One of the Best & Brightest recently asked me to write about the history of automotive safety equipment. Today’s consumers ask how many airbags a car offers as standard equipment but in the 1970s the idea had a difficult time getting accepted, by both automakers and consumers.
The first modern patent on an inflatable safety device to protect people in car accidents was granted in 1952 to a retired industrial designer named John Hetrick, who called it a “safety cushion”. Inspired by a wartime incident involving compressed air and a torpedo he was repairing, Hetrick’s design used a tank of compressed air and inflatable bags located in the steering wheel, the glove box and the middle of the dash as well as in the front seat backs for rear passengers. The system was actuated by a spring loaded weight that was supposed to sense rapid deceleration and then open a valve, releasing the compressed air. Hetrick unsuccessfully tried to get interest from the domestic automakers and because he didn’t have money to develop the idea, it was stillborn. In the late 1950s, when Ford and General Motors both started working on inflatable safety restraints, they determined that any system that worked would have to have a much more sensitive collision sensor and a much faster inflation system. For an airbag to work, it must inflate in the forty milliseconds between the initial collision and the secondary impact of the passengers hitting the dashboard etc.
Around the same time that Hetrick was working on his safety cushion, German inventor Walter Linderer received a German patent for a similar inflatable cushion system, triggered by the driver or activated by by an impacted bumper.
Who it was that finally made airbags practicable were two men, Allen Breed, a former RCA engineer and chemist John Pietz. Breed’s contribution was twofold. Around 1967 he developed a reliable collision sensor that cost only $5 to manufacture. Then he was granted a patent on an airbag using two layers of fabric that were folded to allow the inflating gas to escape, absorbing even more energy and reducing the impact of the passengers on the airbag. Breed marketed his system to the automakers, eventually making a deal with Chrysler. Pietz was working as a chemist for Talley Defense Systems when they were approached by General Motors looking for something that could be used to inflate the restraints quicker than compressed air. In 1968, Pietz started working with sodium azide, which when combined with a metallic oxide would release nitrogen gas explosively. It worked satisfactorily, and didn’t pose any practical danger to drivers and passengers but Pietz had a hard time getting the auto industry to accept it because sodium azide is toxic when ingested in large amounts. For a long time, though, it was the only practical solution. Since then, nitroguanidine has been substituted as a propellant.
By then, Ford had approached automotive supplier Eaton, Yale, and Towne, Inc. about working on an airbag system. Eaton executive William Carey had sold the company on doing airbag research in the mid-1960s in order to develop a safety system to protect children on school buses. He was initially budgeted $100,000 for the project, which was assigned to scientist Charles Simon. Carey’s team looks at things as diverse as diverse as popping popcorn and how party balloons were inflated. They even experimented with blasting caps supplied by a Detroit area demolition company, though the parts to that experimental bag were never all found. In time the team would grow to 100 people, funded with $35 million from Eaton and another $100 million from all three domestic and several overseas automakers.
They developed what was eventually marketed as Eaton’s “Auto-Ceptor” restraints. A sensor was mounted on the firewall which activated a detonator that released pressurized nitrogen into urethane coated nylon bags. Everything worked quickly enough to be practical but the project was not an immediate success. In 1969, Ford sent a team of engineers to Washington D.C. to demonstrate the prototype to the Dept. of Transportaion but the system failed to activate when the button was pushed. Henry Ford II was so angry when he heard about the failed demo that he temporarily cancelled the program, saying he didn’t want any “Rube Goldberg device” in “his” cars.
Eaton carried on with the research and it was decided by Ford to proceed with offering the safety system on its full-sized Ford and Mercury sedans. However, FoMoCo’s chief body engineer, Stuart Frey, sent Eaton back to the drawing board to resolve a number of issues that he felt had to be addressed before airbags went into production cars. To begin with, there were reliability and performance issues with the components. Of even greater concern was child safety. As then designed, the airbags were giving child-sized crash test dummies what would have been fatal blows. The bags were also not effective for angled crashes and Ford discovered that the deployment of airbags often resulted in broken or blown out windshields.
Years later, in the mid-1990s, when concerns over the deaths of 52 children and petite women caused by airbags were prompting regulators to consider warning stickers or even eliminating mandated airbags, Carey, by then retired, mounted his own personal public relations campaign to defend Eaton’s invention. He said that their earliest research showed that unbelted or out of position children could be at risk, something they didn’t hide from automakers or regulators. Carey would eventually be honored by the Automotive Hall of Fame for his team’s development of the first practical airbags.
Much of that development took place at a small test site just south of Eaton’s Southfield, Michigan research center. I found out about it from my brother, who worked as a technician for the company many years ago. He told me that they had a big concrete barrier, mounted on it’s own reinforced foundation that was buried many feet into the ground, and that occasionally they’d hire professional drivers to crash into the barriers to prove their airbags’ effectiveness. That sounded a bit urban legendish, but I learned to trust my big brother a long time ago.
Since the location is just 3 or 4 miles from my house I took the Toyota Tundra Platinum Crew Max I was reviewing for the short drive over there. I found a parking lot with Eaton trucks and my first impression was that the crash facility had been disassembled. There was a concrete pad, but no barrier. Then as I was leaving, I noticed a driveway at the back of the parking lot. My original thought was that it was a private driveway, but as I drove down the ~500 foot straightaway, I spotted the large concrete barrier at the far end of the drive, and I noticed that I was driving directly over two steel tracks embedded in a concrete strip that runs down the length of the otherwise asphalt driveway.
When I got near the barrier and parked the truck, I noticed a second barrier off to the side that was apparently used for testing impacts into poles and the like. The concrete in that second barrier is shaped like a triangle so perhaps it was also used to test offset and angled crashes as Ford body engineer Stuart Frey suggested. Assorted supplemental weights were piled on the main barrier, which I’d estimate was abut 16 feet wide, 4 feet deep and about 4 feet tall, made of reinforced concrete. My guess is that the supplemental weights were used to alter the weight of test sleds. The concrete pad upon which the barrier block stands has some wide fractures, perhaps from all the impacts.
On the cinderblock wall behind the barrier were some no-longer-used electrical utility boxes, with signs of other electrical equipment being formerly located along the path of the track. It’s quite silent and peaceful there now, quite a contrast, I’m sure, to the violent collisions that took place time and again in that location more than four decades ago. In time perhaps the vegetation will encroach on the asphalt track. Some plants are already starting to grow up through the rack at the start of the embedded guides.
I took a few photographs and just for grins I shot some video from the truck as it approached the barrier. Then I went home and sent my brother, who now lives in Jerusalem, an email thanking him for such a cool tip. I’m still not sure about the story about the race drivers driving cars into the barrier. The presence of guide tracks and a small hole through the barrier lead me to believe they used sleds and cables, as are still used in crash test facilities today. Human drivers aren’t very good at uniform speeds and reproducible results. Also, as mentioned before, crash test dummies were already in use when Eaton was working on their airbags.
Click on the settings icon to watch in 2D or your choice of 3D formats. Sorry for the shaky camera work, I wasn’t expecting to shoot video and left my steadycam gizmo at home.
While Carey and Simon may have developed the first practical airbags and can be given credit for saving many lives, their employer didn’t benefit much from the way that the industry and consumers have embraced the technology. Eaton stopped selling airbags in 1975, not being able to justify development costs for the then minimal market demand.
Ronnie Schreiber edits Cars In Depth, a realistic perspective on cars & car culture and the original 3D car site. If you found this post worthwhile, you can dig deeper at Cars In Depth. If the 3D thing freaks you out, don’t worry, all the photo and video players in use at the site have mono options. Thanks for reading – RJS