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Firestone Air Springs Catalog - MRO Stop

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Buy Online at http://www.mrostop.com/products/pneumatics/air-springs/firestone-air-springs.html<br />

<br />

AIRMOUNT<br />

VIBRATION ISOLATION<br />

Up to this point, only the weight and disturbing frequency have<br />

been discussed. THERE ARE MANY OTHER IMPORTANT<br />

CONSIDERATIONS:<br />

CENTER OF GRAVITY<br />

An <strong>Air</strong>mount isolation system is inherently soft (easily deflected);<br />

therefore, precautions must be taken to insure that the<br />

system is stable. First, consider the location of the center of<br />

gravity (c.g.). Ideally, the <strong>Air</strong>mounts should be located on the<br />

same plane (parallel to the ground) as the center of gravity.<br />

Where this is not possible, follow this guideline: The distance<br />

between the most narrow mounting points should be at least<br />

twice the height of the center of gravity.<br />

Height 48"<br />

Width 46"<br />

Length 50"<br />

LATERAL RATES AND STABILITY<br />

Single and double convoluted air springs SHOULD BE USED<br />

AT THE DESlGN HEIGHTS GIVEN, because that is the point<br />

of maximum lateral rate or stability. The lateral rate decreases<br />

as the <strong>Air</strong>mount height decreases. Consider a #22 again at<br />

80 psig:<br />

Height Lateral Rate Vertical Rate<br />

9.5 inch (design height) 325 lbs/in 1,373 lb/in<br />

8.5 inch 212 lbs —<br />

In the above example, the most narrow distance between two<br />

<strong>Air</strong>mounts is 46 inches The height to the c.g. is 48 inches;<br />

therefore, this system does not meet our guideline. Two possible<br />

solutions would be:<br />

1. Increase the base dimensions to meet our guideline by<br />

increasing both the width and length to at least 48 x 2 or<br />

96 inches.<br />

2. Locate the <strong>Air</strong>mounts at the c.g. as shown above (in the<br />

next column).<br />

7.5 inch Unstable —<br />

Notice that the #22 becomes unstable in the horizontal or lateral<br />

direction when moving down only two inches from design height.<br />

Buy Online at www.<strong>MRO</strong><strong>Stop</strong>.com<br />

23

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