Air Spring & Air Suspension Glossary
Clear definitions of the most important air spring, air bellows and commercial vehicle suspension terms — written for buyers, fleet engineers and procurement teams.
- Air Spring
An air spring is a flexible rubber-and-fabric component that uses a column of compressed air as the load-bearing spring element in a vehicle or industrial suspension.
Instead of a steel coil or leaf, an air spring carries load on pressurised air sealed inside a reinforced rubber body. Air pressure can be adjusted to keep ride height constant regardless of load, which is why air springs dominate heavy commercial vehicles. They are also called air bags or air bellows.
Related terms: Air Bellows, Rubber Bellows, Pneumatic Suspension
- Air Bellows
Air bellows is another name for an air spring — particularly the flexible, multi-lobed rubber body that expands and compresses with air pressure.
The term is used interchangeably with air spring across European markets. Strictly, 'bellows' emphasises the convoluted rubber element itself rather than the complete assembly with end plates and pistons.
Related terms: Air Spring, Convoluted Air Spring, Rubber Bellows
- Rolling Lobe Air Spring
A rolling lobe air spring has a cylindrical rubber sleeve that rolls over a shaped piston as the suspension moves, giving a long, smooth stroke.
Rolling lobe (also 'reversible sleeve') designs deliver a near-constant spring rate over a long travel range, which makes them the standard choice for truck drive axles, trailer axles and bus chassis. The piston profile tunes the load curve.
Related terms: Convoluted Air Spring, Sleeve Air Spring, Truck Air Suspension
- Convoluted Air Spring
A convoluted air spring is built from one to three rubber 'convolutions' or lobes, giving high load capacity over a relatively short stroke.
Single, double and triple convoluted springs are used where load is high but travel is limited — cab suspensions, axle lift systems, industrial machinery and vibration isolation. They have a progressive spring rate and a large effective area.
Related terms: Rolling Lobe Air Spring, Air Bellows, Cabin Air Spring
- Sleeve Air Spring
A sleeve air spring uses a compact cylindrical rubber sleeve, offering a small installed diameter and a smooth ride in lighter applications.
Sleeve types are common in passenger cars, vans and light commercial vehicles, as well as cab and seat suspensions, where packaging space is tight and loads are moderate.
Related terms: Rolling Lobe Air Spring, Seat Air Spring, Commercial Vehicle Suspension
- Truck Air Suspension
Truck air suspension is a suspension system that replaces steel springs with air springs to provide automatic load levelling and a smoother ride for heavy trucks.
An electronic or mechanical levelling valve adds or releases air to hold ride height as cargo weight changes. This protects freight, reduces driver fatigue and lowers road wear compared with leaf-sprung trucks.
Related terms: Trailer Air Spring, Bus Air Spring, Heavy Duty Suspension
- Trailer Air Spring
A trailer air spring is an air spring fitted to semi-trailer and full-trailer axles, carrying the trailer load and isolating cargo from road shock.
Trailer air springs are usually rolling lobe units mounted on a trailing-arm axle. Standardised mounting and connection types make cross-referencing between brands straightforward.
Related terms: Truck Air Suspension, Rolling Lobe Air Spring, Aftermarket Air Spring
- Bus Air Spring
A bus air spring is an air spring used on the axles of buses and coaches to deliver passenger ride comfort and a kneeling function at stops.
Bus air springs support precise ride-height control, allowing the vehicle to lower ('kneel') for accessible boarding. They must meet demanding durability and comfort requirements over long service hours.
Related terms: Truck Air Suspension, Convoluted Air Spring, Pneumatic Suspension
- OEM Cross Reference
An OEM cross reference maps an original equipment part number to equivalent, interchangeable air springs from other manufacturers.
Buyers use cross references to find a compatible aftermarket air spring when the original part is unavailable, expensive or slow to source. A reliable cross reference matches dimensions, mounting, connection type and load rating — not just the number.
Search the OEM cross reference →
Related terms: Aftermarket Air Spring, Commercial Vehicle Suspension
- Aftermarket Air Spring
An aftermarket air spring is a replacement air spring produced by a company other than the vehicle's original equipment manufacturer.
Quality aftermarket air springs are built to match or exceed OEM specifications and are typically more cost-effective and widely available. They are identified by OEM cross reference numbers.
Related terms: OEM Cross Reference, Trailer Air Spring
- Heavy Duty Suspension
Heavy duty suspension is a suspension system engineered for the high loads and continuous duty cycles of trucks, trailers and industrial equipment.
Heavy duty systems combine air springs, shock absorbers, axles and levelling controls designed for long service life under maximum gross vehicle weight.
Related terms: Truck Air Suspension, Commercial Vehicle Suspension
- Commercial Vehicle Suspension
Commercial vehicle suspension covers the suspension systems of trucks, buses, trailers and vans, where air springs are the dominant technology.
Commercial vehicle suspension prioritises load levelling, cargo protection, durability and ride comfort over long distances — requirements that air suspension meets better than steel springs.
Related terms: Heavy Duty Suspension, Pneumatic Suspension
- Rubber Bellows
The rubber bellows is the molded, fabric-reinforced rubber body of an air spring that seals the compressed air and flexes with suspension movement.
Rubber bellows are built from layers of rubber and reinforcing fabric (cord) and must resist heat, ozone, oil and millions of flex cycles. The bellows is the part that most often wears out and is replaced.
Related terms: Air Bellows, Air Spring
- Pneumatic Suspension
Pneumatic suspension is another term for air suspension — a suspension that uses compressed air in air springs as the load-bearing medium.
Pneumatic suspension systems include the air springs, an air supply (compressor and tank), levelling valves and the control electronics that maintain ride height.
Related terms: Truck Air Suspension, Commercial Vehicle Suspension
- Cabin Air Spring
A cabin air spring is a small air spring that isolates a truck cab from the chassis, reducing vibration and noise reaching the driver.
Cab mount air springs are usually compact convoluted or sleeve units. They are a major contributor to driver comfort and are a frequent replacement part.
Related terms: Convoluted Air Spring, Seat Air Spring
- Seat Air Spring
A seat air spring is the small air spring inside a suspension seat that cushions the driver from residual vibration.
Seat air springs work together with a shock absorber and a height-adjustment valve so each driver can tune the seat to their weight. They are common in trucks, buses and heavy machinery.
Related terms: Cabin Air Spring, Sleeve Air Spring
Air spring terminology — frequently asked questions
- What is the difference between an air spring and an air bellows?
- The terms are used interchangeably. 'Air spring' usually means the complete assembly, while 'air bellows' emphasises the flexible rubber body. Both use compressed air as the spring medium.
- What is the difference between a rolling lobe and a convoluted air spring?
- A rolling lobe air spring has a sleeve that rolls over a piston for a long, smooth stroke and is used on truck and trailer axles. A convoluted air spring uses one to three lobes for high load over a short stroke, common on cab mounts and industrial uses.
- What does OEM cross reference mean for air springs?
- An OEM cross reference maps an original equipment part number to interchangeable air springs from other brands, so buyers can source a compatible aftermarket replacement that matches dimensions, mounting and load rating.
- Are aftermarket air springs as reliable as OEM?
- Quality aftermarket air springs are manufactured to match or exceed OEM specifications and are typically more cost-effective and easier to source. Reliability depends on the manufacturer, not on whether the part is OEM or aftermarket.