses of the dual clutch assembly. This is another incremental improvement in
traditional transport technology which we will hopefully soon see of in favor
of electrical configurations.
In a way it
is remarkable that we should be squeezing improvements out of the drive train
after a full century of intense development that has never let up. Perhaps someday we will have perfection.
Xtrac
shows seamless gearchange alternative to dual clutch transmission
By Mike
Hanlon
21:41 December 1, 2010
http://www.gizmag.com/xtrac-shows-seamless-gearchange-alternative-to-dual-clutch-transmission/17138/
Xtrac IGS is applicable to a two speed EV
transmission
After
two years secret development in motorsport competition, Xtrac unveiled an
important new driveline technology this week in the form of an Instantaneous
Gearchange System (IGS). It does exactly the same thing a dual clutch
transmission achieves with less weight, cost, and complexity. The secret to
Xtrac IGS is the integration of a ratchet and pawl mechanism between each gear
hub and the main shaft so that two consecutive gear ratios can be selected and
engaged simultaneously, but with only one set of gears driving.
Conventional
gearboxes have always had some serious problems associated with needing to
interrupt engine torque in order to change gear. Apart from increasing fuel
usage, hydrocarbon and CO2 emissions, momentarily cutting power delivery to the
rear wheels obviously also reduces performance.
Porsche
was the first to develop an answer to this problem with its
Doppelkupplungsgetriebe (dual clutch transmission - DCT) and the DCT is now in
common usage in cars and has just been applied to motorcycles for the first
time by Honda.
Size,
weight and complexity are the main drawbacks of the DCT. Now motorsport
transmission specialist Xtrac has applied its high performance
engineering skills to design and develop a seamless gearchange known as IGS or
Instantaneous Gearchange System. IGS is small, lightweight, and is now ready
for commercial development in motorcycles, electric vehicles, cars, trucks and
buses. IGS was unveiled this week in Berlin
The
secret to Xtrac IGS is the integration of a ratchet and pawl mechanism between
each gear hub and the main shaft so that two consecutive gear ratios can be
selected and engaged simultaneously, but with only one set of gears driving.
“When
introducing new technology to the automotive mainstream it’s important to have
progressed beyond the initial research and development phase,” said Xtrac
Technical Director Adrian Moore.
“Car
makers like to see practical demonstrations to show that the technology
actually works and is more than a concept. With our motorsport experience we
have the advantage of two years of racing IGS with professional teams.”
IGS is
protected by worldwide patents, and the company reports that initial
development will focus on improving the efficiency of electric vehicle
powertrains. Xtrac has considerable experience in the design and manufacture of
transmission systems for experimental, prototype, pre-production and specialist
low volume vehicles, and a study is already underway to implement IGS into a
two-speed EV transmission with the aim of ensuring the optimum performance of
the vehicle.
Xtrac is based in Berkshire,
UK, with satellite motorsport operations in located at Indianapolis
and North Carolina in the United States Le Mans
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