6
TEBS E
GIO functions
64
6.3 Integrated electronically controlled air suspension system (ECAS)
Vehicle type
All trailer vehicles with air suspension.
It is possible to implement two control circuits (1-point or 2-point control as of ver-
sion TEBS E2).
System designs:
Semitrailer, central axle trailer: 1-point control or 2-point control as side control in
vehicles with independent wheel suspension.
Drawbar trailer: 2-point control for front and rear axle.
Purpose
The ECAS basic function is the compensation of level changes, which e.g. occur
from changes in the load status or with new nominal value definitions (e.g. from the
remote control unit). These control deviations cause the distance between the ve-
hicle's axle and its superstructure to change. ECAS balances these control devia-
tions by means of level control.
The essential benefit of ECAS lies in the reduced air consumption and faster con-
trol when stationary. While a levelling valve only controls the normal level, ECAS
can keep every level constant.
Function
A height sensor is mounted on the vehicle body and is connected to its axle via a
lever system. The height sensor picks up the distance between the axle and the
vehicle body. The intervals depend on the vehicle's operating condition (driving or
loading operation).
This measured value is used as the actual value in the control loop and is sent to
the ECU. The ECU compares this actual value to the nominal value predefined in
the ECU.
In the event of a difference between the actual value and the nominal value (con-
trol deviation), the ECAS solenoid valve receives an actuating signal. Depending
on the type of actuating signal received, the ECAS solenoid valve now increases or
decreases the air pressure in the support bellow. The change in pressure in the
support bellow alters the distance between the axle and the vehicle body. The new
distance is also picked up by the height sensor, and the cycle begins again.
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