Chassis
Page 4.17
PSM (Porsche Stability Management)
Like the current 911 models with all-wheel drive, the new Cayenne
models also feature enhanced Porsche Stability Management (PSM).
PSM improves active safety thanks to the following additional functions:
• Enhanced braking readiness
• Brake assist function
• New ABS tuning for braking on loose surfaces
Enhanced Braking Readiness
When the accelerator is released quickly, PSM switches the brake
system to a state of enhanced braking readiness: Brake system pre-
filling builds up slight pressure in the system. This moves the brake
pads slightly on to the brake discs. If the driver then actually presses
the brake, maximum braking power can be achieved more quickly. This
results in a shorter stopping distance.
Brake Assist
On identifying full braking i.e. when a defined force is exceeded on the
brake pedal – brake assist supplies the required brake pressure for
maximum deceleration via the PSM hydraulic unit. Brake assist can be
deactivated by switching off PSM. Enhanced braking readiness always
remains active, however, irrespective of whether PSM is on or off.
Off-road ABS
The off-road ABS system used since model year 2004 has been
optimized further.
Off-road ABS control in “Low Range” can now be used for a speed range
of up to 50 mph (80 km/h). The ABS control strategy has been modified
for braking on unpaved surfaces for conditions such as; when loose
gravel, sand or snow build up in front of the tires and create an blocking
barrier and locking of the wheels improves control. Off-road ABS is only
active when driving straight ahead. If the driver needs to steer, off-road
ABS control is switched off automatically to maintain steerability.
Off-road driving in “High Range” mode, the ABS control system that has
been optimized to suit the conditions is activated when the driver brakes
at a speed of up to 50 mph (80 km/h). Also in this case, for conditions
such as; when loose gravel, sand or snow build up in front of the tires
and create an blocking barrier and locking of the wheels improves
control.
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