Your Vehicle s Airbags: Understanding Their Operation

One of the top priorities for automakers is to design vehicles that protect their drivers safety. In the old days, that protection came in the form of seatbelts. A single over the shoulder belt prevented motorists from lurching into their steering wheels and windshields during an accident. Over the years, seatbelt design evolved and today, we have lap belts that offer even more protection.

We re traveling on our roads and highways at faster speeds than ever. As a result, there s more risk of injury in the event of a collision. Responding to a need for greater safety, a law was passed in 1998 requiring all new cars to have air bags installed. Below, we ll explore how they work. You ll learn what triggers their inflation and discover some of the safety issues they caused during the early years. We ll also explain how an evolving design promises more protection for drivers in the future.

What Causes Them To Inflate?

Consider what happens while you re driving. Both you and your vehicle are moving forward at a certain velocity. If something in your path abruptly stops your car, you would continue traveling forward until something stopped you (i.e. steering wheel, windshield, etc.). Your air bags were designed to interrupt your momentum as quickly and softly as possible.

The front air bag (they are also installed in the doors and seats) is made from nylon. It is folded and stuffed into the center portion of your steering wheel. There is a special sensor that monitors interruptions in your car s momentum. It does this by watching a switch. The switch is normally kept open, but if the momentum of your vehicle slows abruptly, it closes and allows an electrical signal through to the sensor. This signal tells the sensor that your car has collided with something in its path. The sensor tells the airbag to inflate.

The air bag inflates as the result of nitrogen gas. The gas is produced by combining sodium azide and potassium nitrate.

Resolving Early Safety Issues

When airbag technology was first integrated into vehicles, little was known about the potential harm their force could cause. Spurred by reports of injuries, researchers identified a safe zone of ten inches between the driver and the bag. This space is considered sufficient to prevent injury from the bag s deployment.

Because children are more susceptible to injury than adults, additional guidelines are needed. Kids under twelve should ride in the rear seat, preferably in a car seat. Babies who are riding in a car seat should also ride in the rear.

Less Power, Fewer Injuries

As the result of safety concerns surrounding the force of airbag deployment, the National Highway Traffic Safety Administration (NHTSA) passed two laws in the late 1990s. The first gave automakers the ability to lower the system s power by up to thirty five percent. The second law gave dealerships and auto repair garages permission to install a cut off switch. The switch essentially gave drivers the ability to turn their airbag systems off.

Not all drivers were eligible to have the cut off switch installed. They were required to meet certain criteria such as an existing medical condition that increased their risk during deployment. These requirements are still in effect today.

Better Protection Through An Evolution Of Design

Airbag technology has evolved dramatically over the last decade. The time between impact and bag deployment has narrowed to a few milliseconds. Meanwhile, the inflation system has become far more intelligent. Deployment is now decided by a computer that monitors the force of a collision and the position of the car s occupants. Bags are deployed with varying degrees of power based on the presumed risk of injury.

Automakers continue to develop better designs and more flexible placement for the airbags throughout their respective fleets. Door mounted, head, and curtain airbags promise to provide even more protection for drivers and passengers in the future.