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The 911 | Transmission
As if one clutch didn’t deliver enough performance already.
Porsche Doppelkupplung (PDK).
The optional Porsche
Doppelkupplung (PDK), with
both manual gearshift and
an automatic mode, enables
smooth gear changes with no
interruption in the flow of power.
This results in significantly
faster ac celeration and lower
fuel consumption, without
having to sacrifice the ease
of automatic trans mission.
In total, PDK has seven gears
at its disposal . Gears 1 to
6 have a sport ratio and
top speed is reached in 6th
gear. The 7th gear has a
long ratio and reduc es fuel
consumption eve n further.
PDK is like having two gearboxes
in one, and thus requires two
clutches—designed as a double
wet-clutch transmission.
This do uble cl utch provides
a n alternating, non-posit ive
connection between the gearbox
and the engine by m eans of
tw o separate input shafts
(input
shaft 1 is nested inside
hollowed-out input shaft 2).
The flow of power from the engine
is on ly ever transmitted through
one clutch at a time, while the
next gear is preselected by the
second clutch. During a gear
change, a conventional shift n o
longer takes place. Instead,
one clutch simply opens and the
other closes at the same time.
Gear changes, therefore, take
place within a few hundredths of
a second.
Clutch 1 controls the odd gears
(1, 3, 5, 7) and Reverse. Clutch 2
controls the even ge ars (2, 4, 6).
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