Front emergency tensioning retractor, function - GF91.40-P-4000-03D

WARNING: This page does not describe the selected car, but rather 42 other vehicles, including the 1999 Mercedes-Benz S600, 1999 Mercedes-Benz S500, 1999 Mercedes-Benz S420, 1999 Mercedes-Benz S320, and 1999 Mercedes-Benz CL600. However, it is still accessible from the selected car via links, so may be relevant.

Model 140 up to 31.5.97

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.

Fig 1: Identifying Tube, Wire Cable And Piston

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

A viewing window (arrow) is located on the emergency tensioning retractor housing, through which a notch is visible.

Emergency tensioning retractors on which the notch is not visible , have been triggered and must be replaced.

Fig 2: Locating Emergency Tensioning Retractor Housing Viewing Window

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.