Active Head Restraints - Mercedes-Benz 2008 S550 Operator's Manual

Emergency tensioning device (ETD),
seat belt force limiter
The seat belts for the front and rear outer
seats are equipped with emergency ten-
sioning devices and seat belt force limit-
ers.
The ETD is designed to activate in the
following cases:
in frontal or rear-end impacts exceed-
ing the system deployment threshold
in certain vehicle rollovers
if the restraint systems are operational
and functioning correctly,
see = indicator lamp ( page 607)
i
The ETDs for the front seats will only acti-
vate if the front seat belt is fastened (latch plate
properly inserted into buckle).
The ETDs for the rear outer seats will activate
with or without the respective seat belt fastened.
In an impact, emergency tensioning
devices remove slack from the seat belts in
such a way that the seat belts fit more
snugly against the body. Seat belt force
limiters, when activated, are employed to
help reduce the peak force exerted by the
seat belts on occupants during a crash.
Warning!
A pyrotechnic emergency tensioning device
(ETD) that was activated must be replaced.
When disposing of the pyrotechnic emer-
gency tensioning device, our safety instruc-
tions must be followed. These are available
at any authorized Mercedes-Benz Center.
®
PRE-SAFE has electrically operated
reversible pre-tensioners that do not require
replacement after activation.
Automatic comfort-fit feature seat belt
An automatic comfort-fit feature for the
front seats and for the rear outer seats*
(only for vehicles with rear power seat*)
reduces the retracting force of the seat
belts when they are in normal use.
Safety and Security

Active head restraints

The active head restraints are intended to
offer the driver and front passenger in-
creased protection from whiplash type in-
G
juries. In the event of a rear-end collision,
the active head restraints on the driver's
and front passenger's seats are designed
to move forward in the direction of travel,
providing the head with increased support
earlier on in the collision sequence. The ac-
tive head restraints move forward whether
the seat is occupied or not.
Warning!
Do not attach any objects (e.g. hangers) to
the head restraint posts. Otherwise, the ac-
tive head restraints may not function prop-
erly or offer the degree of protection they
were designed for in the event of an acci-
dent.
Occupant safety
G
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