spring shackle design question

[angib]

Chris, that "C" notch is quite a neat way to get a few more inches of clearance

Also an excellent way to remove a lot of the strength of the frame..... I guess welding in the really thick-walled half-pipe gets some of the lost strength back, but not much.

Mind you, I don't think there is that big a load on the frame at that position.

I think it would be simpler to make up a trailing arm airbag suspension with the two end 6" of the current axle (plus spindles, brakes, etc) cut off and welded to the trailing arm to re-use them. But it's still a major exercise.

[48Rob]

48Rob wrote:Chris, that "C" notch is quite a neat way to get a few more inches of clearance

Also an excellent way to remove a lot of the strength of the frame.....

Andrew, I kinda wondered about that...
No matter, I have plenty of room, no need to remove part of the frame.

I'm actually excited now, after doing the math, this modification will net me 2 extra inches, giving me 73 inches headroom (my original goal).
The lowest part of the trailer will ride 8+ inches off the ground, and when lowered at camp or for storage, no step is needed.

Cutting and reconfiguring all the existing parts may be the best way to go, but being able to adapt/modify what I have is looking good too.
I suppose once I get a better understanding of all the systems I may ask myself why I didn't just throw it all away and build a brand new trailing arm system... (If I was a fabricator, or worked at a machine shop, the answer would be easy...)

One step at a time, for me, works best.

Rob

[Martiangod]

Theres other ways to do frame notches Rob, just search some of the car lowering sites, Theres lots of guys running 5 and 600 horse power cars that survive quite well with notches and don't break when they step on it, With the additional structure of the coach on top of the frame, it will hold.
As you know, there is nothing strong about a travel trailer, its the sum of all parts.
Would be nice not having to have steps at camp

http://www.google.ca/search?q=frame+notches&hl=en&sa=N&prmd=imvns&tbm=isch&tbo=u&source=univ&ei=mO10T9-DH6Lz0gHR9OGeDQ&ved=0CF0QsAQ&biw=1004&bih=482

[48Rob]

Chris,

Some of those setups do look pretty beefy!

I really like how this is going, I had planned on a short step, maybe 4-5 inch drop, but now I don't think I'll need one at all.
I've designed the at rest height to be just a few inches lower than standard ride height, so I won't need to alter the frame.

Rob

[droid_ca]

Rob do you have an pictures of this new trailer design??

[48Rob]

Rob do you have an pictures of this new trailer design??

No, not yet.

My manual Cad system results are too hard to read...
My neighbor has a real one though and has been helping me get the design on paper, or computer as it were.
Once finished, I'll be happy to share.

Rob

[droid_ca]

Bread-loaf???

[48Rob]

No, that one is on hold... this one is more a canned ham with flair...

Rob

[kludge]

Back to your original question... when you say tool-less, what would you consider a tool, and how much time are you willing to spend in the garage height to ride height conversion process?

This is the same type of question I've been trying to tackle for my needs.

Is a trailer jack considered a tool? a hammer?

Assuming you have an axle with conventional springs, one relatively simple way is to invert the shackle (go from spring shackle up to shackle down). For the ride height difference you would get about the length of the shackle.

But then you can't put the shackle right under the frame, you have to put it inboard or outboard of the frame.

But to go from low to high, you put the trailer on the jacks, remove the shackle bolt, raise the trailer, invert the shackle, put the bolt back in, take the trailer off the jacks, hook up and go.

If my words don't explain it, let me know and I'll draw a picture.

[48Rob]

Hi,

You explained it very well, thank you.

I considered a simple mechanical approach, but then decided against it as I want the process to be easy for someone else if I sell it, or loan it.

While climbing under it and jacking up/down and inserting/removing pins is easy, for me, now, I'm not sure how able I will be in 20 years...
I hope to be "able" well into my 90's, but you never know.

After considering all the advice I got here, researching and thinking about it, the idea of "dropping" the frame/trailer when I wanted to put it in storage, and raising it for travel only made sense, due to the available systems, if I hung the dropped floor below the original height frame, and subtracted the shackle length from that number.

With my dropped floor, my lowest framing is 5" off the ground.
Using air bags, I'll be able to raise the frame 6", giving me 8" of travel clearance.
If I'm off on my calculations, I have enough travel in the air bags to get another inch or two without stiffening up the ride too much.

So, when I'm preparing for a trip, I pull the trailer out of the garage, and inflate the air bags, a little work, maybe 5 minutes?
At the end of the trip, when I'm tired, I push a button, the bags delate and I'm done.
That's the part I like the best. In a few years when I'm "old" pushing a button will be a pleasant way to end the trip, as opposed to crawling around on the ground.

Rob

[kludge]

Here are a couple other ideas I've found...

http://www.youtube.com/watch?v=2yrche2hAGc

Used on JLG trailers: http://www.goldengait.com/brands/jlg/

And this: http://www.knottuk.com/fileadmin/Knott- ... logue1.pdf

Used here: http://www.ultralav.com/ultralav-ADA.php

But both systems look pretty expensive, but the first could probably me made to work with the trailer/scissor jacks and some pins in the frame, but the second is pretty complicated. NOT a diy kind of thing.

I had also given the notched frame a thought.

[48Rob]

Those are all neat designs!

The first one is outboard though, and not well suited to a trailer with the floor over the wheels.

The last two are though.
They look much like the hydraulic fish house frame design which uses a torsion axle(s) that are controlled by a hydraulic lift cylinder.
Great way to drop the frame flat on the ground, the two negatives were price ($4000) and the fact that you still had to install a pin on each side to "lock" the cylinders.

Rob

[Martiangod]

There is the Timbren aproach, pretty niftty and used on alot of horse trailers
basically a half spring



http://www.timbren.com/air-suspensions-in-action.htm

[48Rob]

I finally came up with a plan that looks like it will work for me.
I gave up on the air bag idea, too expensive and too much maintenance.

The new plan is to have a moveable shackle hanger.
The arrangement allows an extra 2.5-3" of lift, and does away with the need for a panhard bar.

The lower/raise process is;

Lift trailer rear to take weight off axle.
Pull lever to slide shackle hangers slightly rearward.
Lower trailer-shackle hangers slide back and trailer drops.

Lift trailer to take weight off axle off axle.
As frame is lifted, springs pull shackle hangers forward.

[angib]

That' a very neat idea. One thought is that when the frame is lowered, the leaf spring is effectively locked for length, so won't any load put on the spring result in a pretty big rearward horizontal force on the moving spring shackle?