TEBS E
5
braking system
41
Characteristic curves
Semitrailer
Drawbar trailer
A = Application range; W = Wear range; S = Stability range
In this example, the nominal value or control pressure
(p
m
) increases in the application range from 0 bar to
0.7 bar. With this control pressure, the braking pressure
(p
cyl
) increases from 0 to 0.4 bar.
At 0.7 bar, the response pressure in the wheel brake is
reached and therefore the vehicle can start to build up
braking force from that point on. This point, being the
response pressure of the entire trailer brake, can be set
in the parameters within EC braking bands.
The braking band indicates, in which range the decel-
eration (in %) must be situated at a certain control
pressure p
m
.
As the sequence continues, the braking pressure fol-
lows a straight-line characteristic when the vehicle is
laden. This line takes it through the calculated value at
6.5 bar.
When the vehicle is unladen, the response pressure is
also applied at 0.7 bar. Afterwards, the braking pres-
sure is reduced relative to the load.
The response pressures of the brakes are once again
output at the limit of the application range. These pres-
sures may also differ from one axle to another. In the
partial braking range pressures are delivered for opti-
mum wear.
In a drawbar trailer with type 24 cylinders on the front
axle and type 20 cylinders on the rear axle, for exam-
ple, the pressure at the front axle is slightly reduced
and that at the rear axle is slightly increased in accor-
dance with the configuration. This ensures that the load
is distributed evenly between all wheel brakes and is
more exact than the function of the adapter valve used
with conventional braking systems.
In the stability range, the pressures are output in such a
way as to ensure the same adhesion utilisation (possi-
ble adhesion utilisation) as a function of the axle load.