Electrohydraulic manual transmission is a type of
semi-automatic transmission system, which uses an
automated clutch unlike conventional
manual transmissions where the driver
operates the clutch. The clutch is controlled by electronic
computers and hydraulics. To change gears, the driver selects the
desired gear with the
transmission shift
lever, and the system automatically operates the clutch and
throttle to match revs and engage the clutch again. Also, many such
transmissions operate in sequential mode where the driver can only
upshift or downshift by one gear at a time. Depending on the
implementation, some computer-controlled electrohydraulic manual
transmissions will automatically shift gears at the right points
(like an
automatic
transmission), while others require the driver to manually
select the gear even when the engine is at the redline.
Despite superficial similarity, clutchless manual transmission
differ significantly in internal operation and driver's 'feel' from
dual clutch transmissions
or
manumatics, the latter of which is an
automatic transmission (using
torque
converter instead of
clutch to manage the
link between the transmission and the wheels) with ability to
signal shifts manually.
Use in road cars
The most
famous application of a sequential transmission on road-cars would
be their use in some Ferraris
since the
late-nineties, beginning with the F355
F1. Their system, the most current version of which is
called "F1-Superfast," with shift times of 60 ms is designed
to serve as a link to their
Formula One
efforts.
This technology has also trickled down to the
cars of their sister company, Maserati
where it is
known as "Cambiocorsa". Alfa
Romeo's
Selespeed in 1999 was the
first sequential transmission in a mainstream car, derived from the
Ferrari system.
BMW offered a system simply called "sequential
manual gearbox" (SMG) on the E36 M3, and later "SMG-II" on the E46
M3. The BMW SMG transmission has both automatic and manual shift
modes. Inside the different modes there are different programmes,
with six settings to control the upshift/downshift speed for manual
operation, and five settings for automatic mode.
Later the 3rd generation
Toyota MR2 used
Toyota's version, known as the "Sequential Manual Transmission"
(SMT). Although it does not perform as well as the
European-designed transmissions, Toyota's is the cheapest system to
manufacture, and the MR2 is the least expensive car to possess a
true sequential gearbox.
Finally
Volkswagen Group (parent
owner of
Lamborghini) introduced a
sequential transmission to the
Lamborghini Gallardo (E gear), and then
adding it to the
Audi R8 (R tronic).
BMW has since switched over to a
dual clutch transmission in the
latest
M3, and Ferrari as well
in in 2009 with the
California
and
458 Italia.
Applications
See also
References
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