What are airbags in a car called: terminology and design

Few people think about the technical name of a device that can save lives in a critical situation. In everyday life, we are accustomed to using the simple phrase “airbag,” but for engineers and in technical documentation this is just the tip of the iceberg. The correct and complete name of the system is: SRS (Supplemental Restraint System), which translates as “additional restraint system.” This is the term you can find on the steering wheel, dashboard or in the operating instructions for your vehicle.

Understanding how these elements are called and classified is important not only for overall development, but also for proper vehicle maintenance. The system includes many components: from shock sensors to pyrotechnic cartridges. Car pillows are only a visible part of a complex mechanism that operates in a fraction of a second. Knowing the correct terminology will help you better understand accident reports or service center recommendations.

In this article we will examine in detail the range of passive safety systems, their historical development and technical features. You will learn why they are called that way and how they differ from seat belts. We will also touch on operational issues and myths that surround this technology.

Official terminology and abbreviations

The main name used throughout the world to refer to the cushion system is SRS. This abbreviation is key to identifying safety features in modern cars. You can often see the inscription on the steering wheel SRS Airbag, which literally means “additional air-cushion restraint system.” It is important to understand that the “Airbag” is only an actuator, and not the entire system.

In the technical documentation of manufacturers such as Toyota, BMW or Volkswagen, there may be various variations of names. For example, German manuals use the term “Gurtstraffer” in conjunction with pillows, emphasizing their joint work. However, the English abbreviation remains the de facto international standard. Engineers always emphasize the word “Supplemental” to indicate that the pads do not replace belts, but only complement them.

⚠️ Warning: Never attempt to repair SRS marked components yourself. Inside there are pyrotechnic charges, careless handling of which can lead to an explosion and injury.

There is also a term Passive Safety System (passive safety system), which is a broader concept. This category includes not only pillows, but also belts, headrests, and deformable areas of the body. Airbags in this classification act as an active element of a passive system, triggered only in the event of an accident. Understanding this hierarchy of terms is necessary to correctly interpret on-board computer data.

Why is the word "Supplemental" used?

The term "Supplemental" was not chosen by chance. The engineers wanted to emphasize that the airbag is not the primary means of protection. Without a seat belt fastened, the effectiveness of the airbag drops to almost zero, and the risk of injury from its deployment, on the contrary, increases. The belt holds the body in the correct position, and the pillow softens the blow.

History of origin and evolution of names

The history of how airbags are called dates back to the middle of the 20th century. The first patents for “devices for inflating protective bags in the event of an accident” appeared in the 1950s. Back then, inventors like Walter Linderer used terms like "bumper" for interior parts, but the names didn't catch on. For a long time, the device did not have a single standardized name.

Mass adoption of the technology began in the 1970s, when companies General Motors and Mercedes-Benz active testing has begun. It was during this period that the name “Air Cushion Restraint System” (ACRS) was established, which translates as “air cushion restraint system.” This term can be found in old American manuals. However, the complexity of pronunciation and the length of the abbreviation led to a gradual transition to a shorter Airbag.

By the 1990s, when pillows became a mandatory element of equipment, the term was finally established. The evolution of names also reflected the development of technology: from simple chemical reactions for inflation to complex electronic systems with pretensioners. Today we are seeing the emergence of “smart” airbags that analyze the weight of the passenger and the force of the impact.

Classification of pillows by location

A modern car can be equipped with a dozen different SRS modules, and each of them has its own specific name depending on the coverage area. Best known frontal pillow (Front Airbag), which is located in the steering wheel and front panel in front of the passenger. These are the ones most often talked about in the news about car recalls.

In addition to the front ones, there are side modules that are built into the body pillars or the outer part of the seats. They protect the chest and pelvis during a side collision. Separately highlighted head curtains (Curtain Airbags), which unfold along the window openings from the A-pillars to the rear ones. Their task is to protect the heads of passengers in all rows from glass fragments and impacts on the pillars.

In premium cars you can find more exotic names and locations:

• 🛡️ Knee pad (Knee Airbag) - located in the lower part of the dashboard, protects the driver’s shins.
• 🛡️ Seat belt cushion (Seatbelt Airbag) - an inflatable element built directly into the belt strap.
• 🛡️ Pedestrian protection cushion — located under the hood, raises the hood when hitting a person.
• 🛡️ Center cushion (Center Airbag) - opens between the driver and front passenger, preventing their heads from hitting each other.

