Ok, let's hear it.

M

9 volt comment about the spring rate is determined by the ride height is a very good observation.

You can modify this by adding a external volume to the air bag to make the rate softer (which is the same as increasing the ride height without actually lifting the suspension)

You could make the spring stiffer by partially filling the air bag with water or someting (same as effectivily decreasing the ride hieght to make the spring stiffer)

The biggest problem I see with airbags is that as you compress the bag the spring rate effectively increases. If you compress the bag in half you effectively double the spring rate. This means that as you get close to fully compressing the bag then the spring rate gets really heigh and impossible to compress. This is why they are difficult to use on a crawler - trying to controll the spring rate.

I think that to use air bags then you must release the air out of the bag as the suspension articulates so you can get full compression. And if you do this then you need some sort of controll system to run the thing and a big arse compressor to inflate the bags up again when the wheel exrtends.

What range rover has done with the new rangie is very clever.

Anyway got to go and do some work.

Later

Sam

It will be interesting to see if the new RR gets bashed becuase its indepentent all around. I hear that its suspenion flex is pretty good.

I have a bunch of EAS components (bags, compressor, valve blocks, etc.) and I was thinking about using them, but then I was like that is just stupid. :barf:

My thought was a big tank and an engine driven compressor would provide enough air to allow then to be independently adjustable at a pretty quick rate. Hit the switch it goes up, hit the switch it goes down, four two way switches on per bag.

I also tried to fit a pair inside of a 110 rear spring but there was not enough space for me to be comfortable with that.

Ron

What I plan on doing is use Firestone bags in pairs. One pair for the front, one for the rear. If they are joined in a 'T' then the bag getting the compression will force the air into the other bag causing it to be pushed downward a bit harder.

I also have a manual pneumatic valve system with guages that I can control ride height from the cab. The front will be treated as a seperate system from the back. (on the project truck that I mothballed there would be 4 different circuits, one for each bag)

My goal with the air springs is to have adjustable ride height depending on load. That is it. I actually don't mind the 'spring rate' as it were with the airbags, so I'mm not too worried about that.

This all originally started out as a Boge replacement air-bag idea, but when I realized the hassle in fabricating bracketry, not to mention plumbing, I figured that it would just be easier to eliminate the coils and basically the same amount of plumbing would run 2 bags instead of one central bag.

I have been in contact with a gentelman at Firestone who used to work for Dunlop in the '80's. He was the main developer of the system that LR used on the LWB's. He sheepishly admitted to me on the phone that Dunlop was not quite happy with the system upon delivery, and the problems they foresaw during development have been the ones that have plagued LWB owners for years. Oh well, at least I can learn from his mistakes.

More to come...

Michael

PS Now about the rockcrawling airbags for the Serious One......

This is gonna be good - Im glad to see some other people have thought about using these things.

The new range rover (as I have read about only) has independent suspension and air bags and what it can do is when its in "off road mode" is connects the two front air bags together and also the two rear air bags together so that it can fully articulate in a very similar way to a live axle rig where the wheel moving up levers the opposite wheel to move down. This could be used in a crawler application.

Theres a guy here in oz that has developed a fully independently controlled air bag system. Meaning hes got single airbags on each corner, each with a air solenoid valve that can either inflate the bag or release the pressure to atmosphere. The whole thing is controlled by a computer and powered by a 64cfm engine driven compressor (this is a realy big compressor - most small workshop compressors are only 15cfm). This thing has about 16in travel at each wheel and can fully articulate while maintaining equal force on each wheel. Its very impressive. Iv not seen it in person but Ive seen a video ofthis thing driving up some fairly difficult stuff with open diffs (it also has maxi drives as well- oh yea its a ranger rover "bush ranger") . The system works very well but it requires a fair bit of computing power to controll it as well as a really big arse compressor to drive it.

By connecting the two front (and rear) bags together (like the RR does and serious was saying) you can achieve the same full articulation with perfect wheel loadings while using a lot less air than the "fielder system" as described above but this brings a lot of problems in terms of roll stability.

Later

Sam

On the current RR it "self levels" if it is parked off kilter.

I am not really familar with what type of sensors it uses but if something like that could be acheived at a much faster rate that would be a good thing for what I would want it for. I think that would just be really hard.

The problem I see with the cross axle thing is that it would really work against you in a side hill situation. All the air would go to the bags on the top side, the exact opposite of what you want!

As far as what Michael is looking for, thats easy. There is a company out there now that has a manual valve block for the current set up. Have not seen one in person but what you are asking for sounds really easy if you had a manual valve block.

I would say take it one step further and give yourself manual control over each bag. Even if it is just a slowish air up or air down. I can think of so many situation where something like that would have helped me out. I wonder if the principles used in the central tire inflation systems would be of any use.

Ron

OK you guys have a think about this.

What if you had two aribags on each corner side by side (ie 8 airbags in total) . Then you connected the two of each of the fronts together, two of each of the rears together, two of each of the left sides together and two of each of the right sides together.

Sort of like this


oo----oo
l...........l
l...........l
l...........l
l...........l
oo----oo

where the " o " are the air bags and the lines are the inter connections and the " . " are nothing and are there cause this editor keeps removing my spaces????

So tell me would this make a bitchen system or what!!!!!!!

