Emergency Tensioning Retractor - Mercedes-Benz SL 320 Operator's Manual

Supplemental Restraint System
(SRS)
The SRS uses two crash severity levels
(thresholds) to activate either the ETR
or airbag or both. Activation depends
on the direction and severity of the
impact, exceeding the thresholds and
fastening of the seat belt.
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 from each other.
Emergency Tensioning
Retractor (ETR)
The seat belts are equipped with
emergency tensioning retractors. These
tensioning retractors are located in each
belt's inertia reel and become
operationally ready with the 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
and front-angled impacts exceeding the
first threshold of the SRS. 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, roll-
overs, certain side impacts, rear
collisions, or other accidents without
frontal forces, the emergency
tensioning retractors will not be
activated. The driver and passenger
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 Safety
Guidelines in Index.
44