Questions You Should Know about Semi-Trailer Air Suspension Solution

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If you’re looking for the smoothest ride for your trailer or tow vehicle, an air bag suspension is a good place to start. There are other suspension springs that cost less and require less maintenance such as the Timbren SES Suspension Enhancement System. But airbag suspensions have proven to be one of the best alternatives to conventional leaf and/or coil suspensions.

Listed below are answers to common questions about air bag suspensions.

What Is an Air Bag Suspension?

Air bag suspensions were first invented in the early 1900s. Ever since then, European and American inventors have continued to develop air bag prototypes for cars and trucks. 

Basically, an air bag suspension consists of a compressor, rubber bags (typically made from reinforced rubber) and a system to regulate the air compression. There are essentially two types of air bag suspensions designed for the automotive aftermarket:

Sleeve-style

A sleeve-style air suspension uses an internally mounted sleeve that inflates inside a rubber spring. The air inside the sleeve lifts the vehicle to the desired ride height.

Bellows-style

The bellows-style air suspension makes use of air bellows made of heavy-duty rubber. They can carry more weight than sleeve-style air bags and are usually designed with two or three convolutions.

Image by TheCarColony

How Does an Airbag Suspension Work?

Most vehicles that leave the factory are equipped with a suspension made of metal springs, either coil or leaf. Airbags are an alternative to metal springs, sometimes installed at the factory but quite often retrofitted as an aftermarket product.

As we’ve already mentioned, air bags are either rubber sleeves or heavy-duty rubber bellows that are installed at each of the four corners of the vehicle. In order for them to work properly, an onboard air system – compressor, dryer and reservoir – adjusts the air pressure to help maintain proper ride height and optimal ride quality.

What Is the Purpose of an Airbag Suspension?

It doesn’t take a rocket scientist to figure out why a car or truck needs a suspension. But why would anyone want to use an air ride system? There are plenty of other suspension systems that don’t cost nearly as much as an airbag suspension.

First of all, an airbag suspension is adjustable. You can lift the vehicle or lower it to suit your purpose. Secondly, it will keep your vehicle level under load. Today’s airbag systems come equipped with sensors that open and close height-control valves when the air pressure needs to be adjusted.

Lastly and most importantly, an air suspension helps maintain good ride quality, particularly when a load has been added to the suspension. Most vehicle owners purchase an airbag suspension so they can enjoy a soft, smooth ride.

How Much Does an Airbag Suspension Cost?

There are 3 issues you need to look at when considering the cost of an airbag suspension. For our purposes, we’re going to examine airbag suspensions designed for the automotive aftermarket. The issues are:

1. Cost of the product over the counter

Depending on which system you want – helper springs to assist your existing suspension, or a complete system retrofitted for both front and rear - the average cost of an airbag suspension can range anywhere from $500.00 US – $1500.00 US. depending on which system you purchased.

2. Cost of installation

The installation can run anywhere from $500.00 US for a simple helper spring kit, and up to $1500.00 US for a complete retrofit for front and rear.

3. Cost of maintenance

Sometimes air bags leak and need to be replaced. The cost to replace an airbag sits somewhere between $1400.00 and $1500.00 US.

How Do You Install an Air Bag Suspension?

Pretty much all types of air suspensions are similar. Most of them contain air bags, air struts, air lines, a height sensor and an air compressor. Here’s a very condensed version on how to install an air bag suspension…

*Warning: Air ride systems use compressed air. Always wear proper eye protection when working with an air ride system.

Part 1. Remove old components

• Using a jack, lift the vehicle and secure it on jack stands


• Remove rear coil springs and front struts


• Remove the spare tire from the trunk

Part 2. Install the air suspension

• Install the rear air springs in place of the previous springs


• Install the front air struts


• Install the air compressor and air tank in the trunk where the spare used to be


• Wire up the compressor for air and power: power to run the compressor comes from the battery; air lines run from the compressor to all four corners of the suspension.


• Check the entire installation and setup for proper connections, making sure the vehicle maintains proper ride height and there are no leaks in the system

How Do You Set Up an Airbag Suspension?

This section is not intended to be an instruction manual for the installation of an air ride system, just an overview of what is involved in the setup.

