Four- W Heel Drive; Dsc - BMW X5 3.0i Owner's Manual

Four- w heel drive

The transm ission of pow er to the four
drive w heels is provided perm anently
through a transfer box. The distribution
of torque betw een the front and rear
axles is 38 % to 62 %.
Traditional differential locks at the front
and rear axles and in the transfer box
are not required. Their function is taken
over by autom atic braking intervention
at all four w heels. These traction inter-
ventions are governed by Automatic
Differential Brake (ADB- X), a sub- func-
tion of DSC.
If a w heel tends to slip, it is braked
autom atically by ADB- X until it once
again gains traction, and drive force
can be transm itted to that w heel. In
addition, the drive force is distributed
to the remaining w heels during this
system intervention. Engine output is
also reduced if necessary.
When the DSC is deactivated, the
ADB- X traction intervention is set for
the maximum drive force. How ever,
the engine intervention and the stability
controls are no longer available. For
this reason, DSC should only be deacti-
vated in the exceptional circum stances
described on page 95.
The BM W X5 is a vehicle for all types of
roads. The perm anent four- w heel drive
provides a significant degree of vehicle
stability and tractive pow er under all
road conditions. It assists in critical
situations such as driving in extrem e
w inter conditions or on bad roads.

DSC

Precision sensors m onitor the w heel
speeds, the steering angle, lateral
acceleration, brake pressure and the
m ovem ent of the vehicle around its
vertical axis.
If differences in w heel speeds occur, the
system recognizes the danger of w heel-
spin and reduces the engine's drive
torque. If necessary, the system also
responds w ith additional braking inter-
vention at all four w heels.
In addition, DSC perm anently m onitors
the vehicle's current operating condition
and com pares it w ith an ideal condition
that is calculated from the sensor
signals. If deviations from this occur
(understeering or oversteering, for
instance), DSC can stabilize the vehicle
in fractions of a second by adapting
engine output and w ith the assistance of
braking intervention at individual
w heels. This w ay, as long as the skid
can still be m anaged under the law s of
physics, these kinds of dangerous skids
are prevented even before they can
start.
You m ay need som e tim e to becom e
accustom ed to this system intervention.
How ever, it provides optim um drive
force and vehicle stability. The braking
intervention m ay be accom panied by
certain sounds specific to the system .
Online Edition for Part No. 01 41 0 155 558 - © 09/00 BMW Group
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