Long time it was considered that the head restraints are only passive elements to support the head while traveling by car, ie elements of comfort. Actually they are intended primarily for head retention in case of impact, being the elements of protection and passive safety.Active Head Restraint system is a passive safety system in a car. Some manufacturers also term it as the ‘Active Headrest’.
Head restraints are some of the most ignored constituent elements of a car. And yet, they can make the difference between a healthy life and one full of atrocious pain to the spine around the neck area (the cervical region). The reason: if another car hits you from behind at speeds above 10 km / h, the position of the head restraints and their geometry have a determinant role in the manner in which head and neck moves following the impact. Usually, the symptoms of those affected range from simple pain caused by stretching muscles and ligaments to nerve damage, vertebrae or, in rare cases extremely harsh, even to tears of the ligaments of the neck or cervical bone fractures.
[Active head restraints accidents occur in the upper vertebrae of the spine. They are part of the passive safety systems, along with seatbelts and airbags.]
The Swedes were the first which mounted Active Head restrain on Saab cars in 1997. Active Headrest acts selectively, differently, depending on body weight, height, sex and speed of the car who are suffering the impact. Volvo immediately bought the patent from Saab in 1999 and the excellent results of the two Swedish constructors have made other car manufacturers to rethink fundamentally the role that headrests play in the economy of a possible accident. Thus, active head restraints have become a necessity and not a luxury – as was the case until a few years ago. And the role of head restraints has become as important as is the airbag or seatbelt.
Seat headrest moves forward, towards the front in case of a rear impact collision to alleviate the shock, and after the impact, under the action of spring returns to its original position. The accident statistics show that the active headrest provides better protection of women in 55% of cases of impact and only 31% for men.
It has been found that by using active head restraints, if collisions occur at speeds below 24 km / h, the number of injuries decreases by 50%. The effectiveness of the head restraints can be maximal adjusted correctly only if they are adjusted correctly and act in close contact with seatbelts.
Different types of head restraints
- refers to a device created to reduce the rearward displacement of an adult occupant’s head relating to the body in order to decrease the chance of injury to the cervical vertebrae in case of a back impact. The most efficient head restraint need to enable a backset movement of lower than 60 millimeters in order to avoid the hyperextension of the neck during impact.
- or fixed head restraint – represents a head restraint shaped by the upper portion of the seat back, or a head restraint which is not height adjustable and also can not be unattached from the seat or the automobile structure besides by using tools or following the partial or complete removal of the seat furnishing.
- refers to a head restraint which is capable of being positioned to suit the morphology of the seated occupant. The device could allow horizontally shift, also known as tilt adjustment, and/or vertical displacement, generally known as height adjustment.
- refers to a device designed to automatically enhance head restraint position and/or geometry during a direct impact.
- refers to a head restraint that automatically modifies the position of the head restraint once the seat position is adjusted.