The Dual Clutch Transmission or DCT is a type of automated manual transmission that uses two clutches which
results in extremely quick gearshifts and acceleration.
Dual clutch transmissions are also known by several other names such as sequential manual gearbox, double clutch
transmissions or a clutchless manual transmission.
A dual clutch transmission takes one set of gear ratios (a seven speed for example) and splits them into odd and
even gears. The odd gears is operated via one clutch and the even gears are operated via another clutch. Any clutch can
be used for reverse.
The entire arrangement is still in one gearbox and both clutches are in one housing with two shafts sharing the same
center axis (the outer shaft is hollow with the inner shaft inside it) is used.
A clutch pedal is not required as with a regular manual. An
ECU and hydraulics operate the clutches so gear changes can be made. Gearshifts
are extremely quick which results in better acceleration as less time is used disconnecting the engine from the driveline
to shift between gears.
These benefits arise because gears can be pre-selected before they are changed so as one clutch selects 2nd gear the
other clutch pre-selects the 3rd gear. The fraction of a second needed for gearshifts will vary between marques but this
is the main benefit over single clutch automated manuals.
You also have the option of driving in automatic mode and let the computer change the gears or you can change the
gears manually by using the regular gearshifter or the paddle shifters to upshift and downshift and features such as
launch control can be easily incorporated into DCTs.
Dual clutch transmissions were originally used on racecars but it has now found its way into production vehicles. They
were brought to production vehicles by Porsche and Audi in the 1980s who started using DCTs in their production performance cars.
It is still used mostly used on performance vehicles such as BMW M cars, Audi S and RS, Ferrari's and others.
There are two types of clutches used in DCTs, one is the wet clutch and the other is the dry clutch. The transmission will
have either two wet or two dry clutches and not one of each. The wet clutch is designed for higher performance vehicles as the
clutches are constantly lubricated so they can deal with the high torque of formula one cars,
supercars and vehicles with similar amounts of power.
The dual clutch transmission has been referred to as the future of automotive transmissions. They are not as cost effective
as the conventional transmissions but some expensive features have a way of reaching down to the everyday car even if its a scaled
down version of it.