Security Systems: Active Head Restraint

| October 15, 2012

The headrest is a security system that is born in the 50’s as a luxury device. Later, with the accident investigation found that an important element of passive safety, and then over the years it compulsory. The headrests are of different types: fixed or adjustable and integrated or assets. Today we focus on the second type, to try to understand something of its operation and the importance of restraint in a vehicle today.

What is the active head restraint?

The headrest is a passive safety system invented in the 50s as a high-end device with a high price. Over the years, the accident investigation found that this was an important safety feature. In 1969, it established the mandatory restraints on all models registered in North America.

In the car market, we find two different types of headrests. First, there are fixed or integrated into the seat frame, pioneers in the market respond effectively to fit properly into position. Then the second type something more modern and current, we find the adjustable or assets as a result of the collision.

active head restraint

For the latter we will focus, as are active head restraints which we will discuss today, both its operation and the importance of proper use. As we saw with other security systems such as active suspension or the airbag.

How do they work?

The active headrest, or ‘Active Head Restraint’, is a passive safety feature that stops the sudden movement of the head backwards when a rear-end collision, avoiding neck injuries.

Thus, preventing the so-called bullwhip effect is produced by the direct hit on the head coming to transfer its power to the cervical area. For this reason, with the movements of the neck after being hit in the back of the vehicle, with a subsequent hyperextension and hyperflexion of the cervical spine, appears whiplash or cervical sprain.

Moreover, the active headrest is mounted on a pressure plate in the seat via a fastening device, which comprises a spring device. If the seat occupant moves or pushes forward with more force than the spring can resist, the plate is moved back within the seat.

All this prompts on the headrest a movement that forces you to climb upwards and forwards, holding his head before the movement between the head and the neck area resulted in significant damage.

The importance of the active headrest

The passive safety system of the headrest is formed in two parts, the headrest bracket and the impact plate, together with the padded portion, which can move forward and upward to reduce the space between it and the head. Depending on the model and age of the car, the active headrest will approach the maximum possible to prevent whiplash.

For this and for the active headrest work properly must stop the movement of the head without causing damage to the vehicle occupants in case of impact or collision, so should this ideal height to cut as soon as the arc of motion head back.

According to some car manufacturers, the correct height of the headrest is obtained when the top of the head is flush with the headrest. In addition we advise that the separation or distance between the headrest and the head of the driver and the occupants should not be less than four or greater than seven centimeters inches.

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Category: Auto Safety

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