Head Restraint
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Head restraints (also called headrests) are an
automotive safety Automotive safety is the study and practice of design, construction, equipment and regulation to minimize the occurrence and consequences of traffic collisions involving motor vehicles. Road traffic safety more broadly includes roadway design. ...
feature, attached or integrated into the top of each
seat A seat is a place to sit. The term may encompass additional features, such as back, armrest, head restraint but also headquarters in a wider sense. Types of seat The following are examples of different kinds of seat: * Armchair (furniture), ...
to limit the rearward movement of the adult occupant's head, relative to the torso, in a
collision In physics, a collision is any event in which two or more bodies exert forces on each other in a relatively short time. Although the most common use of the word ''collision'' refers to incidents in which two or more objects collide with great fo ...
— to prevent or mitigate
whiplash Whiplash may refer to: * The long flexible part of a whip * Whiplash (medicine), a neck injury ** Whiplash Injury Protection System (WHIPS), in automobiles Film and television * ''Whiplash'' (1948 film), a US film noir about a boxer * ''Whiplas ...
or injury to the
cervical vertebrae In tetrapods, cervical vertebrae (singular: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In ...
.UNECE Regulation 17: Uniform Provisions Concerning the Approval of Vehicles With Regard to the Seats, Their Anchorages and Any Head Restraints
/ref>
/ref> 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 Oakland is the largest city and the county seat of Alameda County, California, United States. A major West Coast of the United States, West Coast port, Oakland is the largest city in the East Bay region of the San Francisco Bay Area, the third ...
, in 1921. Additional patents for such devices were issued in 1930US Patent 1781600: Combined Automobile Headrest and Strap Hanger
/ref> and in 1950, and subsequently. The major U. K. supplier of head restraints,
Karobes Karobes Limited was a leading British supplier of car accessories in the 1950s–1970s. The company was based in Leamington Spa in central England. In the 1950s it was the major seller of seat covers in the UK and had the reputation of selling lu ...
, 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, and were mandated by the U.S.
National Highway Traffic Safety Administration The National Highway Traffic Safety Administration (NHTSA ) is an agency of the U.S. federal government, part of the Department of Transportation. It describes its mission as "Save lives, prevent injuries, reduce vehicle-related crashes" rela ...
(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: *During a forward acceleration of at least 8g on the seat supporting structure, the rearward angular displacement of the head reference line shall be limited to 45° from the torso reference line, ''or'' *Head restraints must be at least above the seating reference point in their highest position and not deflect more than under a
moment Moment or Moments may refer to: * Present time Music * The Moments, American R&B vocal group Albums * ''Moment'' (Dark Tranquillity album), 2020 * ''Moment'' (Speed album), 1998 * ''Moments'' (Darude album) * ''Moments'' (Christine Guldbrand ...
. The lateral width of the head restraint, measured at a point either below the top of the head restraint or above the seating reference point must be not less than for use with bench seats and for use with individual seats. The head restraint must withstand an increasing rearward load until there is a failure of the seat or seat back, or until a load of is applied. An evaluation performed by NHTSA in 1982 on passenger cars found that "integral" head restraints—a seat back extending high enough to meet the 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.


Why do so many people find headrests uncomfortable

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. Why are headrests designed this way? Simply because the regulated specs for headrests are set for the 'average' body posture. When the U.S.
National Highway Traffic Safety Administration The National Highway Traffic Safety Administration (NHTSA ) is an agency of the U.S. federal government, part of the Department of Transportation. It describes its mission as "Save lives, prevent injuries, reduce vehicle-related crashes" rela ...
(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.


Whiplash protection

The focus of preventive measures to date has been on the design of
car seat A car seat is the seat used in automobiles. Most car seats are made from inexpensive but durable material in order to withstand prolonged use. The most common material is polyester. Bucket seat and bench seat A bucket seat is a separate ...
s, primarily through the introduction of head restraints, often called
headrest 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 ...
s. 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 Crashworthiness is the ability of a structure to protect its occupants during an impact. This is commonly tested when investigating the safety of aircraft and vehicles. Depending on the nature of the impact and the vehicle involved, different crit ...
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. Head restraint — refers to a device designed to limit the rearward displacement of an adult occupant's head in relation to the torso in order to reduce the risk of injury to the cervical vertebrae in the event of a rear impact. The most effective head restraint must allow a backset motion of less than 60 mm to prevent the hyperextension of the neck during impact. Integrated head restraint or fixed head restraint — refers to a head restraint formed by the upper part of the seat back, or a head restraint that is not height adjustable and cannot be detached from the seat or the vehicle structure except by the use of tools or following the partial or total removal of the seat furnishing”. Adjustable head restraint — refers to a head restraint that is capable of being positioned to fit the morphology of the seated occupant. The device may permit horizontal displacement, known as tilt adjustment, and/or vertical displacement, known as height adjustment. Active head restraint — refers to a device designed to automatically improve head restraint position and/or geometry during an impact. Automatically adjusting head restraint — refers to a head restraint that automatically adjusts the position of the head restraint when the seat position is adjusted. A major issue in whiplash prevention is the lack of proper adjustment of the seat safety system by both drivers and passengers. Studies have shown that a well designed and adjusted head restraint could prevent potentially injurious head-neck kinematics in rear-end collisions by limiting the differential movement of the head and torso. The primary function of a head restraint is to minimize the relative rearward movement of the head and neck during rear impact. During a rear-end collision, the presence of an effective head restraint behind the occupant's head can limit the differential movement of the head and torso. A properly placed head restraint where one can sufficiently protect one's head lower the chances of neck injury by up to 43% during a rear-end collision. In contrast to a properly adjusted head restraint, research suggests that there may be an increased risk of neck injuries if the head restraint is incorrectly positioned. More studies by manufacturers and automobile safety organizations are currently undergoing to examine the best ways to reduce head and torso injuries during a rear-end impact with different geometries of the head restraint and seat-back systems. In most passenger vehicles where manually adjustable head restraints are fitted, proper use requires sufficient knowledge and awareness by occupants. When driving, the height of the head restraint is critical in influencing injury risk. A restraint should be at least as high as the head's center of gravity, or about 9 centimeters (3.5 inches) below the top of the head. The backset, or distance behind the head, should be as small as possible. Backsets of more than 10 centimeters (about 4 inches) have been associated with increased symptoms of neck injury in crashes. Due to low public awareness of the consequence of incorrect positioning of head restraints, some passenger vehicle manufactures have designed and implemented a range of devices into their models to protect their occupants. Some current systems are: *
Mercedes-Benz Mercedes-Benz (), commonly referred to as Mercedes and sometimes as Benz, is a German luxury and commercial vehicle automotive brand established in 1926. Mercedes-Benz AG (a Mercedes-Benz Group subsidiary established in 2019) is headquartere ...
A-Class Active Head Restraint (AHR), NECK-PRO *
Saab Saab or SAAB may refer to: Brands and enterprises * Saab Group, a Swedish aerospace and defence company, formerly known as SAAB, and later as Saab AB ** Datasaab, a former computer company, started as spin off from Saab AB * Saab Automobile, a fo ...
(Responsible for the first active head restraint),
Opel Opel Automobile GmbH (), usually shortened to Opel, is a German automobile manufacturer which has been a subsidiary of Stellantis since 16 January 2021. It was owned by the American automaker General Motors from 1929 until 2017 and the PSA Grou ...
,
Ford Ford commonly refers to: * Ford Motor Company, an automobile manufacturer founded by Henry Ford * Ford (crossing), a shallow crossing on a river Ford may also refer to: Ford Motor Company * Henry Ford, founder of the Ford Motor Company * Ford F ...
,
SEAT A seat is a place to sit. The term may encompass additional features, such as back, armrest, head restraint but also headquarters in a wider sense. Types of seat The following are examples of different kinds of seat: * Armchair (furniture), ...
,
Nissan , trade name, trading as Nissan Motor Corporation and often shortened to Nissan, is a Japanese multinational corporation, multinational Automotive industry, automobile manufacturer headquartered in Nishi-ku, Yokohama, Japan. The company sells ...
,
Subaru ( or ; ) is the automaker, automobile manufacturing division of Japanese transportation conglomerate (company), conglomerate Subaru Corporation (formerly known as Fuji Heavy Industries), the Automotive industry#By manufacturer, twenty-first ...
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Hyundai Hyundai is a South Korean industrial conglomerate ("chaebol"), which was restructured into the following groups: * Hyundai Group, parts of the former conglomerate which have not been divested ** Hyundai Mobis, Korean car parts company ** Hyundai ...
, and
Peugeot Peugeot (, , ) is a French brand of automobiles owned by Stellantis. The family business that preceded the current Peugeot companies was founded in 1810, with a steel foundry that soon started making hand tools and kitchen equipment, and the ...
— Active Head restraint ( SAHR), *
Volvo The Volvo Group ( sv, Volvokoncernen; legally Aktiebolaget Volvo, shortened to AB Volvo, stylized as VOLVO) is a Swedish multinational manufacturing corporation headquartered in Gothenburg. While its core activity is the production, distributio ...
and
Jaguar The jaguar (''Panthera onca'') is a large cat species and the only living member of the genus '' Panthera'' native to the Americas. With a body length of up to and a weight of up to , it is the largest cat species in the Americas and the th ...
— Whiplash Protection System/Whiplash Prevention System (
WHIPS A whip is a tool or weapon designed to strike humans or other animals to exert control through pain compliance or fear of pain. They can also be used without inflicting pain, for audiovisual cues, such as in equestrianism. They are generally e ...
), and *
Toyota is a Japanese multinational automotive manufacturer headquartered in Toyota City, Aichi, Japan. It was founded by Kiichiro Toyoda and incorporated on . Toyota is one of the largest automobile manufacturers in the world, producing about 10 ...
— Whiplash Injury Lessening (WIL). Th
Insurance Institute for Highway Safety
(IIHS) and other testing centers around the world have been involved in testing the effectiveness of head restraint and seat systems in laboratory conditions to assess their ability to prevent or mitigate whiplash injuries. They have found that over 60% of new motor vehicles on the market have “good” rated head restraints.


See also

*
HANS device A HANS device (head and neck support device) is a type of head restraint, a safety device in motorsports. Head restraints are mandatory when competing with most major motorsports sanctioning bodies. They reduce the likelihood of head or neck inj ...


References

{{Commons category, Head restraints Vehicle safety technologies Automotive accessories