Pillow type	Location	Protection zone	Response time
Frontal	Steering wheel, dashboard	Head, chest	20-50 ms
Lateral	Seat, stand	Chest, pelvis	10-30ms
Curtain	Roof (above windows)	Head, neck	20-40 ms
Knee	Bottom of instrument panel	Shins, knees	30-60 ms

Technical device and principle of operation

To understand how they work car airbags, you need to consider their design. The module is based on a durable shell made of nylon fabric impregnated with a special compound. When folded, it is compactly packed in a plastic casing. Inside is a gas generator - a device containing a solid fuel (usually sodium azide) and an oxidizer.

The activation process is started by the electronic control unit (ECU). Impact sensors located in the front of the body and in the cabin detect sudden deceleration. If the acceleration exceeds a preset threshold (usually the equivalent of hitting a wall at 20-25 km/h), the ECU sends an electrical signal to the squib. A chemical reaction occurs, releasing a large volume of harmless gas (nitrogen), which instantly fills the pillow.

It is important to note that after expansion the pillow does not remain inflated. The fabric has special holes for releasing gas. This is made to make the pillow depreciated impact, absorbing the energy of the body's movement, rather than throwing the person back like a solid object. The entire cycle from impact to complete deflation takes less than one second.

Markings and designations on parts

When purchasing parts or studying a vehicle's schematic, it is important to be able to read the labels. The body of the airbag module is always marked with information about the manufacturer, date of manufacture and, most importantly, the safety class. Often there is a coding indicating the type of gas or pyrotechnic composition. For example, marking NaN3 indicates the use of sodium azide.

Also on the elements of the SRS system you can find color coding of the connectors. Airbag wiring connectors are almost always bright yellow. This is an international standard designed to warn the auto mechanic not to disconnect this connector while under voltage or without proper precautions. strictly prohibited. The color yellow serves as a visual anchor of attention.

In diagnostic scanners, system errors may be indicated by codes beginning with the letter "B" (Body) followed by a four-digit number. For example, a code related to driver airbag circuit resistance will be different from a passenger curtain error code. Deciphering these codes requires access to the technical documentation of a specific automaker.

⚠️ Attention: When disposing of a vehicle or removed airbags, special discharge procedures must be followed. Simply disposing of the SRS module in regular trash is prohibited by law and safety regulations.

Myths and reality about car pillows

There are many misconceptions surrounding the topic of security. One of the most common myths is that a pillow can suffocate a person or break a person's neck. The reality is: modern systems SRS calibrated to anthropometric data. The risk of injury from deployment only exists if the passenger is too close to the module (less than 25 cm) or is not wearing a seat belt.

Another myth claims that the airbags are triggered by any impact, even a weak one. In fact, the electronics ignore shocks when parking at low speeds or impacts on the wheels, since the acceleration vector does not coincide with the critical one. The system “understands” the difference between hitting a curb and a head-on collision.

There is also a misconception regarding expiration dates. Many people believe that pillows need to be changed every 10 years. Although gas generator manufacturers indicate service life, in practice pillow resource often coincides with the service life of the car, if there were no violations of the interior seal and power surges. However, after 15-20 years of operation, a diagnostic check of the system is mandatory.

Frequently asked questions (FAQ)

Is it possible to drive if the SRS light on the dashboard is on?

You can drive, the car will not lose speed, but the passive safety system at this moment faulty. In the event of an accident, the airbags may not deploy or, conversely, fire spontaneously. It is necessary to conduct computer diagnostics.

Will the airbags deploy if I am not wearing a seat belt?

In most modern cars, the seat belt sensor is linked to the SRS algorithm. If the seat belt is not fastened, the airbag may not deploy at all or may deploy with a delay and less force to avoid causing additional injury.

What to do if the airbag deploys?

It is necessary to stop the car, turn off the engine and evacuate. Once triggered, the module can only be replaced; it cannot be restored. Impact sensors and often dashboard elements are also changed.

Is the gas released when the airbag inflates harmful?

The main component is nitrogen, which is inert and safe. However, a small amount of caustic alkaline dust may be generated during the reaction. People with asthma are advised to leave the vehicle immediately after an accident.