Air Suspension 101: Part 2

Last month we talked about how an air suspension works and basic components. This month we will talk about the most important part of an air suspension system: the air spring. Air springs can be either an air bag or an air cylinder.

An air bag is made from rubber similar to a tire. There are different types and sizes of air bags. Most air bags found on custom vehicles will either be a double-bellow or sleeve type. Double-bellow air bags are the most common for trucks and some cars. The double-bellow air spring looks like two donuts stacked on top of each other. These air bags do not require any limiting strap or bump stops.

The air sleeve or rolling air sleeve is used in places where a double-bellow air bag is too big. The air sleeve works the same except the air rolls over itself. This keeps the diameter of the bag smaller and allows it to fit in tighter locations. You must run a limiting strap or shocks to keep the sleeve bag from over extending. If the bag over extends, it can be damaged and will not deflate properly. This is a common problem. When this happens, the sleeve is pushed out of the bag. When you deflate the bag, it will just bend over because it no longer can roll over itself. This can be fixed if the bag is not damaged. The air sleeve would need to be rolled back down by hand.

Air strut is a term used to a new hybrid air spring. Basically, an air strut is a McPherson strut with an air bag mounted where a coil spring would normally be mounted. This gives McPherson strut cars the advantages of an air suspension system. The air struts can either have a double-bellow air bag or a rolling sleeve air bag. The advantage of an air strut is that you get shock and air bag combo for a better ride.

Another type of air strut or hybrid unit is the Shockwave by Air Ride Technologies. This is similar to the air strut in that it uses an air bag and shock combination. This is geared more for trucks and most rear wheel drive cars. This unit will replace both the coil spring and shock in one compact unit.

The last air spring is the air cylinder. Air cylinders are metal tubes with a plunger inside. These are very similar to hydraulics cylinders. Air cylinders are popular on vehicles where an air bag won’t fit. Air cylinders have an advantage to do three-wheel due to having a hole on the bottom of the cylinder. The air goes in though the hole and pushes the wheel up. The biggest disadvantage of the air cylinder is the rough ride. Since an air bag is made of rubber, it gives when you hit a bump. Air cylinders are made of metal and have no give what so ever. When you hit a bump, there is no place for the air to go so it is much rougher. Using air accumulators will help eliminate this, but not by much.

I hope this gives you an understanding on the different types of air springs. Check back next month as we look at air compressors. As always, if you have any questions about this, please let me know.

Vincent Wright
sales@kmwperformance.com
http://www.kmwperformance.com