By Christopher A. Sawyer
The Virtual Driver

(December 19, 2013) Today’s safety technologies weren’t created in a vacuum, having arisen from other, sometimes seemingly unrelated, advances that made them possible. What follows are some of the major steps along the way to the automotive safety systems we have today.

Radial Tires

History doesn’t remember Arthur W. Savage of San Diego, Calif., as the inventor of the radial tire, despite receiving U.S. patent 1,203,910 on May 21, 1915. More costly, harder to construct, and less forgiving than its bias-ply cousin, the radial tire nearly disappeared from sight until Michelin stepped in and developed and commercialized it.

From its headquarters in Clermont-Ferrand, France, the tire maker took Savage’s idea — wrapping the cord from side-to-side at a 90-degree angle to the rim and placing circumferential belts between the cords and tread — used steel for the belts, and called it the resulting tire the Michelin X. In an instant, tire life nearly doubled, fuel economy increased, and vehicle ride and handling (once suspension systems were modified for the radial’s unique characteristics) markedly improved.
 
Disc Brakes

The spot-type disc brake, ironically, is another American invention. Elmer Ambrose Sperry of Cleveland, Ohio, designed an electric vehicle in 1898 that featured a large disc integral with each front hub. Electromagnets pressed pads fitted with friction material against the discs when the brake was engaged, while springs caused the pads to retract.

However, it was Englishman William Lanchester who first patented disc brakes four years later, and put them on his cars. With only copper at hand to act as the friction material, Lanchester’s disc brakes had a short service life. Once perfected in the late 1940s, however, disc brakes proved to be much less prone to heat-induced fade, performed better in the wet, and produced shorter stopping distances than drum brakes.

As costs fell and demand for better braking performance increased, disc brakes moved from racing cars to sports cars to every new car and truck on the road today.

Crumple Zones

In 1951, Mercedes engineer Béla Barényi was the first to patent the rigid passenger cell/crumple zone combination we still use today, as well as the safety steering wheel. In an accident, the vehicle’s front and rear structures are designed to deform, progressively absorbing collision energy, and lessening the forces on the passenger structure (or “safety cage”).

Mercedes-Benz’s 1959 W 11 series was the first series production automobile to feature this design, and the first to include a collapsible steering wheel. It featured a large impact absorber connected to the steering column via a plastically deformable element. A few years later, the collapsible steering column was added to Mercedes’ safety repertoire. In 1966, Barényi and Mercedes-Benz development manager Hans Scherenberg put together the definitions of active and passive safety we use today.

Seatbelts and Airbags

Though Edward Claghorn of New York was issued a U.S. patent for a safety belt on February 10, 1885, it was California doctor C Hunter Shelden who first proposed retractable seatbelts in a November 5, 1955 article in the Journal of the American Medical Association. However, it was Volvo’s Nihls Bohlin who developed the 1955 patent of Americans Roger Griswold and Hugh DeHaven into the modern three-point seatbelt we use today. Recently it has been supplemented by an inflatable belt design that reduces injuries of rear seat passengers.

Airbags were first patented in 1951 by German Walter Linderer, though it was former U.S. Navy man John Hedrick whose 1953 patent built on Linderer’s idea and coined the term “airbag”. In 1968, Allen Breed patented the electromechanical crash sensor, and sodium azide (since abandoned) became the first fast-acting propellant.

This combination made it possible to detect a crash and deploy an airbag within the 30 milliseconds needed for it to be effective. Now vehicles have multiple airbags designed for frontal, side and rollover events.

Anti-lock Brakes

An ABS system for airplanes was outlined in 1929 that used a flywheel attached to a drum that ran at the same speed as the plane’s wheel. If the wheel slowed below the speed of the flywheel (i.e. it was skidding), a valve attached to the flywheel opened and released pressure on the brakes.

As far as anyone can tell, this device was never used.

Skip ahead 29 years, however, and Britain’s Road Research Laboratories creates and tests the first practical ABS system (“Maxaret”) on, of all things, a Royal Enfield motorcycle. Maxaret was first used on Britain’s Jensen Interceptor in 1966, but was withdrawn due to cost, complexity and a fundamental lack of reliability. That didn’t stop Lincoln’s 1968 Continental Mark III from featuring a rear brake-only system design by Kelsey-Hayes.

It used wheel-speed sensors on the rear wheels to transmit information to a rudimentary electronic controller, and modulated pressure to the rear brakes via an in-line vacuum-operated valve. Unfortunately, it also proved too costly and unreliable.

ABS as we know it today, was first introduced on Mercedes’ W-116 Series S-Class in 1978. Interestingly, the first patent for the technology was filed by Daimler-Benz’s development manager, Dr. Hans Scherenberg, in 1953; just two years after Mercedes patented the crumple zone.

Microprocessors and Sensors

The low-cost microprocessor sparked the electronics revolution, and made automotive safety systems what they are today. Integrating an entire central processing unit (CPU) on a chip or chips decreased the cost of processing power. Advances in miniaturization doubled that power approximately every 18 months.

Ignition modules were the first major application of automotive microprocessors, and this gradually spread to the fuel system with the advent of electronically controlled carburetors and, later, electronic fuel injection. As automotive sensors came of age, the CPU’s ability to more finely control systems within the vehicle also improved. However, what once were discrete systems in the 1970s, 1980s and most of the 1990s were quickly integrated into larger scale controllers that shared information across the vehicle platform.

Suddenly, ABS became affordable, traction control moved from brake-intervention units to powertrain-intervention designs, electronic stability control was born, and a whole host of other features were created. Today, automakers and suppliers are fusing the data from the sensors around the vehicle to add depth and functionality.

As processor power grows and vehicles communicate with each other and the infrastructure, it may be possible to create a car that never crashes as. However, that day is still somewhere in the future, and the recent revelations about the National Security Agency’s eavesdropping capabilities may increase resistance to these systems. In the near-term, however, fusing advanced electronic stability control, electric steering and radar/lidar will make accident avoidance systems commonplace. From there, it is a short road to the fully autonomous vehicle.

Though legal and other hurdles — especially the wariness of the driving public and the initial cost of these systems — may delay the advent of driverless cars, as with all of the safety technologies featured, this technology will begin at the top of the food chain and trickle down as costs diminish. We may never get to the day when cars don’t crash, but the impossible increasingly is considered commonplace.

The Virtual Driver