Mumbai University > Mechanical Engineering > SEM 8 > Automobile Engineering

Marks: 5M

The line diagram of air suspension system is shown in Figure. It consists of four air bags.

The elastic element consists of housing, diaphragm with suitable air inlet and piston group. The housing is linked with housing is linked with the frame (sprung mass). The housing contains the piston group which is linked with the unsprung mass (rear and the front axle).

The housing and piston group are connected by a metallic diaphragm for better sealing and to friction between the members of elastic elements.

Each air bag is filled with compressed air.

The components of air suspension system are air filter, compressor, air reservoir, relied valve, pressure regulator, solenoid valve, levelling valve and ‘T’ check valve.

Air compressor is mounted on vehicle frame supplies high pressure air into the reservoir. The compressor sucks the air from atmosphere through air filter.

The pressure in the reservoir is maintained at about 20 kg/cm2.

The compressed air in the air bags support the weight of vehicle whenever vehicle comes across the bump of the road surface, the air in the air bag compressed and absorbs the shocks.

Air admitted into the four air bags through two circuits. In one circuit a pressure reduced to 12 kg/cm2 by pressure regulator.

This pressure is kept in air bag through levelling valve if the pressure in one of the bag is low, the levelling arm moves and air is admitted into low pressure air bag through inlet valve.

The outer circuit has air pressure of 20 kg/cm2. This circuit pressure is used for additional loading of vehicle.

This can be achieved by special regulator, which keeps the same distance between wheel and frame under various loads. This circuit maintain the vehicle level constant in loaded or unloaded condition.

For this situation, the air at 20 kg/cm2 pressure is admitted into the levelling valve through solenoid valve.

Also the air is quickly released by levelling valve whenever load is decreased from corresponding air bag. This lower the air bag and hence the vehicle to the proper level.