Driving and Driving Safety
181
Porsche Stability Management
(PSM)
PSM is an active control system for stabilization of
the vehicle during extreme driving maneuvers.
PSM makes use of both the automatic brake
differential (ABD) and anti-slip regulation (ASR)
systems, as well as the functions of the anti-lock
brake system (ABS) and engine drag torque
control system (MSR).
In spite of the advantages of PSM, it is still the
driver’s responsibility to adapt his driving style and
maneuvers in line with road and weather
conditions, as well as the traffic situation.
The increased safety that is provided should not
induce you to take greater risks with your safety.
The limits set by the physics of driving cannot be
overcome, even with PSM.
Risk of accidents due to inappropriate speed
cannot be reduced by PSM.
Advantages of PSM
– Best possible traction and lane-holding ability
in all driving situations – even on road surfaces
with varying friction.
– The system compensates for undesired
vehicle reactions (Ferraria effect) when the
driver releases the accelerator pedal or brakes
on bends. This compensation functions up to
the maximum lateral acceleration.
– PSM actively helps to stabilize the vehicle if
necessary during dynamic driving maneuvers
(e.g. rapid steering movements, during lane
changes, or on alternating bends).
– Improved braking stability on bends and on
different or varying road surfaces.
– Improved brake function and shorter stopping
distance in the event of emergency braking.
Readiness for operation
PSM is switched on automatically every time
you start the engine.
Function
Sensors at the wheels, brakes, steering system
and engine continuously measure:
– Speed
– Direction of travel (steering angle)
– Lateral acceleration
– Axial acceleration
– Rate of turn about the vertical axis
PSM uses these values to determine the direction
of travel desired by the driver.
PSM intervenes and corrects the course if the
actual direction of motion deviates from the
desired course (steering-wheel position):
It brakes individual wheels as required.
If necessary, PSM also influences the engine
power or the gear-changing characteristic of
Porsche Doppelkupplung (PDK) in order to
stabilize the vehicle.
The events below inform the driver of PSM control
operations and warn him to adapt his driving style
to the road conditions:
– PSM warning light on the instrument panel
flashes.
– Hydraulic noises can be heard.
– The vehicle decelerates and steering-wheel
forces are altered as PSM controls the brakes.
– Reduced engine power.
– The brake pedal pulsates and its position is
changed during braking.
In order to achieve full vehicle deceleration,
foot pressure must be increased after the
brake pedal has begun vibrating.
Examples of PSM control operations
– If the “front wheels of the vehicle drift” on
a bend, the engine power is reduced and the
rear wheel on the inside of the bend is braked
if necessary.
– If the rear of the vehicle swings out on a bend,
the front wheel on the outside of the bend is
braked.
– Brake system prefilling:
The brake system is prepared for possible
subsequent emergency braking if the
accelerator pedal is released suddenly and
quickly. The brake system is prefilled and the
brake pads are already applied gently to the
brake disks.
– Brake booster (Hydraulic Brake Assist):
In the event of an emergency braking operation
where the pedal force is insufficient, a brake
booster provides the braking pressure
necessary for maximum deceleration at all
4 wheels.
Loss of control over the
vehicle
WARNING
h
14_991_Turbo_21.book Seite 181 Mittwoch, 9. April 2014 2:19 14
Summary of Contents for 911 Turbo 2014
Page 1: ...911 Turbo Owner s Manual...
