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Freelander - Airbags and Pre-tensioners

Airbags and Pre-tensioners:Split second protection

The ability of seatbelts and airbags to save lives is well-proven. The revised extra capacity airbags (now 60, a 33% increase litre for driver and 150 litre, a 25% increase for passenger) when combined with revised pre-tensioner seat belt buckles and the new load limiter provide improved occupant protection.

The design of an effective occupant restraint system requires a detailed knowledge of how the vehicle and occupants will behave in a crash.

In the early stages of developing Freelander's system, Land Rover engineers used computer modelling techniques such as Mathematical Dynamic Modelling (MADYMO). These utilised data obtained from a series of crash scenarios to simulate what would happen during the milliseconds of a severe forward impact, in order to optimise the combined operation of the airbags and seatbelts.

Testing on-road and off-road

Freelander's low centre of gravity makes it less susceptible to rollover accidents. It has been tested to and complies with the stringent North American dynamic rollover legislation.

Steering Rack

For on-road impact situations, the timing of airbag deployment and pre-tensioner firing was established by conducting and analysing a series of low speed impacts.

The most stringent test were carried out off-road. Freelander's restraint system was tested in the heat of Death Valley in the USA, and in the cold of Northern Canada. Prototypes were proved in car-to-car crashes, driven into ditches, over railway sleepers, and launched off hump-backed bridges.

The aim was to determine a 'no-fire' speed threshold and a 'must-fire' speed threshold. The 'no-fire' speed threshold is the speed below which the system must not deploy, whilst the 'must-fire' threshold is the one above which deployments must take place. Vehicle impacts below the threshold speed should not cause occupant injury; above this speed, the system will be activated to prevent or minimise injury.

The Benefits

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