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Head restraint
Head restraints (also called headrests) 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 some countries beginning 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 British 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 mid-1960s,[citation needed] and were mandated by the U.S. National Highway Traffic Safety Administration (NHTSA) in all new cars sold in the U.S. after January 1, 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.
Headrests are uncomfortable when they push the head forward. In such case there is effectively no gap behind the head and the headrest, or more technically, there's a 'negative' backset (or gap) as the headrest interferes with their natural neutral posture. Data shows that 16% of the population will experience headrest discomfort because of this issue. The rest of the population experiences no discomfort because there is no contact with the headrest, i.e. there is a gap between the head and headrest.
Headrests are designed this way because the regulated specs for headrests are set for the 'average' body posture. When the U.S. National Highway Traffic Safety Administration (NHTSA) revised the standard which governs head restraints for all new cars manufactured after 2008, it established for the first time a requirement for the fore-aft position, or "backset". The backset requirements was set at a 55mm (2.1 in) gap behind the head of the "average" body posture. By definition, not everyone has the 'average' posture. The specs will therefore cause issues for this 16% subset of the population.
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 crashworthiness 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.
For the last 40 years, vehicle safety researchers have been designing and gathering information on the ability of head restraints to mitigate injuries resulting from rear-end collisions. As a result, different types of head restraints have been developed by various manufacturers to protect their occupants from whiplash. Below are definitions of different types of head restraints.
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Head restraint
Head restraints (also called headrests) 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 some countries beginning 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 British 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 mid-1960s,[citation needed] and were mandated by the U.S. National Highway Traffic Safety Administration (NHTSA) in all new cars sold in the U.S. after January 1, 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.
Headrests are uncomfortable when they push the head forward. In such case there is effectively no gap behind the head and the headrest, or more technically, there's a 'negative' backset (or gap) as the headrest interferes with their natural neutral posture. Data shows that 16% of the population will experience headrest discomfort because of this issue. The rest of the population experiences no discomfort because there is no contact with the headrest, i.e. there is a gap between the head and headrest.
Headrests are designed this way because the regulated specs for headrests are set for the 'average' body posture. When the U.S. National Highway Traffic Safety Administration (NHTSA) revised the standard which governs head restraints for all new cars manufactured after 2008, it established for the first time a requirement for the fore-aft position, or "backset". The backset requirements was set at a 55mm (2.1 in) gap behind the head of the "average" body posture. By definition, not everyone has the 'average' posture. The specs will therefore cause issues for this 16% subset of the population.
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 crashworthiness 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.
For the last 40 years, vehicle safety researchers have been designing and gathering information on the ability of head restraints to mitigate injuries resulting from rear-end collisions. As a result, different types of head restraints have been developed by various manufacturers to protect their occupants from whiplash. Below are definitions of different types of head restraints.
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