Entry/Exit Aid
The Steering Column Memory provides the feature of raising the steering column to ease in exiting the vehicle and return it to the previous position after the vehicle is entered.
Raising the Steering Column
- The ignition is switched "off".
- The ignition is switched to KL R and the driver's door is opened.
- The ignition is switched to KL 15, driver's door open with the handbrake applied.
Lowering the Steering Column
- The ignition is switched to KL 15.
- The Handbrake is released or the door is closed.
The steering column recall movement can be interrupted at any time by tapping the adjusting lever.
The servotronic steering system is based on a conventional power assisted steering system. An additional electro-hydraulic solenoid and oil passageways are added to the conventional worn and roller type steering box. The GM monitors the vehicle's road speed and regulates an electro-hydraulic solenoid. The servotronic steering system provides the following
Scheme 380
- A light steering effort at low speeds and while parking.
- Increased steering effort as road speed increases.
The "Direct Hydraulic Reaction" provided by the system allows the frictional forces between the front wheels and road surface to be transmitted to the driver. This allows the driver to make a better judgment in regard to the driving conditions.
This principle of direct hydraulic reaction can be used with the servotronic system because of the spool valves that are already used with the worm and roller steering box.
Refer to appropriate article for further "mechanical" details of Servotronic.
Electro-Hydraulic Solenoid: The solenoid regulates the amount of power steering assist for the servotronic system. It contains a needle valve that can restrict oil flow. When current is applied, the needle valve closes against spring pressure to restrict the oil flow.
With maximum current applied, the valve is closed. This is the condition of the valve for slow speed driving and parking.
Without current applied, the needle valve is held open by spring pressure. This is the condition of the solenoid during higher driving speeds.
Scheme 381
Electro-Hydraulic Solenoid Control: The GM monitors the road speed input and supplies the electro-hydraulic solenoid with power. The road speed signal "A" is supplied from the IKE (and K-Bus) on E38 vehicles and from the DSC Control Module on E39/E53 vehicles.
Scheme 382
The solenoid is pulse width modulated for control and varies the amount of assist based on the road speed. The maximum assist is available while parking and driving at slow speeds.