How to Choose the Correct Replacement Air Spring
Many air springs appear to be similar in design and size at first glance. However, differences in the manufacturing techniques used for similar looking air springs may create substantial differences in operating dimentions. Specifically, the inflated (or operating) diameters of seemingly identical air springs will vary depending on the angle of the reinforcing fabric used in the flexible member.
CAUTION: Numbers molded on the rubber bag (flexible member) are NOT the assembly part numbers. Bags with the same numbers are used with different combinations of top and bottom metals. They may or may not have an internal rubber bumper.
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Start with the orginal equipment or aftermarket part number. It is usually located on a label affixed to the top of the air spring. Once located type number into our search box located at top left of our site.
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If the O.E. part number or aftermarket part number is unknown you should begin your search with the bellows number. The number is molded into the rubber part of the air spring. Get the bellows number and with the air bag handy and give us a call to help determine which bag you have.(1-813-933-1166)
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Measure the width of the top plate and make a note of the bolt pattern or taps.
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Measure the width of the piston or bottom bead plate and make a note how the bolt pattern is oriented compared to the bolts on the top plate (Inline or Rotated). The view of this orientation should appear as if you are looking directly through a clear drinking glass from the top to bottom.
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Measure the height of the air spring with no air pressure from the top plate to the bottom of the piston. This is the extended height.
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Compress the bag as far as possible with no air pressure and measure the height. This is the compressed height or minimum height.
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Measure the distance from center to center of each bolt on the top and bottom of the air spring.
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Determine style of air spring. Bellows or Bellows Sleeve, Rolling Lobe or Rolling Lobe Sleeve. (see below for descriptions)
Air Bag Measurement Examples
PRODUCT DESCRIPTION
Bellows Type Air Spring
Bellows air springs have one, two or three convolutions in the flexible member. There are two styles of bellows; crimped design (shown here) and sleeve type (see below). With the crimped design, the end retainers are permanently attached mechanically crimping the retainer around the built-in bead wire of the flexible member.
Sleeve Type Bellows Air Spring
Sleeve type bellows offer similar characteristics to the crimped design bellows, but, as with the sleeve type rolling lobe, the flexible member is constructed without internally molded bead wires. The end retainers are permanently attached pinching the flexible member between the end retainers and external crimp rings which are than swaged to the proper diameter. Sleeve type bellows offer the lowest force to compress of any type of air spring.
Rolling Lobe Air Spring
Rolling lobe air springs incorporate a piston which allows the flexible member to roll along the piston’s surface as the forces change.
Sleeve Type Rolling Lobe
Sleeve type air spring are similar to the rolling lobe air springs except that the sleeve type assemblies employ a flexible member without an internally molded bead. The flexible member is attached to the end retainers pinching the material between the end retainers and exterior crimp rings which are than swaged to the proper diameter.
For Goodyear Air Bags
PRODUCT INDENTIFICATION SYSTEM
Assembly Number
2 B 12 — 425
(425) These three numbers identify the specific end retainer,
air fittings size, flex member and bumper
(12) This could be a single or double digit number. It is the
nominal outside working diameter of the air spring
assembly, in inches. (it is NOT the maximum diameter)
(B) This letter refers to the type of air spring
B — Bellows
R — Rolling Lobe
S — Sleeve (beadless rolling lobe type)
(2) Number of convolutions in the assembly
1 = Single Convolute
2 = Double Convolute
3 = Triple Convolute
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