50 years after the issue of the crumple zone patent: Mercedes-Benz inaugurates a new era in car safety with PRE-SAFE

• Anticipatory occupant protection system exclusive to the S-Class
• Pre-crash protection activated during emergency braking and skidding
• Advance deployment of PRE-SAFE belt tensioners
• Crumple zone patent issued on August 28, 1952

Pre-crash protection measures activated before an imminent accident include split-second advance tensioning of the seat belts, aimed at ensuring the best possible seating position for the driver and front passenger prior to a collision so that the airbags can do their job as effectively as possible. If required, PRE-SAFE also adjusts the settings for the front passenger seat and the power-adjustable individual seats in the rear. If the vehicle is skidding, the system automatically closes the sunroof.

Mercedes-Benz: a pioneer of passenger car safety for five decades

PRE-SAFE is a further example of the pioneering work performed by Mercedes-Benz in reshaping the concept of vehicle safety. It was exactly 50 years ago that the Stuttgart manufacturer created what was to become the cornerstone of this vital development discipline: on August 28, 1952, Mercedes engineer Béla Barényi obtained the patent for his crumple zone, an invention which would revolutionise body construction throughout the entire automotive industry. Barényi's innovative design principle was first phased into series production at Mercedes-Benz in 1959.

In the years that followed, Mercedes-Benz unveiled further milestones of safety technology – including the airbag, belt tensioner, sidebag, belt force limiter and windowbag – all of which were developed based on the analysis of real road accidents. Thanks to such systems, Mercedes passenger cars have now achieved an outstanding level of safety which it would be difficult to improve on by conventional means. To bring about further advances in occupant safety, the Mercedes engineers developed the PRE-SAFE anticipatory occupant protection concept which complements the tried-and-tested restraint systems on board the S-Class and marks the beginning of a new era in vehicle safety.

PRE-SAFE is based on the findings of the Mercedes-Benz accident researchers, which show that in approximately two thirds of all accidents, there is a relatively long time lapse between recognition of an impending collision and the collision itself. Mercedes-Benz is now using this "window" for advance activation of protection systems in order to further reduce the risk of injury to the vehicle's occupants. The model-year 2003 S-Class will inaugurate this future-oriented safety concept, which will be extended over the course of time.

Synthesis of active and passive safety

PRE-SAFE determines accident probability using sensors belonging to the Electronic Stability Program (ESP®) and Brake Assist whose job is to recognise critical situations at an early stage. The status of the components is reversible, i.e. if the accident is averted at the last moment, the advance seat belt tensioning is automatically terminated and the occupants are able to reset the position of the seats and the sunroof. However, PRE-SAFE is instantly ready to go into action again if required.

The system is the result of some six years' intensive development work by Mercedes engineers. Hundreds of drivers took part in the testing and refining of PRE-SAFE on test tracks and in the DaimlerChrysler driving simulator in Berlin. This acceptance-testing programme delivered a clear verdict: pre-crash occupant protection in no way restricts the freedom of the driver or the drivability of the car but rather gives occupants an enhanced feeling of safety.

Adaptive airbag control takes into account accident situation and the weight of the front passenger

In a further measure to enhance occupant safety in the S-Class, Mercedes-Benz uses "up-front sensors" at the front of the body which are able to ascertain the severity of an accident at an early stage, so that the two-stage front passenger airbag can respond even more appropriately. The up-front sensors are also able to activate the belt tensioners even earlier, thus keeping the occupants optimally secured during an impact.

Also new: the weight of the front passenger is automatically classified with the aid of a special membrane in the seat upholstery. The system then decides whether to trigger one or both passenger airbag stages on the basis not just of accident severity but also of occupant weight.

PRE-SAFE: inaugurating a new era in occupant protection

• The S-Class pioneers a trend-setting safety concept
• Pre-crash protection measures activated during emergency braking and skidding
• Advance deployment of PRE-SAFE belt tensioners

Crumple zones, airbags, belt tensioners, sidebags, belt force limiters, windowbags - these are just some of the milestones clocked up in five decades of intensive and successful safety development work at Mercedes-Benz. These landmark systems have become a matter of course on state-of-the-art passenger cars of today. These pioneering safety features have saved thousands of people's lives and preserved thousands more from serious injury.

Thanks to such systems, Mercedes models have now achieved an outstanding level of safety which it would be difficult to improve on by conventional means, since most of the potential of passive safety technology has now been exploited. Further advances require new concepts. Mercedes-Benz has therefore developed an innovative solution which is now poised to inaugurate a new era in vehicle safety: with PRE-SAFE. The model-year 2003 S-Class points the way - PRE-SAFE will be standard equipment on the flagship Mercedes Saloon range.

The new Mercedes-Benz safety concept is based on the principle of advance protection: PRE-SAFE can detect an imminent collision before it occurs, and goes into action immediately to prepare both the vehicle and its occupants:

• The driver's and front passenger's seat belts are tensioned in advance of the potential impact.
• An unfavourable pre-crash front passenger seat fore/aft setting and/or seat cushion and backrest angle can be corrected.
• The power-adjustable individual seats in the rear can be adjusted to improve the angle of the seat cushions.
• The sunroof is automatically closed.

In two thirds of accidents, there is enough time beforehand to activate PRE-SAFE protection measures

PRE-SAFE is based on the findings of the Mercedes accident researchers, which show that more than two thirds of all accidents are preceded by critical dynamic situations - such as skidding, emergency braking or a sudden evasive manoeuvre - which provide advance warning that a collision is imminent. In the past, no use was made of this valuable "window", which may last up to several seconds: the familiar protection systems like the seat belt, airbag or belt tensioners are triggered only when the impact actually occurs.

