Mercedes-Benz 2001 CLK 55 AMG - Manual (Page 69)

66 Restraint systems
Technical
data
Instruments
and controls
Operation Driving
Instrument
cluster display
Practical hints Car care Index
Supplemental restraint system (SRS)
Airbags are intended as a supplement to seat belts.
Airbags alone cannot protect as well as airbags plus
seat belts in impacts for which the airbags were
designed to operate, and do not afford any protection
whatsoever in crashes for which the airbags are not
designed to deploy.
The SRS uses two crash severity levels (thresholds) to
activate either the emergency tensioning retractor (ETR)
or front airbag or both. Activation depends on the
direction and severity of the impact exceeding the
preset thresholds and whether the seat belt is fastened.
Seat belt fastened
• first threshold exceeded: ETR activates
• second threshold exceeded: airbag also activates
Seat belt not fastened
• first threshold exceeded:
airbag activates, but not ETR
Driver and front passenger systems operate
independently of each other.
Emergency tensioning retractor (ETR)
The seat belts for the front seats are equipped with
emergency tensioning retractors. These tensioning
retractors are located in each belt’s inertia reel and
become operationally ready with the electronic key in
steering lock position 1 or 2.
The emergency tensioning retractors are designed to
activate only when the seat belts are fastened during
frontal impacts exceeding the first threshold of the SRS
and in rear impacts exceeding a preset severity level.
They remove slack from the belts in such a way that the
seat belts fit more snugly against the body restricting its
forward movement as much as possible.
In cases of other frontal impacts, angled impacts, roll-
overs, certain side impacts, or other accidents without
sufficient frontal or rear impact forces, the emergency
tensioning retractors will not be activated. The driver
and passengers will then be protected by the fastened
seat belts and inertia reel in the usual manner.
For seat belt and emergency tensioning retractor safety
guidelines see page 73.