Chevrolet 1996 Tahoe Owner's Manual page 39

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 9 to 16 mph (14 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, rear impacts 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.
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