How airbags work in a car: device and principle of operation
How airbags work in a car: device and principle of operation

Car manufacturers are trying their best to protect their customers by equipping vehicles with various security systems. Now even budget equipment includes ABS and a number of other measures. But in the past, for a long period of time, the only solution was a seat belt. Moreover, this has become a prerequisite when getting into a car, in some modern models you can’t even start the engine if you don’t buckle up.

Later added airbags. This is a softer solution that allows you to save a person's life. In modern cars, their number varies from 2 to 7, or even 8 pieces. But how does an airbag work? Any inquisitive car enthusiast simply cannot but be interested in such a security system!

Pure mechanics

Before we begin to analyze the operation of airbags, it is worth brushing up on the laws of mechanics. As you know, any moving object has momentum (mass multiplied by speed) and under the influence of any force it moves. But as soon as the force stops exerting an influence on it, the object will not stop right there, but will continue to move, reducing its speed. This is called inertia. In the case of a car, the driving force is the engine.

How airbags work in a car
How airbags work in a car

All loose objects in the car, including the driver and passengers, will also continue to move at the speed of the vehicle when braking. To stop them, it is required to apply force for a certain period of time. Its value is very high in the event of an accident, since the car stops abruptly, while the bodies retain inertia, which does not end instantly.

Functionality of soft protection system

Like seat belts, airbags act as cushions to help alleviate the effects of an accident. Their goal is to stop the movement of the driver or passengers, and for the shortest possible period of time, and as evenly as possible. Knowing how airbags work in a car will allow you to once again think about your own safety.


Such an important element of the security system has a not so complicated structure. It can all be conditionally divided into three main components, which together ensure the safety of a person in case ofaccidents. The main components are:

  • bag;
  • shock sensors;
  • gas generator (inflating system).

The whole complex is compactly equipped and located in such a way that it cannot be seen from the salon. Each of these components is very important for the smooth operation of the entire system.

How does an airbag work in a car?
How does an airbag work in a car?

But it is the sensor that is particularly sensitive, because it depends on its decision when the airbag is released. We can assume that the fate of everyone in the car depends on it.


This is an important accessory, in fact, due to which it is called a pillow. It is a thin 0.4mm thick nylon sheath made up of multiple layers. It can withstand short term loads. Moreover, thanks to the heavy-duty material, the pillow is able to perceive a rather large short-term force. Usually it is located in a special tire, which is covered with a plastic lining or cloth.

"Catcher" strike

Many owners are interested in knowing how airbag sensors work, but not everyone understands their purpose. Meanwhile, the importance of these electronic devices should not be underestimated! As a rule, they are located in the front of any car. Their purpose is to make the system work quickly. Indeed, in the event of a collision of a car with another vehicle or a solid obstacle, every second counts.

In this case, the sensors can be twovarieties:

  1. Drums - register the load on the body.
  2. Passenger seat sensors - their presence prevents operation in cases where there is no one in the car except the driver.

Sensors are designed to operate at speeds over 20 km/h. However, the system is still designed in such a way that it will work even when the vehicle is simply standing still in the event of a strong impact.

Airbags in action
Airbags in action

But in addition to sensors, cars can be equipped with accelerometers that allow you to determine the position of the car.

Inflation system

In another way, it is called as a gas generator. Its essence lies in filling the shell of the protective device with gas. It includes a squib, which, in fact, starts the mechanism. Here the question of how the airbag impact sensor works is already interesting?

In fact, here the contacts of the device close under certain circumstances, which leads to the actuation of the executive bodies. They in turn fill their pillows with gas.

Initially, the system included only this element, but in modern "airbags" there are already 2 of them. The first is considered the main one and ensures the release of 80% of the gas. The second one is a squib, it is connected in case of a strong collision, when a person needs a more rigid pillow.

All of these components must be in good condition in order to ensure trouble-free operation of the system.

How airbags work

On what is it basedairbags work? When a car collides with any obstacle, sensors are automatically triggered, which lead to the rapid opening of the nylon shell. It's happening so fast that no human is able to capture the moment.

We already have an idea of how the airbag works in a car, but what is most interesting is that when it opens, it seeks to fill the entire space between the driver (passenger) and the car’s elements in order to avoid a strong impact on them. In other words, during an accident, the protective system provides a kind of isolation of a person from hard contact with the steering wheel, racks, panel, and so on. That is, the impact falls on a soft pillow, which does not promise the damage that could be in the event of a collision with a harder surface.

Pillow after the "shot"
Pillow after the "shot"

In any case, you can avoid injuries completely or avoid serious consequences for the body. In addition, pillows help to eliminate internal injuries when organs collide with bones in the event of a sharp deceleration. Incidentally, this is one of the causes of death in road accidents. A vivid example of this is the impact of the brain on the bone tissue of the skull.

Important note

It is worth paying attention to one important point - the airbags work only once and on the first impact. But an accident can be accompanied by several consecutive collisions. And finally, we should not forget that all mechanisms are, in essence, disposable!

