19
Seat belts
Why wear seat belts? Physical principles of frontal collisions
In the event of a frontal collision, a large amount of kinetic
energy must be absorbed.
Fig. 6 Vehicle about to
hit a wall: the occupants
are not wearing seat
belts
Fig. 7 The vehicle hits
the wall: the occupants
are not wearing seat
belts
It is easy to explain how the laws of physics work in the case of a head-on
collision: When a vehicle starts moving ⇒ fig. 6, a certain amount of energy
known as kinetic energy is produced in the vehicle and its occupants.
The amount of kinetic energy depends on the speed of the vehicle and the
weight of the vehicle and its passengers. The higher the speed and the
greater the weight, the more energy there is to be released in an accident.
The most significant factor, however, is the speed of the vehicle. If the
speed doubles from 25 km/h to 50 km/h, for example, the kinetic energy is
multiplied by four.
Because the passengers in our example are not restrained by seat belts, in
the case of a head-on collision all of their kinetic energy has to be absorbed
at the point of impact ⇒ fig. 7.
Even at speeds of 30 km/h to 50 km/h, the forces acting on bodies in a col-
lision can easily exceed one tonne (1000 kg). At greater speed these forces
are even higher.
Passengers not wearing seat belts are not “attached” to the vehicle. In a
head-on collision, they will move forward at the same speed their vehicle
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Seat belts
Seat belt protection
Passengers not wearing seat belts risk severe injuries in the
event of an accident.
Fig. 10 A driver wearing
the seat belt properly is
secured by the belt in
sharp braking
Properly worn seat belts hold the vehicle occupants in the correct sitting po-
sitions and substantially reduce the kinetic energy in the event of an acci-
dent. Seat belts also help to prevent uncontrolled movements that could
lead to severe injuries. In addition, properly worn seat belts reduce the dan-
ger of being thrown from the vehicle.
Passengers wearing their seat belts correctly benefit greatly from the ability
of the belts to absorb kinetic energy. The front part of your vehicle and other
passive safety features (such as the airbag system) are also designed to ab-
sorb the kinetic energy released in a collision. Taken together, all these fea-
tures reduce the releasing kinetic energy and consequently, the risk of in-
jury.
Our examples describe frontal collisions. Of course, properly worn seat belts
substantially reduce the risk of injury in all other types of accidents. This is
why it is so important to fasten seat belts before every trip, even when "just
driving around the corner". Ensure that your passengers wear their seat belts as well. Accident statistics
have shown that wearing seat belts is an effective means of substantially
reducing the risk of injury and improving the chances of survival in a seri-
ous accident. Furthermore, properly worn seat belts improve the protection
provided by airbags in the event of an accident. For this reason, wearing a
seat belt is required by law in most countries.
Although your vehicle is equipped with airbags, the seat belts must be fas-
tened and worn. The front airbags, for example, are only triggered in some
frontal accidents. The front airbags will not be triggered during minor frontal
collisions, minor side collisions, rear collisions, overturns or accidents in
which the airbag trigger threshold value in the control unit is not exceeded.
Therefore, you should always wear your seat belt and ensure that your pas-
sengers have fastened their seat belts properly before you drive off!
Safety instructions on using seat belts
If seat belts are used correctly, they can reduce the risk of in-
jury in an accident.
– Always wear the seat belt as described in this section.
– Ensure that the seat belts can be fastened at all times and are
not damaged.
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Seat belts
Seat belts
Seat belt adjustment
The seat belts for the front and rear occupants are locked in-
to position by a latch.
Fig. 11 Belt buckle and
latch plate of seat belt
The seat belt cannot offer its full protection if the seat belt is not
positioned correctly.
– Adjust the seat and head restraint correctly.
– To fasten the belt, take hold of the latch plate and pull it slowly
across your chest and lap.
– Insert the latch into the buckle for the appropriate seat and
push it down until it is securely locked with a click ⇒ fig. 11.
– Pull the belt to ensure that the latch plate is securely engaged
in the buckle. The seat belts are equipped with an automatic retractor on the shoulder
strap. Full freedom of movement is permitted when the shoulder belt is
pulled slowly. However, during sudden braking, during travel in steep areas
or bends and during acceleration, the automatic retractor on the shoulder
belt is locked.
