5 Series E60 530d (M57TU) SAL
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Warning light and Check Control
The dedicated-function warning light in the instrument cluster lights up to indicate a fault in the Active Steering.
At the same time a Check-Control message is shown in the LCD display. The text for the Check-Control
message can be called up in the Central Information Display (CID).
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System functions
The Active Front Steering system comprises the following functions:
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Steering assistance (= Servotronic)
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Variable steering-gear ratio (= Active Steering)
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Yaw-rate control (= damping of dynamic yaw)
A new function will be added in further development leading to the start of series production of the BMW 3-Series:
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Yaw-moment compensation when braking on a road surface with non-uniform traction
In further development from the E70, this function is entirely integrated in the Active Steering control unit (3rd
generation). Further model series to follow.
Steering assistance
The steering assistance takes the form of conventional hydraulic steering (rack-and-pinion construction).
The speed-dependent steering assistance (= Servotronic) has been available in the E61 series since 03/2004.
E63 and E64 have Servotronic as standard from start of series production. Servotronic has been standard on
the E60 since 03/2005.
Active Steering and Servotronic are co-ordinated. Servotronic is controlled by the AL control unit.
The AL control unit actuates the Servotronic valve and the ECO valve in the power-steering pump via the Safety
and gateway module (SGM). The ECO valve in the power-steering pump regulates the volume flow in the power-
steering pump.
This arrangement means that only the volume flow needed for steering assistance at any given time is actually
provided. In this way, the ECO valve affects the power consumption of the power-steering pump. Fuel
consumption and carbon dioxide emissions (CO
2
) from the vehicle's engine are reduced accordingly.
In vehicles without Active Steering, Servotronic is controlled directly by the safety and gateway module (except
BMW 1 and 3-Series).
Clearly, therefore, the steering assistance and AFS are complementary, despite the fact that in terms of function,
the two systems are fully independent of each other.
Variable steering-gear ratio
The variable steering-gear ratio function adapts the steering-gear ratio to the vehicle's road speed.
Steering is direct when the vehicle is moving at low speed. The planetary gearbox with override function
contributes significantly to handling when the vehicle is moving at low speeds and when it is being manoeuvred
into tight parking spaces.
It is not longer necessary for the driver to feed the steering wheel through his or her hands in order to
manoeuvre. When the vehicle is at a standstill, less than 2 complete turns of the steering wheel is all that is
needed to move the wheels from lock to lock.
At high speeds the steering-gear ratio increases. The steering becomes less direct, further improving the
intrinsically high standard of steering systems featured to date in BMW vehicles.
The safety function:
SBT Active Steering E60, E61, E63, E64, E70, E81, E87, E90, E91, E92, E93
BMW AG - TIS
22.02.2013 10:20
Issue status (12/2007) Valid only until next DVD is issued
Copyright
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