The FIA Institute has completed testing on sliding tether attachments for Frontal Head Restraint (FHR) devices. The sled tests concluded that a sliding tether offers the same high level of protection as standard tethers, and can be approved using the FIA 8858-2002 methods.

Sliding tethers provide some advantages over their non-sliding counterparts. They are designed to slide back-and-forth through slots in the FHR attachment points thus allowing the driver to move his or her head more freely. Additionally, the sliding configuration allows for shorter tethers to be used, which provides for more effective protection in a crash.

Andy Mellor, FIA Institute Head of Technical Affairs, said: “Many drivers have already commented that they find sliding tethers to be more comfortable. If more drivers like wearing them, it could mean more people will start using frontal head restraints.”

The traditional configuration involves two fixed tethers of equal length that connect the helmet to the frontal head restraint. In an accident, all the load paths are in one direction, causing the head to move forward until both tethers are tight achieving an equal load on each side of the head.

The sliding tethers were sled tested to ensure both the loads in the tethers, and the loading angle of the tethers, relative to the helmet-tether-anchorages, were not excessive. Testing was completed at Advanced Car Technology Systems (ACTS) laboratories in Germany in July.

It was found that the sliding tethers induced a rotating moment to the helmet and head during the early phase of a crash, such that the helmet was fully aligned with the FHR when the peak loads occurred. Based on this positive finding, the FIA Institute OCRG recommended that sliding tethers can be approved using the current FIA 8858-2002 specification; with the same test methods and requirements as for the fixed tethers.