Air suspension: how does it help improve driving?

Air suspension helps improve ride quality and offers greater control than other suspension systems. Furthermore, this type of suspension is much more effective at isolating vibration. Until a few years ago, air suspension was only associated with luxury vehicles, but now many premium cars fit it because of its versatility.

It could be said that air suspension can contribute to a more comfortable ride, lower the driving height to make it easier to get in and out of an SUV, for example, and reduce drag at higher speeds. It can also raise the vehicle for normal use, or raise it even further to increase ground clearance for off-road driving, and it can be designed to change ride height in support of the different driving modes. Air suspension can be used with any type of damping system, including adaptive magnetorheological dampers and variable-stiffness anti-roll bars.

Air spring units replace existing coil springs and are integrated into the suspension struts. Alternatively, air springs can be used independently of the dampers, especially at the rear. Air suspension normally consists of a strong, flexible air bag. They come in several types and sizes, but ultimately they all do the same job, which is to take over the work of the steel coil spring. Using compressed air, they work a bit like a miniature but more sophisticated inflatable castle.

What began as a rather crude arrangement used on trucks and buses has become a precision system controlled by a microprocessor capable of much more than a conventional spring. Unlike steel springs, the suspension deflection (suspension travel) is not proportional to the load applied to it. That is why air suspension can not only work as a spring, but can also be used to raise and lower the ride height.

Air suspension: what makes it special?

Inevitably, as the air chamber has evolved, so has its complexity and capability. In addition to variable ride height, modern systems adapt to different driving modes, while the control software can tailor the settings to individual driving styles.

An example of a more sophisticated system is the three-chamber air spring of Porsche, which offers an even more effective variation between the Comfort, Sport and off-road settings. As the name suggests, each strut is divided into three chambers, two of which can be excluded at any time. For a smoother ride, in Comfort mode all three are brought into play to provide the maximum air volume; then two for Sport and one for Sport Plus, which contains a much smaller compressible air volume, creating a stiffer system.

Despite the elegant names that car manufacturers give their air suspension systems, the hardware is developed by several suppliers, such as BWI and Continental, and manufacturers get involved in the software tuning stage to suit a specific car, as well as the exact specification of the hardware. And that hardware has become very sophisticated, with the simple rubber bellows of the early systems now made of materials such as cross-woven Kevlar or cross-woven nylon fibres for added robustness.