Occupant Safety - Mercedes-Benz B-Class 2011 Owner's Manual

SRS (Supplemental Restraint System)
Introduction
SRS consists of:
the 6 SRS warning lamp
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airbags
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airbag control unit (with crash sensors)
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belt tensioners for the front seat belts and
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the outer seat belts in the rear
seat belt force limiters for the front seat
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belts and the outer seat belts in the rear
SRS reduces the risk of occupants coming
into contact with the vehicle's interior in the
event of an accident. It can also reduce the
forces to which occupants are subjected dur-
ing an accident.
SRS warning lamp
G
WARNING
If SRS is malfunctioning, individual systems
may be triggered unintentionally or might not
be triggered in the event of an accident with
a high rate of vehicle deceleration.
A malfunction has occurred if:
the 6 SRS warning lamp does not light
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up when the ignition is switched on.
the engine is running and the 6 SRS
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warning lamp does not go out after a few
seconds.
the engine is running and the 6 SRS
R
warning lamp lights up again.
In this case, have SRS checked immediately
at a qualified specialist workshop.
SRS functions are checked regularly when
you switch on the ignition and when the
engine is running. Therefore, malfunctions
can be detected in good time.
The 6 SRS warning lamp in the instrument
cluster lights up when the ignition is switched
on. It goes out no later than a few seconds
after the engine is started.

Occupant safety

Triggering of belt tensioners, belt force
limiters and airbags
During the first stage of a collision, the airbag
control unit evaluates important physical
data relating to vehicle deceleration or accel-
eration, such as:
duration
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direction
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magnitude
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Based on the evaluation of this data, the air-
bag control unit pre-emptively triggers the
belt tensioners in the first stage.
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The front belt tensioners can only be trig-
gered if the seat belt tongues on the front
seats are correctly engaged in the seat belt
buckles.
If there is an even higher rate of vehicle decel-
eration or acceleration in a longitudinal direc-
tion, the front airbags are also deployed.
Your vehicle has adaptive, two-stage front air-
bags. The airbag control unit evaluates vehi-
cle deceleration or acceleration in the event
of a collision. In the first deployment stage,
the front airbag is filled with a portion of the
available propellant gas in order to reduce the
risk of injuries. If, within a few milliseconds,
the airbag control unit detects that the vehi-
cle is accelerating or decelerating at a greater
rate than originally anticipated, the front air-
bag is then filled with the maximum amount
of propellant gas.
The belt tensioner and airbag triggering
thresholds are variable and are adapted to the
detected rate of deceleration or acceleration
of the vehicle. This process is pre-emptive in
nature. The triggering process must take
place in good time at the start of the collision.
i
Not all airbags are deployed in an acci-
dent. The different airbag systems work
independently of each other.
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