What Makes An Airbag Inflate; How Does An Airbag Restrain - GMC Sierra 2010 Owner's Manual

The vehicle may or may not have seat mounted side
impact and roof-rail airbags. See Airbag System on
page 2 73. Seat mounted side impact and roof-rail
airbags are intended to inflate in moderate to severe
side crashes. In addition, these roof-rail airbags are
intended to inflate during a rollover or in a severe frontal
impact. Seat mounted side impact and roof-rail airbags
will inflate if the crash severity is above the system's
designed threshold level. The threshold level can vary
with specific vehicle design.
Roof-rail airbags are not intended to inflate in rear
impacts. A seat mounted side impact airbag is intended
to deploy on the side of the vehicle that is struck. Both
roof-rail airbags will deploy when either side of the
vehicle is struck, or if the sensing system predicts that
the vehicle is about to roll over, or in a severe frontal
impact.
In any particular crash, no one can say whether an
airbag should have inflated simply because of the
damage to a vehicle or because of what the repair costs
were. For frontal airbags, inflation is determined by what
the vehicle hits, the angle of the impact, and how
quickly the vehicle slows down. For seat mounted side
impact and roof-rail airbags, deployment is determined
by the location and severity of the side impact. In a
rollover event, roof-rail airbag deployment is determined
by the direction of the roll.

What Makes an Airbag Inflate?

In a deployment event, the sensing system sends an
electrical signal triggering a release of gas from the
inflator. Gas from the inflator fills the airbag causing the
bag to break out of the cover and deploy. The inflator,
the airbag, and related hardware are all part of the
airbag module.
Frontal airbag modules are located inside the
steering wheel and instrument panel. For vehicles with
seat mounted side impact airbags, there are airbags
modules in the side of the front seatbacks closest to the
door. For vehicles with roof-rail airbags, there are airbag
modules in the ceiling of the vehicle, near the side
windows that have occupant seating positions.

How Does an Airbag Restrain?

In moderate to severe frontal or near frontal collisions,
even belted occupants can contact the steering wheel
or the instrument panel. In moderate to severe side
collisions, even belted occupants can contact the inside
of the vehicle.
Airbags supplement the protection provided by safety
belts. Frontal airbags distribute the force of the impact
more evenly over the occupant's upper body, stopping
the occupant more gradually. Seat mounted side impact
and roof-rail airbags distribute the force of the impact
more evenly over the occupant's upper body.
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