Re: [ST] DN01 Transmission musings

["Rick & Joyce" <rnjwes@xxxxxxxxxxx>]

Nice write-up, Jeff.  The CVT's I saw back in the '80's [on Formula
440's - small open-wheel spec racers utilizing a snowmobile engine]
were two-pulley affairs with a belt running between them.  The
variable spacing between the pulley halves would change the effective
size of the pulleys, centrifugally IIRC.  The engine pulley would get
"larger" as the diff. pulley got "smaller" changing the drive ratio.
Modern electro-hydraulic control technology has added reliability to
the design.  Anyway, the cars sounded like a pack of angry hornets
fading into the distance.

Another high-tech transmission in production - VW & Audi call it the
Direct Shift Gearbox (DSG) - was first seen in the 2004 Audi TT and is
now available in the New Beatle TDI.   From http://tinyurl.com/dgd6h :
"... DSG radically shortens shift times by anticipating and
preselecting the next gear. With one gear driving the wheels and
another poised to take over when the computer (or the driver) gives
the nod, the act of shifting becomes a lightning-quick relay race. Two
clutches alternately open and close as one gear after another goes
from at-bat to on-deck status in a scant two-tenths of a second, with
no interruption of the torque flow during full-throttle acceleration."

It's just a matter of time before more of these technologies spin off
to motorcycling.  I for one, welcome them.
--
Rick in Oregon
'01 Sprint ST

-----Original Message-----
 F1 uses pneumatically shifted straight cut sequential gearboxes, more
like our traditional motorcycle gearboxes. This is a CVT (continuously
variable transmission), which have showed up in cages from Honda,
Nissan, and Audi, among others. It doesn't use a set of gears like a
traditional transmission, and offers infinitely variable gear ratios.
I'm not really up on the mechanics of it all, most use a combination
of
pulleys I think.

What this allows is for the engine to stay at peak torque RPM (or peak
efficiency RPM, depending on mode) while you accelerate and cruise.
What
you get is a smooth acceleration while the engine stays at the same
speed. Really strange feeling to be accelerating without the engine
changing note. I've driven a street Audi A4 as well as an open wheeled
racecar with this type of transmission. It's weird.

In any case, yah, no missed shifts, 'cause there's no shifts to
perform.
The "6 speed manual mode" is there to quell the CVT naysayers, as it's
actually forcing the transmission to emulate a traditional gearbox.
There's no reason to have it do that at all. 

CVT is neat technology, and I can definitely see its use in
motorcycles.
I think I'd still miss rowing through the box a bit tho.

- Jeff in CO

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