Rollover Ejection While Wearing Lap and Shoulder Harness: The Role of the Retractor

There have been documented cases of rollover accidents wherein the driver was ejected while wearing the single loop lap/shoulder harness. Three actual incidents will be discussed here. In two of the three cases the vehicle was photographed at the accident scene with the latchplate still in the buckle, whereas in the other case, the evidence of the seatbelt having been latched was found some time after the accident. Rollover accidents are second to frontal collisions in severe injury causation. It is an accepted fact that retention in the vehicle is necessary for an occupant to have a chance at mitigating the injuries associated with a rollover event. It is also the purpose of the seatbelts to restrain the occupant and prevent ejection in this kind of vehicle accident.

In this paper, the design of the seatbelt retractor will be analyzed to determine its role in the retention of occupants in a rollover collision. First the nature of rollover acceleration pulses and occupant motions will be discussed. Then the design of the typical retractor mechanism, particularly the ones in these three accident scenarios will be presented. A review of current seatbelt retractors will also be presented with commentary on which designs may prevent this kind of release.