Mercedes-Benz Active Seat Belt Buckle in Action

Active seat-belt buckle is a moving belt buckle which can be extended by 70 mm and retracted by 40 mm via an electric motor.

Easier fastening of the seat belt

As with most Mercedes-Benz safety features, Active seat belt buckle makes life as much easier for the occupant as safer. The buckle is illuminated in the dark, and extends outward by 70 millimetres when occupants enter the rear. In extended state the belt buckle is more readily accessible and it is easier to insert the belt tongue. Both functions are activated when the doors are opened by passengers entering the rear of the vehicle.

Mercedes-Benz Illuminated Active Seat Belt Buckle

Mercedes-Benz also says that the illuminated buckle will remind the passenger to fasten the seat belts.

Minimised belt slack

After the belt has been inserted, the belt buckle retracts back to its original position. This reduces any belt slack in the area of the pelvis and thorax, and the belt fits correctly in the pelvis area says Mercedes-Benz.

PRE-SAFE® function for rear occupants

PRE-SAFE is Mercedes-Benz’s bouquet of technologies that activate certain safety features in the car in anticipation of a crash. Active seat-belt buckle is fully integrated in the vehicle’s PRE-SAFE® system. Whenever PRE-SAFE® becomes active in critical driving situations or when a critical distance from other objects is detected, reversible belt tensioning is effected in the rear when the belt buckle is retracted by around 40 mm. This increases the belt tensioning on the occupant by up to 80 mm.

Mercedes-Benz Active Seat Belt Buckle for passenger at the Rear

Since the belt buckle is at a lower height due to retraction, this reduces the risk of the pelvis pushing through under the belt. Securing the occupants more effectively in this way reduces the stress to which they are exposed in the event of an accident. If you have been wondering how pre-tensioning, a safety feature on Merc’s sold now, fits into the new scenario, well Mercedes-Benz has said Active seat-belt buckle is set to replace the pyrotechnic belt tensioning. This pyrotechnic system is triggered in the event of actual impact.

POST-SAFE functionality

The system also extends the buckle to make rescue operations easier, in the event of a crash, after making sure the vehicle is stationary.

The Mercedes safety experts have developed active seat-belt buckle using detailed computer models of the human body, as dummies are only able to simulate the human pelvic system along very rough lines.

“Active seat-belt buckle is another element of our ‘PRE-SAFE®’ concept, which is intended to provide our customers with optimum protection in real accident scenarios,” stresses Prof. Dr. Ing. Rodolfo Schöneburg, Head of Passive Safety and Vehicle Functions at Mercedes-Benz Cars. “After all, we aim to offer a high standard of safety not only in all model series, but also in all seats.” Active seat-belt buckle has also been developed with an eye on new markets in which the level of occupied rear seats is up to 30 percent – markedly higher than in Europe. “In the rear of premium saloons in particular, passengers tend to sit in particularly relaxed positions in the generous space which is available,” explains Schöneburg. “Active seat-belt buckle as part of PRE-SAFE® unlocks the full potential of the on-board restraint systems.”