IMPACT PROTECTION
In a serious impact, the steering column is designed to manage two simultaneous events; the intermediate shaft must isolate the steering wheel from any movement of the steering rack (if the angle of the steering wheel changes it will affect the way in which the airbag deploys towards the driver).
In addition, to prevent excessive force causing injury as the driver strikes the airbag, the whole upper-column assembly is designed to progressively move forwards as the driver contacts the airbag. This motion helps to safely and progressively decelerate the driver. The steering column has a 'Horizontal Load Limiting' system which differs from conventional designs that rely on movement along the column axis.
Horizontal Load Limiting System
| Item Number | Description |
|---|---|
| A | Conventional steering column design |
| B | Horizontal load limiting system |
| 1 | Mismatch between direction of force and motion |
| 2 | Motion aligned to force |
The Horizontal Load Limiting System provides a progressive and stable load limiting characteristic as shown in 'B' in the illustration. Loads applied to the column cause the column to move horizontally with the driver. This movement is controlled by an energy management plate. The plate has leaves which peel back in a controlled manner, absorbing energy and allowing the column to move with the driver.
The plate is bolted to the steering column outer bracket attached to cross-car beam and the inner bracket