1995 GMC Safari Owner's Manual - Page 33

When should an air bag inflate? The air bag is designed to inflate in moderate tosevere frontal or near-frontal crashes. The air bag will inflate only if the impact speea 1s 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 11 to 16 mph (18 to 26 km/h). The threshold level can vary, however, withspecific 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 helpthe 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. What makesan air bag inflate? In a frontal impact of sufficient severity, theair 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 collisions, of 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 tosevere frontal or near-frontal collisions. 1-23