System functions

The Servotronic determines most of the steering torque that driver has to apply. The Servotronic is definitively defined by the driving speed:

• Low driving speed range (urban driving, parking) = low steering torque
• High driving speed range (dual carriageway, motorway) = high steering torque

The Servotronic valve is only activated at Terminal 15N On and with the engine running. The Servotronic control loop controls the current for the connected Servotronic valve. A higher current results in greater steering assistance with the same steering torque.

The nominal current for the valves is specified to the Servotronic control unit by the Integrated Chassis Management (ICM).

Exception: For vehicles of the M GmbH, the DME specifies the nominal current. The nominal current varies between 0 mA (minimum) in 860 mA (maximum).

The Servotronic determines the required steering servo as a function of following factors every 100 milliseconds:

• Current driving speed

The specified maximum or minimum values are used if the current value for driving speed is outside the defined range.

The following Servotronic system functions are described:

• Steering servo at low driving speeds
• Steering servo at high driving speeds
• Steering servo with Servotronic valve de-energised