Pressure Switch

A pressure switch is quite a simple device. It has a spring loaded contact inside that raises and lowers based on the pressure that it sees. They come in many different varieties and configurations and some are adjustable and some are not. The most simple is pictured to the left. It simply has two prongs on it. One goes to the relay (explained in the electrical section), and one goes to a power source.

The power source can either be switched or constant. Switched is a better connection, because you can either hook it to a switch, or put it on a power feed on your vehicle that only has power when the vehicle is on. This will prevent your compressors from coming on when the vehicle isn't running. See the "Wiring Info" section for diagrams on wiring up pressure switches.

The pressure switch has a 'window' of when it will activate and deactivate. This is done to make the system practical. A typical window found often in air ride systems is 110/145. This means that a 110 psi, the pressure switch contacts close and activate the compressor. When the pressure reaches 145 psi, the contacts open and deactivate the compressor.

Compressor

Keeping the storage tanks full of air is the air compressors job. The pressure switch is what tells the compressor when it can and cant fill the tank. Air compressors come in a variety of configurations from many different manufacturers so you are bound to find one that suits your needs. If you are building a hot rod with a very small air ride setup, then you won't need a compressor as fast and powerful as a minitrucker who likes to show off at every moment he can. The more powerful the compressors are, the more expensive they get. As a rule of thumb, you should use one compressor for every 5 gallons of air you have

The compressor shown to the left is made by Viair Corp. They produce many compressors for both OE and aftermarket applications including off road and air ride suspensions. They are capable of pumping from 150 to 200 psi based on model, and have a duty cycle range of 25% to 100%. The 450, 460, and 480 models are among the most popular in air ride suspensions.

An alternative to electric compressors are engine driven units; those that operate on the engine of your vehicle. If you have a vehicle with the engine in sideways like many compact cars, this option will probably not work for you, however the folks over at Oasis Mfg. probably have an alterative; a winch driven compressor. Just as fast as an engine driven compressor, but without the engine. These compressors (both engine driven and winch driven) have a very high output compared to electric compressors. The engine driven compressors are 100% duty, they offer quick refills of storage tanks, they have a very very low current draw, and they are high quality, rebuildable pumps.

They do however require more than your standard electric compressor. Even if you piece together an engine driven kit from junkyard parts and brackets, it can still cost upwards of $400. You can purchase kits from Air Lift Company for over $600. Additional parts include leader hoses, brackets, engine belts, extra pulleys and regular oil checks and fills.

Air Filter/Dryer

The filter has a very simple task. It keeps unwanted particles in the air or oil out of your air tanks, valves, and air springs. Traditionally speaking, these go between the air compressor and the storage tanks. They also aid in removing some water from the compressed air to keep your system dry. Keep in mind that these will not remove all moisture. As air is compressed, it heats up. As it cools down in your tanks, it condenses and creates water in your tanks which will need to be drained periodically if you do not live in hot climates.

Storage Tanks

The storage tanks are just that, storage for reserve air for the system. This allows for quick adjustments of the suspension. They come in all sorts of shapes, sizes and colors all with different port variations. Typical tanks have 3-4 ports, while the larger tanks have upwards of 8 ports. Depending on how 'pretty' you want your setup to look, you can tanks that are powdercoated black, chromed, or are made of stainless steel. When looking for tanks, try and find one that has a port that can be mounted facing down so you can easily drain the inevitible water buildup from the tank.

Airline

This is how you will get the air from your storage tanks, to your valves, and then to your air springs. Pictured to the left is Parker Air Brake hose. It is used on almost all vehicles on the road today that utilize air brakes (ie: "18-wheelers"). It is nylon reinforced and has a burst pressure that far exceeds any every day air system.

Alternatives to this include stainless steel hardline, and steel-braided, teflon lined hose. These are much more expensive, both for the airline and the fittings, but the end result can be a real difference in maintenance, as these types of line wont suffer from hot exhaust melting them or sharp corners.

Copper line from your local hardware store SHOULD NOT be used on your vehicle. Not only does it look tacky and it requires a lot of cleaning to maintain its 'nice' appearance, it will also suffer from work hardening from all of the vibrations of your vehicle, causing it to become soft and/or brittle which can cause problems for you.

Valves

Valves control the inflating and deflating procedures of the truck's bags. There are literally thousands of valves on the market today. Most are used in industrial applications to control the flow of gasses and liquids for machine automation. Valves used for air suspension should have decent flow rate, or Cv, and operate of +12v solenoids. The more popular brand valves are SMC, Parker, and Blitzluft. You can find information on flow rates and PSI ratings of different valves on the fact's page.

There are many types of valves available on the market today as well. Below is a description of the different types, as well as some sample pictures to give you an idea of what too look for.

Diaphragm valves, such as the above, are today's most popular choice. There are a couple of different brands, such as SMC, Parker and Airlift, to name a few. These valves work quite well; however, they require constant back pressure from the storage tank. If the reserve pressure drops below the pressure inside the air springs, the air will leak back through the valve as to equalize with the tank. Sometimes, if you lift up the front of the truck, then lift the back, the pressure in the tank may decrease below the pressure in the front springs, and the front will drop a little bit. One way around this is to install a high flow check valve between the fill valve and the air tank(s). These can be pricey though.

Another type of valve is called a spool valve. These valves were formerly used by many people, but have lost popularity due to the constant maintenance required to keep them working properly. The rubber o-rings inside the valves on the spool will dry out and start to crack and fall apart. An advantage to these valves is they don't need back pressure to keep air in the springs. The bags will stay full even if your tank pressure drops to 0 PSI.

