Author Topic: Silly question: what do theair beams do exactly?  (Read 1115 times)

Offline Paladin

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Silly question: what do theair beams do exactly?
« on: January 18, 2008, 03:45:23 PM »
I know, dumb question but what exactly do the air beams do?
Now that I welded that plate over the hole that I had and tested it (it seems to be air tight) will I hold air better or get a better ride or??
Was it a waste of time to do?

'75 MC-8   'Event Horizon'
8V71  HT740
Salt Lake City, Utah

"Have bus will travel read the card of the man, a Knight without armor in a savage land...."

Offline Green-Hornet

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Re: Silly question: what do theair beams do exactly?
« Reply #1 on: January 18, 2008, 04:04:05 PM »
The air in the bag is pushed into the air beam to smooth out the ride. If there were leaks in the system and it was plated over, as long as the newer softer bags were installed the ride should be as smooth. That is my understanding of how that works.

Offline Hartley

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Re: Silly question: what do theair beams do exactly?
« Reply #2 on: January 18, 2008, 04:07:29 PM »
An air beam is a Buffer, That holds additional air pressure/volume so that sudden jumps or drops in air suspension pressure is moderated by the additional volume of available unrestricted air.

Like a shock absorber with a really large volume that slows down sudden jolts.

Shocks used on off road vehicles are usually much larger than normal so that they have the extra capacity to absorb large loads and still perform without transferring the shock loads to actual mechanical parts like axle fittings.

The airbag / airbeam system works in a similar manner.

Many coaches that originally had air beams that started leaking or were disabled now either have a different kind of airbag or a set of blocking plates to block off the section between the old airbeam and airbag.

By installing the blocking plates you are reducing the ability of the air suspension to moderate shocks, bumps and jolts and actually can make the ride a bit harder because more of the jolts are sent to he chassis.

Airbeams can be a bog problem due to rust issues either internally or externally. Moisture can get into them and rust them out from inside. It can also affect them from where body panels, flooring or other attachments might collect dirt and water or road salts. Usually by this time either some serious work is needed to repair the airbeams, Or the optional aftermarket blocking plates are installed and the air lines rerouted to the airbags directly.

Hope that helps....

« Last Edit: January 18, 2008, 04:09:15 PM by DrDave-Reloaded »
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Offline BJ

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Re: Silly question: what do theair beams do exactly?
« Reply #3 on: January 18, 2008, 09:31:57 PM »
they leak air...that is why MCI quit using them, many problems. just plate them and your problems are over..

Offline TomC

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Re: Silly question: what do theair beams do exactly?
« Reply #4 on: January 18, 2008, 11:17:22 PM »
The original air bags that were used with the air beams are called double convoluting (looks like the Michelin man) and are fast reacting-meaning they alone ride stiffer then is desirable for passengers.  To slow down the reaction time, the air beams were used to both increase the air volume of the air bags and to slow down the reaction time thus smoothing the ride out.  My transit bus has the same bags, but instead of air beams, each bag has an aluminum can that is of about 2 gallons in volume that effectively does the same thing as the air beams.
Now buses are equipped with rolling lobe air bags that look like rubber cylinders with a tapered aluminum piston on the bottom.  The piston acts like a load compensator so that for about the first 2 inches of travel there is very little reaction going on.  But as the taper of the piston increases, so does the load carrying capability of the air bag and it causes the air bag then to react quicker to push the bus back up like from a dip. 
The best way to compensate for plating over the air beams is to also change your air bags to rolling lobe.  Then you won't have any loss of ride quality.  Though many have said that the they don't mind the stiffer ride the plated over double convoluting bags give-your choice.  Good Luck, TomC
Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.