Modern cars have a huge number of security systems. So, electronics allows you to not lose control of the machine in case of emergency (skidding, emergency braking, and so on). But not all situations can be avoided. Therefore, in the event of a collision, elements of passive safety are implemented in the car. One of these is the belt. What is it and what types happens? Consider in our article today.
Characteristic
Belts are the most common element of passive safety. Their main task is to prevent human movement in the event of an accident. The use of a seat belt reduces the risk of injury in a collision, and significantly eliminates the possibility of impacts on rigid parts of the body and glass.
Few people know, but belts appeared on cars at the beginning of the 20th century. This system "migrated" to the car from aviation. However, then it was available only as an option. The most common seat belt was after the 50s. And in the USSR, such systems began to appear only with the advent of the "Lada". Installation of seat belts is carried out by the plant itself, at the stage of assembly of the car. Also, the owners are engaged in the installation of so-called sports belts. But more on that later.
About design
The main element of the seat belt is the tape. It is made of dense polyester fibers. Such material is able to withstand significant loads and does not tear. The tape forms a kind of strap that holds the driver and passengers in a predetermined position and prevents the risk of displacement in the event of an accident. There are many examples of how unfastened people hit the glass and simply flew out of the passenger compartment. Using a belt allows you to securely fix the body and prevent accidents.
Also included in the design:
- Castle.
- Limiters.
- Belt attachment points. They may be regulated or unregulated.
- Inertial coils.
- Seat belt pretensioner.
These elements differ only in the number of attachment points. However, injury safety depends on this factor. Below we will consider what types of seat belts are.
Point-to-point
These are the very first systems that appeared in cars. However, they can be found today. As a rule, such belts are used for the average passenger in the back row. The disadvantage of this system is that the length of the tape is not adjustable. Because of this, you have to use a seat belt extension. It is sold separately and costs about $ 25.
This type of belt runs in the waist zone of the passenger, transversely to the seat. From a security point of view, such a system is ineffective. After all, she holds the body only in the lumbar region. With a frontal impact, part of the body will not be fixed and will move forward. The stronger the collision, the higher the risk of spinal damage.
Three point
This is a more modern look, which is used in both driver and passenger seats. The system provides three fixation points, among which one (the one closer to the top of the rack) has the ability to adjust in height.
The lower part is equipped with a reel for winding the tape. Such a scheme provides reliable fixation of the body. Fixation is performed along the chest and in the lumbar region. At the same time, the belt does not limit movements and is very convenient to use. It is enough to lay it and fix it at one point on the latch.
Four-point safety belt
These are already sports options that we talked about earlier. The design is used on cars that participate in rallies and circuit races. In terms of security are the best option. But why was the four-point seat belt so small? All due to usage patterns. To fix all the mechanisms, you have to spend a lot of time. In everyday operation, this is not necessary, and the three-point ones completely cope with their task.
Note that the fixation options may be different. But the most popular is two straps with one-piece fastening and one in the lumbar zone. The advantage of this scheme is that the vertical ribbons are attached directly to the seat, and not to the body.
To use such a belt, you must first throw up the vertical elements on the shoulders (similar to putting on a backpack), and then stretch the lumbar and fix it on the latch.
There are also schemes where vertical tapes can be detached. To do this, at the ends there is an additional lock and tongues.
Seat belt mount
It can be different. If you take into account most cars, fasteners are performed on the elements of the body. This scheme is used to ensure that upon impact (when the maximum load is imposed on the mechanisms) the tape does not fly off the attachment points. If the fasteners were in the standard seat, it could simply be pulled out. But why is such a scheme practiced on sports seats? The fact is that the seat itself has much greater rigidity and all attachment points are calculated in advance for deformation and tension.
Also note that trucks use a special tape installation pattern. Here the belt is pulled out of the back of the seat.
This is done so that the tape does not go up and down on bumps, as the chair has a separate air suspension. Often this design is used on large buses and long-haul tractors. However, do not assume that it is unreliable. At the factory, engineers carefully calculate these attachment points, so we can say with confidence that such belts are very reliable and safe.
How it works?
We will take three-point systems as a basis, since they are the most common. So, after getting into the car, the driver pulls out the tape and fixes the tongue in the lock. Further, the inertial coil automatically removes the excess. In a collision, the sensors will activate the pretensioner. As a result, the strap will be pulled. If the blow intensifies, a torsion bar will enter the work. It gradually increases the length of the belt in order to reduce the pressure exerted on the body. Also note that upon impact, the belt material itself is pulled. Despite its density, polyester can be extended by hundredths of a centimeter. This will soften the inertia.
On old belts (without pretensioners), the coil holds the function of holding a person. With a sharp acceleration of the body, it is blocked. And then the torsion bar is already in action.
Conclusion
So, we found out what a seat belt is and what types it happens. Finally, we note that after a substantial blow, the belts are not subject to reuse. After all, the material is stretched and is no longer able to withstand such a load.