Porsche 911 - Manual (Page 30)

· 62 ·
Traction Management (PTM),
comprising permanent all-wheel
drive with an electronically
controlled multi-plate clutch, an
automatic brake differential
(ABD) and anti-slip regulation
(ASR).
Previously exclusive to the
911 Turbo and now available as
standard on the 911 Carrera 4
and 911 Targa 4 models with all-
wheel drive, the force between
the front and rear axle is no
longer distributed by a viscous
In a 911, engine power is not the
only priority. There is always the
question of how this power can
be effectively and consistently
delivered to the road. One solution
to this is all-wheel drive. An even
better one is intelligent Porsche
At one time, bends would bow before the landscape.
Now they bow before engineering.
Porsche Traction Management (PTM).
· 63 ·
The new 911 | Transmission
multiple-disc clutch, but actively
by an electronically controlled
multi-plate clutch.
In comparison with a viscous
multi-plate clutch, where clutch
regulation is not initiated until
there is a difference in speed
between the front and rear axles,
the electronically controlled
multi-plate clutch responds much
more rapidly. Through continuous
monitoring of the driving condi-
tions, the electronics are able to
respond to a variety of situations.
Sensors check, among other
variables, the rotation speeds of
all four wheels, the longitudinal
and lateral acceleration of the
vehicle, and the steering angle.
By evaluating the sensor data,
the system can quickly adjust the
distribution of drive force to
the front axle in order to achieve
optimum balance. If the rear
wheels threaten to spin under
acceleration, a greater proportion
of drive force is sent forwards
by a more powerful engagement
of the multi-plate clutch. At the
same time, ASR prevents the
rear wheels from spinning. When
cornering, the front wheels only
ever receive as much drive force
as is necessary to prevent lateral
instability. On uneven surfaces,
the rear differential fitted
as standard to all-wheel drive
models, in combination with
ABD, also improves traction.
In this way, PTM, in conjunction
with Porsche Stability Manage-
ment (PSM, p. 70), ensures
that the perfect distribution of
drive is achieved every time.
PTM really comes into its own
in the wet or in ice and snow.
In these conditions, the car’s
acceleration capability is simply
breathtaking.
The result: a high level of safety
and outstanding performance.
Put to use in the most intelligent
way.
Mechanically locking
rear differential.
A mechanically locking rear
differential is standard in the
new 911 all-wheel drive variants
and is available as an option
for all other 911 models in
conjunction with 19-inch wheels.
It further enhances traction at
the driven rear axle on uneven
roads and when accelerating
out of tight bends. This is
accomplished by the damping
of load-change reactions during
fast cornering.