What is an Air Bag Suspension System?
Before you can begin to identify clearly the pros and cons of an air bag suspension, you need to understand the design of such a system.
An air bag suspension system is powered by either an electric pump or compressor that forces air into rubber bags typically made out of polyurethane and textile-reinforced rubber.
A compressor inflates the air bags to a certain air pressure. It’s important to note that it’s the air inside the bag that does the work of a spring. (An air bag suspension should not be confused with a hydropneumatics suspension which uses pressurized hydraulic liquid instead of air.)
What's the Purpose of an Air Bag Suspension System?
Air bag suspensions are used to achieve smooth ride quality by replacing the conventional steel-spring suspension in heavier vehicle applications like trucks, tractor-trailers, passenger buses, and even passenger trains.
The ECAS (Electronically Controlled Air Suspension) includes several features such as:
- Vulcanized, heavy-duty rubber air springs at each of the vehicle's wheels
- A storage tank for compressed air which stores air at an average of 150 psi
- Valve blocks that direct air to the four springs from the storage reservoir
- Air pipes connecting the storage tank to the air bags
- ECAS* computer that communicates where to direct more or less air pressure.
*The Electronically Controlled Air Suspension also features height sensors (height-control valves) used to automatically control the vehicle's ride height.
Types of Air Bag Suspensions
- Sleeve style
Sleeve-style air springs are designed for lift and ride control. The internally mounted sleeve is covered by a bag, made of flexible, heavy-gauge rubber. The bag is crimped into the spring mount on one end and swaged onto the opposite end, sealing the contents inside.
When air is compressed into the spring, the two-piece sleeve extends, lengthening the assembly to achieve the desired ride height.
Sleeve style air springs are extremely well suited for applications when space is limited, and loads are light. Sleeve-style air springs are perfect for light-duty trucks, custom street rods and track cars.
- Bellows style
Bellows-style air springs are made from heavy-duty, reinforced rubber which is configured with either one or more convoluted chambers.
These air bags are typically larger than sleeve-style air springs, giving them greater load-handling capacity. Because of their size and shape, bellows-style air springs can lift the same weight with about half the air pressure of sleeve-style springs.
The most popular bellows-style air spring configurations include single, dual, and triple chamber design. Bellows air springs are great for heavy-duty applications as long as there is plenty of space for proper installation.
What Are the Main Reasons for Using an Air Bag Suspension?
The Pros (+)
Comfort
Car and truck manufacturers are increasingly turning to air bag suspensions as a viable alternative. Doing away with conventional springs allows for a much smoother ride, something you can’t get with metal springs. After all, you are - quite literally - floating on a cushion of air!
Flexibility
Do you want to arrive at the next family reunion with your vehicle riding impressively low to the pavement while at the same time avoid the inevitable scrapes from a large speed bump? No problem. An air bag suspension allows you the best of both worlds with the flip of a switch. If a heavy load has the rear end of your truck squatting lower than usual, the height-control valve (part of the ECAS*) will keep the load level and stable.
*The Electronically Controlled Air Suspension also features height sensors (height-control valves) used to automatically control the vehicle's ride height.
The Cons (–)
The air bag suspension has a few negatives we should mention.
Installation
The biggest drawback of an air bag suspension has always been installing it. Fortunately, the newer air bag suspension kits have reduced the need for cutting and drilling. However, you will need to drill holes to mount the compressor, manifold and tank. If you own a car or light-duty truck, there’s going to be problems with space, not to mention the noise factor whenever the compressor decides to kick in.
Expense
If you want the smooth ride that air bags offer, you’re going to have to pay for it. Without including labor, you’ll be looking at a couple of thousand dollars. If you decide to install it yourself to save on labor costs, there are quite a few components in the box. If you’re not a gear head, the task is probably above your pay grade.
Reliability
Airbags take a pounding. Unless they’re high-quality, they will eventually leak. If they decide to burst on a road trip, it could compromise your brakes, reduce control of your vehicle and lead to an accident.
Maintenance
You need to think twice about using an air bag on your vehicle if you’re the type to ‘set it and forget it’. This complex system is expensive and needs plenty of TLC! Regular checkups are imperative in order to protect your investment.
Conclusion
If you’re considering the purchase of an air bag suspension, you need to be aware of more than just the advantages. Even though you will be rewarded with great ride quality, you should weigh that against the disadvantages:
- Air bag suspension cost
The main roadblock to using an air bag suspension is cost. It’s got to be the most expensive suspension system on the market. If you want air bag ride quality, you’re going to have to pay for it. It’s that simple.
- Air bag suspension installation
Due to the complexity of an air bag suspension system, installation should be given to a qualified mechanic. Proper installation will ensure that safety objectives are met. Not only that, most kits require professional installation for the warranty to be honored by the manufacturer.
- Air bag suspension leaks
Air suspension kits are exposed to harsh road conditions. Like other suspension products, wear and tear will play a factor in the duration of every air bag suspension. Therefore, proper maintenance is required.
For a clear comparison between an air bag suspension vs Timbren SES, click here.