The automatic belt retractors on the front seats are fitted with seat belt ten-
sioners
⇒ page 27.
WARNING
● An incorrectly worn seat belt can cause severe injuries in the event of
an accident.
● The seat belts offer best protection only when the backrests are in an
upright position and the seat belts have been fastened properly.
● Never put the latch plate in the buckle of another seat. If you do this,
the seat belt will not protect you properly and the risk of injury is in-
creased.
● If an occupant is incorrectly belted in, the belt cannot protect him or
her properly. An incorrectly positioned seat belt can cause extremely se-
vere injuries.
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Seat belts
Pregnant women must also fasten their seat belts properly
The best protection for the unborn child is for the mother to
wear the seat belt properly at all times during the pregnan-
cy.
Fig. 14 Positioning seat
belts during pregnancy
The seat belt provides maximum protection only when the seat belt
is properly positioned ⇒ page 24.
– Adjust the front seat and head restraint correctly ⇒ page 10.
– Holding the latch plate, pull the belt evenly across your chest
and as low as possible over the pelvis ⇒ fig. 14.
– Insert the latch plate into the buckle for the appropriate seat
and push it down until it is securely locked with a click ⇒
.
– Pull the belt to ensure that the latch plate is securely engaged
in the buckle.
WARNING
● An incorrectly worn seat belt can cause severe injuries in the event of
an accident.
● For pregnant women, the lap part of the seat belt must lie as low as
possible over the pelvis, never across the stomach, and always lie flat so
that no pressure is exerted on the abdomen.
● Read and observe the warnings ⇒ page 21.
Seat belt release
The seat belt must not be unfastened until the vehicle has
come to a standstill.
Fig. 15 Removing latch
plate from buckle
– Press the red button on the belt buckle ⇒ fig. 15. The latch plate
is released and springs out ⇒
.
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Seat belts
WARNING
● An incorrectly worn seat belt increases the risk of severe injuries.
● Before every trip, instruct your passengers to adjust their seat belts
properly and to wear them for the whole journey.
● Read and always observe information and warnings concerning the
use of seat belts ⇒ page 21.
Seat belt tensioners
Function of the seat belt tensioner
During a frontal collision, the seat belts on the front seats
are retracted automatically. The seat belts for the front occupants are equipped with belt tensioners.
Sensors will trigger the belt tensioners during severe head-on, lateral and
rear collisions only if the seat belt is being worn. This retracts and tightens
the seat belts, reducing the forward motion of the occupants.
The seat belt tensioner can be triggered only once.
The seat belt tensioners will not be triggered in the event of a light frontal,
side or rear collision, if the vehicle overturns or in situations where no large
forces act on the front, side or rear of the vehicle.
Note
● If the seat belt tensioners are triggered, a fine dust is produced. This is
normal and it is not an indication of fire in the vehicle.
● The relevant safety requirements must be observed when the vehicle or
components of the system are scrapped. Specialised workshops are famili-
ar with these regulations, which are also available to you. Service and disposal of belt tensioners
The belt tensioners are components of the seat belts that are installed in
the seats of your vehicle. If you work on the belt tensioners or remove and
install parts of the system when performing other repair work, the seat belt
may be damaged. The consequence may be that, in the event of an acci-
dent, the belt tensioners function incorrectly or not at all.
So that the effectiveness of the seat belt tensioner is not reduced and that
removed parts do not cause any injuries or environmental pollution, regula-
tions, which are known to the specialised workshops, must be observed.
WARNING
● Improper use or repairs not carried out by qualified mechanics in-
crease the risk of severe or fatal injuries. The belt tensioners may fail to
trigger or may trigger in the wrong circumstances.
● Never attempt to repair, adjust, remove or install parts of the belt ten-
sioners or seat belts.
● The seat belt tensioner, seat belt and automatic retractor cannot be
repaired.
● Any work on the belt tensioners and seat belts, including the removal
and refitting of system parts in conjunction with other repair work, must
be performed by a specialised workshop only.
● The belt tensioners will only provide protection for one accident and
must be changed if they have been activated.
