BMW 3 ELECTICAL SYSTEM Bedienungshandbuch PDF herunterladen (Seite 106)

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Antilock Brake System (ABS)

The concept

ABS enhances active safety by helping

to prevent the wheels from locking un-

der braking. This is because locked

wheels are dangerous. When the front

wheels slide, the driver loses steering

control over the vehicle. Traction loss at

the rear wheels can cause the rear end

to break into an uncontrolled skid.

ABS is designed to meet two essential

requirements during every brake appli-

cation:

> To help provide vehicle stability

> To help maintain steering control and

maneuverability – on all types of road

surfaces (asphalt, concrete, mud, wet,

snow, ice).

The system can achieve the shortest

braking distances possible under most

conditions (on straight-aways and in

curves, on asphalt, ice, wet road sur-

faces, etc.).

Braking with ABS

The system becomes operative once

the vehicle exceeds a speed of approx.

6 mph (10 km/h). Below approx. 3 mph

(6 km/h), it is once again deactivated.

This means that the wheels can lock in

the final phase of a panic stop – a factor

of no significance in actual use.

If you are in a situation that requires full

braking, you will exploit the full benefits

of the ABS system if you apply maxi-

mum brake pressure ("panic stop").

Since the vehicle maintains steering re-

sponsiveness, you can avoid possible

obstacles with a minimum of steering

effort, despite the full brake application.

The ABS system closed-loop control

circuit cycles in fractions of a second.

A pulsation at the brake pedal indicates

to the driver that ABS is active, that is,

that the vehicle is within its maximum

braking range. In addition, a pulsation –

a result of the control function cycles –

indicates to the driver that vehicle

speed should be reduced to adapt to

road surface conditions when there is

reduced traction and grip between tires

and road surface (slippery road sur-

face).

On road surfaces that have a loose sur-

face layer on a firm base with good

traction (on gravel or snow, for exam-

ple), or when snow chains are mounted,

braking distances may be longer than

with locked wheels. However, ABS

continues to provide enhanced vehicle

stability and steering response under

these conditions.

Information for your safety

Not even ABS can suspend the laws of

physics. ABS cannot prevent the con-

sequences of brake applications with

inadequate clearances for safety be-

tween vehicles, when exceeding the

speed limit in curves, or the risks in-

volved when aquaplaning occurs. Re-

sponsibility for these types of situations

remains in the hands (and at the feet) of

the driver. You should never allow the

added safety of ABS to lull you into a

false sense of security, or mislead you

into taking increased risks that could af-

fect your own safety and that of others.

Do not make any modifications to

the ABS system.

Service procedures on ABS are to be

performed by authorized technicians

only.<

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