Automotive Design and Production

JUN 2013

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Sperry of Cleveland, Ohio, designed an electric vehicle in 1898 that featured a large disc integral with each front hub. Electromagnets pressed pads ftted 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 frst 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. Mercedes engineer Béla Barényi was the frst to patent (in 1951) the rigid passenger cell/crumple zone combination still used today, as well as the safety steering wheel. In an accident, the vehicle's front and rear structures are designed to deform and progressively absorb collision energy, helping to leave the passenger structure (or "safety cage") intact. Mercedes-Benz's 1959 W 11 series was the frst series production automobile to feature this design, and the frst 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 devised the defnitions of "active" and "passive" safety still used today. 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 frst 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. Only recently has it been supplemented by an infatable belt design that reduces rear seat injuries. Seatbelts and airbags, when combined with the safety cage/crumple zone architecture, pushed the boundaries of survivability. Airbags were frst 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 frst 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 efective. Now vehicles have multiple airbags designed for frontal, side and rollover events. French aviator Gabriel Voisin created an anti-lock brake (ABS) system for airplanes in 1929 that used a fywheel attached to a drum that ran at the same speed as the plane's wheel. If the wheel slowed below the speed of the fywheel (i.e., it was skidding), a valve attached to the fywheel opened and released pressure on the brakes. Twenty-nine years later, Britain's Road Research Laboratories created the frst practical ABS system ("Maxaret"), testing it on a Royal Enfeld motorcycle. It was frst applied to Britain's Jensen Interceptor in 1966, but was withdrawn due to cost, complexity and a lack of reliability. Lincoln's 1968 Continental However, it was the advent of the microprocessor that gave both active and passive safety their biggest leaps forward, and promises to redefne what's possible. 27

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