Servotronic valve

The Servotronic controls the degree of assistance provided by the hydraulic steering depending on the vehicle's speed. The flow of hydraulic fluid is restricted to a greater or lesser extent depending on how the Servotronic valve is actuated. Restriction of the flow depends on the current actuating the Servotronic valve (pulse-width-modulated).

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 Servotronic valve 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).

Fig 1: Identifying Servotronic Valve, Steering Box And Plug Connection

Courtesy of BMW OF NORTH AMERICA, INC.