Pros & cons of air suspension.

[Martyn]

Has anyone explored the concept of using leaf springs that are rated nearer to the trailer's empty capacity and then used air-shocks that are used to supplement vehicle suspensions to take up the difference when adding load?

Seems like it would give you the simplicty of leaf springs with the benefits of airbags.

It's very feasible. Removal of the leaves of the spring so that it is just acting a means to locate the axle.

 

[ntsqd]

Bags have to be separate, if they are linked you get delayed compensation and unpredictable movement side to side.

Exactly what I was about to comment on.
Picture the trailer on a side-hill. With air springs plumbed together the downhill spring will slowly transfer it's volume to the uphill spring. If the side-hill gets steep enough that wouldn't be good!

Re: Gas charged shocks. The gas is there to keep the shock oil from foaming. The extension force exerted by the shock is only the cross sectional area of the shaft (usually far less than 1 inch square) multiplied by the charge pressure, so the extension force must be a fraction of the charge pressure. Even if it doesn't feel like it when you're trying to install them!
If it is too much extension force, reduce the charge pressure. After re-valving I give the shocks a small charge to keep things working as intended while I'm handling them, and then run them up to the intended pressure after installing them.

I'm still waiting for the first trailer to use the ride height setting switches used on some OE air spring systems.....

 

[R_Lefebvre]

On the con side of air suspension, don't they have a sharply rising spring rate? That's not so good for big bumps. Makes them much harsher.

 

[elcoyote]

On the con side of air suspension, don't they have a sharply rising spring rate? That's not so good for big bumps. Makes them much harsher.

Air suspension is great for big bumps, just ask Justin. :Wow1:

 

[Outback]

Here's a few photos of what I've done to mine so far. Even with shocks I still get it swaying a little side to side, so I'm in the process of having a swaybar put in to see if that will help. Other than that that you cant beat the ride off road plus since my tent is on top I can adjust each side to level out. And the great thing about independent is the clearance underneath.
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This is almost certainly a sign of to much weight behind the trailers axle. A sway bar will of course help but loading more weight further forward will fix the problem. The trailer needs more tongue weight.

 

[Martyn]

I'm still waiting for the first trailer to use the ride height setting switches used on some OE air spring systems.....

We have been testing one of these system out. It's not perfect yet for Off-Road conditions, but we are getting there.

It is one of the things we are working on to make the Oasis accessible for the disabled. The user will be able to lower the trailer when it's set up in camp, and then it will automatically lift back up to ride height when they are ready to drive off.

 

[G-force]

I just love you guys:wings:

Now i have all the info i need for my suspesion build. Hopefully everything is set for a build tread in mid september.

Thanks again for all your input.

 

[G-force]

Here's a few photos of what I've done to mine so far. Even with shocks I still get it swaying a little side to side, so I'm in the process of having a swaybar put in to see if that will help. Other than that that you cant beat the ride off road plus since my tent is on top I can adjust each side to level out. And the great thing about independent is the clearance underneath.

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Thanks for your pictures, 686 sahara. They are NICE!

That is a mighty fine trailer, you have there. Is that one home built?!? Hope that i can silently steal your swing arm design, for my trailer. With the possibility to adjust the arms, it is possible to get a perfect following trailer.

Many subtile details on that sweet build. Love it!!:wings:

 

[elcoyote]

The trailer is an Adventure Trailers Fargo, imported from South Africa by us circa 2003. We had axles built in the USA. Looks like the trailer has gone through a few mods to the nose box, side box, tent swap & water tank mod.

Nice independent arm build I must say. My recommendation for controlling the "sway" you are describing is to get a shock with a stiffer rebound valving. We went through multiple dampening scenarios in our own R&D. Also be sure that you are running your tire pressures up for the highway & street. A soft sidewall can result in poor handling as well.

 

[#686 Sahara]

The nose box has been modified with a 6 gl hot water heater on the left side (side vents ) with a quick connect faucet & shower on the right side. It has two 13 gl saddle tanks one on each side connected to a water pump that is plumbed on the inside, 1 5 gl nato can for reserve. I also carry 10 gls. gas in nato cans on the side plus 10 on the back of the jeep for that long haul.

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[#686 Sahara]

The trailer is an Adventure Trailers Fargo, imported from South Africa by us circa 2003. We had axles built in the USA. Looks like the trailer has gone through a few mods to the nose box, side box, tent swap & water tank mod.

Nice independent arm build I must say. My recommendation for controlling the "sway" you are describing is to get a shock with a stiffer rebound valving. We went through multiple dampening scenarios in our own R&D. Also be sure that you are running your tire pressures up for the highway & street. A soft sidewall can result in poor handling as well.

Thanks for the input on the shocks, Iwas thinking on the Rancho 9000's that you can adjust unless you know of something better would be appreciated. I do run the tires at max when on the street for better handling and easier towing.

Thanks Darren

 

[Martyn]

Thanks for the input on the shocks, Iwas thinking on the Rancho 9000's that you can adjust unless you know of something better would be appreciated. I do run the tires at max when on the street for better handling and easier towing.

Thanks Darren

Custom valved Fox shocks.

 

[comrad_zeelaagee]

seems to me that one srious consideration that was left out of the ocnversation is the simplicity and therefore reliability of leaf springs. don't get me wrong- the airbag systems look really slick and probably function just as nicely. however, i have seen photos of blown out bags- and that could create a serious headache when off the reservation and you don't have spares to handle the situation.

i have been considering a trailer build for a while now and have been weighing air/trailing arm, but first things first- i need to learn to weld.

saharah- that's a really nice looking trailer you have. some excellent design and thought went into that one for sure.

 

[UK4X4]

"i have seen photos of blown out bags- and that could create a serious headache when off the reservation and you don't have spares to handle the situation."

The weight of the trailer V's the rating gives me about a 2.5X safety rating,

2 off 2500lbs airbags- V's a weight of less than 1000lbs

leak ye maybe, I'd have to be trying very hard to blow one out as the rating is working pressure not max pressure.

A block of wood would suffice in a breakdown, leaks wise, I used slime in mine
just in case

 

[Martyn]

seems to me that one srious consideration that was left out of the ocnversation is the simplicity and therefore reliability of leaf springs. don't get me wrong- the airbag systems look really slick and probably function just as nicely. however, i have seen photos of blown out bags- and that could create a serious headache when off the reservation and you don't have spares to handle the situation.

i have been considering a trailer build for a while now and have been weighing air/trailing arm, but first things first- i need to learn to weld.

saharah- that's a really nice looking trailer you have. some excellent design and thought went into that one for sure.

There is an article on suspension on our web site that details the evolution of our suspension development. http://www.adventuretrailers.com/suspension.html

In the years we have run air bags I know of two complete failures.

The first due to the upper metal bracket breaking and puncturing the air bag. This was on one of the first trailers we built with air suspension and it had an off the shelf bracket. We realized the bracket wasn't up to off road usage and had our own design made out of 1/4" steel. The fix was an easy bolt on over the original bracket, but the owner had decided not to do the repair.

The second complete failure was on a prototype using the air bag shock combination. The air bag was intact but the shock completely blew apart as we had not limited the upward motion of the shock to within the use range.

I don't think you can fault the air bags for reliability. They are tucked up out of the way and it's hard for anything to get to them. It wouldn't be too difficult to build a protection plate if you were really concerned.

Instead of going the leaf spring route I'd suggest a custom valved Fox Coil Over with remote reservoir. We are building a trailer like this that is going to a customer in Angola. We also did a retro fit to spressomon's Horizon that's now owned by the Muskoka Foundation.