Safety instructions to be scrupulously followed

A seat belt PRE-TENSIONER is a device integrated in the reel assembly which, in the case of a frontal impact, recovers the inevitable extension of the belt due to the action of the weight of the body, keeping the latter close to the seat backrest.

Impacts, vibrations or localized heat in the area of the pre-tensioner can cause its activation; the vibrations produced by road conditions or accidentally driving over small obstacles (e.g. pavements) do not come enter this equation.

Seat belt pre-tensioners are mechanically operated pyrotechnic devices which intervene in the case of an impact, recovering the extension of the seat belt due to pressure from the body.

It is vital for the seat belt to remain as close as possible to the body in order to gradually absorb the kinetic energy produced during an impact.

The main reasons why a seat belt may, during an impact, no longer ensure that the body is held against the backrest are listed below:

• delay in the intervention of the inertia locking device,
• stretching of the belt fibres,
• "wrapping" of the belt around the reel (spooling effect),
• thick clothing creating an excessive gap between the belt and the chest.

Putting together all these causes it is easy to understand that the belt would only be effective after the body has moved forwards a certain amount.

Pre-tensioners are fitted as standard on front seat belts.

Safety instructions to be scrupulously followed

• Do not subject the area surrounding the pre-tensioners (60-70 centimetre radius) to serious impacts due to bodywork repairs (for example the use of a hammer); if necessary, remove the complete reel - pre-tensioner assembly (see Section 70 - Bodywork on page 47 onwards);
• if repairs are being carried out to the vehicle in different areas to those mentioned above, simply remove the reinforcement rod following the instructions given on 106 onwards;
• if heating lamps need to be used for painting operations in the area surrounding the pre-tensioner, then the complete reel - pre-tensioner assembly should be removed (see Section 70 - Bodywork page 47 onwards).