All Types of Automatic Belts,
Passive Belts are Defective
and Pose Serious Safety
Problems

In response to the U.S. federal requirement for passivity in automobile restraint systems, manufacturers developed passive belts, also known as automatic belts.  Through the 1970s and early 1980s, three basic types of automatic belt configurations were developed and installed in vehicles while automobile manufacturers waged what the U.S. Supreme Court described as the equivalent of war on airbags.  All three types are defectively designed and pose serious safety problems.  Distinct injury patterns or modalities, which were or could have been predicted by their designers, result from these belt systems.

Two-Point Shoulder Belt This system is comprised of a two-point shoulder belt attached to a retractor at the console and a motorized buckle or "mouse" that runs along the roof rail. This system is accompanied by a manual lap belt, a non-automatic component. It was developed by Toyota and first appeared in its 1981 Cressidas. It was also found in Ford and Mazda vehicles, among others.

Two-Point, Door-Mounted Belt This second type of automatic belt system was installed in production vehicles by Volkswagen in 1976.  This automatic belt system had a shoulder belt permanently mounted to the window frame on the front doors.  As the door opens, the shoulder belt swings away from the occupant. Volkswagen substituted a knee bolster in place of the lap belt as a pelvic restraint.  In later models a manual lap belt was also provided with this system.  This system was also found in Hyundais and certain GEOs.

Three-Point, Door-Mounted Belt This third form of automatic belt is where the retractors were actually located in the door.  The occupants could use this system in either a automatic or manual mode.  Only between 2% and 9% of the population actually use this system in a automatic mode.  These automatic belts are most commonly found on General Motors vehicles.

Injury Modalities All three automatic restraint belt systems above are defectively designed.  The two-point, motorized shoulder belt and the two-point, door-mounted belt are essentially a return to the old sash belts that were discarded in Europe in the early 1960s.  Nils Bohlin of Volvo recognized as early as 1958 that attempting to restrain vehicle occupants with only a  two-point, diagonal torso belt would produce unreasonable and unnecessary injury patterns.

The motorized and door-mounted, two-point shoulder belt systems are defectively designed in that they do not include an integrated lap belt. Reliable studies, including a study by Ford, have shown that only 30% to 40% of the occupants use the lap belt. The presence of the shoulder belt on their chests caused them to forget to buckle the lap belt.  Non-use of the lap belt produces the types of injury modalities, as described below: • risk of ejection, resulting in a dramatically increased risk of injury and death;   • risk of submarining, which causes the occupant to be restrained primarily by his or her neck, leading to spinal cord injury and even decapitation, and;   • risk of significant thoracic injuries including ruptured aortas and lacerated livers.  These injuries are caused by the forces that are applied to the chest in a crash. In the manual, three-point system the webbing is almost twice as long as that found in a two-point torso belt.  This results in the occupant being restrained by a dangerously stiff belt.  Toyota handled this problem by moving to a webbing material for its two-point system that stretches up to 20%. Ford and Mazda, on the other hand, continued to use the same webbing material as found in their three-point belt systems which stretches only 7% to 10%.  Webbing material that only stretches between 7% to 10% is too stiff, not providing enough ride-down. General Motors' three-point, door-mounted systems have at least two significant injury modalities, as described below: • risk of ejection when the door opens (GM has acknowledged, if a door opens in an accident, the occupant is "effectively unrestrained"), and;   • risk of significant neck and spinal cord injuries.  Mounting belts to the doors results in the shoulder belts being much further forward than in other designs. (06/30/00)