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24
Slight swinging movements of a trailer can amplify
in such a way as to cause a critical driving situation.
This situation usually occurs at road speeds
between 75 and 120 kph.
If the trailer begins to swing when the vehicle is
travelling at a speed above the critical threshold, the
oscillation amplitude of the trailer will progressively
increase. The only way to reduce the swinging of the
trailer is to reduce speed to below the critical
threshold.
The swinging movements also excite periodic
oscillation of the towing vehicle about its vertical
axis. These yaw movements are monitored by the
yaw rate sender and evaluated by the ESP control
unit. If defined limits are exceeded, the ESP control
unit instructs the engine control unit to reduce
torque in order to slow the vehicle down. If this
action is insufficient, all four wheels are braked
simultaneously by the ESP control unit.
Enhanced acc braking comfort
On vehicles with acc, two additional pressure
sensors are installed in the lines between the ESP
unit and the front-axle brake calipers. The previous
method, whereby the actual brake pressure was
calculated in the control unit, is less accurate than
the direct measurement method, particularly at low
brake pressures. Using the data supplied by the
pressure sensors , ESP can control the build-up of
brake pressure more precisely. This results in
shorter reaction times, and braking becomes more
comfortable.
Running gear
344_038
344_041
Brake pressure sensor
Automatic stabilisation of the car-trailer combination
