ZF LIFETEC, a global leader in passive safety systems, has announced the upcoming launch of its latest innovation in occupant protection—the SPR6.1 seatbelt.
The SPR6.1 builds on ZF LIFETEC’s longstanding efforts to minimise injury risks in the rear seat and is the first system of its kind to feature adaptive mechanical decoupling in the event of seatbelt overtightening. This development is particularly relevant for today’s diverse passenger profiles—from children to elderly occupants—and addresses real-world safety scenarios rather than just regulatory compliance.
Harald Lutz, Senior Vice President Global Engineering at ZF LIFETEC, said, “With the SPR6.1, we have developed a solution that significantly increases rear seat safety while improving passenger comfort. Our innovations in passive safety technology continue to set standards and help us achieve our goal of Vision Zero—zero road fatalities and serious injuries.”
The retractor tensioner uses ZF’s proven Snake Pretensioner Retractor (SPR) technology, where a plastic element is driven into a special gear by a pyrotechnic system during a crash to tighten the belt. The innovation lies in the precise mechanical decoupling, which prevents excessive force that could cause injury. This feature is especially useful in vehicles with Autonomous Emergency Braking (AEB), as it counteracts occupant movement during pre-crash deceleration.
SPR6.1 also opens up more design flexibility for OEMs. It can be integrated with additional pretensioners like anchor devices to reduce submarining risk and is compatible with both direct and indirect retraction systems. Sensor compatibility includes standard vehicle-sensitive ball sensors and the premium Silent Locking Side (SLS) pendulum sensor, which emits just 8 dB of noise—an important comfort consideration in today’s ultra-quiet electric vehicles.
With its combination of adaptive safety, compact packaging, and expanded application potential, the SPR6.1 offers automakers a new path toward enhanced occupant protection in rear seats. The system is expected to be available for vehicle integration starting mid-2025.
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