VDC performs this complex task by communicating constantly not only with the brake sensors and the engine control unit, but also with:- the 'Body computer' which constantly exchanges information with the ABS system, and the control units of the engine and automatic transmission;
- the electronic throttle valve (which in turn dialogues with the ABS system);
- the instrument panel (active telltales);
- the steering wheel and steering column (via the steering sensor);
- the gyroscopic sensor installed on the cabin floor to record yaw and lateral acceleration.
ASR (Anti Slip Regulation)
ASR (Anti Slip Regulation) is an integral part of the VDC system, optimising traction at all speeds, assisted by the brakes and the engine control.
The device monitors the wheel speed calculated by the ABS sensors to establish the amount of slip and triggers two different control systems to recover grip. When an excessive demand for power causes both drive wheels to slip (for example, aquaplaning or accelerating on an uneven, snow-covered or icy road surface), the system reduces engine torque by decreasing the throttle valve aperture and thus the airflow. If, on the other hand, only one wheel slips (for example the wheel on the inside of the bend, after acceleration or a dynamic change in the load), this wheel is automatically braked without the driver having to touch the brake pedal. The effect is similar to that of a self-locking differential. This gets the Alfa Romeo 159 out of any difficulties on surfaces where grip is poor.
ASR is engaged automatically every time the engine is started, but can be excluded by a pushbutton on the central console. ASR must be excluded when snow chains are fitted because in this case, in order to transmit torque to the ground, the wheel needs to be able to 'accumulate' the snow, with small slips that the ASR tends to avoid.
HBA and Hill-holder
The safety equipment on the Alfa 159 is completed by the HBA system, the hydraulic electronic hydraulic braking assistant which automatically increases the pressure in the braking circuit during emergency braking. And by the Hill-holder system, which maintains the braking pressure for a few moments after the driver removes his foot from the pedal, to simplify hill starts and prevent the car from slipping backwards.
Unrivalled passive safety
The Alfa 159 Sportwagon represents the state of the art where passive safety is concerned, thanks to the new chassis and the other sophisticated devices that equip the model. Plus the excellent braking system, Xenon headlights and generous tyres which guarantee the highest levels of active and preventive safety. The Alfa 159 Sportwagon belongs to the same family as the model that was recently awarded the prestigious 5-star Euro NCAP rating.
A new chassis for exceptional torsional rigidity
The chassis of the Alfa 159 Sportwagon is of a new generation, which combines the latest European expertise in the fields of safety, rigidity, innovative materials and quality. The new 'premium' floorpan is built with high performance materials, multiply sheet metal and laser welding. From the viewpoint of the architecture, the bodyshell also benefits from numerous measures such as the use of boxed elements that are rigidly connected transversely and vertically, three load lines in the front, longitudinals that run the whole length of the car, built-in structures and a larger number of spot welds around structural nodes. The result is the bodyshell's excellent torsional rigidity, the best in this segment (135,000 daNm/rad), and an equally outstanding value for flexural rigidity: 1310 daN/mm.
This is an excellent result, and it is essential for both safety and comfort; it was achieved thanks to numerous measures that ensure that the passenger compartment of the new model is a real survival cell. It is no coincidence that the Alfa 159 Sportwagon has passed the tests set by the strictest criteria of European and U.S. standards.
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