Think about it. I think it would work very well but it does have a bad stability limitation that could be overcome. (meaning that if you drive steep up or down hill then when you get to the limit you will end up on your roof very easily (much more suddenly with this setup than if you had coils))

Sam

Woah,

Now you guys have thought this out way more than I have. For the sake of simplicity and actually getting it done, I'm going to stick with the basics.

There are a lot of different ways to skin a cat. Once I've gotten this cat skinned (woah) I'll maybe (big MAYBE) go on to figuring out more air suspension stuff. I have a strong suspicion (sp?) that once the 145 is done I'll be done with fabricating trucks for a while.

Have you guys decided which bags you're going to use? I have, but am stuck in the 'fabrication of the adapter plate' stage.

Get the Firestone catalog. It's a good one. I also have an engineers guide that was written by Firestone. Lots of theory and math, so I just skimmed through it.

Later,

Michael

well I damn near got shot for suggesting this on EE awhile back when dweb was down.

helwig makes air-bags that goes inside the coil spring of a ford f150 to help carry snow plows better

its about 2" taller then a disco spring

if you put outboard front shocks on the front to get the longer shock

you could then put a bag at each corner.

using the air brake valves from big rigs and a few cheap presure regulators you could easily build a system that would give you vairable ride height ,forced articulation, off camber leveling

....could be very cool

Or just use a standard air ride suspension stuff.

There is one in the June four wheeler on a Ram that is completely air sprung.

Firestone bags, individually controlled, four compressors and two tanks (hows that work?)

Neat little read out for the pressures with switches. Timely article for this discussion but done in the traditional magizine way.

Ron

you can buy a bolt on kit for TJ's now....http://www.offroadonly.com/airock.htm

The easiest way that I found to allow for forced artic, and individual control is this:

place a solinoid on each bag, so you can let each one down individually (only requires 4 swithces) I would then plumb the feed lines to each bag through a "block" that would be in the cab. This would be plumbed so I could fill any one bag, and could tie and adjoining bags together. If anyone is interested, I can supply a diagram of the block's plumbing.

I would use all manual valves for the block, and would supply the system with a York A/C compressor converted for air, and a 5gal. tank.

I had planned on doing this before I got my unimog.

You got the right idea here. I was thinking of using simply a Peterbilt seat adjustment panel that has four (two way spring return to center) air switches for individual bag control. Of course it wouldn't be much to add two solenoids per bag for more fancy elect control!

Michael, I can see a potential problem with connecting the two bags. I know you're thinking along the same lines as our Air lift helper air bags (inside the coils) but these bags are very low duty. Meaning they can easily pop if you didn't equalize the air pressure during tire stuffage. However, if you did the same thing to Firestone bags, then there exists a possibility of bottoming out the bags. These Firestone bags require a min amount of air to prevent this I'd think.

As someone said earlier, springs rates are harder to control when fully compressed. However, having an accumulator (air tank) for each bag might alleviate this situation. I mean very small units, like the ones you see in Low rider vehicles. But, for Michael and I, who are mostly interested in load carrying/road worthiness, controlling each bag with a pneumatic switch (or solenoid valves) sounds totally doable.

The bags that are used in www.offroadonly.com TJ is 1T26D5. Darn if I can find this bag anywhere. So Michael, see if you can find it through your sources. I played with this TJ during Easter Jeep Safari week and let me tell you it's neat! By pumping all bags up to max, then letting the driver side completely deflate, I was at an angle of 15degrees! This can come in handy in those off-camber positions with a roof rack full of stuff and high APF. These bags don't come apart due to the internal construction from what I can tell and stretched a loooong way.

Sorry for the long winded note.

Ali

I forgot one more thing, the owner of www.offroadonly.com showed keen interest in developing system for our rigs. He is desperately seeking some pics of our springs perches and shock mounts currently. So if you guys got any handy, send them his way.

Thanks.

Ali

Michael,

Since your in Portland, there is a local guy that has perfected the airbag setup. Last time I saw it you could control each corner from in the cab.

His name is "W" and owns Over The Hill 4x4 in St Johns.

Here is a pic of his landcruiser:

http://www.overthehill4x4.com/webpics/suspension2.jpg
http://www.overthehill4x4.com/webpics/suspension3.jpg

<a href=http://www.overthehill4x4.com>Over The Hill 4x4</a>

-Justin

Originally posted by alia176
However, if you did the same thing to Firestone bags, then there exists a possibility of bottoming out the bags. These Firestone bags require a min amount of air to prevent this I'd think.

Some appropriately placed bumpstops should allievate this.


I played with this TJ during Easter Jeep Safari week and let me tell you it's neat! By pumping all bags up to max, then letting the driver side completely deflate, I was at an angle of 15degrees! This can come in handy in those off-camber positions with a roof rack full of stuff and high APF.


Ya, it makes it much easier.....http://bc4x4.com/fv/2000/ben/ben-21.jpg

This guy up in B.C. canada has a sick little 'zuki, with air.
http://bc4x4.com/fv/2000/ben/ben.cfm

now thatS awsome!

off camber where?





I like the air seat four switch idea...have to check that out

Oh yeah W has a trick rig. I've seen it out a couple of times and it'ss cool.

I haven't been up to his place, but I live really close and get to St. Johns quite a bit. I'll have to stop in.

The Firestone bags have an internal bump stop to prevent bottoming out when the bags are completely deflated.

I sent Way some pics of my RR now with the RTE springs.

M