There are 5 necessary components that make up an air suspension: The compressor, the tank, the airlines, the fittings and, of course, the air bags. Let’s take a look at how and where each component could be configured.

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The compressor and the tank are often mounted side by side in the trunk of the car. Depending on the size of the tank and the plate that is meant to house both compressor and tank, you may need to customize the plate to make it work.

If you have a truck, you will more than likely want to position the compressor plate on the inside of the frame under the vehicle. Again, some customizing may be necessary.

The airlines run from the tank to each of the airbags.

The fittings are designed to give the airlines a snug connection to the tank, the compressor and the airbags. It’s important that there are no leaks.

The instructions that are included with your purchase will show in greater detail where each airbag should be situated. Mounting the compressors and running the airlines is a matter of personal preference.

How Do You Adjust an Air Bag Suspension?

You can adjust the ride height of an air bag suspension either manually or digitally depending on which air bag system you have on your car or truck.

Manual Adjustment.  In order to adjust the ride height on a class 8 semi, simply loosen the adjusting rod attached to the height control valve. Move the rod down to decrease the ride height and move it up for an increase. After the correct height is attained, tighten the rod into place to prevent the adjusting rod from moving.

Digital Adjustment. Today’s cars and trucks have high-tech air-ride systems that can be operated by a hand-held controller. Simply follow the steps outlined on the owner’s manual to preset the various digital settings.

What Are the Advantages of an Air Bag Suspension?

There are 2 main advantages to using an airbag suspension:

Comfort

More and more, car and truck manufacturers are doing away with conventional springs (coil and leaf) and turning to air bag suspensions as an alternative. Doing away with old-school springs allows for a much smoother ride, something you can’t get with metal springs. Because after all, you are, quite literally, floating on a cushion of air.

Flexibility

Is ride height an issue? Do you want to ride low-to-the-pavement at certain events but avoid the danger of speed bumps and potholes? No problem. An air bag suspension can give you the best of both worlds. With the flip of a switch, you can adjust the ride height to meet your traveling needs.

What Are the Disadvantages of an Air Bag Suspension?

Before you decide to purchase an air bag suspension, there are a few negatives you should be aware of:

Installation

The main obstacle you will encounter with an air bag suspension is its complexity. Unfortunately, you will need to drill holes to mount the compressor, manifold and tank. Unless you’re up for a challenge, you may find the combined setup of electrical components, airlines and compressors a bit above your pay grade. Also, 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

Another major obstacle is cost. Without including labor, you’ll be looking at a couple thousand dollars plus on-board air parts. If you decide to install it yourself to save on labor costs, there are quite a few components in the box. Unless you’re a professional or at the very least, a DIYer, the task is probably above your pay grade. Therefore, you’re probably looking at the additional cost of installation.

Maintenance

If you’re looking for a system that’s low maintenance, an air bag system is one that you’ll want to avoid. Warning: Don’t go there! You will find that there are too many components to keep an eye on and too many potential problems that could arise at any time.

How Do You Patch an Air Bag Suspension?

Most of the time, problems with your suspension will relate to loss of compression, i.e., you have an air leak somewhere in the system.

Here are some obvious signs your air bag suspension has a leak:

o A small leak in the rubber bladder. Spray each bladder with water and watch for bubbles. A leaking bladder (air bag) will have to be replaced.

o Hose fittings aren’t connected adequately. Replace bad fittings as necessary.

o One of the hoses has a hole. Use a patch fitting that fits the size of hose in question.

Check the air compressor to see if it has failed or is about to fail. If the compressor isn’t working, figure out why. Using a digital multimeter, check that the compressor has power and is properly grounded. Finally, check for problems with the air suspension compressor relay.

Summary

Hopefully, the questions and answers listed above have given you a better understanding of the airbag suspension system: 

• What it looks like


• What it does


• How it works


• What it costs


• Installation


• Setting it up


• Adjustment


• Advantages


• Disadvantages


• Patch & repair

For a simple and less-costly alternative to air bags, check out the Timbren SES Suspension Enhancement System.

If you are looking for more details, kindly visit trailer spare part manufacturer.