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 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.
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.
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.