Michigan Truck Spring
This video demonstrates how to identify and measure W02 type air bags
How To Identify and Measure a Sleeve Spring Air Bag
Sleeve style air bags are smaller than your typical air bag and are used in a variety of applications. The smaller diameter of this type of air spring allows them to be used in tight spaces. They are used under seats in busses and semi-trucks to provide a cushioned air ride, as isolators for truck cab suspensions and for small truck and car load support applications. You can also find them in plants and factories across the world as isolators and actuators in industrial applications.
The sleeve part of the spring is a heavy duty flexible rubber or synthetic rubber compound. The sleeve design allows this type of air bag to be constructed with a smaller overall diameter than other types of air bags. The rubber is crimped into the spring end retainers on one end and swaged onto the opposite end, sealing the contents inside. When compressed air is forced into the spring, the two-piece sleeve extends, lengthening the assembly to achieve the desired ride height.
How to Identify a Sleeve Style Air Spring
1: Locate the Part Number on the Air Spring.
Brands like Firestone Airide Air Springs have a yellow sticker on top of the air spring. If this is still present, locate the part number on the sticker. Firestone uses a metal band on their sleeve style air springs and most of them will have part number stamped into this metal band. It may take some cleaning but if it is present, it is the easiest way to identify which part you are replacing. The number will start with W02 and have 6 digits, example W02-358-7205.
2: Measurements
With the air spring deflated, measure the extended and compressed height. You can use these dimensions and filter the results to the ones closest to your results. The images on our website of the sleeve air springs also show these dimensions.
3. Cap Number
The cap is the top of the air spring. You can narrow down the results and confirm you are selecting the correct part by making sure your cap number matches the cap number of the part you are ordering. The cap will have 2 sets of numbers on it, the NBD number and a 4 digit cap number, ex. Air spring W02-358-7205 has cap numbers of NBD-15430 and 6987. These numbers reference the cap only and are not the part number of the replacement assembly. There are multiple springs that use the same cap number, but by determining which cap you have will narrow down the results.
4. Piston Number
The piston is the bottom of the sleeve air spring. It will have 2 numbers, similar to the top of the spring. Ex. Air spring W02-358-7205 has piston numbers of NBD-15431 and 6986. If you have the cap and piston numbers of your spring, you can greatly narrow down which part is the correct replacement.
5. BCR
BCR stands for Between Clamp Rings. This is the measurement between the top metal ring and the bottom metal ring. You will have to expand the air spring to obtain this measurement. Please note, the BCR measurement on a used spring will typically be a little shorter than noted on our website and in Firestone’s catalog.
6. Logo Color
Firestone uses different logo colors on some of the sleeve style air springs. This is very useful in narrowing down which replacement part you will need. By getting the cap, piston numbers and logo color you can narrow down the results to a couple of springs.
7. Applications / Cross References
Some of the W02 sleeve style springs will list common applications that the part was used in. This is a good confirmation that you are selecting the correct part. Many of the parts will also list a cross reference part number to the manufactures number.
At Michigan Truck Spring we stock the common and the hard to find cab and seat air springs. We warehouse the parts, have an extensive knowledge of these products and install them in our service department. If you are having difficulty finding the correct replacement air spring for your application, feel free to contact us.
The Components of Sleeve Style Springs
1.) Combo Stud - Combination mounting stud and air fitting.
2.) Blind Nut - A blind tapping hole in either the piston or cap
3.) Air Fitting Hole - When using a blind nut or stud instead of a combo stud, a separate air fitting is required.
4.) Clamp Plate - Also called the “Cap”, this is the upper aluminum or plastic end. This provides the mounting hardware, and normally the air fitting.
5.) Bellows - The heart of an air spring is the sleeve, or bellows.
Firestone's are made of four layers: an inner liner of rubber, two plies of cord reinforcement, and an outer cover.
6.) Piston - The lower end of the assembly that the rubber rolls over is called the “piston”. This is also made of either aluminum or plastic. It provides the lower mounting hardware for the assembly.
7.) Clamp Ring - These are the metal rings used to permanently attach the bellows to the clamp plate and piston.