On models without power steering, the steering gear ratio changes depending on the steering angle. This means that the greater the steering angle, the more proportional the steering becomes. As the steering wheel angle increases, it becomes easier to turn, for example when parking a car. In the mid-position region, the steering gear ratio, which approaches direct gear, provides precise control of the vehicle, which is especially important at high speeds.
On some models, power steering is installed. It is designed to reduce the effort required to turn the steering wheel. The power steering consists of a hydraulic pump, expansion tank and pipeline. The hydraulic pump is driven via a V-belt. The pump sucks in liquid from the expansion tank and delivers it at high pressure to the steering gear. There, the regulator assembly, together with the working piston, supports the movement of the control.
With an expanded composition of equipment, an Airbag security system is installed on cars. This is an air bag which, when folded, is stowed behind the steering wheel trim. When hit hard (which corresponds to a frontal collision with a solid obstacle at a speed of at least 18 km/h) sensors are triggered, unlocking the system without danger. The electrical circuit closes and a small fuse is activated in the air bag. In this case, the air bag is filled with the liberated non-toxic gases within about 30 milliseconds. With this rapid filling of the bag, damage to the head and upper body is reduced. Within a few seconds, the air bag contracts again as the gases escape through the holes in the bag.
The Airbag system is constantly monitored by a diagnostic system. After switching on the ignition, the control lamp on the instrument panel lights up and stays on for approximately 6 seconds. This indicates the functionality of the system. If the warning lamp comes on while driving, it indicates a system failure. The fault is stored in a memory in the diagnostic unit and can be interrogated and rectified by a BMW workshop.
Attention: All work related to the airbag system must only be carried out by a BMW Dealership. It is also excluded independent work with the steering wheel and steering column.
1. Block of the Airbag system - In the steering wheel; contains a gas generator, a fuse and a contact ring.
2. Diagnostic block
3. Protection of the knee area (US version only)
4. Crash sensors
5. Pilot lamp-Airbag