Leaf springs movement

[lopet]

Well as we have a few truckers on here I thought that might be a place to ask too.
Right now I am trying to build a undercarriage for a dump box, I had a old truck frame and then I was given a couple of heavy duty trailer axles. The box is a old sander box with a under body hoist and therefore it's a little taller than a gravel box with a post hoist. I am trying to keep the main frame as low as possible  so I can reach over the sides easier with my farm loaders.
Here is the problem, the frame is 34 inches and between the u bolts I have 33.5 inches.  Was trying to move the springs one inch to the outside and failed, guess why. ;D
So I can't get as low as I wanted but wanna get as tight as possible and because I don't want the frame to touch the u bolts when the box is loaded and the springs are compressed, I am trying to find out the movement of the springs.
So here is the million dollar question, lets say I put a ten, twelve ton load on that trailer and have about 60% on the axles and 40% on the tractor draw bar.  How much do those four springs give ?  half inch, one inch , two inches, three inches ?
Maybe I should mention that the trailer was a pup and the tag on the axles  says Clark NSB - 18 , if that's any help.     

[starmac]

The springs themselves will not give much at all. I assume you are talking about a standard spring set up with equalizers between the springs. The equalizers will allow the springs to give some, depending on how much movement there is in them, but even then the ubolts on the axles themselves, will only move half of what the equalizer does.

[mike_belben]

You lost me a bit in the middle. 

What are the spring dimensions?  Length width thickness per leaf x how many leaves? 

[lopet]

Will take some measurements or a pic tomorrow.
The equalizers were full of cancer and not usable so I made some out of square tubing but they're not adjustable. Think they will do the trick as this will be a off road trailer and gets used probably fifty hours or less per year.

[starmac]

If the equalizers have no movement, every bump at all will be putting all the weight on one axle, this will probably work, but I wound up with a rig on it's side once in Oklahoma, cuz the owner didn't think it needed equalizers.

[Neilo]

Put a rubber bump stop between the frame and the U bolt?

[lopet]

The two sets are not identical, one has eight leafs and the rear one seven, both half inch thick.

starmac the "new" equalizer still move up and down, they're just not adjustable in length and don't have a fancy rubber bushing.

Any chance the 18 on the tag stands for 18000 lbs ?

I like the idea of a stopper but could avoid it if someone can give me a idea of how much the frame will come down when the box is loaded.
Sorry for the poor pictures but maybe you can see what I am talking about.


 


 


 

[mike_belben]

Its hard to say without seeing the whole spring and knowing length and width... However half inch is quite a leaf and i would be surprised if you can lay the arch flat.  So if it has a 3" smile then id say full load will drop them 2 to 2.5" as a ballpark. The 18000 could reasonably mean theyre 9ton per pair. 

Yeah its close and stuff may rub but who cares.  You wont be the first guy with some chafed iron.  Getr done.

[Riwaka]

I would say the rusted shackles are likely to break if you ever fully load the leaf springs.

The Europeans have sprung drawbars to reduce the stresses put on the tractor hitch and pin and tractor tires.

Agricultural Trailer Drawbar - STRONGA Ltd

[lopet]

Thanks for the replies.  The  frame hangers and some of the shackles I can use from the truck, they're still solid.
From the pup I am only using the axles and the springs, anything else was shot.

Will see how it's gonna turn out, sometimes plans change as I go along.  ;D

If I succeed it may pop up in mike's fabrication thread. 

[mike_belben]

I looked through your shop gallery, you should own that thread.

[lopet]

Was trying to move the springs one inch to the outside and failed, guess why. ;D

If you were referring to this in your first post I am sorry I missed that. Wasn't sure if you meant me but the answer is pretty simple.

There was enough room to move the springs at least one inch on each side but after I cut the old u bolts I found out that the spring mounting brackets top and bottom were WELDED to the axle.  ppppfff .......... long pause after that........
I aint no quitter so I tried to remove them  and ended up call it a failure.  ............ pause again .........
Put my thinking cap on to work on a plan B. Narrowing the frame wasn't a option because of the box so ended up pulling the u bolts a little more on the outside and release the inside. Gained another quarter inch and that's where I am at, probably weld a stopper between axle and frame.
Thought I clarify this and it may prevent somebody else from doing the same thing. ;D :D
Now all the truckers will come out and say " couldda told ya."   Duuuh     :D :D