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Airbag system
WARNING (Continued)
● To reduce the risk of injury from an inflating airbag, always wear the
seat belt properly ⇒ page 18.
● Always adjust the front seats properly.
The danger of fitting a child seat on the front passenger
seat
Rear-facing child seats must never be used on the front pas-
senger seat when the front passenger airbag is enabled. The front passenger airbag is a serious risk for a child if it is activated. The
front passenger seat is life threatening to a child if he/she is transported in
a rear-facing child seat. Children up to 12 years old should always travel on
the rear seat.
If a rear-facing child seat is secured to the front passenger seat, an inflating
airbag can strike it with such force that it can cause critical or fatal injuries.
Therefore we strongly recommend you to transport children on the rear
seats. That is the safest place for children in the vehicle. Alternatively, the
front passenger airbag can be disabled with a key-operated switch
⇒ page 44. When transporting children, use a child seat appropriate to
the age and size of each child ⇒ page 46.
For those vehicles that do not include a key lock switch to disconnect the
airbag, the vehicle must be taken to a Technical Service.
WARNING
● If a child seat is secured to the front passenger seat, the risk to the
child of sustaining critical or fatal injuries in the event of an accident in-
creases.
● Never secure a rear-facing child seat to the front passenger seat if the
front passenger airbag is enabled. The child can suffer critical or fatal in-
juries if the front passenger airbag is triggered.
● An inflating front passenger airbag can strike the rear-facing child
seat and hurl it with great force against the door, the roof or the back-
rest.
● If, under special circumstances, it is necessary to transport a child in
a rear-facing child seat on the front passenger seat, it is absolutely es-
sential that you observe the following safety measures:
–Deactivate the front passenger airbag ⇒ page 44, Deactivating
airbags.
– The child seat must be approved by the child seat manufacturer for
use on a front passenger seat with front or side airbag.
– Follow the installation instructions given by the child seat manu-
facturer and observe the safety instructions ⇒ page 46, Child safe-
ty.
– Before properly installing the child seat, push the front passenger
seat completely backwards so that the greatest possible distance to
the front passenger airbag is ensured.
– Ensure that no objects prevent the front passenger seat from being
pushed completely back.
– The backrest of the front passenger seat must be in an upright po-
sition.
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Airbag system
WARNING (Continued)
● Any work on the airbag system or removal and installation of the air-
bag components for other repairs (such as repairs to the steering wheel)
should be performed only by a specialised workshop. Specialised work-
shops have the necessary tools, repair information and qualified person-
nel.
● We strongly recommend you to go to a specialised workshop for all
work on the airbag system.
● Never attempt to alter the front bumper or the body.
● The airbags provide protection for just one accident; replace them
once they have deployed.
For the sake of the environment
The airbags, which are a special type of waste, must be disposed of through
an authorised service, because they contain pyrotechnic elements.
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Airbag system
The front airbag system will not be triggered if:
● the ignition is switched off
● there is a minor frontal collision,
● there is a side collision,
● there is a rear-end collision
● the vehicle turns over
WARNING
● The seat belts and airbags can only provide maximum protection if
the occupants are seated correctly ⇒ page 10, Proper sitting position for
occupants.
● If a fault has occurred in the airbag system, have the system checked
immediately by a specialised workshop. Otherwise, during a frontal colli-
sion the system may fail to trigger, or not trigger correctly.
Operation of front airbags
Inflated airbags reduce the risk of head or chest injury.
Fig. 19 Inflated front air-
bags
The airbag system is designed so that the airbags for the driver and front
passenger are triggered in a severe frontal collision.
In certain types of accident the front, curtain and side airbags may be trig-
gered together.
When the system is triggered, the airbags fill with a propellant gas and de-
ploy in front of the driver and front passenger ⇒ fig. 19. The fully deployed
airbags cushion the forward movement of the front occupants and help to
reduce the risk of injury to the head and the upper part of the body.
The special design of the airbag allows the controlled escape of the propel-
lant gas when an occupant puts pressure on the bag. Thus, the head and
chest are surrounded and protected by the airbag. After the collision, the
airbag deflates sufficiently to allow visibility.
The airbags deploy extremely rapidly, within thousandths of a second, to
provide additional protection in the event of an accident. A fine dust may
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