Thread: Air Spring Help

No reason why they shouldn't work for your application. I've long thought of converting my boat trailer for offroad use with air springs, just not high on my list yet.

Firestone are one of the better and larger manufacturer of air springs. They have engineering manuals with good design information that are available as pdf's online. PDF here

There are also books in pdf format that list a range of their springs with sizes for aftermarket use in trucks, etc. - the North American and European ranges are different.

All catalogues here note many pages of listings.

These are far cheaper to buy from the USA online.

Edit: Try starting here.

Originally Posted by Bush65

... I've long thought of converting my boat trailer for offroad use with air springs, ...

That is what I plan to do as well.

Originally Posted by isuzurover

That is what I plan to do as well.

Sorry for going slightly off topic.

Besides better ride from air springs on many kms of corrugations and being able to increase the ride height in rough stuff, my conversion would use larger wheels and tyres (same as tow vehicle) so the ability to lower the springs will help with launching on improvised ramps.

I was also planning to retain solid trailer axle but locate it with reversed (trailing) Land Rover radius arms.

I'm working on independent suspension.

Utilising a wishbone design with the air springs.

Also using design cues from Tatra's king frame.

Thanks for all the information.

David

Originally Posted by Bush65

Sorry for going slightly off topic.

Besides better ride from air springs on many kms of corrugations and being able to increase the ride height in rough stuff, my conversion would use larger wheels and tyres (same as tow vehicle) so the ability to lower the springs will help with launching on improvised ramps.

I was also planning to retain solid trailer axle but locate it with reversed (trailing) Land Rover radius arms.

That is pretty much exactly what I was planning too. I posted a thread on it a while back in the trailer or fishing sections.

david,
if you are building from scratch. Ignore independent in my opinion!
Run a good triangulated 4link or radius arm with panhard onto solid axle.
Cross axle load sharing and fixed camber and toe geometry outweigh by a long way an inde set up.
Inde are just popular and easily packaged, not necessarily the best way to do it.

Steve

Originally Posted by roverrescue

david,
if you are building from scratch. Ignore independent in my opinion!
Run a good triangulated 4link or radius arm with panhard onto solid axle.
Cross axle load sharing and fixed camber and toe geometry outweigh by a long way an inde set up.
Inde are just popular and easily packaged, not necessarily the best way to do it.

Steve

I agree pretty much with that. The best independent suspension I have seen for trailers is the "MC2" system on the army trailers and TVans.

Besides what Steve pointed out, most swing arm independent systems are too short, and show poor engineering in their design detail. Short arms create too much angle change at the spring seat for use with air springs.

Originally Posted by isuzurover

Originally Posted by Bush65

Sorry for going slightly off topic.

Besides better ride from air springs on many kms of corrugations and being able to increase the ride height in rough stuff, my conversion would use larger wheels and tyres (same as tow vehicle) so the ability to lower the springs will help with launching on improvised ramps.

I was also planning to retain solid trailer axle but locate it with reversed (trailing) Land Rover radius arms.

That is pretty much exactly what I was planning too. I posted a thread on it a while back in the trailer or fishing sections.

Ben, I'll have to have a search for your thread.

It was a good while ago when I decided to convert my boat trailer for off road use and those were my thoughts back then - It will still be some time before I get onto it.

Thinking of it again, before dropping off to sleep last night, I now think the disadvantage of radius arms with air springs is not worth their simplicity - I had radius arms laying around back then, but got rid of them before moving.

My thoughts are that it would be better to use a parallel 4 link + panhard system with air springs. This would not be very complicated in my case because I don't have to consider braking in the geometry.

Originally Posted by Bush65

I agree pretty much with that. The best independent suspension I have seen for trailers is the "MC2" system on the army trailers and TVans.

Besides what Steve pointed out, most swing arm independent systems are too short, and show poor engineering in their design detail. Short arms create too much angle change at the spring seat for use with air springs.


Ben, I'll have to have a search for your thread.

It was a good while ago when I decided to convert my boat trailer for off road use and those were my thoughts back then - It will still be some time before I get onto it.

Thinking of it again, before dropping off to sleep last night, I now think the disadvantage of radius arms with air springs is not worth their simplicity - I had radius arms laying around back then, but got rid of them before moving.

My thoughts are that it would be better to use a parallel 4 link + panhard system with air springs. This would not be very complicated in my case because I don't have to consider braking in the geometry.

Here are the threads I was thinking of:
http://www.aulro.com/afvb/trailers-v...t-trailer.html
http://www.aulro.com/afvb/trailers-v...er-tech-2.html
Though I also had a lot or email discussion with Steve / Roverrescue - who had plenty of great advice.

What are the disadvantages of RAs for a trailer? It is not like you need a lot of wheel travel...