Dynamic Stability Control; Asc-X / Adb-X - BMW E61 Sports Wagon 530xiT Owner's Manual

Dynamic Stability Control

DXC8+ offers several new features from April 2005 production vehicles. They are:

• ASC-X / ADB-X

• Hill descent control HDC
• Dry braking
• Brake standby
• Automatic soft stop
• Fading assistance
• Drive-off assistant
• Trailer stabilization control
ASC-X / ADB-X
Unlike regular road vehicles, SAVs are also meant to demonstrate satisfactory handling
characteristics and appropriate traction on unconventional roads. In order to provide opti-
mum propulsion with sufficient cornering stability on both normal roads and other road
surfaces, Automatic Stability Control X (ASC-X) contains a detection function to distin-
guish between them.
When off-road terrain is detected, wheel slip threshold is increased to provide sufficient
traction force with the increased levels of traction loss.
ASC-X is supplemented by the Automatic Differential Brake (ADB-X) function, which
applies the brakes to the wheels per axle, for side to side torque transfer. For example,
when a wheel is spinning on one side (up to the slip setpoint), the brakes are applied to
that wheel and the driving torque is transferred through the axle differential to the wheel
with the higher traction. This provides superb capabilities when there are diagonal trac-
tion losses (ie. left front/right rear).
ADB-X remains active when DSC is deactivated. Furthermore, ADB-X can develop full
capability because the engine power is not reduced, even during extreme four wheel
drive operation. Only that wheel which has a low traction receives the brake application.
The brake disc can overheat with excessive ADB-X intervention with DSC deactivated. In
this situation, the operation is discontinued at a disc temperature of approx. 700 ºC and is
resumed when this temperature drops below approx. 400 ºC. This is a calculation per-
formed by the DSC control unit based on brake application time, pressure, wheel speed,
etc.
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E61 Sports Wagon