Steering column elements and steering wheel
1 - top shaft
2 - lower shaft with cardan joint
3 - elastic connection
4 - steering wheel lock
6 - shaft tube
7 — the top cover of a steering column
8 — the bottom cover of a steering column
11 - steering wheel
The rotation of the steering wheel is transmitted by the driver through the steering column and steering gear, as well as steering rods to the wheels of the car. The steering column can be adjusted manually in height and in the longitudinal direction.
The force required to turn the wheels, especially when the car is stationary, is reduced due to the presence of a hydraulic booster. The power steering consists of an oil pump, an oil reservoir and oil lines. The oil pump is driven by the engine via a ribbed V-belt. The pump draws oil from the reservoir and delivers it under high pressure to the valve body. The valve body is located in the steering gear. It has a mechanical connection with the steering column and, depending on the direction of the steering shift, directs the oil to the corresponding side of the working cylinder. Here, the oil acts on the piston with the rack, thus reducing the force that must be applied to turn the steering wheel.
The steering wheel has an airbag. The airbag is a folded bag that inflates with air in a frontal collision and thus protects the driver's torso and head from hitting the steering wheel. In the event of a frontal collision with a certain force, a small charge is ignited in the airbag through the control device. As a result of the explosion, gases are formed that fill the air bag within a few milliseconds. This time is enough to dampen the forward torso of the driver. The airbag then re-folds within a few seconds as the gases exit the airbag through the exhaust ports.
It is not allowed to carry out welding and leveling work on the steering elements. Self-locking nuts must be replaced with new ones.
Airbag Safety Precautions
Next to the driver airbag in the steering wheel, there is a front passenger airbag located above the glove box, side airbags in the doors and a head airbag above the doors. It is not allowed to install a child seat or any other device to restrain children in the opposite direction of travel in the front passenger seat. In addition, there must be a decal on the door pillar, sun visor or instrument panel on the right side "no child seat in front". In the absence of the latter, the driver may be fined by the German police.
When removing and installing the airbag unit, the following must be observed:
1. Disconnect the negative cable (-) battery with the ignition off. The battery is located in the luggage compartment behind the cover on the right side. For BMW 316i, 318i, the battery is located in the engine compartment.
Disconnecting the battery clears the fault memory of some controls. If necessary, read the fault memory before disconnecting the battery. Refer to Section Troubleshooting. It is desirable to carry out work in the conditions of a service station.
2. Isolate the negative pole (-) battery to prevent accidental contact.
3. Before installing the airbag, check again if the negative battery cable is disconnected.
If these instructions are not followed, the airbag system may eventually fail.
General security measures
After removing the airbag, store it with the soft side facing up.
When connecting the battery, no unauthorized persons are allowed in the car.
If work is interrupted, the airbag must not be left unattended.
Do not disassemble the airbag unit. If there is a defect, it will be replaced as a set. Since the pillow contains an explosive, it must be stored securely. The cushion must be disposed of by a BMW workshop. Under no circumstances should you dispose of the pillow yourself. There is a risk of explosion!
A steering wheel containing an airbag may only be replaced with a steering wheel approved by the vehicle manufacturer.
The soft side of the airbag should not be pasted over, overtightened or otherwise treated in any way. It can only be cleaned with a dry or water-soaked towel and with a cleaner approved by the manufacturer.
If the airbag has been used as a result of an accident, it is necessary to replace its control device, airbag unit and contact block.
The airbag unit and control unit are impact sensitive. If they fell from a height of more than 50 cm, they can no longer be used. If the pillow fell from a lower height, it is necessary to check it at the service station.
The airbag may only be checked by a workshop. In no case should a test lamp, voltmeter or ohmmeter be used to check the pillow.
When carrying out welding work, the terminal of the welding machine must be located in the immediate vicinity of the welding site. Be sure to have a negative battery cable and insulate the battery pole to prevent accidental contact. It is necessary to disconnect the airbag plug connections to the gas generators.
Do not expose the cushion unit and the control unit even for a short time to temperatures above +75°C.
Follow the instructions for the seat belt tensioner, refer to Section Seat belt tensioner. Basic Information and Safety Precautions.
Driving safety instructions
The airbag does not replace the seat belt. The occupants of the car must wear their seat belts, this is the only way to ensure optimal safety.
No child restraint is allowed on the driver's seat. Children under 12 years of age may only sit in the rear seat.
It is not allowed to place any objects between the airbag and the person.