A suspension system ensures to support this and makes a conveyance compatible with different road conditions. While there are a range of suspension systems available in the market, air suspension has gained massive popularity in recent years. 

It utilises pressurised bladders instead of metal springs allowing drivers to effortlessly customise the vehicle's height. 

An air suspension, also known as a pneumatic suspension system,  comes with airbags or air springs instead of metal springs or coils to support the axles of a vehicle. These springs or bags are made of textile-reinforced rubber or plastic. 

They contain compressed air that aerates the bellows and elevates the chassis to adjust the overall height (lifting or lowering) of a vehicle. 

Unlike other suspension systems which use metal springs for shock absorption, this pneumatic configuration permits bellows to draw in shocks keeping the system unharmed. 

The history of air suspensions dates back centuries. In January 1901, a British engineer named Archibald Sharp patented a sealing method using hydraulic and pneumatic equipment. Another individual, known as William W. Humphreys, patented the concept of pneumatic springs. 

A couple of years later, in 1909, Air Springs Ltd manufactured A.S.L bikes with air suspension systems at both front and rear. The inception of World War II has brought the notion of pneumatic suspension massively to the news. The United States has started implying air suspensions to heavy-duty vehicles (trucks, trailers, and aircraft) to balance the weight.  

The 1957 Cadillac Eldorado Brougham introduced pneumatic suspension to commuter vehicles. After that, several contemporary four-wheelers, such as Rambler Ambassadors, Eldorado Seville, American motors station wagon, Borgward P 100, and Mercedes-Benz W112, strengthened the core of air suspensions in the automobile industry. Later, numerous market leaders, such as Rolls Royce, Toyota, Tesla, and Ford, followed its progression. 

One can differentiate air suspension systems according to two aspects. They are: 

• Design of air springs 

• Working process 

Bellow-type air suspension system

In this system, the convolutional rubber bellows replace the conventional coil spring structure. The flexible bellows collapse and expand to offer improved stability and significantly reduce vibration.

Piston-type air suspension system

This type of suspension system makes use of an inverted drum-shaped metal container as a spring. This air container is supported by a sliding piston which is attached to a lower wishbone.

Elongated bellows type air suspension system.

This air suspension is installed on the rear axle of a four-wheeler. It is similar to the bellow type system, except here, the bellows come in a rectangular shape with dual semi-circular sides. This system bridges the gap between a rear axle and a vehicle's frame.

Full air suspension system

Fully automatic or adjustable systems fall under this category. When applied to both axles, this system strains out even the minor bumps delivering unmatched riding comfort.

Semi-air suspension system

It is a conventional system that includes air springs. The spring sits between the chassis and rear axle. It offers two advantages. Firstly, it raises riding stature during the addition of supplemental weight. Secondly, it maintains a proper ride height even after removing the load.

Numerous components are coupled together to assemble an aerial suspension system. Here is a detailed discussion of its main parts to make things clear:

1. Air Compressor

The air compressor is this suspension system’s primary element. It is usually fitted under a car frame or in a trunk. It captivates the atmospheric air into its in-built pump and then initiates a compression process to an estimated 240 MPa pressure. If the compressor of an air suspension system activates automatically, then its integral electronic system can control it. 

2. Air Accumulator

Suspension comprises a storage medium to preserve the pressurised air. This medium is an air accumulator. It owns the capability of storing air at 150 psi or 1.03421 MPa. This accumulator also encompasses a relief valve to release excess air. 

3. Supply Line

Supply lines are utilised to convey the compacted air to airbags. It is implemented alongside the vehicle's frame. Moreover, this line resembles regular pressurised airlines. These are generally made of a composition of elastic and polyurethane and are usually 6mm dense.

4. Air Bags

Another quintessential component of this entire air suspension system, air bags or air bellows are mostly made using standard polyurethane or rubber. These bags take advantage of the compressive quality of air and flexibility of rubber to soak in the vibrations. They also act as a frontier to raise or decrease the height of a vehicle.

5. Height Control Valve

Height control valves or height sensors are located at four corners of a conveyance. Fitted to the frame, an L-designed linkage connects these valves to the axle. Encapsulating contact resistance, these valves can detect even the slightest change in axles’ height according to the frame. They comprise an exhaust port to liberate some air during the deflation of airbags.

6. Solenoid

This is not a compulsory component of an air suspension. A solenoid is available just in electronic pneumatic suspension frameworks. One can install it on the vehicle's floor. When the control linkage is in motion, this electronic sensor processes data and shares the same with the control unit. 

The ECU is the focal point of an electronic suspension's framework. As ECU receives data, it regulates the solenoid valves to blow up or collapse airbags.

A pneumatic suspension follows a systematic work pattern to perform seamlessly. Following is a step-by-step representation of the working of the air suspension system for a better understanding: 

Step 1: The air compressor captivates atmospheric air and supplies it to the air accumulator via filters.

Step 2: The accumulator surpasses the air-to-high control valves that are attached to the vehicle's frame. 

Step 3: When a load is added to the vehicle, this HCV linkage swings and travels the valve as per the added load to retain the suspension at a steady height.

Step 4: The deflection of valves allows the air to move to the airbags via the supply line. With the inflation of airbags, the suspension returns to its original position. 

Step 5: Since the HCV linkage and valves restore their original positions, the airbags ensure to maintain an ideal ride height. 

Step 6: When the load is removed from the vehicle, the axle retains its former state.

Step 7: As soon as the weight on the axle clears out, the airbags release the air through the exhaust port of the vehicle permitting the HCV linkage to remain in its neutral position.

Step 8: Once the air is released, the exhaust port becomes closed locking the remaining air in the bags to maintain an accurate riding stature. 

The key characteristics of pneumatic suspension are as follows: 

• The stiffness of air springs syncs directly with the load. These springs remain soft at first when the vehicle is not stacked. Its firmness increases with loading because of an expanding pneumatic force inside. In this way, the riding quality remains unchanged. 

• With enhanced adaptability in different conditions, this system peaks the rider's comfort. 

• Springs draw in all kinds of road shocks offering peerless stability. 

• With the enlisted characteristics, air springs enhance your ride with strength, flexibility, and quality. 

Air suspension packs a wide array of advantages. Take a look: 

• The suspension offers hassle-free height adjustment. 

• This mechanism notably extends the operational life of the system by absorbing road shocks and vibrations.  

• An air spring deviates less between the stacked and dumped positions than a steel spring.

• Since this suspension suits all types of roads, drivers can corner or turn cars seamlessly with it.  

• The compressed air offers consistent stability in all wheels, bringing down risks of breakage, body roll, or other type of damage. 

• It offers a high-quality driving experience even on poor roads. This not only elevates comfort but also scores high in terms of fuel economy. It permits drivers to reach their destinations comfortably and on time despite terrible road conditions.