Head restraint

Head restraints are an automotive safety feature, attached or integrated into the top of each seat to limit the rearward movement of the adult occupant's head, relative to the torso, in a collision — to prevent or mitigate whiplash or injury to the cervical vertebrae. Since their mandatory introduction in the late 1960s, head restraints have prevented or mitigated thousands of serious injuries.

A patent for an automobile "headrest" was granted to Benjamin Katz, a resident of Oakland, California, in 1921. Additional patents for such devices were issued in 1930 and in 1950, and subsequently. The major U. K. supplier of head restraints, Karobes, filed patents in the late 1950s and was still competitive in 1973 when British tests evaluated the quality of these devices.

Optional head restraints began appearing on North American cars in the late 1960s, and were mandated by the U.S. National Highway Traffic Safety Administration (NHTSA) in all new cars sold in the U.S. after 1 January 1969. The U.S. regulation, called Federal Motor Vehicle Safety Standard 202, requires that head restraints meet one of the following two standards of performance, design, and construction:

An evaluation performed by NHTSA in 1982 on passenger cars found that "integral" head restraints—a seat back extending high enough to meet the 27.5 in (698.5 mm) height requirement—reduces injury by 17 percent, while adjustable head restraints, attached to the seat back by one or more sliding metal shafts, reduce injury by 10 percent. NHTSA has said this difference may be due to adjustable restraints being improperly positioned.

The focus of preventive measures to date has been on the design of car seats, primarily through the introduction of head restraints, often called headrests. This approach is potentially problematic given the underlying assumption that purely mechanical factors cause whiplash injuries — an unproven theory. So far the injury reducing effects of head restraints appears to have been low, approximately 5–10%, because car seats have become stiffer in order to increase crash-worthiness of cars in high-speed rear-end collisions which in turn could increase the risk of whiplash injury in low-speed rear impact collisions. Improvements in the geometry of car seats through better design and energy absorption could offer additional benefits. Active devices move the body in a crash in order to shift the loads on the car seat.

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Wikipedia