PRE-SAFE, on the other hand, reads the danger signals in advance and uses the remaining time prior to the potential accident to activate precautionary safety measures. In other words, PRE-SAFE equips the car with "reflexes", like those of a living organism. Just as sudden danger triggers a reflex action on the part of the organism, which takes precautions to protect itself, so the innovative safety technology of the S-Class immediately triggers special systems, designed to reduce the risk of injury to the occupants.

Sensors detect accident risk in advance

PRE-SAFE gains advance warning of an impending collision due to unprecedented collusion between the active and passive safety systems. PRE-SAFE is linked up to the anti-lock braking system, Brake Assist and the Electronic Stability Program (ESP®), whose sensors identify critical driving manoeuvres and relay appropriate messages to the control units of these standard-fitted active safety systems. Now, for the first time, Mercedes-Benz is also using the information provided by these sensors as a basis for anticipatory occupant protection, thus opening up a whole new dimension in automotive safety.

PRE-SAFE belt tensioners return to their original status if the accident is averted

The pre-crash protective measures initiated by PRE-SAFE ensure that by the time an accident takes place, the seating position of the occupants has been optimised and the seat belts and airbags can operate more effectively. In other words, PRE-SAFE is not intended as a substitute for the tried-and-trusted restraint systems such as the front airbags, belt tensioners, sidebags and windowbags but as a complement to them. It does not encroach on their operation and efficiency in any way.

If the accident is prevented, the advance tensioning of the seat belts is automatically terminated and the occupants can reset the seats and the sunroof to their original positions. This reversible design means that PRE-SAFE is instantly ready to go into action again if required.

Emergency braking triggers pre-crash activation of the belt tensioners

If the Brake Assist system on board the S-Class carries out an emergency braking operation, the PRE-SAFE system is triggered too, and takes appropriate precautionary measures:

• The reversible PRE-SAFE belt tensioners prevent the driver's and front passenger's bodies from moving too far forward during braking. The belt tensioner, driven by a powerful electric motor, can reduce the belt slack within just 120 milliseconds. The engineers have carried out measurements which show that the forward movement of a front passenger who was not expecting sudden emergency braking is reduced by up to 150 millimetres.
• PRE-SAFE preemptively corrects the position of the front passenger seat : if the seat is positioned too far forwards, it is automatically moved further back. At the same time, if the backrest is angled too far back, it is automatically adjusted to an upright position. Then the angle of the seat cushion is also adjusted if necessary. In this way the system adjusts the front passenger seat to a position in which the airbag can deploy more effectively and the shoulder belt can develop a more effective restraining effect. The risk of submarining, with consequent injuries, is also reduced. If a rear-end impact is also imminent, the steeper backrest angle provides better support for the front passenger.
• PRE-SAFE also optimises the position of the power-adjustable individual rear seats (optional) in the Mercedes-Benz S-Class during emergency braking. If one or both seat cushions is in a very flat position, PRE-SAFE will adjust it to a more steeply inclined position. This significantly reduces the risk of the rear passengers submarining, with consequent injuries.

In a skid, PRE-SAFE also closes the sunroof

PRE-SAFE uses data supplied by the sensors of the Electronic Stability Program (ESP®) to identify dangerous skidding movements of the vehicle (strong understeer or oversteer). If such a situation is detected, it automatically intervenes:

• The reversible belt tensioners on the front seats reduce belt slack. Tests show that in this way lateral movements of the torso can be reduced by up to 300 millimetres, depending on the situation.
• If necessary, as in the case of emergency braking, PRE-SAFE can correct the positions of the front passenger seat and the power-adjustable individual seats in the rear. The system increases the distance between the front passenger and the dashboard, adjusts the front passenger's backrest to an upright position and modifies the angle of the rear seat cushions so that, if an accident risk is detected, the passengers' seats in the S-Class are adjusted to a safe position. The belts, belt tensioners and airbags can thus offer optimal protection.
• In critical skidding situations, PRE-SAFE also automatically closes the (optional) sunroof . This precautionary measure is based on the findings of the Mercedes-Benz accident researchers which show that violent skidding is frequently followed by a roll-over. Closing the sunroof reduces the risk of occupants being thrown out of the vehicle in a roll-over, or of external objects intruding into the interior and causing injury.

Real and simulated crash tests demonstrate the high efficiency of PRE-SAFE

PRE-SAFE is the result of some six years' intensive development work by Mercedes engineers. Hundreds of drivers took part in the testing and refining of PRE-SAFE on test tracks and in the DaimlerChrysler driving simulator in Berlin. This acceptance-testing programme delivered a clear verdict: pre-crash occupant protection in no way restricts the freedom of the driver or the drivability of the car but rather gives occupants an enhanced feeling of safety

The PRE-SAFE systems now making their world debut in the S-Class represent the first generation of a ground-breaking new Mercedes safety concept. The engineers are already working on further components of an adaptive pre-crash occupant protection system. They see this as the biggest challenge on the safety front in the coming years. Their long-range goal is to develop a vehicle whose protection systems take into account occupant characteristics such as size, weight and age and thus combine "advance deployment" with customised protection.

Although New-Cars.com checks with auto manufacturers and their representatives to confirm the accuracy of the data, it makes no guarantee or warranty, either expressed or implied with respect to the data presented here. All specifications, prices and equipment are subject to change without notice.

New-Cars.com Home - News Archives - Car Reviews - New Car Price Quote - Privacy Policy - Contact Us

Copyright © 2002 New-Cars.com