Air Bag Systems: Description and Operation

PURPOSE
The Supplementary Restraint System (SRS) airbag system further improves the protection afforded by the car's seat belts.

CONSTRUCTION
The system consists of two front sensors connected in parallel, a control module and the steering wheel with gas generator and airbag. The airbag is mounted in the center of the steering wheel.

The belt tensioner on the passenger side is also connected to the system.

There is also a knee shield mounted on the steering column assembly which prevents submarining.

OPERATION
The system is always activated when at least one of the two front sensors is subjected to a force corresponding to a frontal collision with a steel barrier at a speed of 15 MPH (25 km/h). In a collision the airbag inflates and, together with the seat belt, prevents the driver from striking the steering wheel, dashboard and windshield.

The whole system is controlled by a control module. The front sensors transmit information to the control module which sends a current pulse to an electric detonator. The detonator sets off an explosive charge in a gas generator and causes the airbag to inflate.

PASSENGER SIDE AIR BAG
Model year 1994 cars are or can be equipped with an airbag on the passenger's side as well. The two airbag systems are then connected together and controlled by the same front sensor and control module. In a collision, the two systems and both seat-belt tensioners are activated simultaneously. The passenger airbag is mounted in the dashboard where the glove box is normally located. To prevent passenger submarining, U.S. specification cars have a knee shield on the passenger side also.