On one camp, you have Mercedes-Benz, which was the first to introduce a passenger airbag in a production car. At the opposite side of the divide was Audi, which believed that its Procon-ten (programmed contraction and tension) technology was safer for the driver.
At that time, airbag technology was still in its infancy. As its essentially an explosive device, storing and transporting airbag modules was particularly tricky, and nobody could be certain that this explosive device will remain safe for use, and will continue to deploy as designed decades later. For example, how would humidity affect the tightly folded airbag after ten years? Nobody knew for sure. Many tests were done by Mercedes-Benz to ascertain their safety but only time could vindicate their safety performance in the real world.
There were also reports of drivers suffering secondary injuries caused by a deploying airbag – burns on the skin caused by the chemicals used to inflate the airbag quickly, smaller-built drivers breaking their nose or fingers when the airbag deployed too strongly.
While many cars today are fitted with multi-stage airbags that will adjust the force of their deployment based on the weight of the occupant, early generation airbags had only one standard setting, which was usually calibrated for larger-built American or European occupants.
Audi’s Procon-ten system, introduced in the Audi 80 in 1986, is a purely mechanical solution, and does not rely on any complex electronic modules/sensors or chemical propellants.
It’s a pretty ingenious, low cost solution that works by simply harnessing the physical forces that naturally occur in a severe frontal collision – that the engine will be pushed back. By routing a system a steel cables and pulleys around the engine block, and linking them to the steering wheel, Procon-ten is able to pull the steering wheel away from the driver in the event of a severe frontal collision.
The system was effective enough to minimise a large number of head and chest injuries, without using costly airbags.
In fact, Audi was the last major German carmaker to introduce airbags into its models, in 1994.
There was one problem with Procon-ten, and a pretty serious one too – the system could only work with longitudinally positioned engines, thus severely limiting its application on future Audi models like the TT and the A3, which uses a transverse engine.
A transverse engine would not be able to provide sufficient leverage for the cables and pulleys to pull the steering wheel into the dashboard.
By the mid ‘90s it was clear that many of the early problems with airbags could be resolved, and airbags can be further developed to provide protection against side impact.
So when the B5 generation Audi A4 was introduced in 1994, the Procon-ten system was replaced with airbags.
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