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When should an air bag inflate?
The
air
bag is designed to inflate in moderate to severe frontal or near-frontal
crashes. The air bag will inflate only if the impact speed is above the system's
designed "threshold level." If your vehicle goes straight into a wall that doesn't
move or deform, the threshold level is about 12 to 16 mph (19 to 26
km/h).
The threshold level can vary, however, with specific vehicle design, so that it
can be somewhat above or below this range. If your vehicle strikes something
that will move or deform, such as a parked car, the threshold level will be
higher. The air bag is not designed to inflate in rollovers, side impacts, or rear
impacts, because inflation would not help the occupant.
In any particular crash, no one can say whether an air bag should have
inflated simply because of the damage to a vehicle or because of what the
repair costs were. Inflation is determined by the angle of the impact and the
vehicle's deceleration. Vehicle damage is only one indication of this.
The air bag system is designed to work properly under a wide range of
conditions, including off-road usage. Observe safe driving speeds,
especially on rough terrain. As always, wear your safety belt. See
"Off-Road Driving" in the Index for more tips on off-road driving.
What makes an air bag inflate?
In a frontal or near-frontal impact of sufficient severity, the air bag sensing
system detects that the vehicle is suddenly stopping as a result of a crash.
The sensing system triggers a chemical reaction of the sodium azide sealed
in the inflator. The reaction produces nitrogen gas, which inflates the air
bag. The inflator, air bag, and related hardware are all part of the air bag
module packed inside the steering wheel.
How does an air bag restrain?
In moderate to severe frontal or near-frontal collisions, even belted
occupants can contact the steering wheel. The air bag supplements the
protection provided by safety belts. Air bags distribute the force of the
impact more evenly over the occupant's upper body, stopping the occupant
more gradually. But air bags would not help you in many types of collisions,
including rollovers and rear and side impacts, primarily because an
occupant's motion is not toward the air bag. Air bags should never be
regarded as anything more than a supplement to safety belts, and then only
in moderate to severe frontal or near-frontal collisions.
What will you see after an air bag inflates?
After the air bag inflates,
it
quickly deflates. This occurs so quickly that some
people may not even realize the air bag inflated. Some components of the air
bag module in the steering wheel hub will be hot for a short time, but the part
of the bag that comes into contact with you will not be hot to the touch. There
will be some smoke and dust coming from vents in the deflated air bag. Air
bag inflation will not prevent the driver from seeing or from being able to
steer the vehicle, nor will it stop people from leaving the vehicle.
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