Happy birthday to the airbag!

Saturday, 9 January 2021

Ten years ago Mercedes-benz celebrated that airbag's 30th birthday. They didn't do a video for its 40th...

Almost exactly 40 years ago a new innovation hit the automotive market that would save many, many lives in the decades since: the driver's airbag.

While we take it for granted that new cars are bristling with airbags these days, the airbag was, in those days, the latest cutting-edge innovation in safety from Mercedes-Benz and was first previewed in December 1980.

The ‘supplementary restraint system’ – or ‘airbag as we know it today - was a joint development between the then Daimler-Benz AG and Bosch, and late in 1980 a limited number of S-Class sedans (126 model series) were the first cars to be delivered with a driver’s side airbag, while more than 100 S-Class vehicles fitted with the new safety systems rolled off the assembly line in January and February 1981.

A not-at-all-staged promotional photo of an airbag in action. And visual proof of how style has changed in the last 40 years too.

The airbag made its world premiere at the Amsterdam International Motor Show in February 1981 and one month later, Mercedes-Benz presented it to the public at the Geneva Motor Show.

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A patent drawing of Mercedes-Benz’s first airbag system.

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The centre of steering wheels had to grow considerably to house the workings of the earliest airbags.

The airbag was initially only available for the S-Class and SEC Coupes as an optional extra, but was soon available as an optional extra for all Mercedes-Benz passenger cars. By 1992, the driver's airbag was standard equipment in all models, followed by a front passenger airbag as a standard safety feature in 1994.

But it wasn’t just the airbag that Mercedes-Benz debuted four decades ago, the company had another innovation up its sleeve that it revealed at the same time – a restraint system for the front passenger, at the time known as the 'belt tightener.'

First offered as a part of the same optional package as the driver’s airbag, the seat belt tensioner (as this safety feature is now more commonly known) also became standard equipment for the front seats of all Mercedes-Benz passenger cars in 1984.

The seat belt tensioner reacts to the same sensor signal as the driver's airbag and is also triggered by controlled pyrotechnics: a propellant charge is fired to tighten the seat's three-point seat belt within milliseconds. This eliminates the typical slack between the occupant's upper body and the seat belt and both driver and front passenger are held firmly in the seat by the seat belt.

The basic idea for the airbag was attributed, amongst others, to the hobby inventor, Walter Linderer.

In the 1950s, he had designed what he described as an 'inflatable container in a folded state, which automatically inflates in the event of danger” and on the 6th of October, 1951, the Munich-born inventor filed for a patent for his 'device to protect persons in vehicles against injury in the event of collisions' from the German Patent Office.

Although in his application Linderer precisely described the principle of an airbag, the technical requirements for the sensors as well as those for rapid gas generation simply did not exist in those days.

Conventional compressed air was not suitable for generating pressure because it took far too long to inflate the airbag, while the elastic and extremely tear-resistant material required to make the airbag was also not available at the time.

This remained the case for a number of years, but Mercedes-Benz returned to the idea of the airbag in 1966 and started the initial trials for effective gas generation in 1967. The patent for an 'impact protection device for vehicle occupants' was filed by Daimler-Benz AG in October 1971.

Similar systems were launched by American car manufacturers in the early 1970s, but while broadly similar in concept, they differed in their operation and were intended solely to be a replacement for a shoulder belt, rather than an extra layer of safety that Mercedes-Benz intended it to be and would become the “airbag” we know and love today.

After approximately 250 crash tests, more than 2,500 sled tests and thousands of trials on individual components, Mercedes-Benz safety engineers managed to bring the technology to series production maturity over the next fifteen years.

When the system first debuted the impact absorbers in the steering wheels were rather large because they had to accommodate a large fabric cover, and when inflated, the first driver's airbags had a volume of between 60 to 70 litres. The same is true for the development of the front passenger airbag. When it was presented at the International Motor Show in Frankfurt/Main in 1987, it occupied the entire glove box.

As airbag components became increasingly smaller over the years without compromising safety, it was possible to incorporate the airbag in other places inside the vehicle, apart from in the steering wheel or glove box.

Today we see side airbags, window airbags, head/thorax side airbags, knee airbags, thorax/pelvis side airbags, inflatable seatbelts and centre airbags, as well as 'adaptive airbags' that deploy in two stages depending on accident severity.

As with most things in the motoring world, what we once considered revolutionary quickly becomes commonplace and while it is impossible to accurately calculate how many lives the innovation has saved in the past 40 years, the number would be very large indeed.