The Mystery & Misery Behind The Head Rest
Car headrests were they deliberately designed to be removed so that they can be used to smash windows during emergencies? A question that most of the car enthusiast will ask time and again.
While it is possible to break a car window with a removable headrest, quite easy as well, this is an incidental application of that object rather than a deliberate one. The primary intended function of the modern car headrest was to prevent whiplash in case of accident: When Benjamin Katz filed a patent for an automobile headrest in 1921, he noted that the device could stabilize the head when it was subjected to the “jolts and irregular movements” inherent in driving an automobile. The car headrest has since gone through many changes, but these primarily focus on safety, comfort, and manufacturing, not emergency uses.
“We are establishing the new head restraint requirements to ensure that vehicle occupants receive better protection from whiplash and related injuries. To achieve this purpose, the agency wants to take reasonable steps to increase the likelihood that a head restraint is available when needed. If head restraints were too easily removable, chances are greater that they will be removed. That, in turn, increases the chances that the restraints might not be reinstalled correctly, if at all. By prohibiting removability without the use of deliberate action distinct from any act necessary for adjustment, the likelihood of inadvertent head restraint removal will be reduced, thus increasing the chances that vehicle occupants will receive the benefits of properly positioned head restraints. States NHTSA paper.
Since January 1, 1969, passenger cars have been required by FMVSS 202 to have head restraints in the front outboard seating positions. FMVSS 202 also applies to light trucks manufactured after August 31, 1991. The standard requires that either of two conditions be met:
- 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 45o from the torso reference line: or
- Head restraints must be at least 700 mm (27.5 inches) above the seating reference point in their highest position and not deflect more then 100 mm (4 inches) under a 372 Nm (3,300 inch-pound) moment. The lateral width of the head restraint, measured at a point either 65 mm (2.56 inches) below the top of the head restraint or 635 mm (25 inches) above the seating reference point, must be not less than 254 mm (10 inches) for use with bench seats and 171 mm (6.75 inches) 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 890N (200 pounds) is applied.
The head restraint evaluation performed by NHTSA in 1982 on passenger cars found that the effectiveness of integral restraints was 17 percent in reducing rear impact injuries, while adjustable head restraints were 10 percent effective in reducing rear impact injuries.
The occupant may adjust the restraint to the top, bottom, or intermediate positions. The difference in effectiveness may have been due in part to adjustable restraints not being as high as integral restraints when in their lowest position and not being properly positioned.
While the 1982 evaluation estimated the benefits of any injury in a rear impact, for the most part, head restraints are designed to reduce whiplash injuries. This assumption that head restraints are only effective in reducing whiplash injuries has been challenged by a number of writers.
While all this was part of national study in the USA, in another part of the world, Nissan asserted that there are potential production difficulties arising from front head restraint non-removability. Installing a large seat fitted with a head restraint into a small vehicle, Nissan asserted, might be a tedious task. While, Honda wanted all restraints to be removable by hand, out of concern that non-removable head restraints would limit seat design flexibility. Honda believed that a non-removability prohibition would prevent it from offering the “fully flat seat” option in its CRV model vehicle.
What ever the manufacturers had in mind might not be of big help to the guy trapped inside the automobile, but the headrest can be the only tool at your reach to save your self, just keep in mind.