Porsche 911 Carrera 4 Brochure & Specs page 30

At one time, bends would bow before the landscape.
Now they bow before engineering.
Porsche Traction Management (PTM).
In a 911, engine power is not the Traction Management (PTM),
only priority. There is always the comprising permanent all-wheel
question of how this power can drive with an electronically
be effectively and consistently controlled multi-plate clutch, an
delivered to the road. One solution automatic brake differential (ABD)
to this is all-wheel drive. An even and anti-slip regulation (ASR).
better one is active Porsche
Featured as standard in
911 Carrera 4 and 911 Targa 4
models with all-wheel drive,
the force between the front and
rear axle is distributed actively
by an electronically controlled
multi-plate clutch.
In comparison with a viscous ever receive as much drive force
multi-plate clutch, where clutch as is necessary to prevent lateral
regulation is not initiated until instability. On uneven surfaces,
there is a difference in speed the rear differential fitted
between the front and rear axles, as standard to all-wheel drive
the electronically controlled models, in combination with
multi-plate clutch responds much ABD, also improves traction.
more rapidly. Through continuous
monitoring of the driving con- In this way, PTM, in conjunction
ditions, the electronics are able to with Porsche Stability Manage-
respond to a variety of situations. ment (PSM, p. 70), ensures that
Sensors check, among other the perfect distribution of drive
variables, the rotation speeds of is achieved every time.
all four wheels, the longitudinal
and lateral acceleration of the PTM really comes into its own
vehicle, and the steering angle. in the wet or in ice and snow.
By evaluating the sensor data, In these conditions, the car's
the system can quickly adjust acceleration capability is simply
the distribution of drive force to breathtaking.
the front axle in order to achieve
optimum balance. If the rear The result: a high level of safety
wheels threaten to spin under and outstanding performance.
acceleration, a greater proportion Put to use in the most intelligent
of drive force is sent forwards way.
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
The 911 |
Transmission
Mechanically locking
rear differential.
A mechanically locking rear
differential is standard in the
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.