About how the pillow workssecurity, you can also say the following. During everyday trips, the operation of the protective system is completely excluded, since its performance is fully dependent on sensors. And they are set up not anyhow, but with a competent approach that takes into account many factors. In other words, the pillows open only under certain circumstances - an accident. And if, passing by any obstacle, touch it with a mirror (even if it knocks it down), then the pillows will still not open - there is no significant reason.

Types of pillows

Fortunately, in our time it is almost impossible to meet cars that would be produced without airbags with the rarest exception. Depending on the configuration, their number varies, but at least 2 of them are definitely present. Usually there are from 2 to 7, in premium cars there can be 8, 9, or even 10.

Passive frontal safety

This is the most common type and these pillows are included in the basic equipment of most modern cars - for the driver and front passenger. This measure avoids serious consequences in the event of a frontal collision.

Front airbags
Front airbags

How does a front airbag work? In fact, the principle of operation is the same, the only difference lies in the localization of the impact of the body. In this case, the system is activated in a frontal collision, including an oblique impact to the front of the body.

In addition, thanks to such pillows, a person’s slowdown is not so fast,therefore, the body experiences less stress. In turn, this reduces the risk of injury to internal organs.

The driver's airbag is located in the central part of the steering wheel, while the passenger airbag is in the upper area of the front panel. Moreover, each of them differs in its size, because the distance between the driver and the steering wheel is much less than the distance of the passenger's head and the panel. The localization of pillows is indicated by the icon or the inscription airbag.

Side airbags. Features

How do side airbags work on a Mercedes or any other car model? They can be located both in front and behind the cabin. The reason for their activation is a side impact to the body. These airbags are usually equipped with more expensive vehicle equipment. In this case, the following body parts fall into the protection zone in a side collision:

  • shoulders;
  • chest;
  • belly;
  • pelvis.

The front airbags are located inside the seats, while the rear airbags are integrated into the side trim of the passenger compartment. Unlike the frontal pillows, the side ones are not so widespread, again, due to the high cost of such a configuration. Nevertheless, there are inexpensive car models that also have this type of passive safety - Lada Vesta, Renault Logan, Datsun On-do.

Side airbags
Side airbags

Such vehicles require compliance with certain rules for the carriage of goods, since you should consider how the airbags work. Therefore, it is unacceptable to place strongly protruding objects in the door pockets. In case of an accident, they will not only interfere with the operation of the protective system, but also threaten the person himself.

Protective curtains

In fact, these elements can also be considered head airbags, since they are designed to protect this most important part of the body from side impacts, including scattering of glass fragments. Vehicles are generally equipped with two types of curtains:

  • only for the first row;
  • for both rows (front and back).

Their localization falls on the side of the interior ceiling, respectively, above the windows themselves. When hitting the side of the car, the curtains open in such a way as to completely cover the side windows. That is, it provides protection from splinters, impacts against racks and other solid objects.

Knee Airbags

These elements are designed to protect the driver's knees in the event of a frontal collision. They are relevant for cars of the middle price category, and this is the C-class. Among them are Volkswagen Golf and Suzuki SX4. And such systems are certainly present in the more expensive Toyota LC200 and the like.

Knee airbags
Knee airbags

How the side airbags work, we now understand, but where are the knee elements? They are usually hidden under the steering wheel and dashboard. Cars equipped with this airbag also have certain requirements regarding proper safety. That is, the driver needs to adjust his seat - it must be onat least 10 cm from the bottom of the panel.

Pillow and strap combination

Some of the motorists believe that since there are already airbags, then belts are already an extra measure, and you can do without it. However, this is the opinion of a man who has a meager margin in terms of automotive safety. At the same time, smart people go to various tricks in order to deceive the sensor in the case of an unfastened seat belt (if any). It is enough to pass the belt behind your back and calmly snap the lock.

But it is highly undesirable to do this. Airbags were designed to work with seat belts! One has only to imagine that in the event of an accident, the life-saving pillow breaks out of its shelter at a speed of up to 200-300 km/h! And it just can not save from serious injuries. It's worth remembering - belts without pillows will provide safety, which can not be said about the pillows themselves without belts!

Incompetent drivers

Does the airbag work when the seat belt is not fastened? Everyone who is just too lazy to buckle up every time is interested in a similar question, because he is driving at low speed. Unfortunately, there are such people. But returning to the question, one thing can be said - on expensive models they will not work if the belt is not fastened. For other cars, this does not matter, and the airbag may go off.

But if you figure it out, then based on the fact that the airbag develops a rapid speed, then if the driver is not fastened, he cannot avoid serious injuries, as already mentioned. For this reason, goodairbags and will not deploy if the belt is not "connected".

passenger airbag
passenger airbag

But at the same time it is important to consider the state of the entire system, and if there are any problems, then the airbags may not work even with the belt fastened. The main thing is to keep an eye on your car and not ignore the errors that appear on the dashboard.