E 430 (210.070) V8-4.3L (113.940) (1999)
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Seat Belt Tensioner: Description and Operation
Model 210.0 as of 8/98, 210.2 as of 6/98
Emergency Tensioning
In the event of a crash (Head-on or rear end collision) the emergency tensioning retractor eliminates slack in the seat belt and prevents the seat belt film
winding effect.
The tight seat belt allows the passenger to start decelerating with the body sooner.
When a crash occurs an electrical signal for triggering the emergency tensioning tractor is output by the airbag control module (N2/2 or N2/7) after
reaching a certain deceleration/acceleration value.
The emergency tensioning retractor is equipped with a force limitation feature which reduces the tension exerted on the body by the seat belt when the
seat belt is tensioned during a crash without reducing the protective effect of the seat belt. In a second crash the normal protective function of the seat
belt is still available. The belt reel is arrested by the locking system without tensioning or force limitation so that it absorbs the entire load.
ETR Function Sequence
1
Electric ignition of squib (a) by airbag control module.
2
The propellant gas resulting from ignition creates a high gas pressure causing the piston (b) to rotate and tensioning the seat belt.
3
The gas pressure transports the cap 1(c) in the direction of the ignition cartridge 1 (d).
4
The ignition cartridge is triggered mechanically by the cap.
5
The gas pressure moves the piston (b) on tensioning the seat belt further.
6
The gas pressure transports cap 2 (e) in the direction of ignition cartridge 2 (f).
7
Ignition cartridge 2 is fired.
8
The gas pressure moves the piston (b) to the end position.
Actuation Sequences for Emergency Tensioning Retractors During Rear End Collision:
