Get Seat belts -> Forces acting in a collision Guide for Audi A5 4 Door First Generation (2007-2013)

Seat belts 171

Controls Safety Driving tips General maintenance Self-help Technical data

Important safety instructions for using seat

belts

There are a number of safety points concerning the seat

belts which you should remember. This will help to reduce

the risk of injury in an accident.

WARNING

• The seat belts can only provide maximum protection if the

seats are adjusted properly ⇒ page 70, “Seats and storage”.

• To ensure proper protection, it is important to wear the seat

belts in the correct position ⇒ page 173, “How to wear seat belts

properly”. Ensure that the seat belts are worn exactly as recom-

mended in this chapter. Belts which are not worn properly can

increase the risk of injury in accidents considerably.

• Do not allow the seat belt to become twisted or jammed, or to

rub on any sharp edges.

• Never allow two passengers (even children) to share the same

seat belt. It is especially dangerous to place a seat belt over a child

sitting on your lap.

• Do not wear the belt over hard or fragile objects (such as

glasses or pens, etc.) because this can cause injuries.

• Loose, bulky clothing (such as an overcoat over a jacket)

impairs the proper fit and function of the belts.

• The belts must be kept clean, otherwise the retractors may not

work properly ⇒ page 226, “Seat belts”.

• The slot in the seat belt buckle must not be blocked with paper

or other objects, as this can prevent the latch plate from engaging

properly.

• The latch plate of the belt must always be engaged in the

correct buckle for that seat, otherwise the belt will not be fully

effective.

• Check the condition of the seat belts at regular intervals. If you

notice that the belt webbing, fittings, retractor mechanism or

buckle of any of the belts is damaged, the belt must be replaced

by a qualified workshop.

• The seat belts must not be removed or modified in any way. Do

not attempt to repair a damaged belt yourself.

• Seat belts which have been worn in an accident and stretched

must be replaced by a qualified workshop. The belt anchorages

should also be checked.

Forces acting in a collision

The physical principles involved in a frontal

impact

Very large forces are generated during a collision; these

forces have to be absorbed.

WARNING (continued)

Fig. 178 Passengers of

a vehicle which is

headed for a brick wall.

They are not using seat

belts.

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Seat belts172

The physical principles involved in a frontal collision are relatively

simple:

Both the moving vehicle and the passengers possess energy, which

is known as “kinetic energy” ⇒ page 171, fig. 178. The amount of

“kinetic energy” depends on the speed of the vehicle and the weight

of the vehicle and passengers. The higher the speed and the greater

the weight, the more energy there is to be absorbed 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 increases by a factor of four. Because these passengers are

not restrained by seat belts, the entire amount of kinetic energy has

to be absorbed at the point of impact ⇒ fig. 179. This would result

in serious or potentially fatal injury.

Even at urban speeds of 30 km/h to 50 km/h, the forces acting on the

occupants in a collision can reach the equivalent of 1 ton (1000 kg)

or more. At greater speed these forces are even higher. A rule of

thumb: if the speed doubles, the forces increase by a factor of four.

Passengers who do not wear seat belts are not “attached” to the

vehicle. In a frontal collision they will continue to move forward at

the speed their car was travelling just before the impact.

What happens to passengers not wearing

seat belts?

Passengers not wearing seat belts risk fatal injuries in the

event of an accident.

In a frontal collision, unbelted passengers will be thrown forwards

and make violent contact with the steering wheel, dashboard, wind-

screen, etc ⇒ fig. 180. Passengers not wearing their belts risk being

thrown out of the car, resulting in potentially fatal injuries.

The common belief that occupants can brace their weight with their

hands in a minor collision is false. Even at low speeds the forces

acting on the body in a collision are so great that it is not possible

to hold yourself in the seat.

Fig. 179 The vehicle

crashes against the

wall

Fig. 180 A driver not

wearing a seat belt can

be thrown forwards

Fig. 181 A rear

passenger not wearing

a seat belt can be

thrown forwards

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Seat belts -> Forces acting in a collision for Your Audi A5 4 Door First Generation (2007-2013)

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