Description of Function of Airbag with Seat Belt Tensioner E. - Automatic Seat Belt Height Adjustment - ra9100140e600x(0600)

Model 140 

General 

The risk of injury to the head and chest in the case of serious frontal collisions is further reduced by means of the driver's/front passenger's airbag unit in combination with the three-point seat belt and the energy-absorbing covers on the driver's and/or front passenger's side.

The driver's and front passenger's airbag units are marked "SRS Airbag". The warning light is marked SRS (Supplemental Restraint System).

Both systems are activated electrically by means of a control device in the event of a moderate to serious frontal collision. Our present knowledge indicates that, if undamaged, the entire airbag and seat belt tensioner restraint system should have a fully operational life of at least ten years. In contrast to the three-point seat belt, which only offers protection when worn, the vehicle occupant cannot influence the protection afforded by the airbag and seat belt tensioner system in any way. A properly worn three-point seat belt and the driver's airbag and front passenger's seat belt tensioner system are essential if this increased protection is to be fully effective.

The airbag and seat belt tensioner restraint system offers increased protection in the event of a frontal collision only. No protection at all is offered to a vehicle occupant not wearing a three-point seat belt in the event of a side collision, rear collision or roll-over.

Fig 1: Identifying Airbag Function For Seat Belt Tensioner

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Driver's Airbag 

Fig 2: Identifying Driver's Airbag Components

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Driver's/Front Passenger's Airbag 

Fig 3: Identifying Driver's/Front Passenger's Airbag Components

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Driver's Airbag USA Version 

Fig 4: Identifying Driver's Airbag (USA Version) Components

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Driver's/Front Passenger's Airbag USA Version 

Fig 5: Identifying Driver's/Front Passenger's Airbag (USA Version) Components

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Arrangement of Components 

Driver's Airbag with Seat Belt Tensioners 

Fig 6: Components Arrangement - Driver's Airbag With Seat Belt Tensioners

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Arrangement of Components 

Driver's/Front Passenger's Airbag with Seat Belt Tensioners 

Fig 7: Components Arrangement - Driver's/Front Passenger's Airbag With Seat Belt Tensioners

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

NOTE: In the case of vehicles in the version the components listed are located in the same position.

Stick-on Label for Replacement Date of the Driver's Airbag Unit 

The stick-on label with the replacement date of the airbag unit is located on the left-hand center pillar below the belt fastener.

Fig 8: Identifying Label For Replacement Date Of Driver's Airbag Unit

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Stick-on Label for Replacement Date of the Driver's/Front Passenger's Airbag Unit 

On the left-hand center pillar below the belt fastener there is a stick-on label with the replacement date of the driver's and front passenger's airbag unit. The replacement date refers to the entire driver's and front passenger's airbag unit in each case. The operating life is at least ten years.

Fig 9: Identifying Label For Replacement Date Of Driver's/Front Passenger's Airbag Unit

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Driving with the Airbag and Belt Tensioner Restraint System 

When the ignition key is in position "1", the red warning light with the "SRS" symbol in the instrument cluster should light up.

The warning light shows that the airbag and seat belt restraint system is in proper working order. In ignition key position "1" it should light up for approx. 4 secs and then go out again. If it fails to light up or to go out after the stated time, there is a fault in the system. The error time is recorded by the control device (N2/2) and can be read out afterwards.

Fig 10: Locating SRS Warning Light

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Should an error be indicated in the above-mentioned way, the entire system must be checked as exhaustively as possible by trained staff via impulse output.

The operation of the standard-fitted driver's and front passenger's seat belts is not impaired by such a fault.

The complete airbag and seat tensioner restraint system consists of the following components:

1. Driver's airbag unit
2. Front passenger's airbag unit
3. Seat belt tensioner unit
4. Control device
5. Warning light
6. Energy-absorbing cover under dashboard (driver's and front passenger's side)

E. Automatic Seat Belt Height Adjustment 

Fig 11: Identifying Automatic Seat Belt Components

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Important Components 

Fig 12: Identifying Automatic Seat Belt Height Adjustment

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Function 

Sequence of movements:

The automatic seat belt adjusting device mainly consists of a guide rail with toothing (2), in which a pinion (6) is engaged.

A guide roller (7) and a guide element are connected to the hinge pin of the pinion.

When the front seats are adjusted from front to back, the guide element is pulled backwards into the upper position in a ratio of 2:1 via a double pulley block.

When the front seats are adjusted from back to front, a rewind spring (8) assumes the downward movement of the guide element.

The adjusting path of the seat belt height adjustor is 105 mm, i.e. the seat adjustor can activate the seat belt height adjustor linearly from 0-210 mm.

When the seat is adjusted from 210-300 mm, the seat belt height adjustor is against the upper stop.

The Bowden cable (9) is pulled through the adjusting system due to the pretensioned overtravel spring (11).

When the seat is adjusted from 300-210 mm, the overtravel springs pull the released cable slack as far as the stop of the cable nipple (10).

Locking:

The pinion is attached to a guide part, to which a locking plate (5) with a sliding retaining spring (3) is attached.

On the locking plate the belt forces are led via the screwed on deflection brace.

If the force affecting the locking plate exceeds the force of the retaining springs, these are pushed into the pinion toothing and the guide element is locked.

As the seat belt height adjustment is automatic and therefore cannot be influenced, the shoulder belt position cannot be individually changed.

This means that in the case of unusual sitting positions or changes in the longitudinal or height adjustment of the seat which are not adapted to the body of the occupant, the shoulder belt cannot be in an optimal position.

In the case of complaint that occupants positioned in the rear third of the seat adjustment are unhappy with the position of the shoulder belt ("belt rubs against neck"), the preset characteristic curve can be changed by installing a special stop (available as spare part) (see diagram).

Diagram 

Height of shoulder belt bracket (mm)

Fig 13: Longitudinal Seat Adjustment And Height Of Shoulder Belt Bracket Graph

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.