In the case of an air-suspended vehicle, those coil springs or leaf springs are swapped for pressurized flexible rubber bellows called air springs. An air spring at each corner is monitored by the vehicle for internal air pressure and ride height. With help from an onboard compressor, air dryer, and air reservoir, the air pressure (which determines the equivalent spring rate) and ride height can be adjusted to provide optimal ride quality and ground clearance for the task at hand.
The idea for air suspension has been around nearly as long as the automobile; a "Pneumatic Spring for Vehicles" was patented in 1901. It was utilized by the U.S. military in World War II on heavy trucks to maintain ride height independent of vehicle load. By the late 1950s, air suspension was standard equipment on the Cadillac Eldorado Brougham, and today the tech is near ubiquitous on high-end luxury cars.
Most of the advantages of equipping a car with air suspension relate to adjustability. By increasing or decreasing the volume of air in the spring, an air suspension system can raise or lower a vehicle's ride height and consequent ground clearance in seconds, which has myriad benefits.
The first is improving off-road capability. Countless SUVs, from the Mercedes-Benz GLS to the Lamborghini Urus and Jaguar I-Pace, utilize air suspension to increase ground clearance and improve approach, breakover, and departure angles. Raising the suspension reduces the likelihood of a vehicle getting stuck off-road or taking underbody damage from hazards on the trails.
