600SEL (140.057) V12-6.0L (120.980) (1993)
Seat Belt Tensioner: Description and Operation
Purpose/Function
Model
140 up to May 31, 1997
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.
If an electrical impulse from the ETR control module with airbag is received by the emergency tensioning retractor squibs, a combustion gas is generated
at high pressure. This propellant gas is fed through a T-fitting to the piston (1) which accelerates upward in the tube (2).
The connected wire cable(3) turns the cable pulley which is positively connected to the retractor shaft by a clutch.
The retractor shaft is turned back eliminating any slack in the belt and the film reel effect.
The force of the emergency tensioning retractor is designed so that it is not capable of pulling the passenger back into the seat with the seat belt.