Headband (also called headrest) is an automotive safety feature, mounted or integrated into the top of each seat to restrict backward movement of the adult head, relative to the torso, in collision - to prevent or reduce whiplash or injury to the cervical vertebra. Since mandatory introduction in the late 1960s, head restrictions have prevented or reduced thousands of serious injuries.
Patents for car headrest were given to Benjamin Katz, resident of Oakland, California, in 1921. Additional patents for such devices were issued in 1930 and 1950, and subsequently. The chief supplier of restrictions, Karobes, filed a patent in the late 1950s and was still competitive in 1973 when the British test evaluated the quality of this device.
Optional head restrictions began to appear in North American cars in the late 1960s, and were mandated by the US National Highway Traffic Safety Agency (NHTSA) in all new cars sold in the US after January 1, 1969. The US regulation, called the Federal Motor Vehicle Safety Standard 202, requires that head restrictions meet one of the following two performance, design, and construction standards:
- During advance acceleration of at least 8g on the seat support structure, the displacement of the rear angle of the head reference line should be limited to 45 ° from the torso reference line, or
- The head restraints should be at least 700 mm (27.6 in) above the seat reference point at the highest position and do not deflect more than 100 mm (3.9 inches) below 372 Ã, Â °? m (3.292 in? lbf) moment. The lateral width of head restraints, measured at either 65 mm (2.56 in) points below the top of the holding head or 635 mm (25.0 in) above the reference point of the seat shall be not less than 254 mm (10.0 in ) for use with bench seats and 171 mm (6.73 inches) for use with individual seats. The head barrier must withstand increasing backward loads until there is a failure of the chair or seatrest, or until a load of 890 N (200 lbf) is applied.
An evaluation conducted by NHTSA in 1982 on passenger cars found that "integral" head restraints - the rear seats extend high enough to meet 27.5 in (698.5 mm) of high need - reduce injuries by 17 percent, while adjustable head restraints, mounted into the rear seats by one or more sliding metal shafts, reducing injury by 10 percent. NHTSA says that this difference may be caused by improperly adjustable restrictions.
Video Head restraint
Whiplash Protection
The focus of preventative measures to date is on car seat design, especially through the introduction of head restraints, which are often called headrests. This approach is potentially problematic given the underlying assumption that pure mechanical factors cause whiplash injury - an unproven theory. So far the effect of reducing injuries from head restraints appears to be low, about 5-10%, as car seats become more rigid to increase the lethargy of cars in high-speed rear collisions which in turn may increase the risk of whiplash injury in low-impact collisions. Improvements in the geometry of the car seat through better design and energy absorption may offer additional benefits. The active device moves the body in a collision to shift the load in the car seat.
Over the past 40 years, vehicle safety researchers have designed and collected information on the ability of head restraints to reduce injuries from rear-end collisions. As a result, various types of head restrictions have been developed by various manufacturers to protect their occupants from whiplash. Below is the definition of different types of head restraints.
Head barrier - refers to a device designed to limit the displacement of adult headaches with respect to the torso to reduce the risk of injury to the cervical vertebra in the event of a collision in the back.. The most effective head barrier should allow backset movement of less than 60 mm to prevent neck hyperextension during impact.
Integrated headguards or fixed headgear - refers to the head restraints formed by the top of the backrest, or unregulated head restraints and can not be removed from seat or vehicle structures except by means of tools or following removal part or total of the furniture of the chair ".
Adjustable head barrier - refers to head restraints capable of being positioned to fit the morphology of occupants sitting. The device can allow horizontal displacements, known as tilt adjustments, and/or vertical displacements, known as high adjustments.
Active head dismissal - refers to devices designed to automatically increase the position of head restraints and/or geometry in the event of a collision ".
Automatically adjust head restraints - refers to head restraints that automatically adjust the position of the headrest when the seat position is adjusted.
A major problem in the prevention of whiplash is the lack of proper adjustment of the seat security system by drivers and passengers. Studies have shown that a well designed and well-designed head buffer can prevent potentially adverse head-neck kinematics on rear collisions by limiting the differential motions of the head and torso. The main function of head restraints is to minimize relative rear and head back movements during the back collision. During a rear-end collision, the presence of an effective head restrain behind the occupants' head can limit the differential motion of the head and torso. Properly placed head control where a person can protect a person's head with a lower, lower chance of neck injury by up to 43% during a back-end collision.
In contrast to well-adjusted headgear, studies show that there may be an increased risk of neck injury if the head restraint is not positioned correctly. More studies by manufacturers and car safety organizations are currently undergoing to examine the best way to reduce head and torso injuries during rear-end impacts with different geometries of head control and headrest systems.
In most passenger vehicles where manual adjustable head restraints are installed, proper use requires sufficient knowledge and awareness by occupants. While driving, the height of head restraints is very important in influencing the risk of injury. The barrier must be at least as high as the center of gravity of the head, or about 9 centimeters (3.5 inches) below the top of the head. The backset, or the distance behind the head, should be as small as possible. Backsets of more than 10 cm (about 4 inches) have been associated with increased symptoms of neck injury in crashes.
Because of the low public awareness of the consequences of incorrect placement of head restrictions, some passenger vehicle manufacturers have designed and implemented various devices into their models to protect their occupants.
Some of the current systems are:
- Mercedes-Benz A-Class Active Head Restraint (AHR), NECK-PRO
- Saab (Responsible for first active head control), Opel, Ford, Nissan, Subaru, Hyundai and Peugeot - Active Head Restraints (SAHR),
- Volvo and Jaguar - Whiplash Protection System/Whiplash Prevention System (WHIPS), and
- Toyota - Whiplash Injury Lessening (WIL).
Insurance Agencies for Highway Safety (IIHS) and other testing centers around the world have been involved in testing the effectiveness of head and seat restraint systems in laboratory conditions to assess their ability to prevent or reduce whiplash injuries. They have found that over 60% of new motor vehicles in the market have "good" head tightness.
Maps Head restraint
See also
- HANS devices
References
Source of the article : Wikipedia
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