Even though airbags have been around for quite a number of
years, they have undergone a number of changes in recent years. Some other safety systems are dependent on
the airbag system for their operation.
Therefore it is important to understand how they operate. It is also imperative
for your own safety to know how they operate and to possibly dispel some of the
myths about airbags.
American
John Hetrick and German Walter Linderer first patented airbags in 1951. Linderer’s
system was deemed ineffective as it depended on compressed air either released
by bumper contact or by manual release by the driver, but it inflated too
slowly to provide any margin of safety. Hetrick however, was an industrial
engineer and had also worked with torpedoes in World War II. He put this knowledge to use in designing and
building an operable airbag. He actually worked for one of the “Big Three”
automakers at the time. Even though
airbags are now required standard safety equipment on every car, when he showed
his invention to each of the Big Three, there was no interest in purchasing or
using it in their cars. At that time, the automakers could not see any way that
it would make their cars more saleable or increase their profits. Saftety was
not considered that important then as it is today. After his patent expired in
1971, Ford experimented with it in a few cars.
The first
major breakthrough in airbag technology came in 1967 when Allen Breed developed
an electromechanical airbag crash sensor, which would detonate a small charge
of sodium azide. Ford, Chrysler and an Italian company were soon experimenting
with variations of this. In the early 1970s, both Ford and GM offered airbags
on government fleet vehicles. Oldsmobile offered a drivers airbag on their
Toronado model, but it was dropped in 1977 for lack of interest. Part of the
problem of acceptance at that time was the fact that seatbelt usage was
approximately ten percent of the driving public. During this era, airbag
manufacturers required that the drivers use their seatbelt at all times, so
this meant that most people wanted nothing to do with it.
In 1981,
Mercedes Benz introduced an airbag system that integrated a seatbelt with a
pretensioner that would tighten the belt to limit forward movement in the event
of a frontal collision. This essentially became the first supplemental
restraint system (SRS). In 1987, Porsche became the first manufacturer to offer
standard driver and passenger airbags on the 944 Turbo and as an option on the
other 944 models. In 1988, Chrysler became the first US automaker to offer
standard driver’s airbags on its most popular models, followed a year later by
its availability across its entire product line.
During the 1990s, airbags became more common in many
different vehicles; especially after the US Transportation Efficiency Act of
1991 mandated that all passenger cars and light trucks built after September 1,
1998 must have driver and passenger front airbags as standard equipment. During
the 2000s, side impact airbags became commonplace, first on high-end luxury
cars, later on many medium-priced cars and then even on some entry-level models.
In recent years, head curtain, knee and torso airbags have been installed on
some vehicles.
The early
2000s brought some changes in the front airbag systems. The first change was
the second-generation airbags, which deployed with less force than the earlier
bags, especially in lower speed collisions. The next innovation was integrating
a sensor into the system, which determined when there was no one occupying the
passenger seat or someone who weigh less than a predetermined weight and
deactivated the passenger bag. This also resulted in lower repair costs as the
passenger airbag and the dashboard cover did not have to be replaced. There are some inherent limitations to
airbags. First is the fact that airbags will not protect someone in the event
of multiple impacts. Once an airbag deploys, it deflates quickly and then is
rendered useless.
A second
even more dangerous and more common situation is called an underride collision.
This takes place when an auto strikes the rear of a large delivery truck or
tractor-trailer. The ICC bumper which is standard on most North American
tractor trailers, will often break away when struck from behind. This means
that the vehicle will go under the back of the truck, sometimes as far as the
windshield or on rare occasion even further, resulting in serious injuries or
even death by decapitation. The problem here is that the impact is not
sufficient enough to set off the airbag until the vehicle could potentially be
way under the truck, without the airbag having deployed. European trucks
require a much stronger rear bumper, and many newer North American trucks have
a better-built reinforcement system.
However, there is no requirement to retrofit the thousands of trucks on
the road that are not reinforced.
A third
problem has recently surfaced and received a lot of press coverage due to a
major recall of GM vehicles and now some other automobiles too. This is due to
if the power to the airbag system is interrupted because of defective ignition
switch or other factors, the airbags will not deploy in the event of a
crash. This loss of ignition also
affects many other systems such as power steering and brakes and there is a
high likelihood of a crash if the switch cuts out while the car is in motion.
The final
limitation or hazard of airbags is the risk of injury from airbag deployment if
the front seat occupants are not wearing seatbelts and move toward the airbag
at time of impact. Also, children or adults of small stature have a risk if
seated too close to the airbag. The people
who place a rear-facing child seat in the front place the child at high risk of
serious injury or death if the airbag deploys.
However, when you consider that between 1990 and 2000, the US National
Highway Traffic Safety Administration estimates that airbags are directly
responsible for saving approximately 6,400 lives as opposed to 175 fatalities
caused by airbags (104 of those being children).
Next week, we
will examine how airbags operate. Some information for this column was sourced
from Wikipedia.org.
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