How it began
Nils Bohlin had worked as an aircraft engineer at Saab on ejection seats and their belts for pilots. Volvo hired him in 1958 as its first chief safety engineer to develop a suitable belt for cars. A patent application for the three-point belt was filed in Sweden on August 29, 1958, and Bohlin, working in Gothenburg, completed the design in less than a year. Volvo introduced it in its cars in 1959, and a United States patent was issued to Bohlin on July 10, 1962.
Before it existed
Seat belts in one form or another had existed for decades, and designs ranged from the simple two-point lap belt to six-point harnesses in racing cars. No belt system had become established in car construction, and belt use was limited mostly to race car drivers. The two-point belt, which buckled over the abdomen, had been known to cause severe internal injuries in high-speed crashes.
How it works
Two straps, one across the chest and one across the hips, join at hip level and fasten into a single anchor point. In the words of the patent, the belt retains the upper as well as the lower part of the body against forward forces in a physiologically favorable manner and is easy to fasten and unfasten. It holds the body in place and reduces the effect of the sudden deceleration in a crash.
How it spread
Volvo released the design to other car manufacturers without payment or claims, and it became standard worldwide. In the United States, the National Traffic and Motor Vehicle Safety Act of 1966 made seat belts a required feature on all new vehicles from the 1968 model year.
Who pushed back
Acceptance by drivers was slow. In Germany, despite road safety campaigns in the 1970s, it took a long time to persuade people to buckle up every time. Three-point belts became compulsory on all car seats there only on July 1, 2004; until then lap belts were tolerated in the rear.
What lasted
Engineers have refined seat belts since, adding belt tensioners and force limiters, but the basic structure is still Bohlin's. Seat belt use is estimated to cut the risk of death and serious injury in collisions by about half, and Volvo credits the invention with saving at least a million lives.
