Light Duty Truck Air Ride Suspension

F550? Light Duty? Okay, maybe in some part of the truck world, that is light duty. I haven't done business with any of the suppliers you named, or ever owned an F550.

I have fitted cars and house trailers with auxiliary air suspension, and I have come close to buying cars with primary air suspension, and as always (ask around), I have something to say.

The bags themselves seem to come from just one or two suppliers. On cars, they work great, but seem to have a service life of just a couple of years. This is a deal- killer in cars, as has been proven in several generations. I do not seriously believe that there's anything special about the larger bags used on trucks and truck trailers, except the size. ... and maybe that makes a difference.

I took a serious look at rolling diaphragms for small pumps some time ago. For those devices, equations exist that can predict the service life with reasonable statistical accuracy. In my application, the stroke was equal to the mean diameter, and the predicted lifetime was 10,000 cycles, which I verified by actual test.

In cars, the stroke required of an air suspension bag is nearly equal to the diameter.

In trucks, the stroke required of an air suspension bag is considerably less than the diameter. If the governing equations exist, and are similar to those for rolling diaphragms, one might expect a lifetime considerably greater than for car air suspension bags. Or maybe the trucking industry is willing to tolerate a finite lifetime, provided it's predictable, and replacement is relatively easy. ... Nah.



Mike Halloran
Pembroke Pines, FL, USA