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Reversible Belt Tensioner, Basic Function - GF91.40-P-9890A

Model All (CAR) 

Example illustration of reversible belt tensioner 

Fig 1: Reversible Belt Tensioner Components Location - Model All (Car)
G16152346Courtesy of MERCEDES-BENZ USA

Overview 

This document contains information on:

General 

Seat belt tensioner, which in contrast to conventional pyrotechnically triggered seat belt tensioners is triggered via an electric motor.

In the event of an impending accident, electric motors pull on the seat belts and fasten the vehicle occupants to the seat so that airbags and seat belts can provide their optimum protective effect.

In contrast to the conventional seat belt tensioner, it does not need to be replaced after triggering (reversible = recoverable).

Function 

The reversible belt tensioners (1, 2) have the task of tensioning the seat belt of the driver's or front passenger seat in certain hazardous situations by actuating the integrated actuator motor. Securing the vehicle occupants in the seat in a more optimal fashion minimizes the consequences of a potentially impending accident. If the seat belt adjustment function is active, the seat belt slack is additionally reduced when the seat belt is fastened.

The reversible belt tensioners (1, 2) are connected to the network architecture of the vehicle.

The reversible belt tensioners (1, 2) process, among other things, the following information:

The reversible belt tensioners (1, 2) process this information and actuate the integrated actuator motors accordingly. Faults and malfunctions are communicated to the driver.

IMPORTANT The seat belt tensioners are equipped with a mechanical acceleration sensor which locks the belt tension in the event of vehicle deceleration of over 0.3 g. Therefore, the seat belt can remain mechanically locked despite the emergency tensioning having ended.

  Component descriptions     
  Component description for front reversible emergency tensioning retractors Model 223
with code 460 (Canada version)
with code 562 (Driver seat belt buckle with integrated tensioning function)
Model 223
with code 494 (US version)
with code 562 (Driver seat belt buckle with integrated tensioning function)
GF91.40-P-4020A
    Model 243
with code 299 (PRE-SAFE®)
GF91.40-P-4020B
    Model 206
with code 299 (PRE-SAFE®)
GF91.40-P-4020C
    Model 297
with code 299 (PRE-SAFE®)
GF91.40-P-4020D
    Model 295
with code 299 (PRE-SAFE®)
GF91.40-P-4020E
    Model 232
with code 299 (PRE-SAFE®)
GF91.40-P-4020F
    Model 296
with code 299 (PRE-SAFE®)
GF91.40-P-4020G
    Model 254
with code 299 (PRE-SAFE®)
GF91.40-P-4020H
    Model 214 GF91.40-P-4020K
    Model 118, 177, 247
as of Model year 2023
with code 299 (PRE-SAFE®)
GF91.40-P-4020L
    Model 167
as of Model year 2023
GF91.40-P-4020M
    Model 294
with code 299 (PRE-SAFE®)
GF91.40-P-4020N