There is one type of valve, or set of valves, that is truly a convenience. That is called the electric manifold valve. These manifolds contain a set of valves, all mounted together, that you can put in one place, such as on top, or in front of your air tanks. You run one or two lines from your tank into the manifold, and then from the manifold you run the lines to your valves. Then you just hook up a switchbox to it, and you're all set. These valves can also come with ports for gauges, so you just run a small air line from the port to the gauge inside the vehicle.

The last type of valve is a manual manifold type of valve. These are rarely found in today's setups since the introduction of electric valves. They are not as fast as electrics of comparable size, and also may require come cleaning over time to keep them working properly. These valves use no electricity and are operated by toggle or momentary switches that are connected to the airline. One challenge with these valves, is running the airline into the cab of the truck, then back out to the respectable corner of the truck.

Air Springs

Here they are, the air springs. They are made of either rubber or a nylon compound. Extreme care must be taken when mounting them they have a clear unobstructed path of travel. If not, they will get worn and will get a hole in them which cannot be repaired. You will have to replace the spring. Many of the FAST FAST bag systems use dual, and quad port airbags to maximize the amount of air flow traveling to the bag. Standard setups use single port bags, and even then, you can still hop the vehicle depending on what the rest of the setup on the vehicle is.

The amount of travel you will receive from a bag varies from bag to bag, and manufacturer to manufacturer. They come in many sizes from many different manufacturers, so you have a wide range of options available to you. The amount of travel is also called the bag's stroke. Every bag also has a maximum pressure, as well as well as a capacity rating at that pressure. These figures should not be ignored. For particular numbers on bags, take a look at the fact page here at airridetalk.com.

Switchboxes

One of the more common switchboxes used today is the 10 switch box. It has a total of 10 switches, which perform a total of 20 actions. Each switch is a momentary toggle switch. After being pushed one way, it automatically returns to the center (off) position.

There are also different types of boxes made by AVS and EAI that have push button switches, rather than toggle switches and are easier to operate. The downfall to these is that they do not have as many functions as the 10 switch box.

Bracketry

Different types of vehicles use different brackets. Many cars use struts, while most trucks use custom made brackets. Shown to the left are a set of cups for mounting the air springs on the front of a full size truck. These cups are fairly easy to make yourself, but for the installer who wants a pain free install, they are available premade from many popular air ride retailers.

Some front mounts are bolt in, and some are 'free floating', as they don't bolt to the frame, just to the air springs. I've used both on my truck and the only difference you could possibly notice is that the free floaters will 'pop' into place if you air up the vehicle from 0 psi. This isn't a bad thing, but some people dislike it.

Rear mounts are normally all weld on. Kits can be bought from just about any air ride retailer, or you can make your own if you have the time and patience.

Fittings

There are two types of fittings used in todays air ride systems. The first, shown to the left is the Push-To-Connect, or PTC fitting. You simply thread the fitting into the port of your air tank, or air spring, or wherever else, and simply push the airline into the fitting, then give a small tug to secure it. They are very reliable if installed properly and make disassembly of parts easy.

The other type of fitting is called a compression fitting. There are 4 parts to this fitting: the body, a ferrule, a sleeve and a nut. The body is threaded into the port. The ferrule fits inside of the fitting, and the tubing fits over the ferrule. The sleeve fits over the tubing and then the nut fits over the sleeve. It is then all pushed together and the nut crimps the sleeve which tightens the air line around the ferrule, thus securing it. Installation of these can be somewhat more challenging, but when installed properly, they will be leak free forever.

The compression fittings that you can buy at Home Depot or Lowes in the plumbing department ARE NOT the fittings to use. You should use DOT approved fittings on your air suspension, as they are made to better tolerances, and conform to tests that hardware store fittings are not. Regular brass fittings such as nipples or tees are fine from hardware stores, but you may find them cheaper online.

Gauges

Gauges come in many different varieties and sizes. Shown to the left is a 200 PSI gauge from KP Components. Most gauges have a small light behind them. You can get gauges in single and dual needle configurations. Traditionally, two dual needle gauges are used for air springs, and one single needle gauge is used to monitor the storage tanks. If you only decided to get one gauge, make it a single need to monitor the storage tanks.

If you install an adjustable pressure switch, you WILL need a gauge to determine what the cut in and cut out pressures are to make sure you don't over work your compressor, and you also need a gauge on the tank so that in case you end up with an electrical short on your compressor, it doesn't keep filling past the pressure switch cut off. I have seen quite a distaster when a pressure switch stayed closed and the compressor kept filling. The tank reached upwards of 400 psi before the tank split and blew open.

Electrical

The system wouldn't work without electricity. The valves, compressors and gauges depend on it. Here are a few things that you will need when wiring your vehicle for air ride:

Relays - Relays allow you to turn the compressors on and off with the pressure switch. Pressure switches are not made to handle high current flows that the compressors use. A relay has a small circuit built into it, that when activated, closes two contacts inside, thus turning on your compressor. If you are running a compressor that pulls 30 amps or less, you can use a simple automotive relay found at many auto parts stores and radio shack. It looks like a small box with 4 or 5 prongs on the bottom of it. Another type of relay is a solenoid. Starter solenoids like from the auto store should only be used if they are continuous duty. It will say that on the box if they are. Otherwise you can look into car audio solenoids, like that from Stinger. They make an 80 and 200 amp model. The 80 amp model will easily handle any two electrical compressors you put on it.

Wires - For wiring up compressors, you should use no less than 8 AWG wire. Switchbox to valve wires can be 18 AWG wire. I like using speaker wire because it is paired, so one wire can be used for the fill valve, and one used for the dump valve. If all of your valves are in one place, you can purchase some '9 wire' cable from any car audio shop and run a single cable with 9 wires in it to your vavles.

Connectors - Some people like to solder and tape up connections. I prefer to use connectors, incase things need to come apart in the future. You can find a wide variety of connectors are your local car audio shop, hardware store, or electronics store.