How to deflate air bags.

Kristinsgrandpa · August 17, 2006, 06:45:11 PM

I recently bought an air operated 20 ton jack and want to see if it will slide under the coach with the air bags deflated. If it won't then I am going to buy a shorty jack while they are on sale.

I have been waiting for about 2 months now and the coach has only dropped about a half an inch. I have to start it up to position it for genset insertion which will re-elevate it.

I'm hoping there is a valve somewhere to deflate all the bags at once.

Oh... the coach is a 1988 Neoplan AN340

Thanks in advance, Ed.

NJT5047 · August 17, 2006, 07:09:19 PM

I'lll hazard a guess...What about air tank drains? Or a water drain on the compressor outlet line? Does the dash air gage show system pressure?
Amazing that it won't leak down. That bus is special!
I would think that draining the air tanks would cause the suspension (doesn't have Torsilastic suspension does it? That ain't coming down) to exhaust.
Get your awning hook and pull the drain loops on the air tanks...does a Neoplan have air tank drains? Find any air tanks and look for a small valve with a loop hanging near the bottom of the tank. Chock the wheels before you try this.
If all else fails, you could let the air out of a steering axle tire and see how low it will go.

Cheers, JR

Busted Knuckle · August 17, 2006, 07:25:07 PM

JR the idea of letting the air out of the tire is actually probably the best scenario ! After all most of the time someone needs to jack a coach up is for a flat tire and if it's not broke down you can start it for air for the suspension! Now OTOH most air suspension systems have a oneway valve that does drain the air bags when the tanks are bled off, and the bags themselves have to bleed off ! It is unusuall to find one that holds air that long but still possible ! I wish I knew a safe way to suggest, but I CHEAT and pull 'em over the pit and disconnect teh ride height linkage and manipulate it to drain the valves! Which gives me another idea ! Ed go ahead and jack up the body now and once you get it up some it will cause the bags to deflate, if you have 2 jacks after jacking the body you can jack up the axle to be sure you can get the body jack back out once the air is deflated, and you let it down! Then if the axle jack is stuck under there just place a board or block under the tire and get the jack out ! hey more than one way to skin a Neoplan! BK

akbusguy2000 · August 17, 2006, 09:35:20 PM

I the jack will slide under there with air bags and tires inflated, I wouldn't worry about it. Make yourself a run-up block that'll give you a 4 or 5 inch lift. Run up on the block and the jack should go under there OK. The only situation where you might encounter a problem would be if your wheel is sunk in soft ground - and your jack is just about useless in this situation anyway.

tg

kyle4501 · August 18, 2006, 05:16:06 AM

If it is a radial tire, Be carefull about letting it go flat. Over flexing the sidewall like that can (not will) cause sidewall belts to break loose from the rubber, take a permanent set, or just break. If that happens, its just a matter of time until the tire fails (think blow-out).

I have a tire on my bus that went flat. It has a flat spot on it now that was still there after 100 miles. I'm replacing that tire before any more trips.

But, as has been said "Do it your way"

sommersed · August 18, 2006, 09:40:21 AM

Let the air out of all tanks then jack up a wheel. The Bus (Coach) will try to adjust to the "too high" condition by letting out air from the bag, and there will be no air to refil!

Busted Knuckle · August 18, 2006, 10:02:52 AM

Quote from: sommersed on August 18, 2006, 09:40:21 AM
Let the air out of all tanks then jack up a wheel. The Bus (Coach) will try to adjust to the "too high" condition by letting out air from the bag, and there will be no air to refil!

Sommersed you have almost hit the mark in a perfect way except you would need to jack up the body after draining all the air! As jacking up one wheel would result in an under inflated air bag condition and it would try to fill the bag instead of trying to deflate it ! When a wheel or axle goes up in relation to the body the air bags fill to raise the body, when the body goes up in relation to the wheels/axle the bags deflate to return normal ride height ! Great therory just in reverse of actual action ! Thanks for your idea, it is a great idea when in the used correct way! BK

Kristinsgrandpa · August 18, 2006, 07:06:38 PM

Thanks for all the ideas, I guess playing with the leveling valves is the best way, I can reach them with a rod or a hoe handle. If I had an ol' lady I could put her under there. (Angelina Jolie is taken already so I guess I'm doomed to be a bachelor.)

I should have thought about the levelling valves because if it isn't parked level it goes down in a week or so. This time I parked it I levelled it.

As for letting the air out of the front tire, I guess that would tell me exactly what I'd like to know, but to save some time and trouble I'll just measure the sidewall and subtract that froim the available space I have now.

Neoplan put steel skids underneath it so that it won't go all the way down, which is nice, but it worries me about high centering.

Thanks again to all.

Ed