In a crash, this is the explosion you’ll want to hear
THE most common airbag is the one mounted in the centre hub of the steering wheel but bags are now included for the passenger (in front and to the side) as well as side and curtain airbags for the rear-outboard passengers in highend luxury cars. There are even knee airbags for front occupants.
The airbag— most commonly made from nylon— is packed away with lubricating powder in the hub beneath the covering trim (which has seams on the inside to allow it to split when required).
The airbag is linked to numerous sensors— impact sensors and accelerometers among others— to recognise deceleration on impact and trigger the car’s safety systems and deploy the supplemental restraint systems.
The airbag system uses nitrogen gas, which is fired by a solid-propellant inflator system, to detonate the bag from the steering wheel hub in 0.05sec and at up to 300km/h, ballooning up in front of the driver’s head and torso and slowly deflating to lessen the occupant’s impact on hard interior surfaces such as the dashboard or steering wheel.
Early airbags were sometimes labelled as doing more harm than good (in some cases causing death) because of their excessive force of deployment.
The more modern systems match the airbag force with the crash impact and whether the occupant is using a seat belt.
For comic effect, Hollywood would have you believe they stay inflated for comic effect but most airbags deflate shortly after the impact has dissipated, although some side-curtain airbags will remain inflated for longer to maintain protection in a rollover.